ISSN 1783-3426
|
Obituaries Paul Kunasz and David
Hummer
Fizeau exchange visitors
program
Classical Oe Stars in the Field of the
Small Magellanic Cloud
An Apparent
Precessing Helical Outflow from a Massive Evolved Star: Evidence for
Binary Interaction
A Comprehensive
Comparative Test of Seven Widely-Used Spectral Synthesis Models
Against Multi-Band Photometry of Young Massive Star Clusters
Modeling
X-ray emission line profiles from massive star winds – A
review
Long-Wavelength, Free-Free
Spectral Energy Distributions from Porous Stellar Winds
The
Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC
(RIOTS4)
Eta Carinae's Thermal
X-ray Tail Measured with XMM-Newton and NuSTAR
Stellar
modelling of Spica, a high-mass spectroscopic binary with a beta Cep
variable primary component
Observational
signatures of past mass-exchange episodes in massive binaries: The
case of HD149404
The Galactic
O-Star Spectroscopic Survey (GOSSS). III. 142 additional O-type
systems
Probing the Dragonfish
star-forming complex: the ionizing population of the young massive
cluster Mercer 30
Short-term
variability and mass loss in Be stars I. BRITE satellite photometry
of eta and mu Centauri
Luminous
blue variables: An imaging perspective on their binarity and near
environment
OB stars at the lowest
Local Group metallicity. GTC-OSIRIS observations of Sextans
A
Herschel observations of the
nebula M1-67 around the Wolf-Rayet star WR 124
The
Massive Stellar Population of W49: A Spectroscopic Survey
Line-driven
ablation of circumstellar disks: I. Optically thin decretion disks of
classical Oe/Be stars
Two Faculty Positions in Astrophysics
at Instituto de Astrofisica de Atacama, Copiapo (Chile)
11
postdoc positions at Instituto de Astrofisica de Canarias
Postdoctoral position on Gaia and massive
stars
Bridging the
gap: from massive stars to supernovae
Frontiers
of massive-star evolution and core-collapse supernovae
Supernova
Remnants: An Odyssey In Space After Stellar Death
Potsdam
Astrophysical Summer School "Quantitative Spectroscopy in
Astrophysics"
Dear colleagues,
some of you might already have
heard the sad news that David Hummer has passed away recently. I was
just informed that also Paul Kunasz has died, already in August 2015.
Together with Dimitri Mihalas, we thus lost, during the last year,
three of the world-leading pioneers and experts on radiative
transfer, stellar atmospheres and may more topics. As an example, you
might remember the most influential series of papers on comoving
frame transfer, published by Mihalas, Kunasz & Hummer in the
1970ies.
I am sure that everybody will miss them.
An
obituary for Paul Kunasz can be found on
http://www.legacy.com/obituaries/dailycamera/obituary.aspx?pid=175559352
and an obituary for David Hummer on
http://www.dailycamera.com/features/ci_29348396/friends-peers-raise-final-pint-david-hummer-co
Those of you who are not aware of David's other 'profession',
as a founder of one of the first micro-breweries in the USA, might be
particularly interested in the latter article.
Jo
Puls
Weblink:
Email:
uh101aw@usm.uni-muenchen.de
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J. Hron & L.
Misoni
European Interferometry Initiative
The
Fizeau exchange visitors program in optical interferometry funds
(travel and accommodation) visits of researchers to an institute of
his/her choice (within the European Community) to perform
collaborative work and training on one of the active topics of the
European Interferometry Initiative. The visits will typically last
for one month, and strengthen the network of astronomers engaged in
technical, scientific
and training work on optical/infrared
interferometry. The program is open for all levels of astronomers
(Ph.D. students to tenured staff), non-EU based missions will only be
funded if considered essential by the Fizeau Committee. Applicants
are strongly encouraged to seek also partial support from their home
or host institutions.
The deadline for applications is March
15. Fellowships can be awarded for missions starting in May 2016.
Further informations and application forms can be found at
www.european-interferometry.eu
The program is funded by
OPTICON/FP7.
Please distribute this message also to
potentially interested colleagues outside of your community!
Looking forward to your applications,
Josef Hron &
Laszlo Mosoni
(for the European Interferometry
Initiative)
Reference: Deadline March 15
Status:
Other
Weblink: www.european-interferometry.eu
Comments:
Please circulate not later than March 1
Email:
fizeau@european-interferometry.eu
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Jesse B. Golden-Marx (1), M. S. Oey (1), J. B. Lamb (2),
Andrew S. Graus (3), Aaron S. White (1)
((1) University of
Michigan, (2) Nassau Community College, (3) University of California,
Irvine)
We present 29±1 classical Oe stars from RIOTS4, a
spatially complete, spectroscopic survey of Small Magellanic Cloud
(SMC) field OB stars. The two earliest are O6e stars, and four are
earlier than any Milky Way (MW) Oe stars. We also find ten Ope stars,
showing He~\textsc{i} infill and/or emission; five appear to be at
least as hot as ∼O7.5e stars. The hottest, star 77616, shows
He~\textsc{ii} disk emission, suggesting that even the hottest O
stars can form decretion disks, and offers observational support for
theoretical predictions that the hottest, fastest rotators can
generate He+-ionizing atmospheres. Our data also demonstrate that Ope
stars correspond to Oe stars earlier than O7.5e with strong disk
emission. We find that in the SMC, Oe stars extend to earlier
spectral types than in the MW, and our SMC Oe/O frequency, 0.26±0.04,
is much greater than the MW value, 0.03±0.01. These results are
consistent with angular momentum transport by stronger winds
suppressing decretion disk formation at higher metallicity. In
addition, our SMC field Oe star frequency is indistinguishable from
that for clusters, which is consistent with the similarity between
rotation rates in these environments, and contrary to the pattern for
MW rotation rates. Thus, our findings strongly support the viscous
decretion disk model and confirm that Oe stars are the high-mass
extension of the Be phenomenon. Additionally, we find that
Fe~\textsc{ii} emission occurs among Oe stars later than O7.5e with
massive disks, and we revise a photometric criterion for identifying
Oe stars to J−[3.6]≥0.1.
Reference: Accepted for
publication in ApJ
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1601.03405
Email:
jessegm@umich.edu
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Ryan M. Lau$^{1,2}$, Matthew J. Hankins$^{1}$, Terry L.
Herter$^{1}$, Mark R. Morris$^{3}$, Elisabeth A. C. Mills$^{4}$,
Michael E. Ressler$^{2}$
1 - Cornell Astronomy Department;
2 - Caltech/JPL; 3 - Department of Physics and Astronomy, UCLA; 4 -
National Radio Astronomy Observatory
Massive, evolved stars
play a crucial role in the metal-enrichment, dust budget, and
energetics of the interstellar medium; however, the details of their
evolution are uncertain because of their rarity and short lifetimes
before exploding as supernovae. Discrepancies between theoretical
predictions from single-star evolutionary models and observations of
massive stars have evoked a shifting paradigm that implicates the
importance of binary interaction. We present mid- to far-infrared
observations from the Stratospheric Observatory for Infrared
Astronomy (SOFIA) of a conical ``helix'' of warm dust ($\sim180$ K)
that appears to extend from the Wolf-Rayet star WR102c. Our
interpretation of the helix is a precessing, collimated outflow that
emerged from WR102c during a previous evolutionary phase as a rapidly
rotating luminous blue variable. We attribute the precession of
WR102c to gravitational interactions with an unseen compact binary
companion whose orbital period can be constrained to $800\,\mathrm{d}
< P < 1400$ d from the inferred precession period, $\tau_p \sim
1.4\times 10^4$ yr, and limits imposed on the stellar and orbital
parameters of the system. Our results concur with the range of
orbital periods ($P\lesssim 1500$ d) where spin-up via mass exchange
is expected to occur for massive binary systems.
Reference:
arXiv:1512.07639
Status: Manuscript has been
accepted
Weblink:
http://arxiv.org/abs/1512.07639
Comments:
Revised version to be updated Tuesday 1/19/2016
Email:
ryanlau@caltech.edu
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A. Wofford, S. Charlot, G. Bruzual, J. J. Eldridge, D.
Calzetti, A. Adamo, M. Cignoni, S. E. de Mink, D. A. Gouliermis, K.
