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Call for next Massive Star Meeting organization
Kepler sheds new and unprecedented
light on the variability of a blue supergiant: gravity waves in the
O9.5Iab star HD 188209
Uncrowding
R 136 from VLT/SPHERE extreme adaptive optics
The
early B-type star Rho Oph A is an X-ray lighthouse.
First
Detection of Mid-Infrared Variability from an Ultraluminous X-Ray
Source Holmberg II X-1
Does the
Wolf-Rayet binary CQ Cep undergo sporadic mass transfer events?
On
the Absence of Non-thermal X-Ray Emission around Runaway O
Stars
Wolf-Rayet spin at low
metallicity and its implication for Black Hole formation
channels
Revealing the structure
of the outer disks of Be stars
Chemical
abundances of fast-rotating massive stars. I. Description of the
methods and individual results
Observational
signatures of past mass-exchange episodes in massive binaries: The
case of LSS 3074
Massive star
formation by accretion II. Rotation: how to circumvent the angular
momentum barrier?
The Evolution
and Physical Parameters of WN3/O3s: a New Type of Wolf-Rayet Star
The
wind speeds, dust content, and mass-loss rates of evolved AGB and RSG
stars at varying metallicity
Observation
of a Deep Visual "Eclipse" in the WC9-Type Wolf-Rayet Star,
WR 76
The evolution of magnetic fields in hot
stars
Massive stars in advanced
evolutionary stages, and the progenitor of GW150914
XXIX Canary
Islands Winter School of Astrophysics "Applications of Radiative
Transfer to Stellar and Planetary Atmospheres"
Stars
with a stable magnetic field: from pre-main sequence to compact
remnants
Eta Carinae, LBVs, and
Supernova Impostors (2nd announcement)
Massive
Stars as Cosmic Monsters
Be stars
in X-ray binaries 2017
Dear Colleagues,
After
the fantastic meeting in Auckland (thanks to JJ Eldridge and the
whole organizing team) we have to start preparing the next Massive
Stars Meeting. We expect this to take place some time in 2020.
With
this call the Organizing Committee (OC) of our Massive Stars
Commission invites any interested individuals/institutions to send an
email before September 1st, 2017 expressing an interest in organizing
the next meeting. IAU has the final authority to select a symposium,
but the Massive Star Commission OC will support one application based
on a number of criteria. Once selected, the OC will assist the
meeting organizer in the whole application to IAU process, including
preparation and submission, SOC selection, etc. Our criteria for
selection include:
- the meeting location (traditionally,
our group prefers locations near a beach with a relaxed atmosphere
that encourages personal contacts)
- the availability of hotels
with large conference rooms (at least 200 people) and meeting
facilities at affordable prices
- the support of a local
astronomical community
- the balance of locations hosting all
our previous meetings
If possible, your email to the OC
should contain the following information:
- A list of
local volunteers willing to help organizing the meeting
- A
list of hotels that can guarantee accommodation of at least 200
participants, and with appropriate conference facilities
-
Approximate hotel room prices
- Approximate distance from the
nearest airport to the meeting venue/hotel
- Alternative
sponsors or ways to support the meeting
- The best dates for
the meeting, and/or black out dates
(because of school holidays
or high touristic season, etc.)
- Add any other information you
consider will be useful to OC.
The email should be sent
directly to the President of the Commission, Artemio Herrero
(ahd-at-iac.es).
The massive stars meeting is one of the
central pillars of
our community and therefore the OC thanks in
advance anyone interested in organizing this important meeting.
with best regards,
Artemio Herrero,
on behalf
of the Organizing Committee of the G2 Commission
Weblink:
Email: ahd@iac.es
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Aerts, C.; Simon-Diaz, S.; Bloemen, S.; Debosscher, J.;
Papics, P. I.; Bryson, S.; Still, M.; Moravveji, E.; Williamson, M.
H.; Grundahl, F.; Fredslund Andersen, M.; Antoci, V.; Palle, P. L.;
Christensen-Dalsgaard, J.; Rogers, T. M.
1 Instituut
voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven,
Belgium
e-mail: Conny.Aerts@ster.kuleuven.be
2 Department
of Astrophysics/IMAPP, Radboud University Nijmegen, 6500 GL Nijmegen,
The Netherlands
3 Instituto de Astrofísica de Canarias, 38200,
La Laguna, Tenerife, Spain
4 Departamento de Astrofísica,
Universidad de La Laguna, 38205, La Laguna, Tenerife, Spain
5
NASA Ames Research Center, Mo ett Field, CA 94095, USA
6 Bay
Area Environmental Research Institute, 560 Third Street W., Sonoma,
CA 95476, USA
7 Center of Excellence in Information Systems,
Tennessee State University, 3500 John A. Merritt Blvd., Box 9501,
Nashville, TN
37209, USA
8 Stellar Astrophysics Centre,
Department of Physics and Astronomy, Aarhus University, DK-8000
Aarhus C, Denmark
9 Department of Mathematics and Statistics,
Newcastle University, UK
10 Planetary Science Institute,
Tucson, AZ 85721, USA
Stellar evolution models are most
uncertain for evolved massive stars. Asteroseismology based on
high-precision uninterrupted space photometry has become a new way to
test the outcome of stellar evolution theory and was recently applied
to a multitude of stars, but not yet to massive evolved
supergiants.Our aim is to detect, analyse and interpret the
photospheric and wind variability of the O9.5Iab star HD 188209 from
Kepler space photometry and long-term high-resolution spectroscopy.
We used Kepler scattered-light photometry obtained by the nominal
mission during 1460d to deduce the photometric variability of this
O-type supergiant. In addition, we assembled and analysed
high-resolution high signal-to-noise spectroscopy taken with four
spectrographs during some 1800d to interpret the temporal
spectroscopic variability of the star. The variability of this blue
supergiant derived from the scattered-light space photometry is in
full in agreement with the one found in the ground-based
spectroscopy. We find significant low-frequency variability that is
consistently detected in all spectral lines of HD 188209. The
photospheric variability propagates into the wind, where it has
similar frequencies but slightly higher amplitudes. The morphology of
the frequency spectra derived from the long-term photometry and
spectroscopy points towards a spectrum of travelling waves with
frequency values in the range expected for an evolved O-type star.
Convectively-driven internal gravity waves excited in the stellar
interior offer the most plausible explanation of the detected
variability.
Reference:
http://adsabs.harvard.edu/abs/2017arXiv170301514A
Status:
Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2017arXiv170301514A
Comments:
Email: conny.aerts@ster.kuleuven.be
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Z. Khorrami , F. Vakili , T. Lanz, M. Langlois, E.
Lagadec , M. R. Meyer , S. Robbe-Dubois , L. Abe , H. Avenhaus , JL.
