scholarly journals Luminous Infrared Sources in the Local Group: Identifying the Missing Links in Massive Star Evolution

2014 ◽  
Vol 9 (S307) ◽  
pp. 92-93
Author(s):  
N. Britavskiy ◽  
A. Z. Bonanos ◽  
A. Mehner
Keyword(s):  
Massive Star ◽  
Local Group ◽  
Massive Stars ◽  
Star Evolution ◽  
Irregular Galaxies ◽  
Nearby Galaxies ◽  
Massive Star Evolution ◽  
Infrared Sources ◽  
Dwarf Irregular Galaxies

AbstractWe present the first systematic survey of dusty massive stars (RSGs, LBVs, sgB[e]) in nearby galaxies, with the goal of understanding their importance in massive star evolution. Using the fact that these stars are bright in mid-infrared colors due to dust, we provide a technique for selecting and identifying dusty evolved stars based on the results of Bonanos et al. (2009, 2010), Britavskiy et al. (2014), and archival Spitzer/IRAC photometry. We present the results of our spectroscopic follow-up of luminous infrared sources in the Local Group dwarf irregular galaxies: Pegasus, Phoenix, Sextans A and WLM. The survey aims to complete the census of dusty massive stars in the Local Group.

scholarly journals DDO68-V1: an extremely metal-poor LBV in a void galaxy

2018 ◽  
Vol 14 (S344) ◽  
pp. 392-395
Author(s):  
Yulia Perepelitsyna ◽  
Simon Pustilnik
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Rare Event ◽  
Local Universe ◽  
Hii Region ◽  
V Band ◽  
Star Evolution ◽  
Low Metallicity ◽  
Massive Star Evolution

AbstractThe lowest metallicity massive stars in the Local Universe with $Z\sim \left( {{Z}_{\odot }}/50-{{Z}_{\odot }}/30 \right)$ are the crucial objects to test the validity of assumptions in the modern models of very low-metallicity massive star evolution. These models, in turn, have major implications for our understanding of galaxy and massive star formation in the early epochs. DDO68-V1 in a void galaxy DDO68 is a unique extremely metal-poor massive star. Discovered by us in 2008 in the HII region Knot3 with $Z={{Z}_{\odot }}/35\,\left[ 12+\log \left( \text{O/H} \right)\sim 7.14 \right]$, DDO68-V1 was identified as an LBV star. We present here the LBV lightcurve in V band, combining own new data and the last archive and/or literature data on the light of Knot3 over the 30 years. We find that during the years 2008-2011 the LBV have experienced a very rare event of ‘giant eruption’ with V-band amplitude of 4.5 mag ($V\sim {{24.5}^{m}}-{{20}^{m}}$).

scholarly journals Luminous Blue Variables, cool hypergiants and some impostors in the H-R diagram

2003 ◽  
Vol 212 ◽  
pp. 38-46
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Magnetic Fields ◽  
Mass Loss ◽  
Surface Activity ◽  
Massive Star ◽  
Massive Stars ◽  
High Mass ◽  
Luminous Blue Variables ◽  
Star Evolution ◽  
High Mass Loss ◽  
Massive Star Evolution

Current observations of the S Dor/LBVs and candidates and the implications for their important role in massive star evolution are reviewed. Recent observations of the cool hypergiants are altering our ideas about their evolutionary state, their atmospheres and winds, and the possible mechanisms for their asymmetric high mass loss episodes which may involve surface activity and magnetic fields. Recent results for IRC+10420, ρ Cas and VY CMa are highlighted. S Dor/LBVs in eruption, and the cool hypergiants in their high mass loss phases with their optically thick winds are not what their apparent spectra and temperatures imply; they are then ‘impostors’ on the H-R diagram. The importance of the very most massive stars, like η Carinae and the ‘supernovae impostors’ are also discussed.

scholarly journals Identification of dusty massive stars in star-forming dwarf irregular galaxies in the Local Group with mid-IR photometry

2015 ◽  
Vol 584 ◽  
pp. A33 ◽  
Author(s):  
N. E. Britavskiy ◽  
A. Z. Bonanos ◽  
A. Mehner ◽  
M. L. Boyer ◽  
K. B. W. McQuinn
Keyword(s):  
Local Group ◽  
Massive Stars ◽  
Star Forming ◽  
Irregular Galaxies ◽  
Dwarf Irregular Galaxies ◽  
Ir Photometry

scholarly journals Massive Star Modeling and Nucleosynthesis

2021 ◽  
Vol 8 ◽  
Author(s):  
Sylvia Ekström
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Massive Star ◽  
Nuclear Reactions ◽  
Massive Stars ◽  
Reaction Rates ◽  
Star Evolution ◽  
Structural Impact ◽  
Massive Star Evolution ◽  
The Impact