Grasha, E. K. Grebel, J. Lee, G. Ostlin, L. J. Smith, L. Ubeda, E.
Zackrisson
Sorbonne Universites, UPMC-CNRS, UMR7095,
Institut d’Astrophysique de Paris
We test the predictions of
spectral synthesis models based on seven different
massive-star
prescriptions against Legacy ExtraGalactic UV Survey
(LEGUS)observations of eight young massive clusters in two local
galaxies, NGC 1566 and NGC 5253, chosen because predictions of all
seven models are available at the published galactic metallicities.
The high angular resolution, extensive cluster inventory and full
near-ultraviolet to near-infrared photometric coverage make the LEGUS
dataset excellent for this study. We account for both stellar and
nebular emission in the models and try two different prescriptions
for attenuation by dust. From Bayesian fits of model libraries to the
observations, we find remarkably low dispersion in the median E(B-V)
(~0.03 mag), stellar masses (~10^4 M_\odot) and ages (~1 Myr) derived
for individual clusters using different models, although maximum
discrepancies in these quantities can reach 0.09 mag and factors of
2.8 and 2.5, respectively. This is for ranges in median properties of
0.05-0.54 mag, 1.8-10x10^4 M_\odot and 1.6-40 Myr spanned by the
clusters in our sample. In terms of best fit, the observations are
slightly better reproduced by models with interacting binaries and
least well reproduced by models with single rotating stars. Our study
provides a first quantitative estimate of the accuracies and
uncertainties of the most recent spectral synthesis models of young
stellar populations, demonstrates the good progress of models in
fitting high-quality observations, and highlights the needs for a
larger cluster sample and more extensive tests of the model parameter
space.
Reference: Accepted for publication in MNRAS.
Pre-print available at arxiv.
Status: Manuscript has been
accepted
Weblink:
http://arxiv.org/pdf/1601.03850.pdf
Email:
wofford@iap.fr
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Richard Ignace
East Tennessee State
University
The Chandra and XMM-Newton X-ray telescopes have
led to numerous advances in the study and understanding of
astrophysical X-ray sources. Particularly important has been the much
increased spectral resolution of modern X-ray instrumentation.
Wind-broadened emission lines have been spectroscopically resolved
for many massive stars. This contribution reviews approaches to the
modeling of X-ray emission line profile shapes from single stars,
including smooth winds, winds with clumping, optically thin versus
thick lines, and the effect of a radius-dependent photoabsorption
coefficient.
Reference: Advances of Space
Research
Status: Manuscript has been accepted
Weblink:
http://www.sciencedirect.com/science/article/pii/S0273117716000041
Email:
ignace@etsu.edu
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Richard Ignace
East Tennessee State
University
The influence of macroclumps for free-free spectral
energy distributions (SEDs) of ionized winds is considered. The goal
is to emphasize distinctions between microclumping and macroclumping
effects. Microclumping can alter SED slopes and flux levels if the
volume filling factor of the clumps varies with radius; however, the
modifications are independent of the clump geometry. To what extent
does macroclumping alter SED slopes and flux levels? In addressing
the question, two specific types of macroclump geometries are
explored: shell fragments (``pancake''-shaped) and spherical clumps.
Analytic and semi-analytic results are derived in the limiting case
that clumps never obscure one another. Numerical calculations based
on a porosity formalism is used when clumps do overlap. Under the
assumptions of a constant expansion, isothermal, and fixed ionization
wind, the fragment model leads to results that are essentially
identical to the microclumping result. Mass-loss rate determinations
are not affected by porosity effects for shell fragments. By
contrast, spherical clumps can lead to a reduction in long-wavelength
fluxes, but the reductions are only significant for extreme volume
filling factors.
Reference: to appear in MNRAS
Status:
Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1601.06715
Email:
ignace@etsu.edu
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J. B. Lamb (1,2), M. S. Oey (1), D. M. Segura-Cox (1,3), A.
S. Graus (1,4), D. C. Kiminki (5), J. B. Golden-Marx (1), J. Wm.
Parker (6)
(1) U. Michigan, (2) Nassau Community College,
(3) U. Illinois, (4) UC Irvine, (5) U. Arizona, (6) SwRI
We
present the Runaways and Isolated O-Type Star Spectroscopic Survey of
the SMC (RIOTS4), a spatially complete survey of uniformly selected
field OB stars that covers the entire star-forming body of the SMC.
Using the IMACS multislit spectrograph and MIKE echelle spectrograph
on the Magellan telescopes, we obtained spectra of 374 early-type
field stars that are at least 28 pc from any other OB candidates. We
also obtained spectra of an additional 23 field stars in the SMC bar
identified from slightly different photometric criteria. Here, we
present the observational catalog of stars in the RIOTS4 survey,
including spectral classifications and radial velocities. For three
multi-slit fields covering 8% of our sample, we carried out
monitoring observations over 9-16 epochs to study binarity, finding a
spectroscopic, massive binary frequency of at least ∼60% in this
subsample. Classical Oe/Be stars represent a large fraction of RIOTS4
(42%), occurring at much higher frequency than in the Galaxy,
consistent with expectation at low metallicity. RIOTS4 confirmed a
steep upper IMF in the field, apparently caused by the inability of
the most massive stars to form in the smallest clusters. Our survey
also yields evidence for in-situ field OB star formation, and
properties of field emission-line star populations, including sgB[e]
stars and classical Oe/Be stars. We also discuss the radial velocity
distribution and its relation to SMC kinematics and runaway stars.
RIOTS4 presents a first quantitative characterization of field OB
stars in an external galaxy, including the contributions of sparse,
but normal, star formation; runaway stars; and candidate isolated
star formation.
Reference: Astrophysical Journal (in
press)
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1512.01233
Comments:
Email: joellamb@umich.edu
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Kenji Hamaguchi(1,2), Michael F. Corcoran(1,3), Theodore R.
Gull(4), Hiromitsu Takahashi(5), Brian Grefenstette(6), Takayuki
Yuasa(7), Martin Stuhlinger(8), Christopher M. P. Russell(4,9),
Anthony F. J. Moffat(10), Neetika Sharma(2), Thomas I. Madura(1,3),
Noel D. Richardson(10), Jose Groh(11), Julian M. Pittard(12), Stan
Owocki(13)
1 - CRESST and X-ray Astrophysics Laboratory
NASA/GSFC, Greenbelt, MD 20771; 2 - Department of Physics, University
of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD
21250; 3 - Universities Space Research Association, 7178 Columbia
Gateway Dr., Columbia, MD 21044; 4 - Astrophysics Science Division,
NASA Goddard Space Flight Center, Greenbelt, MD 20771; 5 - Department
of Physical Sciences, Hiroshima University, Higashi-Hiroshima,
Hiroshima 739-8526, Japan; 6 - Space Radiation Lab, California
Institute of Technology, Pasadena, CA 91125; 7 - Nishina Center,
RIKEN, 2-1, Hirosawa, Wako, Saitama, Japan, 351-0198, Japan; 8 -
European Space Astronomy Centre (ESAC), P.O. Box 78, 28691 Villanueva
de la Cañada, Madrid, Spain; 9 - NASA Postdoctoral Program Fellow;
10 - Departement de physique and Centre de Recherche en Astrophysique
du Quebec (CRAQ), Universite de Montreal, C.P. 6128; 11 - Geneva
Observatory, Geneva University, Chemin des Maillettes 51, CH-1290
Sauverny, Switzerland; 12 - School of Physics and Astronomy, The
University of Leeds, Woodhouse Lane, Leeds LS2 9JT, UK; 13 - Bartol
Research Institute, Department of Physics and Astronomy, University
of Delaware, Newark, DE 19716, USA
The evolved, massive highly
eccentric binary system, eta Car, underwent a periastron passage in
the summer of 2014. We obtained two coordinated X-ray observations
with XMM-Newton and NuSTAR during the elevated X-ray flux state and
just before the X-ray minimum flux state around this passage. These
NuSTAR observations clearly detected X-ray emission associated with
eta Car extending up to ~50 keV for the first time. The NuSTAR
spectrum above 10 keV can be fit with the bremsstrahlung tail from a
kT~6 keV plasma. This temperature is Delta kT ~2 keV higher than
those measured from the iron K emission line complex, if the shocked
gas is in collisional ionization equilibrium. This result may suggest
that the companion star's pre-shock wind velocity is underestimated.
