ISSN 1783-3426
|
Talks from Sp7@EWASS2015 "Science
with large spectroscopic surveys of Galactic OB stars: getting ready
for Gaia" now available online
Athena
Science Working Groups
Update on
the Complementary Science Program of the ESA PLATO mission (PLATO-CS:
launch 2024, 6 years of operations)
Shape and evolution of wind-blown
bubbles of massive stars: on the effect of the interstellar magnetic
field
Characterizing the Rigidly
Rotating Magnetosphere Stars HD 345439 and HD 23478
Cold
gas in hot star clusters: the wind from the red supergiant W26 in
Westerlund 1
Accurate fundamental
parameters and distance to a massive early-type eclipsing binary in
the Danks 2 cluster
Magnetically
Confined Wind Shocks in X-rays - a Review
X-ray
emission from interacting massive binaries: a review of 15 years of
progress
A Runaway Red Supergiant
in M31
Identification of dusty
massive stars in star-forming dwarf irregular galaxies in the Local
Group with mid-IR photometry
Massive
open star clusters using the VVV survey IV. WR 62-2, a new very
massive star in the core of the VVV CL041 cluster
The
Impact of Enhanced Iron Opacity on Massive Star Pulsations: Updated
Instability Strips
Properties of
massive stars in four clusters of the VVV survey
Massive star population synthesis with
binaries
The True origin of
Wolf-Rayet stars
Postdoctoral Position: Circumstellar
Disks
Postdoctoral position in
stellar astrophysics
PhD Position on Quantitative Spectroscopy
Supernova Remnants: An Odyssey In Space After Stellar Death
Dear friends,
For your interest, the talks from
the Special Session "Science with large spectroscopic surveys of
Galactic OB stars: getting ready for Gaia" held during the last
EWASS are now available online in the link below. Thanks to all who
participated in this meeting!
The organizers (S. Simón-Díaz
& F. Martins)
Weblink:
http://www.iac.es/proyecto/iacob/pages/sp7ewass2015.php
Email:
ssimon@iac.es
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Dear Colleagues,
ESA is currently studying the
next generation X-ray observatory called Athena to be launched in
2028. Approximately 1 year ago the Athena Science Study Team (ASST)
issued a call for membership of the Athena Working Groups who assist
ESA in this exercise.
To ensure that all interested
scientists, willing to dedicate some time to the preparation of
Athena, have an opportunity to participate, ASST has recently
re-opened the application process at the following web site:
http://fs6.formsite.com/ATHENA2028/form4/index.html
The
Working Groups are divided into a number of sub-panels (Topical
Panels) covering specific subject areas. In particular, Topical Panel
SWG3.2 deals with "Star formation and evolution" and
addresses the science relevant for massive stars research.
New
candidates are expected to apply for membership of a single Topical
Panel. In exceptional circumstances, you may request membership of
two panels, but in this case you are asked to provide a
justification.
The deadline for applications is 31 December
2015. Applications will be assessed soon after this with the aim to
appoint new members in February 2016.
Thanks for your
support.
Gregor Rauw, co-chair of topical panel
SWG3.2
Weblink:
http://fs6.formsite.com/ATHENA2028/form4/index.html
Email:
rauw@astro.ulg.ac.be
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- 8% of the observing time will
be used for PLATO-CS; this implies some 40,000
targets per
pointing (there are 2 long pointings of 3&2 years each,
and a
step-and-star phase with several pointings of several weeks each);
- ESA will install a Guest Observer program with calls to the
community to
decide about the targets for PLATO-CS; successful
Guest Observers will have 1
year proprietory rights. The GO
programme is open to anyone interested;
- a
Target-of-Opportunity (ToO) option has been accepted for the mission
so that
transient phenomena can be observed (reaction time to
measure ToO is
to be worked out with ESA);
PLATO has
various observing modes, including 2-colour information for the
brightest objects, downloading of imagettes, lightcurves computed
onboard,
etc. Various sampling rates will be used, ranging from
2.5 to 600 seconds.
Registered participants will be updated
on PLATO-CS and will be able to provide
input on the definition
and organisation of the GO procedures. New participants
are
welcome:
https://fys.kuleuven.be/ster/Projects/plato-cs/registration
PLATO-CS conferences will be organised on a regular basis as
of 2017, with the
aim to discuss the field and target selection,
optimal observing strategies and
analyses methods, etc. so as to
ensure excellent science exploitation of the
mission.
