scholarly journals Red noise and pulsations in evolved massive stars

2021 ◽  
Author(s):  
Yaël Nazé ◽  
Gregor Rauw ◽  
Eric Gosset
Keyword(s):  
High Frequency ◽  
Massive Stars ◽  
Ob Stars ◽  
Luminous Blue Variables ◽  
Clean Sample ◽  
High Cadence

Abstract We examine high-cadence space photometry taken by the Transiting Exoplanet Survey Satellite (TESS) of a sample of evolved massive stars (26 Wolf-Rayet stars and 8 Luminous Blue Variables or candidate LBVs). To avoid confusion problems, only stars without bright Gaia neighbours and without evidence of bound companions are considered. This leads to a clean sample, whose variability properties should truly reflect the properties of the WR and LBV classes. Red noise is detected in all cases and its fitting reveals characteristics very similar to those found for OB-stars. Coherent variability is also detected for 20% of the WR sample. Most detections occur at moderately high frequency (3–14 d−1), hence are most probably linked to pulsational activity. This work doubles the number of WRs known to exhibit high-frequency signals.

scholarly journals Working Group on Hot Massive Stars (Groupe De Travail Sur Les Etoiles Massives Chaudes)

2000 ◽  
Vol 24 (1) ◽  
pp. 176-185
Author(s):  
Philippe Eenens ◽  
Joseph Cassinelli ◽  
Peter Conti ◽  
Catharine Garmany ◽  
Karel van der Hucht ◽  
...  
Keyword(s):  
Executive Committee ◽  
Working Group ◽  
Collaborative Research ◽  
Massive Stars ◽  
Starburst Galaxies ◽  
General Assembly ◽  
Hot Stars ◽  
Ob Stars ◽  
Luminous Blue Variables

The Working Group on Hot Massive Stars has been officially recognized by the IAU Executive Committee during the XXIII General Assembly in August 1997. Its origins are the Hot Star Newsletter, launched in 1994, and a long tradition of interaction and collaborative research strengthened by a series of meetings on hot beaches. It gathers over 500 researchers working on OB stars, Luminous Blue Variables, Wolf-Rayet stars, and in general all topics related to the evolution of massive stars and to the physics and consequences of winds from hot stars. The very successful recent symposium on “Wolf-Rayet phenomena in massive stars and starburst galaxies” is an indicator of the increasing interest of the extragalactic community in the study of these extraordinary stars.

scholarly journals Searching for emission line and OB stars in Cl 1806-20 using a NIR narrow-band technique

2010 ◽  
Vol 6 (S272) ◽  
pp. 606-607 ◽  
Author(s):  
Michelle L. Edwards ◽  
Reba M. Bandyopadhyay ◽  
Stephen S. Eikenberry ◽  
Valerie J. Mikles ◽  
Dae-Sik Moon
Keyword(s):  
Emission Line ◽  
Massive Star ◽  
Near Infrared ◽  
Narrow Band ◽  
Massive Stars ◽  
Narrow Band Imaging ◽  
Ob Stars ◽  
Luminous Blue Variables ◽  
Upper Limit

AbstractWe survey the environment of Cl 1806-20 using near-infrared narrow-band imaging to search for Brγ features indicative of evolved massive stars. Using this technique, we successfully detect previously identified massive stars in the cluster. We detect no new emission line stars, establishing a firm upper limit on the number of Wolf Rayets and Luminous Blue Variables; however, we do find several candidate OB supergiants, which likely represent the bulk of the heretofore undiscovered massive star population.

scholarly journals The Complex Upper HR Diagram

Galaxies ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 75
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Historical Overview ◽  
Ob Stars ◽  
Luminous Blue Variables ◽  
Evolved Stars ◽  
Nearby Galaxies ◽  
Introductory Review ◽  
Hr Diagram

Several decades of observations of the most massive and most luminous stars have revealed a complex upper HR Diagram, shaped by mass loss, and inhabited by a variety of evolved stars exhibiting the consequences of their mass loss histories. This introductory review presents a brief historical overview of the HR Diagram for massive stars, highlighting some of the primary discoveries and results from their observation in nearby galaxies. The sections in this volume include reviews of our current understanding of different groups of evolved massive stars, all losing mass and in different stages of their evolution: the Luminous Blue Variables (LBVs), B[e] supergiants, the warm hypergiants, Wolf–Rayet stars, and the population of OB stars and supergiants in the Magellanic Clouds.

scholarly journals Massive stars in their death throes

2008 ◽  
Vol 366 (1884) ◽  
pp. 4441-4452 ◽  
Author(s):  
John J Eldridge
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Evolution Theory ◽  
Luminous Blue Variables ◽  
Show Evidence ◽  
Red Supergiants ◽  
Working Backwards

The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently, there are eight detected progenitors with another 21 non-detections, for which only a limit on the pre-explosion luminosity can be placed. This new avenue of supernova research has led to many interesting conclusions, most importantly that the progenitors of the most common supernovae, type IIP, are red supergiants, as theory has long predicted. However, no progenitors have been detected thus far for the hydrogen-free type Ib/c supernovae, which, given the expected progenitors, is an unlikely result. Also, observations have begun to show evidence that luminous blue variables, which are among the most massive stars, may directly explode as supernovae. These results contradict the current stellar evolution theory. This suggests that we may need to update our understanding.