The NuSTAR observation near the X-ray minimum state showed a gradual
decline in the X-ray emission by 40% at energies above 5 keV in a
day, the largest rate of change of the X-ray flux yet observed in
individual eta Car observations. The column density to the hardest
emission component, NH~1e24 cm-2, marked one of the highest values
ever observed for eta Car, strongly suggesting increased obscuration
of the wind-wind colliding X-ray emission by the thick primary
stellar wind prior to superior conjunction. Neither observation
detected the power-law component in the extremely hard band that
INTEGRAL and Suzaku observed prior to 2011. If the non-detection by
INTEGRAL is caused by absorption, the power-law source must be small
and located very near the WWC apex. Alternatively, it may be that the
power-law source is not related to either eta Car or the GeV
gamma-ray source.
Reference: ApJ, 817, 23
(2016)
Status: Manuscript has been accepted
Weblink:
http://iopscience.iop.org/article/10.3847/0004-637X/817/1/23/meta;jsessionid=76A9B4FEB605C936E1B0430C36DEDDAD.c3.iopscience.cld.iop.org
Email:
Kenji.Hamaguchi@nasa.gov
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A. Tkachenko(1), J. M. Matthews(2), C. Aerts(1,3), K.
Pavlovski(4), P. I. Papics(1), K. Zwintz(5), C. Cameron(2,6), G. A.
H. Walker(2), R. Kuschnig(7), P. Degroote(1), J. Debosscher(1), E.
Moravveji(1), V. Kolbas(4), D. B. Guenther(8), A. F. J. Moffat(9), J.
F. Rowe(10), S. M. Rucinski(11), D. Sasselov(12), W. W. Weiss(7)
(1)
Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001
Leuven, Belgium
(2) Department of Physics and Astronomy,
University of British Columbia, 6224 Agricultural Road, Vancouver, BC
V6T 1Z1, Canada
(3) Department of Astrophysics, IMAPP, Radboud
University Nijmegen, 6500 GL Nijmegen, The Netherlands
(4)
Department of Physics, University of Zagreb, Bijenicka cesta 32,
10000 Zagreb, Croatia
(5) Institute for Astro- and Particle
Physics, University of Innsbruck, Technikerstrasse 25/8, Austria
(6)
Department of Mathematics, Physics & Geology, Cape Breton
University, 1250 Grand Lake Road, Sydney, Nova Scotia, Canada, B1P
6L2
(7) University of Vienna, Institute of Astronomy,
Turkenschanzstrasse 17, 1180 Vienna, Austria
(8) Department of
Astronomy and Physics, St. Marys University, Halifax, NS B3H 3C3,
Canada
(9) Department de physique, Universite de Montreal,
C.P.6128, Succ. Centre-Ville, Montreal, QC H3C 3J7, Canada
(10)
NASA-Ames Research Park, MS-244-30, Mo ffett Field, CA 94035, USA
(11) Department of Astronomy & Astrophysics, University of
Toronto, 50 St. George Street, Toronto, ON M5S 3H4, Canada
(12)
Harvard-Smithsonian Center for Astrophysics, 60 Garden Street,
Cambridge, MA 02138, USA
Binary stars provide a valuable test
of stellar structure and evolution, because the masses of the
individual stellar components can be derived with high accuracy and
in a model-independent way. In this work, we study Spica, an
eccentric double-lined spectroscopic binary system with a beta Cep
type variable primary component. We use state-of-the-art modelling
tools to determine accurate orbital elements of the binary system and
atmospheric parameters of both stellar components. We interpret the
short-period variability intrinsic to the primary component, detected
on top of the orbital motion both in the photometric and
spectroscopic data. The non-LTE based spectrum analysis reveals two
stars of similar atmospheric chemical composition consistent with the
present day cosmic abundance standard defined by Nieva&Przybilla
(2012). The masses and radii of the stars are found to be
11.43+/-1.15 M_sun and 7.21+/-0.75 M_sun, and 7.47+/-0.54 R_sun
and 3.74+/-0.53 R_sun for the primary and secondary, respectively.
We find the primary component to pulsate in three independent modes,
of which one is identified as a radial mode, while the two others are
found to be non-radial, low degree l modes. The frequency of one of
these modes is an exact multiple of the orbital frequency, and the
l=m=2 mode identification suggests a tidal nature for this particular
mode. We find a very good agreement between the derived dynamical and
evolutionary masses for the Spica system to within the observational
errors of the measured masses. The age of the system is estimated to
be 12.5+/-1 Myr.
Reference: main journal of
MNRAS
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1601.08069
Comments:
Email: Andrew.Tkachenko@ster.kuleuven.be
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F. Raucq (1), G. Rauw (1), E. Gosset (1), Y. Naze(1), L.
Mahy (1), A. Herve(2), F. Martins (3)
(1) Univ. of Liege,
(2) Astronomical Institute of the Czech Academy of Sciences, (3)
Montpellier Univ.
Mass and momentum exchanges in close massive
binaries play an important role in their evolution, and produce
several observational signatures such as asynchronous rotation and
altered chemical compositions, that remain after the stars detach
again. We investigated these effects for the detached massive O-star
binary HD149404 (O7.5If + ON9.7I, P = 9.81 days), which is thought to
have experienced a past episode of case A Roche-lobe overflow (RLOF).
Using phase-resolved spectroscopy, we performed the disentangling of
the optical spectra of the two stars. The reconstructed primary and
secondary spectra were then analysed with the CMFGEN model atmosphere
code to determine stellar parameters, such as the effective
temperatures and surface gravities, and to constrain the chemical
composition of the components. We complemented the optical study with
the study of IUE spectra, which we compare to the synthetic binary
spectra. The properties of the stars were compared to evolutionary
models. We confirmed a strong overabundance in nitrogen
([N/C]$\sim$150[N/C]$_{\odot}$) for the secondary and a slight
nitrogen overabundance ([N/C]$\sim$5[N/C]$_{\odot}$) for the primary
star. Comparing the two stars, we found evidence for asynchronous
rotation, with a rotational period ratio of 0.50$\pm$0.11. The
hypothesis of a past case A RLOF interaction in HD149404 is most
plausible to explain its chemical abundances and rotational
asynchronicity. Some of the observed properties, such as the
abundance pattern, are clearly a challenge for current case A binary
evolution models, however.
Reference: accepted by
A&A
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1601.08083
Comments:
Email: fraucq@doct.ulg.ac.be
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J. Maíz Apellániz, A. Sota, J. I. Arias, R. H. Barbá, N.
R. Walborn, S. Simón-Díaz, I. Negueruela, A. Marco, J. R. S. Leão,
A. Herrero, R. C. Gamen, and E. J. Alfaro
CAB (CSIC-INTA),
IAA-CSIC, ULS, ULS, STScI, IAC+ULL, UA, UA+UF, UFRN, IAC+ULL,
CONICET+UNLP, and IAA-CSIC
This is the third installment of
GOSSS, a massive spectroscopic survey of Galactic O stars, based on
new homogeneous, high signal-to-noise ratio, R~2500 digital
observations selected from the Galactic O-Star Catalog (GOSC). In
this paper we present 142 additional stellar systems with O stars
from both hemispheres, bringing the total of O-type systems published
within the project to 590. Among the new objects there are 20 new O
stars. We also identify 11 new double-lined spectroscopic binaries
(SB2s), of which 6 are of O+O type and 5 of O+B type, and an
additional new tripled-lined spectroscopic binary (SB3) of O+O+B
type. We also revise some of the previous GOSSS classifications,
present some egregious examples of stars erroneously classified as
O-type in the past, introduce the use of luminosity class IV at
spectral types O4-O5.5, and adapt the classification scheme to the
work of Arias et al. (2016).
Reference: Accepted for
publication in ApJS
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1602.01336
Comments:
Email: jmaiz@cab.inta-csic.es
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D. de la Fuente (1), F. Najarro (1), J. Borissova (2,3), S.