Best
regards,
Conny Aerts, Coordinator PLATO-CS
Weblink:
https://fys.kuleuven.be/ster/Projects/plato-cs/home
Email:
conny.aerts@ster.kuleuven.be
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contents
Allard Jan van Marle$^{1,2}$,
Zakaria Meliani$^{3,4}$,
and
Alexandre Marcowith$^5$
1-Centre for mathematical
Plasma-Astrophysics, University of Leuven;
2-Institute of
Astronomy, University of Leuven;
3-LuTh, Observatoire de Paris;
4-APC, Universite Paris Diderot;
5-LUPM, Universite
Montpellier;
The winds of massive stars create large (>10
pc) bubbles around their progenitors. As these bubbles expand they
encounter the interstellar coherent magnetic field which, depending
on its strength, can influence the shape of the bubble. We wish to
investigate if, and how much, the interstellar magnetic field can
contribute to the shape of an expanding circumstellar bubble around a
massive star. We use the MPI-AMRVAC code to make
magneto-hydrodynamical simulations of bubbles, using a single star
model, combined with several different field strengths: B=5, 10, and
20 muG for the interstellar magnetic field. This covers the typical
field strengths of the interstellar magnetic fields found in the
galactic disk and bulge. Furthermore, we present two simulations that
include both a 5 muG interstellar magnetic field and a 10,000 K
interstellar medium and two different ISM densities to demonstrate
how the magnetic field can combine with other external factors to
influnece the morphology of the circumstellar bubbles. Our results
show that low magnetic fields, as found in the galactic disk, inhibit
the growth of the circumstellar bubbles in the direction
perpendicular to the field. As a result, the bubbles become ovoid,
rather than spherical. Strong interstellar fields, such as observed
for the galactic bulge, can completely stop the expansion of the
bubble in the direction perpendicular to the field, leading to the
formation of a tube-like bubble. When combined with a warm,
high-density ISM the bubble is greatly reduced in size, causing a
dramatic change in the evolution of temporary features inside the
bubble. The magnetic field of the interstellar medium can affect the
shape of circumstellar bubbles. This effect may have consequences for
the shape and evolution of circumstellar nebulae and supernova
remnants, which are formed within the main wind-blown
bubble.
Reference: Astronomy & Astrophysics
Status:
Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1509.00192
Email:
allardjan.vanmarle@wis.kuleuven.be
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J. P. Wisniewski(1), S. D. Chojnowski(2), J.R.A.
Davenport(3), J. Bartz(4), J. Pepper(4), D. G. Whelan(5), S. S.
Eikenberry(6), J. R. Lomax(1), S. R. Majewski(7), N.D.
Richardson(8,9), M. Skrutskie(7)
(1) University of
Oklahoma, (2) New Mexico State University, (3) University of
Washington, (4) Lehigh University, (5) Austin College, (6) University
of Florida, (7) University of Virginia, (8) CRAQ, (9) University of
Montreal
The SDSS III APOGEE survey recently identified two
new sigma Ori E type candidates, HD 345439 and HD 23478, which are a
rare subset of rapidly rotating massive stars whose large (kGauss)
magnetic fields confine circumstellar material around these systems.
Our analysis of multi-epoch photometric observations of HD 345439
from the KELT, SuperWASP, and ASAS surveys reveals the presence of a
~0.7701 day period in each dataset, suggesting the system is amongst
the faster known sigma Ori E analogs. We also see clear evidence that
the strength of H-alpha, H I Brackett series lines, and He I lines
also vary on a ~0.7701 day period from our analysis of multi-epoch,
multi-wavelength spectroscopic monitoring of the system from the APO
3.5m telescope. We trace the evolution of select emission line
profiles in the system, and observe coherent line profile variability
in both optical and infrared H I lines, as expected for rigidly
rotating magnetosphere stars. We also analyze the evolution of the H
I Br-11 line strength and line profile in multi-epoch observations of
HD 23478 from the SDSS-III APOGEE instrument. The observed periodic
behavior is consistent with that recently reported by Sikora and
collaborators in optical spectra.