Beuzit, R. Gratton , D. Mouillet , A. Origné , C. Petit, J. Ramos
1
Universitè Côte d’Azur, OCA, CNRS, Lagrange, France e-mail:
KhorramiZ@cardiff.ac.uk
2 School of Physics and Astronomy,
Cardiff University, The Parade, Cardiff CF24 3AA, UK
3 Univ
Lyon, Univ Lyon1, Ens de Lyon, CNRS, CRAL UMR5574, F-69230,
Saint-Genis-Laval, France
4 Aix Marseille Université, CNRS,
LAM - Laboratoire d’Astrophysique de Marseille, UMR 7326, 13388,
Marseille, France
5 Institute for Astronomy, ETH Zurich,
Wolfgang-Pauli-Strasse 27, CH-8093 Zurich, Switzerland
6
Department of Astronomy, University of Michigan, Ann Arbor, MI 48109,
U.S.A.
7 Departamento de Astronomìa, Universidad de Chile,
Casilla 36-D, Santiago, Chile
8 Université Grenoble Alpes,
CNRS, IPAG, 38000 Grenoble, France 9 INAF - Astronomical Observatory
of Padua, Italy
10 ONERA - Optics Department, 29 avenue de la
Division Leclerc, F-92322 Chatillon Cedex, France
11
Max-Planck-Institut fur Astronomie, Konigstuhl 17, D-69117
Heidelberg, Germany
This paper presents the sharpest
near-IR images of the massive cluster R136 to date,
based on
the extreme adaptive optics of the SPHERE focal instrument
implemented on the ESO Very Large Telescope and operated in its IRDIS
imaging mode.
The crowded stellar population in the core
of the R136 starburst compact cluster remains still to be
characterized in terms of individual luminosities, age, mass and
multiplicity. SPHERE/VLT and its high contrast imaging possibilities
open new windows to make progress on these questions.
Stacking-up
a few hundreds of short exposures in J and Ks spectral bands over a
Field of View (FoV) of 10.9" x 12.3" centered on the R136a1
stellar component, enabled us to carry a refined photometric analysis
of the core of R136. We detected 1110 and 1059 sources in J and Ks
images respectively with 818 common sources.
Thanks to
better angular resolution and dynamic range, we found that more than
62.6% (16.5%) of the stars, detected both in J and Ks data, have
neighbours closer than 0.2" (0.1").
%We found that
more than 62.6% (16.5%) of the stars, detected both in J and Ks data,
have visual companion closer than 0.2" (0.1").
The
closest stars are resolved down to the full width at half maximum
(FWHM) of the point spread function (PSF) measured by Starfinder.
Among newly resolved and detected sources R136a1 and R136c are
found to have optical companions and R136a3 is resolved as two stars
(PSF fitting) separated by 59±2 mas. This new companion of R136a3
presents a correlation coefficient of 86% in J and 75% in Ks.
The
new set of detected sources were used to re-assess the age and
extinction of R136 based on 54 spectroscopically stars that have been
recently studied with HST slit-spectroscopy (Crowther et al. 2016) of
the core of this cluster.
Over 90% of these 54 sources
identified visual companions (closer than 0.2").
We found
the most probable age and extinction for these sources are
$1.8^{+1.2}_{-0.8}$ Myr, A_J=(0.45±0.5)mag and A_K=(0.2±0.5)mag
within the photometric and spectroscopic error-bars.
Additionally,
using PARSEC evolutionary isochrones and tracks, we estimated the
stellar mass range for each detected source (common in J and K data)
and plotted the generalized histogram of mass (MF with error-bars).
Using SPHERE data, we have gone one step further and
partially resolved and studied the IMF covering mass range of (3 -
300) M_{\odot} at the age of 1 and 1.5 Myr. The density in the core
of R136 (0.1 - 1.4 pc) is estimated and extrapolated in 3D and larger
radii (up to 6pc).
We show that the stars in the core are still
unresolved due to crowding, and the results we obtained are upper
limits. Higher angular resolution is mandatory to overcome these
difficulties.
Reference: Accpeted by A&A
Status:
Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1703.02876
Comments:
Email: KhorramiZ@cardiff.ac.uk
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Ignazio Pillitteri $^1$ $^2$, Scott J. Wolk $^2$, Fabio
Reale $^3$, and Lida Oskinova $^4$
1-
INAF-Osservatorio Astronomico di Palermo - Italy;
2- Harvard
Smithsonian Center for Astrophysics Cambridge MA - USA;
3-
Universita` degli Studi di Palermo Italy; 4- Institut für Physik und
Astronomie, Universität Potsdam Germany
We present the
results of a 140 ks XMM-Newton observation of the B2 star ρ Ophiuchi
A. The star exhibited strong X-ray variability: a cusp-shaped
increase of rate, similar to the one we partially observed in 2013,
and a bright flare. These events are separated in time by about 104
ks, which likely correspond to the rotational period of the star (1.2
days). Time resolved spectroscopy of the X-ray spectra shows that the
first event is almost only due to an increase of the plasma emission
measure, while the second increase of rate is mainly due is a major
flare, with temperatures in excess of 60 MK (kT∼5 keV). From the
analysis of its rise we infer a magnetic field of ≥300 G and a size
of the flaring region of ∼1.4−1.9x10^11 cm, which corresponds to
∼25%−30% of the stellar radius. We speculate that either an
intrinsic magnetism that produces a hot spot on its surface, or an
unknown low mass companion are the source of such X-rays and
variability. A hot spot of magnetic origin should be a stable
structure over a time span of ≥2.5 years, and suggests an overall
large scale dipolar magnetic field that produce an extended feature
on the stellar surface. In the second scenario, a low mass unknown
companion is the emitter of X-rays and it should orbit extremely
close to the surface of the primary in a locked spin-orbit
configuration, almost on the verge of collapsing onto the primary. As
such, the X-ray activity of the secondary star would be enhanced by
both its young age and the tight orbit like in RS Cvn systems and Rho
Oph would constitute an extreme system worth of further
investigation.
Reference: A&A, accepted
Status:
Manuscript has been accepted
Weblink:
Comments:
Email: ignazio.pillitteri@gmail.com
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Ryan M. Lau (1,2), Marianne Heida (2), Mansi M. Kasliwal
(2), Dominic J. Walton (3)
1 - Jet Propulsion
Laboratory, California Institute of Technology,
4800 Oak Grove
Drive, Pasadena, CA 91109, USA
2 - Division of Physics,
Mathematics and Astronomy, Department
of Astronomy, California
Institute of Technology,
Pasadena, CA 91125, USA
3 -
Institute of Astronomy, Madingley Road, CB3 0HA Cambridge,
United
Kingdom
We present mid-infrared (IR) light curves of the
Ultraluminous X-ray Source (ULX) Holmberg II X-1 from observations
taken between 2014 January 13 and 2017 January 5 with the Spitzer
Space Telescope at 3.6 and 4.5 μm in the Spitzer Infrared Intensive
Transients Survey (SPIRITS). The mid-IR light curves, which reveal
the first detection of mid-IR variability from a ULX, is determined
to arise primarily from dust emission rather than from a jet or an
accretion disk outflow. We derived the evolution of the dust
temperature (Td∼600−800 K), IR luminosity (LIR∼3×10^4 L⊙),
mass (Md∼1−3×10^{−6} M⊙), and equilibrium temperature radius
(Req∼10−20 AU). A comparison of X-1 with a sample
spectroscopically identified massive stars in the Large Magellanic
Cloud on a mid-IR color-magnitude diagram suggests that the mass
donor in X-1 is a supergiant (sg) B[e]-star. The
sgB[e]-interpretation is consistent with the derived dust properties
and the presence of the [Fe II] (λ=1.644 μm) emission line revealed
from previous near-IR studies of X-1. We attribute the mid-IR
variability of X-1 to increased heating of dust located in a
circumbinary torus. It is unclear what physical processes are
responsible for the increased dust heating; however, it does not
appear to be associated with the X-ray flux from the ULX given the
constant X-ray luminosities provided by serendipitous,
near-contemporaneous X-ray observations around the first mid-IR
variability event in 2014. Our results highlight the importance of
mid-IR observations of luminous X-ray sources traditionally studied
at X-ray and radio wavelengths.