29. Stellar Spectra (Spectres Stellaires)

1991 ◽  
Vol 21 (1) ◽  
pp. 309-326
Keyword(s):  
Milky Way ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Dynamical Interaction ◽  
Stellar Spectra ◽  
Luminous Blue Variables ◽  
Classical Novae ◽  
Giant Stars ◽  
Red Giant ◽  
Sydney Australia

In the triennium under review, from the late second half of 1987 to the early second half of 1990, Commission 29 has sponsored or cosponsored the following IAU Conferences: Coll. No. 106, “Evolution of Peculiar Red Giant Stars,” Bloomington, Indiana, July 1988; CoU. No. 114, “White Dwarfs,” Hanover, New Hamsphire, August 1988; Coll. No. 113, “Physics of Luminous Blue Variables,” Val Morin, Quebec, August 1988; Coll. No. 122, “Physics of Classical Novae,” Madrid, Spain, June 1989; Symp. No. 143, “Wolf-Rayet Stars and Interrelations with Other Massive Stars in Galaxies,” Denpasar, Indonesia, June 1990; Symp. No 148, “The Magellanic Clouds and their Dynamical Interaction with the Milky Way,” Sydney, Australia, July 1990; Symp. No. 145, “Evolution of Stars: the Photospheric Abundance Connection,” Druzba, Bulgaria. August 1990.

scholarly journals The stability of massive stars

1994 ◽  
Vol 162 ◽  
pp. 73-74
Author(s):  
W. Glatzel ◽  
M. Kiriakidis ◽  
K.J. Fricke
Keyword(s):  
Massive Stars ◽  
Mass Limit ◽  
Physical Explanation ◽  
Stellar Objects ◽  
Fundamental Interest ◽  
Stability Properties ◽  
Luminous Blue Variables ◽  
Stellar Models ◽  
The Stability

An investigation of the stability properties of stellar models describing massive stars is motivated observationally by the necessity to explain the observed Humphreys - Davidson (HD) limit and the variability of the most massive stars known, i.e. the existence of luminous blue variables (LBVs). Theoretically, a determination of the upper mass limit for stable stellar objects together with its physical explanation and interpretation is of fundamental interest.

scholarly journals Magnetic fields, winds and X-rays of massive stars in the Orion nebula cluster

2010 ◽  
Vol 6 (S272) ◽  
pp. 208-209 ◽  
Author(s):  
Véronique Petit ◽  
Gregg A. Wade ◽  
Evelyne Alecian ◽  
Laurent Drissen ◽  
Thierry Montmerle ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Massive Stars ◽  
Theoretical Models ◽  
Magnetic Star ◽  
X Rays ◽  
Orion Nebula ◽  
X Ray ◽  
Ob Stars ◽  
The Impact ◽  
The Relationship

AbstractIn some massive stars, magnetic fields are thought to confine the outflowing radiatively-driven wind. Although theoretical models and MHD simulations are able to illustrate the dynamics of such a magnetized wind, the impact of this wind-field interaction on the observable properties of a magnetic star - X-ray emission, photometric and spectral variability - is still unclear. The aim of this study is to examine the relationship between magnetism, stellar winds and X-ray emission of OB stars, by providing empirical observations and confronting theory. In conjunction with the COUP survey of the Orion Nebula Cluster, we carried out spectropolarimatric ESPaDOnS observations to determine the magnetic properties of massive OB stars of this cluster.

scholarly journals Taking the Measure of Massive Stars and their Environments with the CHARA Array Long-baseline Interferometer

2016 ◽  
Vol 12 (S329) ◽  
pp. 156-160
Author(s):  
Douglas R. Gies
Keyword(s):  
Angular Resolution ◽  
Massive Stars ◽  
High Angular Resolution ◽  
State University ◽  
Luminous Blue Variables ◽  
University Center ◽  
Long Baseline ◽  
Multiple Stars ◽  
Mount Wilson Observatory ◽  
Georgia State University

AbstractMost massive stars are so distant that their angular diameters are too small for direct resolution. However, the observational situation is now much more favorable, thanks to new opportunities available with optical/IR long-baseline interferometry. The Georgia State University Center for High Angular Resolution Astronomy Array at Mount Wilson Observatory is a six-telescope instrument with a maximum baseline of 330 meters, which is capable of resolving stellar disks with diameters as small as 0.2 milliarcsec. The distant stars are no longer out of range, and many kinds of investigations are possible. Here we summarize a number of studies involving angular diameter measurements and effective temperature estimates for OB stars, binary and multiple stars (including the σ Orionis system), and outflows in Luminous Blue Variables. An enlarged visitors program will begin in 2017 that will open many opportunities for new programs in high angular resolution astronomy.

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