Reference: Accepted
in ApJL
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1509.00128
Email:
wisniewski@ou.edu
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Jonathan Mackey (1,2), Norberto Castro (2), Luca Fossati
(2), Norbert Langer (2)
(1) I. Physikalisches Institut,
Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
(2) Argelander-Institut für Astronomie, Auf dem Hügel 71, 53121
Bonn, Germany
The massive red supergiant W26 in Westerlund 1
is one of a growing number of red supergiants shown to have winds
that are ionized from the outside in. The fate of this dense wind
material is important for models of second generation star formation
in massive star clusters. Mackey et al. (2014) showed that external
photoionization can stall the wind of red supergiants and accumulate
mass in a dense static shell. We use spherically symmetric
radiation-hydrodynamic simulations of an externally photoionized wind
to predict the brightness distribution of Halpha and [N II] emission
arising from photoionized winds both with and without a dense shell.
We analyse spectra of the Halpha and [N II] emission lines in the
circumstellar environment around W26 and compare them with
simulations to investigate whether W26 has a wind that is confined by
external photoionization. Simulations of slow winds that are
decelerated into a dense shell show strongly limb-brightened line
emission, with line radial velocities that are independent of the
wind speed. Faster winds (>22 km/s) do not form a dense shell,
have less limb-brightening, and the line radial velocity is a good
tracer of the wind speed. The brightness of the [N II] and Halpha
lines as a function of distance from W26 agrees reasonably well with
observations when only the line flux is considered. The radial
velocity of the simulated winds disagrees with observations, however:
the brightest observed emission is blueshifted by 25 km/s relative to
the radial velocity of the star, whereas a spherically symmetric wind
has the brightest emission at zero radial velocity because of limb
brightening. Our results show that the bright nebula surrounding W26
must be asymmetric, and we suggest that it is confined by external
ram pressure from the extreme wind of the nearby supergiant W9. We
obtain a lower limit on the nitrogen abundance within the nebula of
2.35 times solar. The line ratio strongly favours photoionization
over shock ionization, and so even if the observed nebula is pressure
confined there should still be an ionization front and a
photoionization-confined shell closer to the star that is not
resolved by the current observations, which could be tested with
better spectral resolution and spatial coverage.
Reference:
DOI:10.1051/0004-6361/201526159, arXiv:1508.07003
Status:
Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2015arXiv150807003M
Comments:
Astronomy & Astrophysics, in press
Email:
mackey@ph1.uni-koeln.de
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M. Kourniotis$^1,2$, A.Z. Bonanos$^1$, S.J. Williams$^1$,
N. Castro$^3$, E. Koumpia$^4$, J.L. Prieto$^5,6$
1 -
IAASARS, National Observatory of Athens, GR-15236 Penteli, Greece; 2
- Section of Astrophysics, Astronomy and Mechanics, Faculty of
Physics, University of Athens, Panepistimiopolis, GR15784 Zografos,
Athens, Greece; 3 - Argelander-Institut für Astronomie der
Universität Bonn, Auf dem Hügel 71, 53121, Bonn, Germany; 4 - SRON
Netherlands Institute for Space Research, Landleven 12, 9747 AD
Groningen, The Netherlands; Kapteyn Institute, University of
Groningen, The Netherlands; 5 - Nucleo de Astronomia de la Facultad
de Ingenieria, Universidad Diego Portales, Av. Ejercito 441,
Santiago, Chile; 6 - Millennium Institute of Astrophysics, Santiago,
Chile
We present a study of the properties of the O-type,
massive eclipsing binary 2MASS J13130841-6239275 located in the
outskirts of the Danks 2 cluster in the G305 star-forming complex,
using near-infrared spectroscopy from VLT/ISAAC. We derive the masses
and radii to be 24.5±0.9 M$_{\sun}$ and 9.2±0.1 R$_{\sun}$ for the
primary and 21.7±0.8 M$_{\sun}$ and 8.7±0.1 R$_{\sun}$ for the
secondary component. In addition, we evaluate the sensitivity of our
parameters to the choice of the spectral features used to determine
the radial velocities. Both components appear to be main-sequence
O6.5-O7 type stars at an age of ~5 Myr, which is in agreement with
the age of the cluster. A high visual extinction of A_{5495}=11.9±0.1
mag is reported, which is likely attributed to the cold molecular gas
contaminating the north-east region of the cluster. By fitting the
spectral energy distribution of the system to the available
BVI_{c}JHK_{s} photometry, we determine a distance to the system of
3.52±0.08 kpc with a precision of 2%, which is the most
well-determined distance to the Danks 2 cluster and the host complex
reported in the literature.