Reference: Accepted
by ApJ Letters
Status: Manuscript has been accepted
Weblink:
https://arxiv.org/abs/1703.03802
Comments:
Email: ryanlau@caltech.edu
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G. Koenigsberger, W. Schmutz, S.L Skinner
Instituto
de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico;
Physikalisch-Meteorologisches Observatorium Davos and
World Radiation Center (PMOD/WRC);
CASA, Univ. of
Colorado
Stellar wind mass-loss in binary systems carries
away angular momentum causing a monotonic increase in the orbital
period, P-dot>0. Despite possessing a significant stellar wind,
the eclipsing Wolf-Rayet binary system CQ Cep does not show the
expected monotonic period increase, in fact, it is sometimes reported
to display the opposite behavior. The objective of this paper is to
perform a new analysis of the rate of period change P-dot and
determine the conditions under which Roche Lobe overflow (RLO)
mass-transfer combined with wind mass loss can explain the discrepant
behavior. The historic records of times of light curve minima were
reviewed and compared with the theoretical values of P-dot for cases
in which both wind mass-loss and RLO occur simultaneously. The
observational data indicate that P-dot alternates between positive
and negative values on a timescale of years. The negative values
(P-dot ~ -0.6 to -8.5 s/yr) are significantly larger in absolute
value than the positive ones (P-dot ~+0.2 to +1.2 s/yr). We find that
a plausible scenario for CQ Cep is one in which the O star undergoes
intense but sporadic RLO events that lead to accretion onto the WR
star, at which times P-dot<0. At other times, P-dot>0 when the
WR wind, and possibly material swept up from the O star, carries
angular momentum away from the system. A scenario in which the WR
star is the mass donor cannot be excluded, but requires that either
the WR wind mass-loss rate undergoes large sporadic enhancements or
that an additional process that removes angular momentum from the
system be present.
Reference: A&A, in
press
Status: Manuscript has been accepted
Weblink:
http://www.fis.unam.mx/~gloria/2017feb24_CQCep_paper.pdf
Comments:
Email: gloria@astro.unam.mx
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Toala$^1$, Oskinova$^2$, Ignace$^3$
1 -
Institute of Astronomy and Astrophysics (ASIAA, Taiwan); 2 -
Institute for Physics and Astronomy, University of Postdam (Germany);
3 - Department of Physics and Astronomy, East Tennessee State
University (USA)
Theoretical models predict that the
compressed interstellar medium around runaway O stars can produce
high-energy non-thermal diffuse emission, in particular, non-thermal
X-ray and γ-ray emission. So far, detection of non-thermal X-ray
emission was claimed for only one runaway star, AE Aur. We present a
search for non-thermal diffuse X-ray emission from bow shocks using
archived XMM-Newton observations for a clean sample of six
well-determined runaway O stars. We find that none of these objects
present diffuse X-ray emission associated with their bow shocks,
similarly to previous X-ray studies toward ζ Oph and BD+43°3654. We
carefully investigated multi-wavelength observations of AE Aur and
could not confirm previous findings of non-thermal X-rays. We
conclude that so far there is no clear evidence of non-thermal
extended emission in bow shocks around runaway O stars.
Reference:
ApJL, 838, L19
Status: Manuscript has been
accepted
Weblink:
http://iopscience.iop.org/article/10.3847/2041-8213/aa667c/pdf
Comments:
Email: toala@asiaa.sinica.edu.tw
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Jorick S. Vink & Tim J. Harries
Armagh
Observatory & Planetarium
University of Exeter
The
spin of Wolf-Rayet (WR) stars at low metallicity (Z) is most relevant
for our understanding of gravitational wave sources such as GW
150914, as well as the incidence of long-duration gamma-ray bursts
(GRBs). Two scenarios have been suggested for both phenomena: one of
them involves rapid rotation and quasi-chemical homogeneous evolution
(CHE), the other invokes classical evolution through mass loss in
single and binary systems. WR spin rates might enable us to test
these two scenarios. In order to obtain empirical constraints on
black hole progenitor spin, we infer wind asymmetries in all 12 known
WR stars in the Small Magellanic Cloud (SMC) at Z = 1/5 Zsun, as well
as within a significantly enlarged sample of single and binary WR
stars in the Large Magellanic Cloud (LMC at Z = 1/2 Zsun), tripling
the sample of Vink (2007). This brings the total LMC sample to 39,
making it appropriate for comparison to the Galactic sample. We
measure WR wind asymmetries with VLT-FORS linear spectropolarimetry.
We report the detection of new line effects in the LMC WN star
BAT99-43 and the WC star BAT99-70, as well as the famous WR/LBV HD
5980 in the SMC, which might be evolving chemically homogeneously.
With the previous reported line effects in the late-type WNL
(Ofpe/WN9) objects BAT99-22 and BAT99-33, this brings the total LMC
WR sample to 4, i.e. a frequency of ~10%. Perhaps surprisingly, the
incidence of line effects amongst low-Z WR stars is not found to be
any higher than amongst the Galactic WR sample, challenging the
rotationally-induced CHE model. As WR mass loss is likely
Z-dependent, our Magellanic Cloud line-effect WR stars may maintain
their surface rotation and fulfill the basic conditions for producing
long GRBs, both via the classical post-red supergiant (RSG) or
luminous blue variable (LBV) channel, as well as resulting from CHE
due to physics specific to very massive stars (VMS).
Reference:
Astronomy & Astrophysics, Astro-ph 1703.09857
Status:
Manuscript has been accepted
Weblink:
https://arxiv.org/abs/1703.09857
Comments:
Email: jsv@arm.ac.uk
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Klement, R.(1,2); Carciofi, A.C.(3); Rivinius, T.(1);
Matthews, L. D.(4); Vieira, R.G.(3); Ignace, R.(5); Bjorkman,
J.E.(6); Mota, B.C.(3); Faes, D.M.(3); Bratcher, A.D.(6); Curé,
M.(7); Štefl, S.