Ramirez Alegria (2,3), M. M. Hanson (4), C. Trombley (5), D. F. Figer
(5), B. Davies (6), M. Garcia (1), R. Kurtev (2,3), M. A. Urbaneja
(7), L. C. Smith (8), P. W. Lucas (8), A. Herrero (9,10)
1
- Centro de Astrobiologia (CSIC/INTA); 2 - Universidad de Valparaiso;
3 - Millennium Institute of Astrophysics (MAS); 4 - University of
Cincinnati; 5 - Center for Detectors, Rochester Institute of
Technology; 6 - Astrophysics Research Institute, Liverpool John
Moores University; 7 - Institute for Astro- and Particle Physics,
University of Innsbruck; 8 - Centre for Astrophysics Research,
University of Hertfordshire; 9 - Instituto de Astrofisica de
Canarias; 10 - Universidad de La Laguna
The Dragonfish Nebula
has been recently claimed to be powered by a superluminous but
elusive OB association. Instead, systematic searches in near-infrared
photometric surveys have found many other cluster candidates on this
sky region. Among these, the first confirmed young massive cluster
was Mercer 30, where Wolf-Rayet stars were found. We perform a new
characterization of Mercer 30 with unprecedented accuracy, combining
NICMOS/HST and VVV photometric data with multi-epoch ISAAC/VLT H- and
K-band spectra. Stellar parameters for most of spectroscopically
observed cluster members are found through precise non-LTE atmosphere
modeling with the CMFGEN code. Our spectrophotometric study for this
cluster yields a new, revised distance of d = (12.4 +- 1.7) kpc and a
total of Q = 6.70 x 10^50 Lyman ionizing photons. A cluster age of
(4.0 +- 0.8) Myr is found through isochrone fitting, and a total mass
of (1.6 +- 0.6) x 10^4 Msol is estimated thanks to our extensive
knowledge of the post-main-sequence population. As a consequence,
membership of Mercer 30 to the Dragonfish star-forming complex is
confirmed, allowing us to use this cluster as a probe for the whole
complex, which turns out to be extremely large (400 pc across) and
located at the outer edge of the Sagittarius-Carina spiral arm (11
kpc from the Galactic Center). The Dragonfish complex hosts 19 young
clusters or cluster candidates (including Mercer 30 and a new
candidate presented in this work) and an estimated minimum of 9 field
Wolf-Rayet stars. The sum of all these contributions accounts for, at
least, 73% of the Dragonfish Nebula ionization and leaves little or
no room for the alleged superluminous OB association; alternative
explanations are discussed.
Reference: A&A,
accepted
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1602.02503
Comments:
Email: delafuente@cab.inta-csic.es
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D.Baade1, Th. Rivinius2, A. Pigulski3, A.C.Carciofi4,
Ch.Martayan2, A.F.J.Moffat5, G.A.Wade6, W.W.Weiss7,
J.Grunhut1,
G.Handler8, R.Kuschnig9,7, A.Mehner2, H. Pablo5, A. Popowicz10,
S.Rucinski11, and G.Whittaker11
1 European Organisation
for Astronomical Research in the Southern Hemisphere (ESO),
Karl-Schwarzschild-Str. 2,
85748 Garching, Germany; e-mail:
dbaade@eso.org
2 European Organisation for Astronomical Research
in the Southern Hemisphere (ESO), Casilla 19001, Santiago 19, Chile
3 Astronomical Institute, Wrocław University, Kopernika 11,
51-622 Wrocław, Poland
4 Instituto de Astronomia, Geofísica e
Ciências Atmosféricas, Universidade de São Paulo, Rua do Matão
1226,
Cidade Universitária, 05508-900 São Paulo, SP, Brazil
5
Département de physique and Centre de Recherche en Astrophysique du
Québec (CRAQ), Université de Montréal, C.P. 6128,
Succ.Centre-Ville, Montréal, Québec, H3C 3J7, Canada
6
Department of Physics, Royal Military College of Canada, PO Box
17000, Stn Forces, Kingston, Ontario K7K 7B4, Canada
7 Institute
of Astronomy, University of Vienna, Universitätsring 1, 1010 Vienna,
Austria
8 Nicolaus Copernicus Astronomical Center, ul.Bartycka
18, 00-716 Warsaw, Poland
9 Department of Physics and Astronomy,
University of British Columbia, Vancouver, BC V6T1Z1, Canada
10
Institute of Automatic Control, Silesian University of Technology,
Gliwice, Poland
11 Department of Astronomy & Astrophysics,
University of Toronto, 50 St.George St, Toronto, Ontario, M5S 3H4,
Canada
Context. Empirical evidence for the involvement of
nonradial pulsations (NRP’s) in the mass loss from Be stars ranges
from (i) a singular case (μ Cen) of repetitive mass ejections
triggered by multi-mode beating to (ii) several photometric reports
about enormous numbers of pulsation modes popping up during outbursts
and on to (iii) effective ingle-mode pulsators.
Aims. Develop a
more detailed empirical description of the star-to-disk mass
transfer. Check the hypothesis that spates of transient nonradial
pulsation modes accompany and even drive mass-loss episodes.
Methods. The BRITE Constellation of nanosatellites was used to
obtain mmag photometry of the Be stars η and μ Cen.
Results. In
the low-inclination star μ Cen, light pollution by variable amounts
of near-stellar matter prevented any new insights into the
variability and other properties of the central star. In the
equator-on star η Cen, BRITE photometry and Heros echelle
spectroscopy from the 1990s reveal an intricate clockwork of
star-disk interactions. The mass transfer is modulated with the
frequency difference
of two NRP modes and an amplitude three
times as large as the amplitude sum of the two NRP modes. This
process feeds a highamplitude circumstellar activity running with the
incoherent and slightly lower so-called Štefl frequency. The mass
loss-modulation cycles are tightly coupled to variations in the value
of the Štefl frequency and in its amplitude, albeit with strongly
drifting phase differences.
Conclusions. The observations are
well described by the decomposition of the mass loss into a
pulsation-related engine in the star and a viscosity-dominated engine
in the circumstellar disk. Arguments are developed that large-scale
gas-circulation flows occur at the interface. The propagation rates
of these eddies manifest themselves as Štefl frequencies. Bursts in
power spectra during mass-loss events can be understood as the noise
inherent to these gas flows.
Reference: Astronomy &
Astrophysics
Status: Manuscript has been accepted
Weblink:
http://esoads.eso.org/abs/2016arXiv160201744B
Comments:
Email: dbaade@eso.org
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Christophe Martayan (1), Alex Lobel (2), Dietrich Baade
(3), Andrea Mehner (1), Thomas Rivinius (1), Henri M. J. Boffin (1),
Julien Girard (1), Dimitri Mawet (4), Guillaume Montagnier (5), Ronny
Blomme (2), Pierre Kervella (6,7), Hugues Sana (8), Stanislav
\v{S)tefl (deceased,9), Juan Zorec (10), Sylvestre Lacour (6),
Jean-Baptiste Le Bouquin (11), Fabrice Martins (12), Antoine M\'erand
(1), Fabien Patru (11), Fernando Selman (1), Yves Fr\'emat (2)
1:
European Organisation for Astronomical Research in the Southern
Hemisphere, Alonso de C\'ordova 3107, Vitacura, Casilla 19001,
Santiago de Chile, Chile
2: Royal Observatory of Belgium, 3
Avenue Circulaire, 1180 Brussels, Belgium
3: European
Organisation for Astronomical Research in the Southern
Hemisphere,
Karl-Schwarzschild-Str.\ 2, 85748 Garching b.\ M\"unchen,
Germany
4: Department of Astronomy, California Institute of
Technology, 1200 E. California Blvd, MC 249-17, Pasadena, CA 91125
USA
5: Observatoire de Haute-Provence, CNRS/OAMP, 04870
Saint-Michel-l'Observatoire, France
6: LESIA, UMR 8109,
Observatoire de Paris, CNRS, UPMC, Univ. Paris-Diderot, PSL, 5 place
Jules Janssen, 92195 Meudon, France
7: Unidad Mixta Internacional
Franco-Chilena de Astronom\'{i}a (UMI 3386), CNRS/INSU, France \&
Departamento de Astronom\'{i}a, Universidad de Chile, Camino El
Observatorio 1515, Las Condes, Santiago, Chile
8: ESA / Space
Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD
21218, United States of America
9: ESO/ALMA - The Atacama Large
Millimeter/Submillimeter Array, Alonso de C\'ordova 3107, Vitacura,
Casilla 763 0355, Santiago, Chile
10: Sorbonne Universit\'es,
UPMC Universit\'e Paris 6 et CNRS, UMR7095 Institut d'Astrophysique
de Paris, F-75014 Paris, France
11: UJF-Grenoble 1/CNRS-INSU,
Institut de Plan\'etologie et d'Astrophysique de Grenoble (IPAG) UMR
5274, BP 53, 38041 Grenoble C\'edex 9, France
12: LUPM,
Universit\'e de Montpellier, CNRS, Place Eug\`ene Bataillon, F-34095
Montpellier Cedex 05
Context: Luminous blue variables (LBVs)
are rare massive stars with very high luminosity. They are
characterized by strong photometric and spectroscopic variability
related to transient eruptions. The mechanisms at the origin of these
eruptions is not well known. In addition, their formation is still
problematic and the presence of a companion could help to explain how
they form.