Reference: A&A, in
press.
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1508.05939
Comments:
13 pages, 9 figures, 6 tables.
Email:
mkourniotis@astro.noa.gr
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contents
Asif ud-Doula (1), Yael Naze (2)
1 - Penn State
Worth. Scranton ; 2 - ULg
A subset ($\sim$ 10\%) of massive
stars present strong, globally ordered (mostly dipolar) magnetic
fields. The trapping and channeling of their stellar winds in closed
magnetic loops leads to magnetically confined wind shocks (MCWS),
with pre-shock flow speeds that are some fraction of the wind
terminal speed. These shocks generate hot plasma, a source of X-rays.
In the last decade, several developments took place, notably the
determination of the hot plasma properties for a large sample of
objects using XMM-Newton and Chandra, as well as fully
self-consistent MHD modelling and the identification of shock retreat
effects in weak winds. Despite a few exceptions, the combination of
magnetic confinement, shock retreat and rotation effects seems to be
able to account for X-ray emission in massive OB stars. Here we
review these new observational and theoretical aspects of this X-ray
emission and envisage some perspectives for the next generation of
X-ray observatories.
Reference: accepted for
publication by Advances in Space Research (special issue "X-ray
emission from hot stars and their winds")
Status: Manuscript
has been accepted
Weblink:
http://arxiv.org/abs/1509.06482
Email:
naze@astro.ulg.ac.be
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Gregor Rauw, Yael Naze
University of Liege,
Belgium
Previous generations of X-ray observatories revealed a
group of massive binaries that were relatively bright X-ray emitters.
This was attributed to emission of shock-heated plasma in the
wind-wind interaction zone located between the stars. With the advent
of the current generation of X-ray observatories, the phenomenon
could be studied in much more detail. In this review, we highlight
the progress that has been achieved in our understanding of the
phenomenon over the last 15 years, both on theoretical and
observational grounds. All these studies have paved the way for
future investigations using the next generation of X-ray satellites
that will provide crucial information on the X-ray emission formed in
the innermost part of the wind-wind interaction.
Reference:
Advances in Space Research, special issue on "X-ray Emission
from Hot Stars and their Winds"
Status: Manuscript has been
accepted
Weblink: arXiv:1509.06480
Comments:
Email: rauw@astro.ulg.ac.be
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Kate Anne Evans (1,2) and Philip Massey (1,3)
1
- Lowell Observatory, Flagstaff, AZ 86001;
2 - REU participant,
currently at the California Institute of Technology, Pasadena, CA
91125;
3 - Department of Physics and Astronomy, Northern Arizona
University, Flagstaff, AZ 86011
A significant percentage of OB
stars are runaways, so we should expect a similar percentage of their
evolved descendants to also be runaways. However, recognizing such
stars presents its own set of challenges, as these older, more
evolved stars will have drifted further from their birthplace, and
thus their velocities might not be obviously peculiar. Several
Galactic red supergiants (RSGs) have been described as likely
runaways, based upon the existence of bow shocks, including
Betelgeuse. Here we announce the discovery of a runaway RSG in M31,
based upon a 300 km/s discrepancy with M31's kinematics. The star is
found about 21' (4.6 kpc) from the plane of the disk, but this
separation is consistent with its velocity and likely age (~10 Myr).
The star, J004330.06+405258.4, is an M2 I, with an absolute visual
magnitude of -5.7, log(L/L(solar))=4.76, an effective temperature of
3700 K, and an inferred mass of 12-15 solar masses. The star may be a
high-mass analog of the hypervelocity stars, given that its peculiar
space velocity is probably 400-450 km/s, comparable to the escape
speed from M31's disk.
Reference: Astronomical Journal
(in press)
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1509.07251
Comments:
Email: kevans@caltech.edu
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N. E. Britavskiy (1), A. Z. Bonanos (1), A. Mehner (2), M.