1 - European Southern Observatory,
Alonso de Córdova 3107, Vitacura, Casilla 19001, Santiago, Chile
2
- Astronomical Institute of Charles University, Charles University, V
Holešovičkách 2, 180 00 Prague 8
3 - Instituto de
Astronomia, Geofísica e Ciencias Atmosféricas, Universidade de Sao
Paulo, Rua do Matao 1226, Cidade Universitária, 05508-090, Sao
Paulo, SP, Brazil
4 - MIT Haystack Observatory, off Route
40, Westford MA 01886, USA
5 - Department of Physics &
Astronomy, East Tennessee State University, Johnson City, TN 37614,
USA
6 - Ritter Observatory, Department of Physics &
Astronomy, University of Toledo, Toledo, OH 43606, USA
7
- Instituto de Física y Astronomía, Facultad de Ciencias,
Universidad de Valparaíso, Casilla 5030, Valparaíso, Chile
The
structure of the inner parts of Be star disks (~< 20 stellar
radii) is well explained by the viscous decretion disk (VDD) model,
which is able to reproduce the observable properties of most of the
objects studied so far. The outer parts, on the other hand, are not
observationally well-explored, as they are observable only at radio
wavelengths. A steepening of the spectral slope somewhere between
infrared and radio wavelengths was reported for several Be stars that
were previously detected in the radio, but a convincing physical
explanation for this trend has not yet been provided. We test the VDD
model predictions for the extended parts of a sample of six Be disks
that have been observed in the radio to address the question of
whether the observed turndown in the spectral energy distribution
(SED) can be explained in the framework of the VDD model, including
recent theoretical development for truncated Be disks in binary
systems. We combine new multi-wavelength radio observations from the
Karl.~G.~Jansky Very Large Array (JVLA) and Atacama Pathfinder
Experiment (APEX) with previously published radio data and archival
SED measurements at ultraviolet, visual, and infrared wavelengths.
The density structure of the disks, including their outer parts, is
constrained by radiative transfer modeling of the observed spectrum
using VDD model predictions. In the VDD model we include the presumed
effects of possible tidal influence from faint binary companions. For
5 out of 6 studied stars, the observed SED shows strong signs of SED
turndown between far-IR and radio wavelengths. A VDD model that
extends to large distances closely reproduces the observed SEDs up to
far IR wavelengths, but fails to reproduce the radio SED. Using a
truncated VDD model improves the fit, leading to a successful
explanation of the SED turndown observed for the stars in our sample.
The slope of the observed SEDs in the radio is however not well
reproduced by disks that are simply cut off at a certain distance.
Rather, some matter seems to extend beyond the truncation radius,
where it still contributes to the observed SEDs, making the spectral
slope in the radio shallower. This finding is in agreement with our
current understanding of binary truncation from hydrodynamical
simulations, in which the disk does extend past the truncation
radius. Therefore, the most probable cause for the SED turndown is
the presence of binary companions that remain undetected for most of
our sources.
Reference: A&A (in press)
Status:
Manuscript has been accepted
Weblink:
https://doi.org/10.1051/0004-6361/201629932
Comments:
Email: robertklement@gmail.com
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Cazorla, Constantin$^1$; Morel, Thierry$^1$; Naze,
Yael$^1$; Rauw, Gregor$^1$; Semaan, Thierry$^{2,1}$; Daflon,
Simone$^3$; Oey, M. S.$^4$
1 - University of Liege,
Belgium
2 - Observatoire de Geneve, Switzerland
3 -
Observatorio Nacional, Rio de Janeiro, Brazil
4 - University of
Michigan, Ann Arbor, USA
Recent observations have
challenged our understanding of rotational mixing in massive stars by
revealing a population of fast-rotating objects with apparently
normal surface nitrogen abundances. However, several questions have
arisen because of a number of issues, which have rendered a
reinvestigation necessary; these issues include the presence of
numerous upper limits for the nitrogen abundance, unknown
multiplicity status, and a mix of stars with different physical
properties, such as their mass and evolutionary state, which are
known to control the amount of rotational mixing. We have carefully
selected a large sample of bright, fast-rotating early-type stars of
our Galaxy (40 objects with spectral types between B0.5 and O4).
Their high-quality, high-resolution optical spectra were then
analysed with the stellar atmosphere modelling codes DETAIL/SURFACE
or CMFGEN, depending on the temperature of the target. Several
internal and external checks were performed to validate our methods;
notably, we compared our results with literature data for some
well-known objects, studied the effect of gravity darkening, or
confronted the results provided by the two codes for stars amenable
to both analyses. Furthermore, we studied the radial velocities of
the stars to assess their binarity. This first part of our study
presents our methods and provides the derived stellar parameters, He,
CNO abundances, and the multiplicity status of every star of the
sample. It is the first time that He and CNO abundances of such a
large number of Galactic massive fast rotators are determined in a
homogeneous way.
Reference: A&A in
press
Status: Manuscript has been accepted
Weblink:
https://arxiv.org/abs/1703.05592
Comments:
Email: rauw@astro.ulg.ac.be
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Raucq, F.$^1$; Gosset, E.$^1$; Rauw, G.$^1$; Manfroid,
J.$^1$; Mahy, L.$^1$; Mennekens, N.$^2$; Vanbeveren, D.$^2$
1
- University of Liege, Belgium
2 - Vrije Universiteit Brussel,
Belgium
The role of mass and momentum exchanges in close
massive binaries is very important in the subsequent evolution of the
components. Such exchanges 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 close O-star binary LSS 3074 (O4 f + O6-7:(f):), which is a
good candidate for a past Roche lobe overflow (RLOF) episode because
of its very short orbital period, P = 2.185 days, and the luminosity
classes of both components. We determined a new orbital solution for
the system. We studied the photometric light curves to determine the
inclination of the orbit and Roche lobe filling factors of both
stars. Using phase-resolved spectroscopy, we performed the
disentangling of the optical spectra of the two stars. We then
analysed the reconstructed primary and secondary spectra 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 confirm the apparent
low stellar masses and radii reported in previous studies. We also
find a strong overabundance in nitrogen and a strong carbon and
oxygen depletion in both primary and secondary atmospheres, together
with a strong enrichment in helium of the primary star. We propose
several possible evolutionary pathways through a RLOF process to
explain the current parameters of the system. We confirm that the
system is apparently in overcontact configuration and has lost a
significant portion of its mass to its surroundings. We suggest that
some of the discrepancies between the spectroscopic and photometric
properties of LSS 3074 could stem from the impact of a strong
radiation pressure of the primary.