Aims: This article presents a study of seven LBVs
(about 20\% of the known Galactic population), some Wolf-Rayet stars,
and massive binaries. We probe the environments that surround these
massive stars with near-, mid-, and far-infrared images,
investigating potential nebula/shells and the companion stars.
Methods: To investigate large spatial scales, we used
seeing-limited and near diffraction-limited adaptive optics images to
obtain a differential diagnostic on the presence of circumstellar
matter and to determine their extent. From those images, we also
looked for the presence of binary companions on a wide orbit. Once a
companion was detected, its gravitational binding to the central star
was tested. Tests include the chance projection probability, the
proper motion estimates with multi-epoch observations, flux ratio,
and star separations.
Results: We find that two out of seven of
LBVs may have a wide orbit companion. Most of the LBVs display a
large circumstellar envelope or several shells. In particular,
HD168625, known for its rings, possesses several shells with possibly
a large cold shell at the edge of which the rings are formed. For the
first time, we have directly imaged the companion of LBV
stars.
Reference: Astronomy & Astrophysics
Status:
Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2016arXiv160103542M
Comments:
Email: cmartaya@eso.org
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I. Camacho^1,2, M. Garcia^3, A. Herrero^1,2, and S.
Simón-Díaz^1,2
1. Instituto de Astrofísica de Canarias,
C/ vía Láctea s/n 38205 La Laguna, Tenerife, Spain
2.
Departamento de Astrofísica, Universidad de La Laguna, Avda.
Astrofísico Francisco Sánchez, s/n, 38200 La Laguna, Tenerife,
Spain
3. Centro de Astrobiología (CSIC/INTA), Instituto Nacional
de Técnica Aeroespacial, Ctra de Torrejón de Ajalvir, km 4, 28850
Torrejón de Ardoz, Madrid, Spain
Context: Massive stars play
an important role in the chemical and dynamical evolution of the
Universe. The first metal-poor stars may have started the
reionization of the Universe. To understand these early epochs it is
necessary to know the behavior and the physical properties of massive
stars in very metal-poor environments. We focus on the massive
stellar content of the metal-poor irregular galaxy Sextans A.
Aims:
Our aim is to find and classify OB stars in Sextans A, so as to later
determine accurate stellar parameters of these blue massive stars in
this low-metallicity region (Z ∼ 0.1 Zsun).
Methods: Using
UBV photometry, the reddening-free index Q and GALEX imaging, we
built a list of blue massive star candidates in Sextans A. We
obtained low-resolution (R ∼ 1000) GTC-OSIRIS spectra for a
fraction of them and carried out spectral classification. For the
confirmed O-stars, we derived preliminary stellar parameters.
Results: The target selection criteria and observations were
successful and have produced the first spectroscopic atlas of OB-type
stars in Sextans A. From the whole sample of 18 observed stars, 12
were classified as early OB-types, including 5 O-stars. The radial
velocities of all target stars are in agreement with their Sextans A
membership, although three of them show significant deviations. We
determined the stellar parameters of the O-type stars using the
stellar atmosphere code FASTWIND and revisited the sub-SMC
temperature scale. Two of the O-stars are consistent with relatively
strong winds and enhanced helium abundances, although results are not
conclusive. We discuss the position of the OB stars in the HRD.
Initial stellar masses run from slightly below 20 up to 40 solar
masses.
Conclusions: The target selection method worked well
for Sextans A. The stellar temperatures are consistent with findings
in other galaxies. Some of the targets deserve follow-up spectroscopy
because of indications of a runaway nature, an enhanced helium
abundance, or a relatively strong wind. We observe a correlation
between HI and OB associations similar to the irregular galaxy IC
1613, confirming the previous result that the most recent star
formation of Sextans A is currently ongoing near the rim of the HI
cavity.
Reference: A&A
Status: Manuscript has
been accepted
Weblink:
http://www.aanda.org/articles/aa/abs/2016/01/aa25533-14/aa25533-14.html
http://arxiv.org/abs/1510.05408
Email:
icamacho@iac.es
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C. Vamvatira-Nakou(1), D. Hutsemékers(1), P. Royer(2), C.
Waelkens(2), M. A. T. Groenewegen(3), and M. J. Barlow(4)
"1
- Institut d’Astrophysique et de Géophysique, Université de
Liège, Quartier Agora, Allée du 6 août, 19C - Bât. B5c, B-4000
Liège (Sart-Tilman), Belgium; 2 - Instituut voor Sterrenkunde, KU
Leuven, Celestijnenlaan 200D, Bus 2401, B-3001 Leuven, Belgium; 3 -
Koninklijke Sterrenwacht van België, Ringlaan 3, B-1180 Brussels,
Belgium; 4 - Department of Physics and Astronomy, University College
London, Gower Street, London WC1E 6BT, UK"
Infrared
Herschel imaging and spectroscopic observations of the nebula M1-67
around the Wolf-Rayet star WR 124 have been obtained along with
optical imaging observations. The infrared images reveal a clumpy
dusty nebula that extends up to 1 pc. The comparison with the optical
images shows that the ionized gas nebula coincides with the dust
nebula, the dust and the gas being mixed together. A
photodissociation region is revealed from the infrared spectroscopic
analysis. The analysis of the infrared spectrum of the nebula, where
forbidden emission lines of ionized elements were detected, showed
that the nebula consists of mildly processed material with the
calculated abundance number ratios being N/O = 1.0 +/- 0.5 and C/O =
0.46 +/- 0.27. Based on a radiative transfer model, the dust mass of
the nebula was estimated to be 0.22 Msun with a population of large
grains being necessary to reproduce the observations. The comparison
of the mass-loss rate and the abundance ratios to theoretical models
of stellar evolution led to the conclusion that the nebular ejection
took place during a RSG/YSG evolutionary phase of a central star with
an initial mass of 32 Msun.
Reference: A&A in
press
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1602.03422
Comments:
-
Email: C.VamvatiraNakou@alumni.ulg.ac.be
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Shi-Wei Wu (1), Arjan Bik (2,1), Joachim M. Bestenlehner
(1), Thomas Henning (1), Anna Pasquali (3), Wolfgang Brandner (1) and
Andrea Stolte (4)
(1) Max-Planck-Institut f\"{u}r
Astronomie, K\"{o}nigstuhl 17, 69117 Heidelberg, Germany;
(2)
Department of Astronomy, Stockholm University, AlbaNova University
Centre, 106 91 Stockholm, Sweden;
(3) Astronomisches
Rechen-Institut, Zentrum f\"ur Astronomie der Universit\"at
Heidelberg, M\"onchhofstr. 12 - 14, 69120 Heidelberg, Germany;
(4) Argelander Institut f\"ur Astronomie, Auf dem H\"ugel
71, 53121 Bonn, Germany
Massive stars form on different scales
ranging from large, dispersed OB associations to compact, dense
starburst clusters. The complex structure of regions of massive star
formation, and the involved short timescales provide a challenge for
our understanding of their birth and early evolution. As one of the
most massive and luminous star-forming region in our Galaxy, W49 is
the ideal place to study the formation of the most massive stars. By
classifying the massive young stars deeply embedded into the
molecular cloud of W49, we aim to investigate and trace the star
formation history of this region. We analyse near-infrared $K$-band
spectroscopic observations of W49 from LBT/LUCI combined with $JHK$
images obtained with NTT/SOFI and LBT/LUCI. Based on $JHK$-band
photometry and K-band spectroscopy the massive stars are placed in a
Hertzsprung Russell diagram. By comparison with evolutionary models,
their age and hence the star formation history of W49 can be
investigated. Fourteen O type stars as well as two young stellar
objects (YSOs) are identified by our spectroscopic survey. Eleven
O-stars are main sequence stars with subtypes ranging from O3 to
O9.5, with masses ranging from $\sim 20$ $M_{\odot}$ to $\sim 120$
$M_{\odot}$. Three of the O-stars show strong wind features, and are
considered to be Of-type supergiants with masses beyond 100
$M_{\odot}$ . The two YSOs show CO emission, indicative for the
presence of circumstellar disks in the central region of the massive
cluster. The age of the cluster is estimated as $\sim1.5$ Myr, with
star formation still ongoing in different parts of the region. The
ionising photons from the central massive stars have not yet cleared
the molecular cocoon surrounding the cluster. W49 is comparable to
extragalactic star-forming regions and provides us with an unique
possibility to study a starburst in detail.