L. Boyer (3), K. B. W. McQuinn (4)
(1) IAASARS, National
Observatory of Athens, Greece
(2) ESO -- European Organisation
for Astronomical Research in the Southern Hemisphere, Chile
(3)
Observational Cosmology Lab, Code 665, NASA Goddard Space Flight
Center, USA
(4) Minnesota Institute for Astrophysics, School of
Physics and Astronomy, USA
Increasing the statistics of
spectroscopically confirmed evolved massive stars in the Local Group
enables the investigation of the mass loss phenomena that occur in
these stars in the late stages of their evolution. We aim to complete
the census of luminous mid-IR sources in star-forming dwarf irregular
(dIrr) galaxies of the Local Group. To achieve this we employed
mid-IR photometric selection criteria to identify evolved massive
stars, such as red supergiants (RSGs) and luminous blue variables
(LBVs), by using the fact that these types of stars have infrared
excess due to dust. The method is based on 3.6 μm and 4.5 μm
photometry from archival Spitzer Space Telescope images of nearby
galaxies. We applied our criteria to 4 dIrr galaxies: Pegasus,
Phoenix, Sextans A, and WLM, selecting 79 point sources, which we
observed with the VLT/FORS2 spectrograph in multi-object spectroscopy
mode. We identified 13 RSGs, of which 6 are new discoveries, also 2
new emission line stars, and 1 candidate yellow supergiant. Among the
other observed objects we identified carbon stars, foreground giants,
and background objects, such as a quasar and an early-type galaxy
that contaminate our survey. We use the results of our spectroscopic
survey to revise the mid-IR and optical selection criteria for
identifying RSGs from photometric measurements. The optical selection
criteria are more efficient in separating extragalactic RSGs from
foreground giants than mid-IR selection criteria, however the mid-IR
selection criteria are useful for identifying dusty stars in the
Local Group. This work serves as a basis for further investigation of
the newly discovered dusty massive stars and their host
galaxies.
Reference: arXiv:1510.01340, A&A in
press.
Status: Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1510.01340
Comments:
Email: britavskiy@noa.gr
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A.-N. Chené (1), S. Ramírez Alegría (2,3), J. Borissova
(2,3), E. O'Leary (1), F. Martins (4), A. Hervé (4,5), M. Kuhn
(2,3), R. Kurtev (2,3), P. Consuelo Amigo Fuentes (2,3), C. Bonatto
(6), D. Minniti (3,7,8,9)
1 - Gemini Observatory, 2 - U.
de Valparaíso, 3 - Millennium Institute of Astrophysics, 4 - U.
Montpellier, 5 - Astronomical Institute of the ASCR, 6 - U. Federal
do Rio Grande do Sul, 7- Pontificia Universidad Católica de Chile, 8
- Vatican Observatory, 9 - Universidad Andres Bello
Context
The ESO Public Survey VISTA Variables in the V\'ia L\'actea (VVV)
provides deep multi-epoch infrared observations for an unprecedented
562 sq. degrees of the Galactic bulge and adjacent regions of the
disk. Nearly 150 new open clusters and cluster candidates have been
discovered in this survey. Aims We present the fourth article in a
series of papers focussed on young and massive clusters discovered in
the VVV survey. This article is dedicated to the cluster VVV CL041,
which contains a new very massive star candidate, WR 62-2. Methods
Following the methodology presented in the first paper of the series,
wide-field, deep JHKs VVV observations, combined with new infrared
spectroscopy, are employed to constrain fundamental parameters
(distance, reddening, mass, age) of VVV CL041. Results We confirm
that the cluster VVV CL041 is a young (less than 4 Myrs) and massive
(3 +/- 2 x 10^3 Msol) cluster, and not a simple asterism. It is
located at a distance of 4.2 +/- 0.9 kpc, and its reddening is A_V =
8.0 +/- 0.2 mag, which is slightly lower than the average for the
young clusters towards the centre of the Galaxy. Spectral analysis
shows that the most luminous star of the cluster, of the WN8h
spectral type, is a candidate to have an initial mass larger than 100
Msol.
Reference: A&A in press,
arXiv:1510.02539
Status: Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2015arXiv151002539C
Comments:
Email: andrenicolas.chene@gmail.com
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Ehsan Moravveji
Institute of Astronomy, KU
Leuven
Recently, Bailey et al. (2015) made a direct
measurement of the Iron opacity at the physical conditions of the
solar tachocline. They found that the wavelength-integrated Iron
opacity is roughly 75% higher than what the OP and OPAL models
predict. Here, we compute new opacity tables with enhanced Iron and
Nickel contributions to the Rosseland mean opacity by 75% each, and
compute three dense MESA grids of evolutionary models for Galactic O-
and B-type stars covering from 2.5 to 25 M_sun from ZAMS until
T_eff=10 000 K after the core hydrogen exhaustion. We carry out
non-adiabatic mode stability analysis with GYRE, and update the
extension of the instability strips of heat-driven p- and g-mode
pulsators, and the hybrid pulsating SPB - beta Cep stars.