Reference: A&A
in press
Status: Manuscript has been accepted
Weblink:
https://arxiv.org/abs/1703.03247
Comments:
Email: rauw@astro.ulg.ac.be
Back
to contents
L. Haemmerlé (1,2), P. Eggenberger (1), G. Meynet (1),
A. Maeder (1), C. Charbonnel (1,4), and R. S. Klessen (2,3)
(1)
Observatoire de Genève, Université de Genève, chemin des
Maillettes 51, CH-1290 Sauverny, Switzerland;
(2) Institut für
Theoretische Astrophysik, Zentrum für Astronomie der Universität
Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg, Germany;
(3)
Interdisziplinäres Zentrum für wissenschaftliches Rechnen der
Universität Heidelberg, Im Neuenheimer Feld 205, D-69120 Heidelberg,
Germany;
(4) IRAP, UMR 5277 CNRS, 14 Av. É. Belin, 31400
Toulouse, France
Rotation plays a key role in the
star-formation process, from pre-stellar cores to pre-main-sequence
(PMS) objects. Understanding the formation of massive stars requires
taking into account the accretion of angular momentum during their
PMS phase. We study the PMS evolution of objects destined to become
massive stars by accretion, focusing on the links between the
physical conditions of the environment and the rotational properties
of young stars. In particular, we look at the physical conditions
that allow the production of massive stars by accretion. We present
PMS models computed with a new version of the Geneva Stellar
Evolution code self-consistently including accretion and rotation
according to various accretion scenarios for mass and angular
momentum. We describe the internal distribution of angular momentum
in PMS stars accreting at high rates and we show how the various
physical conditions impact their internal structures, evolutionary
tracks, and rotation velocities during the PMS and the early main
sequence. We find that the smooth angular momentum accretion
considered in previous studies leads to an angular momentum barrier
and does not allow the formation of massive stars by accretion. A
braking mechanism is needed in order to circumvent this angular
momentum barrier. This mechanism has to be efficient enough to remove
more than 2/3 of the angular momentum from the inner accretion disc.
Due to the weak efficiency of angular momentum transport by shear
instability and meridional circulation during the accretion phase,
the internal rotation profiles of accreting stars reflect essentially
the angular momentum accretion history. As a consequence, careful
choice of the angular momentum accretion history allows circumvention
of any limitation in mass and velocity, and production of stars of
any mass and velocity compatible with structure
equations.
Reference: DOI:
10.1051/0004-6361/201630149
Status: Manuscript has been
accepted
Weblink:
http://arxiv.org/pdf/1703.08357.pdf
Comments:
Email: lionel.haemmerle@unige.ch
Back
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Kathryn F. Neugent (1,2), Philip Massey (1,2), D. John
Hillier (3), and Nidia I. Morrell (4)
(1) Lowell
Observatory, (2) Dept of Physics and Astronomy, Northern Arizona
University, (3) Dept of Physics and Astronomy, University of
Pittsburgh, (4) Las Campanas Observatory
As part of a
search for Wolf-Rayet (WR) stars in the Magellanic Clouds, we have
discovered a new type of WR star in the Large Magellanic Cloud (LMC).
These stars have both strong emission lines, as well as HeII and
Balmer absorption lines and spectroscopically resemble a WN3 and O3V
binary pair. However, they are visually too faint to be WN3+O3V
binary systems. We have found nine of these WN3/O3s, making up ∼ 6%
of the population of LMC WRs. Using CMFGEN, we have successfully
modeled their spectra as single stars and have compared the physical
parameters with those of more typical LMC WNs. Their temperatures are
around 100,000 K, a bit hotter than the majority of WN stars (by
around 10,000 K) although a few hotter WNs are known. The abundances
are what you would expect for CNO equilibrium. However, most
anomalous are their mass-loss rates which are more like that of an
O-type star than a WN star. While their evolutionary status is
uncertain, their low mass-loss rates and wind velocities suggest that
they are not products of homogeneous evolution. It is possible
instead that these stars represent an intermediate stage between O
stars and WNs. Since WN3/O3 stars are unknown in the Milky Way, we
suspect that their formation depends upon metallicity, and we are
investigating this further by a deep survey in M33, which posses a
metallicity gradient.
Reference: ApJ, in
press
Status: Manuscript has been accepted
Weblink:
https://arxiv.org/abs/1704.05497
Comments:
Email: phil.massey@lowell.edu
Back
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Steven R. Goldman (1), Jacco Th. van Loon (1), Albert A.
Zijlstra (2), James A. Green (3,4), Peter R. Wood (5), Ambra Nanni
(6), Hiroshi Imai (7), Patricia A. Whitelock (8,9), Mikako Matsuura
(10), Martin A. T. Groenewegen (11), and José F. Gómez (12)
1
- Astrophysics Group, Lennard–Jones Laboratories, Keele University,
Staffordshire ST5 5BG, UK
2 - Jodrell Bank Centre for
Astrophysics, Alan Turing Building, School of Physics and Astronomy,
The University of Manchester, Oxford Road, Manchester M13 9PL, UK
3
- SKA Organisation, Jodrell Bank Observatory, Lower Withington,
Macclesfield, Cheshire SK11 9DL, UK
4 - CSIRO Astronomy and
Space Science, Australia Telescope National Facility, PO Box 76,
Epping, NSW 1710, Australia
5 - Research School of Astronomy
and Astrophysics, Australian National University, Weston Creek, ACT
2611, Australia
6 - Dipartimento di Fisica e Astronomia Galileo
Galilei, vicolo dell’Osservatorio 3, I-35141 Padova PD, Italy
7
- Department of Physics and Astronomy, Kagoshima University, 1-21-35
Korimoto, Kagoshima 890-0065, Japan
8 - South African
Astronomical Observatory (SAAO), PO Box 9, 7935 Observatory, South
Africa
9 - Astronomy Department, University of Cape Town, 7701
Rondebosch, South Africa
10 - School of Physics and Astronomy,
Cardiff University, Queen’s Buildings, The Parade, Cardiff CF24
3AA, UK
11 - Royal Observatory of Belgium, Ringlaan 3, B-1180
Brussels, Belgium
12 - Instituto de Astrof´ısica de
Andaluc´ıa, CSIC, Glorieta de la Astronom´ıa s/n, E-18008
Granada, Spain
We present the results of our survey of
1612-MHz circumstellar OH maser emission from asymptotic giant branch
(AGB) stars and red supergiants (RSGs) in the Large Magellanic Cloud
(LMC). We have discovered four new circumstellar maser sources in the
LMC, and increased the number of reliable wind speeds from infrared
(IR) stars in the LMC from 5 to 13. Using our new wind speeds, as
well as those from Galactic sources, we have derived an updated
relation for dust-driven winds: vexp ∝ ZL0.4. We compare the
subsolar metallicity LMC OH/IR stars with carefully selected samples
of more metal-rich OH/IR stars, also at known distances, in the
Galactic Centre and Galactic bulge. We derive pulsation periods for
eight of the bulge stars for the first time by using near-IR
photometry from the Vista Variables in the Via Lactea survey. We have
modelled our LMC OH/IR stars and developed an empirical method of
deriving gas-to-dust ratios and mass-loss rates by scaling the models
to the results from maser profiles. We have done this also for
samples in the Galactic Centre and bulge and derived a new mass-loss
prescription which includes luminosity, pulsation period, and
gas-to-dust ratio M˙ = 1.06+3.5 −0.8 × 10−5(L/104 L) 0.9±0.1(P
/500 d)0.75±0.3(rgd/200)−0.03±0.07 M yr−1. The tightest
correlation is found between mass-loss rate and luminosity. We find
that the gas-to-dust ratio has little effect on the mass-loss of
oxygen-rich AGB stars and RSGs within the Galaxy and the LMC. This
suggests that the mass-loss of oxygen-rich AGB stars and RSGs is
(nearly) independent of metallicity between a half and twice
solar.