After a brief introduction to stellar modeling, the main lines of massive star evolution are reviewed, with a focus on the nuclear reactions from which the star gets the needed energy to counterbalance its gravity. The different burning phases are described, as well as the structural impact they have on the star. Some general effects on stellar evolution of uncertainties in the reaction rates are presented, with more precise examples taken from the uncertainties of the 12C(α, γ)16O reaction and the sensitivity of the s-process on many rates. The changes in the evolution of massive stars brought by low or zero metallicity are reviewed. The impact of convection, rotation, mass loss, and binarity on massive star evolution is reviewed, with a focus on the effect they have on the global nucleosynthetic products of the stars.

scholarly journals Massive star evolution: feedbacks in low-Z environment

2018 ◽  
Vol 14 (S344) ◽  
pp. 153-160
Author(s):  
Sylvia Ekström ◽  
Georges Meynet ◽  
Cyril Georgy ◽  
José Groh ◽  
Arthur Choplin ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Stellar Evolution ◽  
Massive Star ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
Star Evolution ◽  
Massive Star Evolution

AbstractMassive stars are the drivers of the chemical evolution of dwarf galaxies. We review here the basics of massive star evolution and the specificities of stellar evolution in low-Z environment. We discuss nucleosynthetic aspects and what observations could constrain our view on the first generations of stars.

scholarly journals Massive star evolution in nearby galaxies

1984 ◽  
Vol 105 ◽  
pp. 279-297 ◽  
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Observational Data ◽  
Stellar Evolution ◽  
Massive Star ◽  
Stellar Content ◽  
Individual Stars ◽  
Star Evolution ◽  
Different Types ◽  
Nearby Galaxies ◽  
Massive Star Evolution

In this review I will primarily be discussing the observational data relevant to understanding the process of stellar evolution in galaxies of different types. This discussion will focus on the stellar content of the nearer galaxies; those galaxies in which the brightest individual stars are resolved and can be observed.

scholarly journals Booms and Busts: the Burstiness of Star Formation in Nearby Dwarf Galaxies

2010 ◽  
Vol 27 (3) ◽  
pp. 234-241 ◽  
Author(s):  
A. A. Cole
Keyword(s):  
Galaxy Evolution ◽  
Local Group ◽  
Dwarf Galaxies ◽  
Starburst Galaxy ◽  
Ic 10 ◽  
Irregular Galaxies ◽  
Magnitude Diagram ◽  
Nearby Galaxies ◽  
Dwarf Irregular Galaxies ◽  
The Universe

AbstractIn this review I summarise recent advances in our understanding of the importance of starburst events to the evolutionary histories of nearby galaxies. Ongoing bursts are easily diagnosed in emission-line surveys, but assessing the timing and intensity of fossil bursts requires more effort, usually demanding color–magnitude diagrams or spectroscopy of individual stars. For ages older than ∼1 Gyr, this type of observation is currently limited to the Local Group and its immediate surroundings. However, if the Local Volume is representative of the Universe as a whole, then studies of the age and metallicity distributions of star clusters and resolved stellar populations should give statistical clues as to the frequency and importance of bursts to the histories of galaxies in general. Based on starburst statistics in the literature and synthetic colour-magnitude diagram studies of Local Group galaxies, I attempt to distinguish between systemic starbursts that strongly impact galaxy evolution and stochastic bursts that can appear impressive but are ultimately of little significance on gigayear timescales. As a specific case, it appears as though IC 10, the only starburst galaxy in the Local Group, falls into the latter category and is not fundamentally different from other nearby dwarf irregular galaxies.

scholarly journals Low-metallicity (sub-SMC) massive stars

2016 ◽  
Vol 12 (S329) ◽  
pp. 313-321 ◽  
Author(s):  
Miriam Garcia ◽  
Artemio Herrero ◽  
Francisco Najarro ◽  
Inés Camacho ◽  
Daniel J. Lennon ◽  
...  
Keyword(s):  
Local Group ◽  
Massive Stars ◽  
Current Knowledge ◽  
High Redshift ◽  
Evolutionary Models ◽  
Irregular Galaxies ◽  
Low Metallicity ◽  
High Redshift Universe ◽  
Dwarf Irregular Galaxies ◽  
Review Current

AbstractThe double distance and metallicity frontier marked by the SMC has been finally broken with the aid of powerful multi-object spectrographs installed at 8-10m class telescopes. VLT, GTC and Keck have enabled studies of massive stars in dwarf irregular galaxies of the Local Group with poorer metal-content than the SMC. The community is working to test the predictions of evolutionary models in the low-metallicity regime, set the new standard for the metal-poor high-redshift Universe, and test the extrapolation of the physics of massive stars to environments of decreasing metallicity. In this paper, we review current knowledge on this topic.

scholarly journals Massive Star Evolution

1999 ◽  
Vol 190 ◽  
pp. 192-199 ◽  
Author(s):  
N. Langer ◽  
A. Heger
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Open Problems ◽  
Star Evolution ◽  
Massive Star Evolution

The evolution of massive stars is far from being fully understood, as we outline by pointing to a number of open problems related to massive stars in the Magellanic Clouds. We argue that rotation may be a key ingredient in the physics of massive stars. We report on recent results obtained including rotation, and their relevance to these remaining questions.

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