Reference:
article to be published in A&A
Status: Manuscript has been
accepted
Weblink:
http://arxiv.org/pdf/1602.05190v1.pdf
Comments:
16 pages, 8 figures, 5 tables
Email:
shiwei@mpia.de
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N.D. Kee (1), S.P. Owocki (1),
and J.O. Sundqvist (2,3)
(1) Department of Physics and
Astronomy, Bartol Research Institute, University of Delaware, Newark,
DE 19716, USA
(2) Centro de Astrobiologia, Instituto Nacional de
Tecnica Aerospacial, 28850 Torrejon de Ardoz, Madrid, Spain
(3)
Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001
Leuven, Belgium
The extreme luminosities of hot, massive stars
drive strong stellar winds through UV line-scattering. For OB stars
with an orbiting circumstellar disk, we explore the effect of such
line-scattering in ablating disk material, initially focusing on the
marginally optically thin decretion disks of classical Oe and Be
stars. For this we apply a multi-dimensional radiation-hydrodynamics
code, assuming optically thin ray tracing for the stellar continuum
and a multi-ray Sobolev treatment of the line transfer. This accounts
for desaturation of line-absorption by Keplerian shear in the disk,
and associated driving by non-radial photons. Results show dense,
intermediate-speed surface ablation, consistent with the strong,
blue-shifted absorption seen in UV wind lines of Be shell stars. The
asymptotic ablation rate is typically an order-unity factor times the
stellar wind mass loss rate, leading to disk destruction times of
order months to years for Be disks, consistent with observations. The
much stronger radiative forces of O stars reduce this time to order
days, making sustaining a disk difficult, and so providing a natural
explanation for the rarity of Galactic Oe stars. Additionally, the
weakened line-driving at lower metallicity implies both a reduction
in the winds that help spin-down stars from near-critical rotation,
and in the ablation of decretion disks, thus providing a natural
explanation for the higher fraction of Classical Be stars, and the
presence of Oe stars, in the Magellanic Clouds. We conclude with a
discussion of future extensions to study line-driven ablation of
denser, optically thick, accretion disks around pre-main-sequence
massive stars.
Reference: Article to be Published in
MNRAS
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/pdf/1602.07874v1.pdf
Comments:
14 pages, 20 figures, 7 tables
Email: dkee@udel.edu
The massive Wolf-Rayet type star WR 102c is located near the
Quintuplet Cluster - one of the three massive star clusters in the
Galactic Center region. Previous studies indicated that WR 102c may
have a dusty circumstellar nebula and is among the main ionizing
sources of the Sickle Nebula associated with the Quintuplet cluster.
We obtained observations with the ESO's VLT integral field
spectrograph SINFONI in the K-band, extracted the stellar spectra,
and analyzed them by means of stellar atmosphere models. Our new
analysis supersedes the results reported for WR 102c previously. We
significantly revise down its bolometric luminosity and hydrogen
content. We detect four early OB type stars close to WR 102c. These
stars have radial velocities similar to that of WR 102c. We suggest
that together with WR 102c these stars belong to a distinct star
cluster with a total mass of about 1000 M_sun. We identify a new WR
nebula around WR 102c in the SINFONI map of the diffuse Br$\gamma$
emission and in the HST's Pa$\alpha$ images. The Br$\gamma$ line at
different locations is not significantly broadened and similar to the
width of nebular emission elsewhere in the H II region around WR
102c. The massive star WR 102c located in the Galactic Center region
resides in a star cluster containing further early type stars. The
stellar parameters of WR 102c are typical for hydrogen-free WN6
stars. We newly identify a nebula surrounding WR 102c that has a
morphology similar to other nebulae around hydrogen-free WR stars,
and propose that the formation of this nebula is linked to
interaction of the fast stellar wind with the matter ejected at
previous evolutionary stage of WR 102c.
Weblink:
http://arxiv.org/abs/1601.03395
Email:
steinke@ph1.uni-koeln.de
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Mauro Barbieri
Universidad
de Atacama
Copayapu 485, Copiapo, Chile
http://www.uda.cl
The
Instituto de Astrofisica de Atacama (IAA) at the Universidad De
Atacama (UDA) in Copiapo (Chile) invites applications for two faculty
positions to join the IAA team.
The successful candidates will
join a group of five faculty working on a broad range of research
topics and will have access to the Chilean Time in a broad array of
facilities, including ALMA, VLT, Gemini, Magellan, LSST, GMT and the
E-ELT.
We are particularly interested in candidates with
strong experience in one or more of these fields:
-Origin,
structure and evolution of planets, satellites, and minor bodies in
the Solar System;
-Extrasolar Planets;
-Formation, structure
and evolution of stars;
-Milky Way: stellar populations, star
clusters, variable stars, galactic structure;
-Terrestrial Mars
analogs;
-Astrobiology.
The positions carry teaching
duties in astronomy at the undergraduate level, with a load of 6h per
week. The working language is English. While knowledge of Spanish is
not required (teaching can be done in English), the successful
candidates are expected to teach in Spanish within two years.
The
appointment at UDA will be for three years, with a first probation
year, and the position is further extendable subject to performance.
Applicants should have a PhD in astronomy or physics or
related sciences completed at least 3 years prior to the starting day
of the contract.
To receive full consideration, applications
must be sent by Friday 18 of March 2016, although the positions will
remain open until filled. Start date is expected to be October 2016.
Applications must be submitted by e-mail to Mauro Barbieri
(mauro.barbieri @ uda.cl), and they should include:
1) Cover
letter,
2) Curriculum Vitae,
3) List of publications,
4)
Statement of recent research achievements (max. 2 pages),
5) An
outline of future research (min. 2 pages, max. 10 pages),
6) The
contact details of three referees (one needs to be the last employer,
the others needs to be aware of the recent work of the candidate).
Questions may be addressed to the previous e-mail address.
Relevant links:
Universidad de Atacama
http://www.uda.cl
Instituto de Astrofisica de Atacama
https://sites.google.com/site/grupoastrouda
Convocatoria
Programa de Insercion de Investigadores en la UDA
http://www.vrip.uda.cl/frontend/noticia_completa/104
Weblink:
http://eas.unige.ch/jobs.jsp?id=671
Email:
mauro.barbieri@uda.cl
Deadline: 18 March 2016
(positions will remain open until filled)
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Dr.
Enric Palle, IAC Research Head
Instituto
de Astrofisica de Canarias
C/
Via Lactea s/n
E-38205
La Laguna, Tenerife
Spain
The
IAC offers 11 postdoc positions in the frame of the Severo Ochoa
program for excellence research centers in Spain.
Some
of the positions are for five years (so-called Severo Ochoa Advanced
Fellowships).
The
positions cover many different fields in
Astrophysics.
Attention/Comments:
see
the link below for details of each position
Weblink:
http://www.iac.es/info.php?op1=26&lang=en
Email:
corinv@iac.es
Deadline:
may
31, 2016 or july 31, 2016
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Dr.