Reference: MNRAS, 465, 403 (2017)
Status:
Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2017MNRAS.465..403G
Comments:
Email: s.r.goldman@keele.ac.uk
Back
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Rod Stubbings (1) and Peredur
Williams (2)
1 - Tetoora Road Observatory, 2643
Warragul-Korumburra Road, Tetoora Road, 3821, Victoria, Australia;
2- Institute for Astronomy, Royal Observatory, Blackford Hill,
Edinburgh, EH9 3HJ, United Kingdom
The WC9-Type Wolf-Rayet
star WR 76 is one of the most prolific dust makers identified from
its infrared emission. WR 76 experienced a deep fading eclipse in
2016. The ~3.1 magnitude depth of the eclipse exceeds fadings in
similar eclipses observed in WR stars thus far. Conclusions from
recent and earlier analyses of eclipses observed suggests that WR 76
may be a prolific eclipser.
Reference: JAAVSO (in
Press)
Status: Manuscript has been accepted
Weblink:
https://arxiv.org/ftp/arxiv/papers/1704/1704.05720.pdf
Comments:
Email: pmw@roe.ac.uk
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Mary E. Oksala(1,2), Coralie Neiner(2), Cyril Georgy(3),
Norbert Przybilla(4), Zsolt Keszthelyi(5,6), Gregg Wade(5), Stephane
Mathis(7,2), Aurore Blazere(8,2), Bram Buysschaert(2,9)
(1)
Department of Physics, California Lutheran University, 60 West Olsen
Road #3700, Thousand Oaks, CA 91360, USA; (2) LESIA, Observatoire de
Paris, PSL Research University, CNRS, Sorbonne Universites, UPMC
Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cite, 5 place
Jules Janssen, 92195 Meudon, France; (3) Geneva Observatory,
University of Geneva, chemin des Maillettes 51, 1290 Sauverny,
Switzerland; (4) Institut fur Astro- und Teilchenphysik, Universitat
Innsbruck, Technikerstr. 25/8, 6020, Innsbruck, Austria; (5)
Department of Physics, Royal Military College of Canada, PO Box 17000
Station Forces, Kingston, ON K7K 0C6, Canada; (6) Department of
Physics, Engineering Physics and Astronomy, Queen's University,
99 University Avenue, Kingston, ON K7L 3N6, Canada; (7) Laboratoire
AIM Paris-Saclay, CEA/DRF - CNRS - Universite Paris Diderot, IRFU/SAp
Centre de Saclay, 91191 Gif-sur-Yvette, France; (8) Institut
d'Astrophysique et de Geophysique, Universite de Liege, Quartier
Agora (B5c), Allee du 6 aout 19c, 4000 Sart Tilman, Liege, Belgium;
(9) Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D,
3001, Leuven, Belgium
Over the last decade, tremendous
strides have been achieved in our understanding of magnetism in main
sequence hot stars. In particular, the statistical occurrence of
their surface magnetism has been established (~10%) and the field
origin is now understood to be fossil. However, fundamental questions
remain: how do these fossil fields evolve during the post-main
sequence phases, and how do they influence the evolution of hot stars
from the main sequence to their ultimate demise? Filling the void of
known magnetic evolved hot (OBA) stars, studying the evolution of
their fossil magnetic fields along stellar evolution, and
understanding the impact of these fields on the angular momentum,
rotation, mass loss, and evolution of the star itself, is crucial to
answering these questions, with far reaching consequences, in
particular for the properties of the precursors of supernovae
explosions and stellar remnants. In the framework of the BRITE
spectropolarimetric survey and LIFE project, we have discovered the
first few magnetic hot supergiants. Their longitudinal surface
magnetic field is very weak but their configuration resembles those
of main sequence hot stars. We present these first observational
results and propose to interpret them at first order in the context
of magnetic flux conservation as the radius of the star expands with
evolution. We then also consider the possible impact of stellar
structure changes along evolution.
Reference:
Proceeding -- IAUS329
Status: Conference
proceedings
Weblink:
https://arxiv.org/abs/1702.06924
Comments:
Email: meo@udel.edu
Back
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Hamann, W.-R.; Oskinova, L.; Todt,
H.; Sander, A.; Hainich, R.; Shenar, T.; Ramachandran, V.
University
Potsdam, Germany
The recent discovery of a gravitational
wave from the merging of two black holes of about 30 solar masses
each challenges our incomplete understanding of massive stars and
their evolution. Critical ingredients comprise mass-loss, rotation,
magnetic fields, internal mixing, and mass transfer in close binary
systems. The imperfect knowledge of these factors implies large
uncertainties for models of stellar populations and their feedback.
In this contribution we summarize our empirical studies of Wolf-Rayet
populations at different metallicities by means of modern non-LTE
stellar atmosphere models, and confront these results with the
predictions of stellar evolution models. At the metallicity of our
Galaxy, stellar winds are probably too strong to leave remnant masses
as high as 30 solar masses, but given the still poor agreement
between evolutionary tracks and observation even this conclusion is
debatable. At the low metallicity of the Small Magellanic Cloud, all
WN stars which are (at least now) single are consistent with evolving
quasi-homogeneously. O and B-type stars, in contrast, seem to comply
with standard evolutionary models without strong internal mixing.
Close binaries which avoided early merging could evolve
quasi-homogeneously and lead to close compact remnants of relatively
high masses that merge within a Hubble time.
Reference:
in: Proceedings of the IAU Symposium No. 329 "The lives and
death-throes of massive stars" (in press) -
arXiv:1702.05629
Status: Conference proceedings
Weblink:
http://www.astro.physik.uni-potsdam.de/~www/research/abstracts/hamann-iau329.html
Comments:
Email: wrh@astro.physik.uni-potsdam.de
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November 13th to 17th, 2017
Venue: La
Laguna, Tenerife,
Spain
===========================================================================================
First announcement of the XXIX Canary Islands Winter
School of Astrophysics
Applications of Radiative Transfer
to Stellar and Planetary Atmospheres
La Laguna (Tenerife,
Spain) -- November 13th to 17th, 2017
Website:
www.iac.es/winterschool/2017/
Deadline for both the
Registration and Applications is 23rd June 2017
===========================================================================================
Since 1989, the Instituto de Astrofísica de Canarias
organizes yearly a Winter School whose
aim is to train PhD
students and recent post-docs in frontier topics of Astrophysics.
The XXIX Canary Islands Winter School of Astrophysics, to
be held in San Cristobal de La
Laguna (Tenerife, Spain) in
November 2017, focuses on Applications of Radiative Transfer
to
Stellar and Planetary Atmospheres.
The audience will be
limited to 50 participants. The aim of this Winter School is to bring
together in a relaxed working environment distinguished
scientists who, in recent years,
have paved the way to major
advances in the treatment and applications of radiative
transfer
and young researchers who want to broaden their knowledge in this
specific
field of Astrophysics by attending advanced lectures
and interchanging acquired expertise
and skills among them.