We
compare the position of two confirmed late O-type beta Cep and eight
confirmed hybrid B-type pulsators with the new instability domains,
and justify that ~75% enhancement, only in Iron opacity, is
sufficient to consistently reproduce the observed position of these
stars on the log T_eff versus log g plane. We propose that this
improvement in opacities be incorporated in the input physics of new
stellar models.
Reference: MNRAS Letters, in
press
Status: Manuscript has been accepted
Weblink:
http://adsabs.harvard.edu/abs/2015arXiv150908652M
Comments:
All software to compute new opacity tables, the pre-compiled
opacity tables and the new instability strips are freely available
for download through the following URL:
https://fys.kuleuven.be/ster/Projects/ASAMBA
Email:
Ehsan.Moravveji@ster.kuleuven.be
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A. Hervé^1,2, F. Martins^2,
A.-N. Chené^3, J.-C. Bouret^4, J. Borissova^5,6,7
1
Astronomical Institute ASCR, Czech Republic
2 LUPM, Université
de Montpellier, CNRS, Montpellier, France
3 Gemini Observatory,
Hilo, Hawaii
4 Laboratoire d’Astrophysique de Marseille, France
5 Instituto de Fısica y Astronomıa, U. de Valparaıso, Casilla,
Chile
6 The Milky Way Millennium Nucleus, Santiago, Chile
7
Millenium Institute of Astrophysics, Valparaiso, Chile
The
evolution of massive stars is only partly understood. Observational
constraints can be obtained from the study of massive stars located
in young massive clusters. The ESO Public Survey VISTA Variables in
the Via Lactea (VVV) discovered several new clusters hosting massive
stars. We present an analysis of massive stars in four of these new
clusters. Our aim is to provide constraints on stellar evolution and
to better understand the relation between different types of massive
stars. We use the radiative transfer code CMFGEN to analyse K-band
spectra of twelve stars with spectral types ranging from O and B to
WN and WC. We derive the stellar parameters of all targets as well as
surface abundances for a subset of them. In the Hertzsprung-Russell
diagram, the Wolf-Rayet stars are more luminous or hotter than the O
stars. From the log(C/N) - log(C/He) diagram, we show quantitatively
that WN stars are more chemically evolved than O stars, WC stars
being more evolved than WN stars. Mass loss rates among Wolf-Rayet
stars are a factor of 10 larger than for O stars, in agreement with
previous findings.
Reference: New Astronomy
Status:
Manuscript has been accepted
Weblink:
http://arxiv.org/abs/1510.07450
Comments:
Email: herve@asu.cas.cz
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D. Vanbeveren and N. Mennekens
AARG, Vrije
Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
We
first give a short historical overview with some key facts of massive
star population synthesis with binaries. We then discuss binary
population codes and focus on two ingredients which are important for
massive star population synthesis and which may be different in
different codes. Population simulations with binaries is the third
part where we consider the initial massive binary frequency, the
RSG/WR and WC/WN and SNII/SNIbc number ratio's, the probable initial
rotational velocity distribution of massive stars.
Reference:
Review paper to appear in the conference proceedings of the June
2015 Potsdam WR workshop, edited by W.-R. Hamann, A. Sander, and H.
Todt
Status: Conference proceedings
Weblink: arXiv:
1508.04282
Email: dvbevere@vub.ac.be
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Jorick S. Vink
Armagh Observatory
The
Wolf-Rayet (WR) phenomenon is widespread in astronomy. It involves
classical WRs, very massive stars (VMS), WR central stars of
planetary nebula CSPN [WRs], and supernovae (SNe). But what is the
root cause for a certain type of object to turn into an emission-line
star? In this contribution, I discuss the basic aspects of radiation
driven winds that might reveal the ultimate difference between WR
stars and canonical O-type stars. I discuss the aspects of (i)
self-enrichment via CNO elements, (ii) high effective temperatures
(Teff), (iii) an increase in the helium abundance (Y), and finally
(iv) the Eddington factor Gamma. Over the last couple of years, we
have made a breakthrough in our understanding of Gamma-dependent mass
loss, which will have far-reaching consequences for the evolution and
fate of the most massive stars in the Universe. Finally, I discuss
the prospects for studies of the WR phenomenon in the highest
redshift Ly-alpha and He II emitting galaxies.