Eric Gosset and Prof. Gregor Rauw
Institute
of Astrophysics and Geophysics
Quartier
Agora, Batiment B5c
Allee
du 6 Aout, 19c
4000
Liege
Belgium
The
High-Energy Astrophysics Group
(http://www.gaphe.ulg.ac.be/index_e.html) of the Department of
Astrophysics, Geophysics and Oceanography
(http://www.ago.ulg.ac.be/index_e.php) of the University of Liege
(Belgium) is offering a postdoctoral position to participate in the
development of projects related to massive stars and the ESA
cornerstone mission Gaia. The position is funded by Concerted
Research Actions (ARC) programme.
The
High-Energy Astrophysics Group (GAPHE) carries out a variety of
research projects aiming at studying single and binary massive stars
(OB, Wolf-Rayet, Luminous Blue Variables, ...) and the interactions
with their environment based on data obtained with world-class,
space-borne (XMM, Chandra, ...) or ground-based (ESO, ...)
facilities.
The
Gaia satellite is currently performing an all-sky survey providing
astrometry and photometry for about one billion stars, and
spectroscopy for a subsample. The first data are due to be released
to the whole community in summer 2016. This release will include
parallaxes and proper motions of unprecedented accuracy for about 2.5
million bright sources (see
http://www.cosmos.esa.int/web/gaia/release), among which a large
number of massive stars. On the other hand, members of the GAPHE are
involved in the Gaia-ESO survey (https://www.gaia-eso.eu/), whose
main goal is to complement the Gaia data by providing precise
chemical abundances. As part of this survey, spectroscopic data are
being collected for numerous hot stars in young open clusters (Carina
Nebula, ...).
The
successful candidate will develop projects making use of the data for
hot stars from the first (2016) and second (2017) Gaia data releases.
In parallel, he/she is expected to analyse the data for OB stars
obtained by the Gaia-ESO survey, with a particular emphasis on the
determination of the atmospheric parameters, chemical composition and
wind properties.
Applicants
with interest and previous experience in massive star research are
invited to apply. Expertise in the determination of fundamental
parameters and abundances of massive stars, analysis of spectroscopic
data, knowledge of model atmosphere codes for hot stars (CMFGEN,
TLUSTY, ...) and astronomical softwares (IRAF, MIDAS, ...) are an
advantage but are not mandatory.
Applicants
should have a record of publications in peer-reviewed journals,
demonstrated creativity, independence, high motivation, good
communication skills, and the ability to work independently as well
as in collaboration with other members of our research group.
The
appointment is initially for one year with a possible extension for a
second year subject to funding and performance. The starting date is
negotiable but preferably before June 1st, 2016. To be eligible, the
applicant should not have lived or worked in the 'Federation
Wallonie-Bruxelles' for more than 24 months over the last three
years. The salary is on the official Belgian public employee pay
scale for a young Post-Doc. Funding for travel and research equipment
is available.
Interested
persons should send their application material including a curriculum
vitae, a summary (one page at most) of past and current research
activities, a letter of interest, a full publication list and a list
of three reference persons by e-mail to: Eric Gosset/Gregor Rauw,
Institute of Astrophysics and Geophysics, Quartier Agora, Batiment
B5c, Allee du 6 Aout, 19c, 4000 Liege, Belgium (e-mail:
gosset@astro.ulg.ac.be, rauw@astro.ulg.ac.be). The application
deadline is May 1st, 2016. For any further inquiry, please e-mail:
gosset@astro.ulg.ac.be.
Weblink:http://www.ago.ulg.ac.be/Edu/Jobs/Job_54.pdf
Email:gosset@astro.ulg.ac.be
Deadline:May
1st, 2016
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1-2 June 2016
Venue: Kavli Royal Society
Centre, Chicheley Hall, England
Synopsis: The few seconds it
takes to explode a massive star separate millions of years of stellar
evolution from thousands of years of supernova evolution. In this
meeting, we will discuss massive stars both before and after the
explosion, from theoretical and observational perspectives,
addressing how the pre-collapse life affects the explosion mechanism
and supernova display.
Invited Speakers:
Selma De Mink,
Raphael Hirschi, Philipp Podsiadlowski, Jose Groh, Phillip Massey,
Nathan Smith, Jorick Vink, Ben Davies, Sean Couch, Luc Dessart, Dan
Kasen, Claes Fransson, Avishay Gal-Yam, Maryam Modjaz, Ferdinando
Patat
Organisers:
Justyn Maund, Paul Crowther,
Hans-Thomas Janka and Norbert Langer
Attending this event:
Interested participants should request an invitation to attend by
Monday 29 February 2016. All requests will be reviewed by the
scientific organisers and attendance is at their discretion.
Successful applicants will be sent a link to register for the
meeting.
Call for contributions (oral/posters) – deadline
Monday 29 February 2016: Participants are invited to submit an
abstract for consideration for either a 15 minute contributory talk
(12 mins presentation + 3 mins for questions), or a poster. To apply
to make a contribution to the programme, please email a title and
short abstract (200-250 words), and specify if you would like your
submission to be considered for a contributory talk or poster. If
submitting an abstract for a poster, please include the proposed
presenter and list of authors. This must be received by Monday 29
February 2016.
This is a residential conference, which allows
for increased discussion and networking. It is free to attend,
however, participants need to cover travel, accommodation and
catering costs.
Weblink:
https://royalsociety.org/events/2016/06/massive-stars/
Email:
kavli.events@royalsociety.org
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contents
6-8 July, 2016
Venue: European Week of
Astronomy and Space Sciences (EWASS), Athens, Greece
Dear
colleagues,
We are pleased to announce the symposium (S16)
“Frontiers of massive-star evolution and core-collapse supernovae”,
that will be held at the European Week of Astronomy and Space Science
(EWASS) in Athens, Greece, between 4-8 July 2016. This will be a
three-day symposium (6-8 July) focusing on both massive star
evolution and core-collapse SNe.
We aim to bring together
observers and theoreticians whose diverse interests are related to
how massive stars evolve and die as core-collapse supernovae. We
particularly hope to foster collaboration between observers and
theoriticians by having a programme that is balanced between
observational and theoretical work. Recent surveys such as
Pan-STARRS, the Palomar Transient Factory, and PESSTO have led to a
revolution in the number and types of supernovae detected, a trend
that will accelerate in future large surveys such as Euclid and LSST.
Better observational data has led to equally strong progress in
theoretical stellar evolution, and modelling of stellar winds and
supernovae. (see the poster attached)
Our goal is to discuss
recent developments and the most pressing challenges in massive star
evolution and SNe. We also intend to identify future avenues to
explore in an open discussion session led by the organizers. Topics
that will be discussed in this symposium include:
- Latest
observational constraints on mass loss in massive stars
- Massive
star evolution and mass loss
- Effects of binarity and
multiplicity in massive star evolution
- Supernova progenitors,
interacting supernovae and impostors
- Theoretical modelling of
supernova light curves and spectra
- Superluminous supernovae and
other peculiar explosions
Invited Speakers:
Selma de Mink
(Amsterdam)
Miriam Garcia (Madrid)
Raphael Hirschi (Keele)
Raffaella Margutti (NYU)
Sergei Blinnikov (Moscow)
Andrea
Pastorello (Padua)
We welcome applications for contributed
talks and posters. The deadline for abstract submission is March 15.
You can submit your abstract at
http://eas.unige.ch/EWASS2016/abstract_submission.jsp. Information
about the registration and fees is at
http://eas.unige.ch/EWASS2016/registration.jsp
Please take
notice of the rich scientific program of the EWASS 2016 at
http://eas.unige.ch/EWASS2016/program.jsp In particular, we highlight
that science related to massive stars and supernovae will also be
discussed at S14: New Classes and Unique Events in Time Domain
Astronomy.
Please forward this email to interested
colleagues.
Useful links:
EWASS webpage, including
general information on venue, etc:
http://eas.unige.ch/EWASS2016/index.jsp
Symposium webpage:
http://eas.unige.ch/EWASS2016/session.jsp?id=S16
Scientific
Organisers:
Morgan Fraser (University of Cambridge)
Jose Groh
(Trinity College Dublin)
Cosimo Inserra (Queen's University
Belfast)
Anders Jerkstrand (Queen's University Belfast)
Jorick
Vink (Armagh Observatory)
We apologise if you receive
this email more than once.