** The deadline for both the Registration and
Applications is 23rd June 2017 **
Distinguished
specialists in their field of research have been invited to give
advanced
lectures on the following topics:
*
Fundamental physical aspects of radiative transfer
*
Mathematical background and computer codes
* Phenomenology and
physics of atmospheres of early-type and late-type stars
*
Phenomenology and physics of atmospheres of brown dwarfs and
extrasolar giant planets
* Near IR high resolution spectroscopy
Lectures will be complemented by tutorial activity
consisting in the running of standard
computer codes to trace
the effects of both physical assumptions and a different choice of
key parameters on the stellar spectra synthesized in the case
of both hot and cool stars.
Participants will have the
opportunity to display their current work by presenting a poster.
The basic registration fee amounts to 350 euros and
includes conference fee, welcome
cocktail, morning and
afternoon coffee during the lecture days, conference dinner, copy of
the proceedings, and visit to the Teide observatory on November
18th (including lunch).
An optional daily trip to the
Roque de los Muchachos Observatory (La Palma) will be
organized
on November 19th. The extra cost of 250 euros includes the flights
from/to
Tenerife/La Palma, transfers, lunch and a guided tour
of the principal telescopes.
A limited number of grants
will be provided by the organization to cover accommodation
(double
room - breakfast included - shared with another participant in Hotel
Nivaria,
a **** hotel in San Cristobal de La Laguna, where
teachers and most participants are
expected to stay).
Rationale of the school:
=======================
The quantitative analysis of the electromagnetic
radiation emitted by astrophysical
objects is the unique tool
we have at hands for the diagnostics of their physical
properties.
The study of stellar atmospheres has experienced in the last decades
a
great step forward, both in theory and computational
techniques. However, a
well-founded fear is starting to arise
that, at the generational turnover, young
practitioners in the
field may lack in a firm grip on the underlying physics and
use
the available computer codes as black-boxes. In addition, radiative
transfer
in Astrophysics is living nowadays a period of
transition from old to new fields
of applications. Among them
the investigation of exoplanets, which implies the
quantitative
study of planetary atmospheres, and the interpretation of high
resolution infrared spectra, for which theoretical progress did
not yet go with the
impressive technological advances achieved.
Therefore, an advanced school dedicated to the
fundamental physical processes in
both stellar and planetary
atmospheres, as well as the bases of the numerical
treatment of
radiative transfer, is more timely than ever, both to prevent the
risk above mentioned and to form researchers with the
background required to face
the present and future challenges.
Lectures and topics:
===================
*
Artemio Herrero (Instituto de Astrofísica de Canarias, Spain)
>>
Fundamental physical aspects of radiative transfer
* Olga
Atanackovic (Faculty of Mathematics, Univ. of Belgrade, Servia):
>>
Numerical methods in radiative transfer
* Mats Carlsson
(Institute of Theoretical Astrophysics, Univ. of Oslo, Norway):
>>
Stellar atmosphere codes
* Joachim Puls
(Universitaetssternwarte der LMU Munchen, Germany):
>>
Radiative transfer in the (expanding) atmospheres of early-type
stars, and related problems
* Maria Bergemann (Institute
for Astronomy, Heidelberg, Germany):
>>
Phenomenology and physics of late-type stars
* Mark S.
Marley (NASA Ames Research Center, Space Science & Astrobiology
Division, USA):
>> Modeling the atmospheres of
brown dwarfs and extrasolar giant planets
* Giuseppe Bono
(Dipartamento di Fisica, Univ. di Roma Tor Vergata, Italy):
>>
Near IR high resolution spectroscopy
* Carlos Allende
Prieto (Instituto de Astrofísica de Canarias, Spain):
>>
Tutorial on the application of radiative transfer codes to the cool
star domain
* Sergio Simón-Díaz (Instituto de
Astrofísica de Canarias, Spain):
>> Tutorial on
the application of radiative transfer codes to the hot star domain
Organizing Committee:
====================
L. Crivellari (Co-Director of the School);
S.
Simón Díaz (Co-Director of the School);
M. J. Arévalo
Morales (Head of the IAC Teaching Department);
R. Rebolo
López (Director of the IAC).
Secretariat:
===========
L. González Pérez
Weblink:
www.iac.es/winterschool/2017
Email:
ssimon@iac.es
Back to contents
August 28 - September 01, 2017
Venue:
Masaryk University, Brno, Czech Republic
Magnetic
fields play an important role in the evolution of all stellar
objects, through their ability to influence and alter the angular
momentum evolution, internal mixing, activity phenomena, surface
abundances and mass-loss of stars. This research field benefits from
new highly accurate measurements and numerical simulations, enabling
stellar astrophysicists to take magnetic fields into account in most
models of stellar structure and evolution. We want to bring together
researchers from different fields where magnetic fields play an
important role to join their efforts and discuss their common
interests.
Main Topics of the Conference:
•Characteristics of surface magnetic fields in early-type
stars
•Magnetic fields and the stellar structure and
evolution
•Magnetism, accretion and braking of PMS stars
•Surface structure formation in the presence of magnetic
field: connection with diffusion and accretion
•Magnetic
field origin and stability
•Magnetically-confined winds
•Stellar pulsations in the presence of global magnetic fields
•Post main sequence evolution of early-type magnetic stars
•Final phases of stellar evolution: magnetism in compact
objects
•The future of magnetic field measurements in hot
stars
The registration is now open. The normal
registration fee is 6000 CZK, the reduced fee for students is 3000
CZK and 1500 CZK for accompanying persons.
The
proceedings of the conference will be published in the Contributions
of the Astronomical
Observatory Skalnaté Pleso.
SOC:
•Adela Kawka, AsU, Czech Republic
•Jiří Krtička,
MU Brno, Czech Republic
•Coralie Neiner, Observatoire de
Paris, France
•Mary Oksala, Observatoire de Paris, France
•Stan Owocki, Univ. Delaware, USA
•Ernst Paunzen
(chair), MU Brno, Czech Republic
•Veronique Petit (chair),
Florida Institute of Technology, USA
•Olga Pintado, CONICET,
Argentina
•Jose Pons, Universitat d'Alacant, Spain
•Gregg
Wade, RMC, Canada
Weblink:
http://magnetic17.physics.muni.cz/
Email:
magnetic17@physics.muni.cz
Back to
contents
June 19 - 23, 2017
Venue: University
of Pittsburgh, Pittsburgh, USA
A five-day workshop which
will bring both observational and theoretical researchers together to
discuss massive stars, LBVs, and Supernova (SN) Impostors will be
held June 19 - 23, 2017 at the University of Pittsburgh.
With
the advent of new surveys, many more SN impostors and peculiar SNe
are being found. These discoveries are challenging our current
understanding of massive star evolution. Some of the questions we
intend to address at the workshop are:
What is the relationship
between massive stars, LBVs and SN impostors?
What can current
observations tell researchers about massive star evolution and
instabilities?
Are Type IIn SNe related to classical LBVs or do
they arise from another mechanism?