Reference:
To appear in proceedings of International Workshop on Wolf-Rayet
Stars (editors W.R. Hamann, A. Sander, and H. Todt) publisher
Universitatsverlag Potsdam
Status: Conference
proceedings
Weblink: astro-ph/1366754
Email:
jsv@arm.ac.uk
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John Wisniewski
University of Oklahoma
Department of Physics & Astronomy
440 W Brooks St
Norman, OK 73019 USA
Applications are invited for a
postdoctoral research position in observational studies of
circumstellar disks at the University of Oklahoma. The successful
applicant will work with Dr John Wisniewski and will analyze ground-
and space-based photometric and polarimetric observations of
circumstellar disk systems.
Applicants must have a Ph.D. in
Astronomy or Physics. Previous experience analyzing circumstellar
disks or polarimetric imagery is highly desirable. The initial
appointment will be for 1 year, renewable for additional years
contigent on satisfactory performance and continued funding. The
expected start date for the position is August 2016 or earlier.
To
apply, send a curriculum vitae, bibliography, and statement of
research interests to wisniewski@ou.edu with the subject line
"Postdoc position: circumstellar disks". Pdf format is
preferred. Applicants should also arrange for 3 letters of reference
to be submitted. Applications received by December 15, 2015 will
receive full consideration.
Weblink:
http://jobregister.aas.org/job_view?JobID=51794
Email:
wisniewski@ou.edu
Deadline: Dec 15, 2015
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Emily Levesque
University of Washington
Department
of Astronomy
Box 351580
Seattle, WA 98195 USA
Applications
are invited for a full time postdoctoral position in stellar
astrophysics at the University of Washington. The candidate will work
with Prof. Emily Levesque on observational and theoretical studies of
massive stars. Of particular interest are postdoctoral candidates
interested in the role of massive star populations in star-forming
galaxies; progenitors and host galaxies of transient events;
asteroseismology; or the late stages of massive star evolution. The
successful candidate will have the opportunity to join existing
projects and will also be encouraged to develop and pursue their own
research program.
The position is initially for two years,
with a possible extension for a third year subject to a performance
review and availability of funds. The successful candidate must have
a Ph.D. in Physics, Astronomy, or a related field by the start date
of the position (nominally September 1, 2016).
To be
considered for the position, please send the following application
materials as a single PDF to Prof. Emily Levesque at emsque@uw.edu :
1) curriculum vitae, 2) list of publications, and 3) summary of
previous and current research (no more than three pages). Applicants
should also arrange for three letters of reference to be submitted to
the same email address directly from the writers by the deadline. To
receive full consideration, all application materials must be
received by January 1, 2016.
University of Washington faculty
engage in teaching, research and service. The University of
Washington is an affirmative action and equal opportunity employer.
All qualified applicants will receive consideration for employment
without regard to race, color, religion, sex, sexual orientation,
gender identity, national origin, age, protected veteran or disabled
status, or genetic information.
Weblink:
http://ap.washington.edu/ahr/academic-jobs/position/nn14451/
Email:
emsque@uw.edu
Deadline: 1 January 2016
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Norbert Przybilla
Institute
for Astro- and Particle Physics
University of Innsbruck
Technikerstr. 25/8
6020 Innsbruck
Austria
Applications
are invited to a newly established doctoral programme in physics
"Atoms, Light, and Molecules" at the University of
Innsbruck. One of the PhD projects addresses quantitative
spectroscopy of massive stars, with a focus on non-LTE modelling of
light-matter interactions.
Attention/Comments: For
additional information on the project contact
Norbert Przybilla,
phone +43 512 50752100, email: norbert.przybilla@uibk.ac.at
Further
information regarding the doctoral programme and the application
procedure are outlined under the following weblink.
Weblink:
http://www.uibk.ac.at/dk-alm/index.html.en
Email:
norbert.przybilla@uibk.ac.at
Deadline: November 6,
2015
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June 6-11, 2016
Venue: Chania, Crete,
Greece
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), T. Temim
(USA), S. Van Dyk (USA), B. Williams (USA)
Weblink:
http://snr2016.astro.noa.gr/
Email:
bonanos@astro.noa.gr
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