We are looking forward to see you
in Athens!
Weblink:
http://eas.unige.ch/EWASS2016/session.jsp?id=S16
Email:
jose.groh@unige.ch
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June 6-11, 2016
Venue: Chania, Crete,
Greece
3rd Announcement of the Conference
Registration
is open and the deadline for abstract submission is March 4, 2016. To
register, please follow the "Register" button on the
website: http://snr2016.astro.noa.gr
We encourage delegates
to:
(a) book accommodation well in advance as hotels impose
strict release dates for reservations and there is a limited number
of rooms available. After these dates no guarantee can be made that
rooms will be available.
(b) book their flight-tickets to Chania
well in advance since it is a very touristic destination and the cost
becomes very high within the last 2 months.
For both (a) and
(b) you can find more information below.
Background and
Scientific Rationale
The meeting “Supernova Remnants: An
Odyssey in Space after Stellar death” will explore the exciting
recent observational and theoretical progress in the structure,
evolution and physics of SNRs. The Institute for Astronomy,
Astrophysics, Space Applications & Remote Sensing of the National
Observatory of Athens, invites you to the beautiful island of Crete,
the home of many well known myths, i.e. of Deadalus and Icarus,
Theseus and the Minotaur, the birth of Zeus.
The conference
will build upon spectral and imaging observations from radio to
gamma-ray wavelengths of SNR blast waves, pulsar wind nebulae and SN
ejecta and their interpretation through models and numerical
simulations. The goals of the meeting are understanding the evolution
of SNRs and their interaction with interstellar gas, elucidating the
physical processes that govern shock waves and relativistic plasmas,
and inferring characteristics of supernova explosions from SNR
observations.
We will focus on narrowing the gap between
observations and theories with the help of powerful new
instrumentation such as hard X-ray and gamma-ray satellites, large
optical telescopes, and sub-mm and low-frequency radio arrays on the
one hand, and increasingly detailed and realistic numerical
simulations on the other. New understanding of the nature of
supernova remnants and processes that occur there offers new insights
into the role of SNRs in the structure and evolution of galaxies and
the nature of supernova explosions.
Looking forward to seeing
you in Crete!
Scientific Topics & Session Chairs
*
Radiation studies from gamma-rays to radio in Galactic and
Extragalactic SNRs (D. Green)
* The search for the binary
companions of SN progenitors in SNRs (W. Blair)
* Pulsar winds
nebulae (including Crab flares) (P. Slane)
* Magnetic fields in
SNRs and PWNe (R. Kothes)
* Collisionless shock waves in SNRs (A.
Decourcelle)
* Jets and Asymmetries in SNe and their Remnants (R.
Fesen)
* SNRs as probes and drivers of galaxy structure (A. Rest)
* SNe and SNRs cosmic ray acceleration (T. Bell)
* SN ejecta
– abundances, clumpiness (K. Borkowski)
* SNe and SNRs with
circumstellar interactions (J. Raymond)
Invited Speakers
(confirmed)
R. Chevalier (USA - Opening plenary talk), J.
Vink (Netherlands – Summary plenary talk), E. Amato (Italy), C.
Badenes (USA), G. Dubner (Argentina), P. Ghavamian (USA), W.
Kerzendorf (Canada), S-H. Lee (Japan), M. Lemoine-Goumard (France),
I. Leonidaki (Greece), L. Lopez (USA), R. McCray (USA), D.
Milisavljevic (USA), D. Patnaude (USA), W. Reich (Germany), S.
Reynolds (USA), S. Safi-Harb (Canada), N. Soker (Israel), A.
Spitkovsky (USA), T. Temim (USA), S. Van Dyk (USA), B. Williams (USA)
Important Dates:
2016 March 04 Deadline for abstract
submission for contributed talks
2016 April 01 Notification on
selected abstracts for oral presentations
2016 April 08 Deadline
for early registration and payment (€350)
2016 April 08
Deadline for abstract submission for posters
2016 May 03 Deadline
for hotel reservation with guaranteed special meeting prices
2016
May 13 Deadline for late registration and payment (€400)
2016
June 05 On-site registration opens (€450 – payment in cash only)
2016 June 06 The conference starts
Registration
Online
registration by all participants, including invited speakers, SOC and
LOC members is mandatory. Participants need to complete (or update if
already registered) the registration form to submit poster or
contributed talk abstracts.
The meeting registration fee will
be € 350 and includes the welcome reception, 4 lunches and coffee
breaks, providing the payment is received by April 08th, 2016. Beyond
this date a late registration fee of € 400 will be charged.
We
are planning the following social events-excursions:
(a) a
welcome reception (Sunday, June 5th)
(b) an afternoon excursion
to the Town of Chania (Wednesday, June 8th)
(c) a conference
banquet (Thursday, June 9th)
(d) a full day Boat Excursion to
Gramvousa and Balos (Saturday, June 11th)
More information on
these events can be found on the conference website. Please note that
the cost of the conference banquet and excursions are not covered by
the registration fee.
Participants are expected to arrive in
Chania by Sunday, June 5th and to depart from Chania not earlier than
Saturday, June 11th.
Venue & Accommodation
The
meeting will take place at the luxury 5* beachside hotel Minoa Palace
Luxury Resort & Spa, situated in the cosmopolitan area of
Platanias, 12 km west of the picturesque town of Chania and only a 30
min drive from Chania International Airport. Instructions for
reaching the hotel can be found here.
The Local Organizing
Committee has secured rooms at special rates for our meeting
attendees at a number of hotels apart the main conference hotel. All
reservations must be made directly with the hotels through their
special link.
We invite interested participants to visit the
conference website for more information: http://snr2016.astro.noa.gr
Scientific Organizing Committee
P. Boumis (co-chair),
J. Raymond (co-chair), T. Bell, W. Blair, K. Borkowski, A.
Decourchelle, R. Fesen, D. Green, R. Kothes, A. Rest, P. Slane
Local Organizing Committee
P. Boumis (co-chair),
A. Bonanos (co-chair), D. Abartzi, S. Akras, A. Chiotellis, M.
Kopsacheili, M. Kourniotis, I. Leonidaki, A. Manousakis, M.
Pliatsika, Z.T. Spetsieri, S. Williams
Weblink:
http://snr2016.astro.noa.gr/
Email:
bonanos@noa.gr
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20th - 24th June 2016
Venue: Leibniz
Institute for Astrophysics Potsdam (AIP), Potsdam,
Germany
Spectroscopy is a universal tool used in modern
Astrophysics, from solar physics to the high-redshift Universe.
Essential for the study of most astrophysical phenomena, uses of
spectroscopy are manifold:
- Solar physics: probing solar
activity
- Stellar physics: characterizing stellar parameters,
the ambient medium, stellar activity and evolution
- Interstellar
and intergalactic medium: understanding the composition by emission
and absorption processes
- Galaxies and their kinematics:
studying the evolution of the Milky Way and the Universe on
cosmological scales
- Exoplanets: unveiling their atmospheres
... and many more
The Leibniz Graduate School for
Quantitative Spectroscopy in Astrophysics will host the Potsdam
Astrophysical Summer School at the Leibniz Institute for Astrophysics
Potsdam (AIP) from June 20th to 24th, 2016.
Invited are
interested graduate students in Physics or Astrophysics to join a
week of lectures and hands-on exercises given by experienced
scientists in their fields from the AIP and the University of
Potsdam.
Participants will get an insight into
state-of-the-art research via the recent progress in quantitative
spectroscopy both in theoretical methods and observational
techniques. No matter which field you are interested in, learning the
techniques to extract information from spectra and couple this
information with dedicated models to gain quantitative insights is
vital to start a scientific career in modern Astrophysics.
For
more information please see the website:
https://meetings.aip.de/pass/
Registration is open now till
March 31st, 2016.
For inquiries please send an email to
pass2016@aip.de .
The Leibniz Graduate School for
Quantitative Spectroscopy in Astrophysics is a collaborative project
of the Leibniz Institute for Astrophysics Potsdam (AIP) and the
Institute of Physics and Astronomy of the University of Potsdam
(UP).
Weblink: https://meetings.aip.de/pass/
Email:
pass2016@aip.de
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