Do LBVs originate from the
most massive stars?
Is binarity required for a star to go
through the LBV stage?
How important is inflation for massive
star outbursts?
How do massive stars influence enrichment
leading to molecule and dust formation?
Our tentative
schedule, intended to maximize discussion at each stage, will devote
the first three to four days to massive stars, LBVs and SN impostors
in general. The last one to two days will focus more on Eta Carinae,
one of the most enigmatic objects in our local group of galaxies and
one of the most massive and luminous stars in our galaxy that is
conveniently in the LBV stage. Despite extensive investigations we
still have many outstanding questions: Which star underwent the
outburst? What caused the outburst? How much material was ejected?
What is the enriched ejection telling us about molecules and dust
formation? Were there only the 1840s and 1890s events, or were there
previous massive ejections in addition to the pre-LBV winds? What is
the evolutionary stage of the secondary star?
The
workshop will examine how this massive binary fits into our
understanding of these questions and discuss the studies, both
theoretical and observational, that are needed as the 2020 periastron
event approaches. We will also address what other massive stars, LBVs
and SN impostors can and should be studied to provide new
insights into massive star evolution.
A block of rooms
has been reserved at Hilton Garden Inn Pittsburgh in Oakland
(Pennsylvania), which is within walking distance of the conference
room. Details will be placed on the conference website at
http://kookaburra.phyast.pitt.edu/hillier/Eta2017_workshop in
the near future. There is no registration fee.
As
attendance is limited to approximately 35 participants, all attendees
must be approved by the Scientific Organizing Committee. If you are
interested in attending the workshop, and in presenting a talk,
please send an email to John Hillier at hillier@pitt.edu. Please use
the words "Pittsburgh Workshop" in the subject
line.
Weblink:
http://kookaburra.phyast.pitt.edu/hillier/Eta2017_workshop
Email:
hillier@pitt.edu
Back to contents
June 19 - 23, 2017
Venue: University
of Pittsburgh, Pittsburgh, PA, USA
A five-day workshop
which will bring both observational and theoretical researchers
together to discuss massive stars, LBVs, and Supernova (SN) Impostors
will be held June 19 - 23, 2017 at the University of Pittsburgh.
With the advent of new surveys, many more SN impostors
and peculiar SNe are being found. These discoveries are challenging
our current understanding of massive star evolution. Some of the
questions we intend to address at the workshop are:
What is the
relationship between massive stars, LBVs and SN impostors?
What
can current observations tell researchers about massive star
evolution and instabilities?
Are Type IIn SNe related to
classical LBVs or do they arise from another mechanism?
Do LBVs
originate from the most massive stars?
Is binarity required for
a star to go through the LBV stage?
How important is inflation
for massive star outbursts?
How do massive stars influence
enrichment leading to molecule and dust formation?
Our
tentative schedule, intended to maximize discussion at each stage,
will devote the first three to four days to massive stars, LBVs and
SN impostors in general. The last one to two days will focus more on
Eta Carinae, one of the most enigmatic objects in our local group of
galaxies and one of the most massive and luminous stars in our galaxy
that is conveniently in the LBV stage. Despite extensive
investigations we still have many outstanding questions: Which star
underwent the outburst? What caused the outburst? How much material
was ejected? What is the enriched ejection telling us about molecules
and dust formation? Were there only the 1840s and 1890s events, or
were there previous massive ejections in addition to the pre-LBV
winds? What is the evolutionary stage of the secondary star?
The
workshop will examine how this massive binary fits into our
understanding of these questions and discuss the studies, both
theoretical and observational, that are needed as the 2020 periastron
event approaches. We will also address what other massive stars, LBVs
and SN impostors can and should be studied to provide new insights
into massive star evolution.
A block of rooms has been
reserved at Hilton Garden Inn Pittsburgh in Oakland (Pennsylvania),
which is within walking distance of the conference room. Details will
be placed on the conference website at
http://kookaburra.phyast.pitt.edu/hillier/Eta2017_workshop in
the near future. There is no registration fee.
As
attendance is limited to approximately 35 participants, all attendees
must be approved by the Scientific Organizing Committee. If you are
interested in attending the workshop, and in presenting a talk,
please send an email to John Hillier at hillier@pitt.edu. Please use
the words "Pittsburgh Workshop" in the subject
line.
Weblink:
http://kookaburra.phyast.pitt.edu/hillier/Eta2017_workshop/
Email:
hillier@pitt.edu
Back to contents
July 6 2017
Venue: NAM (UK)
National Astronomy Meeting (Hull, England)
The discovery
of gravitational waves from the merger of two Black Holes -- with
masses 30-40 times that of the Sun -- has raised the question of how
our Universe was capable of producing such large masses. These stars
must have been very massive to begin with, and should not have lost
much mass during their lives, hinting at a low metallicity
environment.
We propose to bring together experts in blue
massive OB, Wolf-Rayet (WR) stars, red supergiants (RSGs), and both
canonical and superluminous supernovae (SNe), as well as massive
binaries, including high-mass X-ray binaries (HMXBs) and
ultra-luminous X-rays sources (ULXs).
We will bring
together stellar evolution theorists and observers of massive stars
in the Milky Way and the local low-metallicity Universe (LMC, SMC) as
well as larger distances at higher redshift, including Ly alpha
emitters and Lyman-break galaxies (LBGs) to tackle the question
of
how the properties, evolution, and fate of massive stars in the
earlier Universe is fundamentally different from that at solar
metallicity.
Finally, we will discuss the role of massive
stars for the line emission seen in high redshift galaxies and their
role in cosmic reionisation.
SOC: Jorick Vink (Chair),
Elizabeth Stanway & Ben Davies
Invited speakers:
Jose Groh (Dublin):
"The surprising look of
massive stars before death"
Miriam Garcia (Madrid):
"Towards the first (very massive) stars of the Universe:
First Stop"
Rebecca Bowler (Oxford):
"No
evidence for Population III stars or a Direct Collapse Black Hole in
the z = 6.6 Lyman-alpha emitter CR7"
ABSTRACT
DEADLINE: *April 14*
Weblink:
https://nam2017.org/
Email: jsv@arm.ac.uk
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11 - 13 Sept 2017
Venue: Heraklion,
Crete
On the line of the previous workshops (BeXRB 2011
and BeXRB 2014), a new meeting will take place in Heraklion on 11-13
September 2017.
Be stars, Be disks & models in the
context of explaining the BeXRB phenomenon.
Phenomenology
of BeXRB transient outbursts in the X-ray domain (normal vs giant,
pre-flares, complex shaped outbursts, pulse profiles ...).
Observations in other wavebands and their implications.
BeXRBs in external galaxies compared to the Milky Way
population.
The high-energy gamma-ray connection (LS I
+61 303, HESS J0632+057 & PSR B1259-63)
Transient
outbursts as laboratories of accretion physics.
BeXRBs
with Black Hole or White Dwarf companions.
Weblink:
https://sites.google.com/site/bexrb2017/
Email:
mjcoe@soton.ac.uk
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