The Wolf-Rayet Stars in 30 Doradus

1982 ◽  
Vol 99 ◽  
pp. 545-549 ◽  
Author(s):  
Jorge Melnick
Keyword(s):  
Star Formation ◽  
Chemical Composition ◽  
Massive Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Hii Regions ◽  
Young Star ◽  
Hii Region ◽  
Formation And Evolution ◽  
Young Star Clusters

Giant HII regions as sites of massive star formation.Giant HII regions are the brightest extragalactic emission line objects that can be studied in detail. With diameters of several hundreds of parsecs, these nebulae can be easily resolved out to distances of a few Mpc. Typically 100 or more 0 stars are required to account for the observed ionization of the nebular gas and this implies that the cores of giant HII regions contain populous young star clusters. The stars in these clusters have essentially the same age and chemical composition. Thus, giant HII region cores provide excellent sites where theories of the formation and evolution of massive stars and, in particular, of Wolf-Rayet (WR) stars can be tested.

scholarly journals Metallicity and X-ray luminosity variations in NGC 922

2020 ◽  
Vol 500 (1) ◽  
pp. 962-975
Author(s):  
K Kouroumpatzakis ◽  
A Zezas ◽  
A Wolter ◽  
A Fruscione ◽  
K Anastasopoulou ◽  
...  
Keyword(s):  
Star Formation ◽  
Stellar Population ◽  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Main Driver ◽  
Young Star Clusters

ABSTRACT We present a systematic study of the metallicity variations within the collisional ring galaxy NGC 922 based on long-slit optical spectroscopic observations. We find a metallicity difference between star-forming regions in the bulge and the ring, with metallicities ranging from almost solar to significantly sub-solar ($\rm {[12+\log (O/H)]\sim 8.2}$). We detect $\rm{He\,{\small I}}$ emission in all the studied regions of the bulge and the ring, indicating ionization from massive stars associated with recent (<10 Myr) star formation, in agreement with the presence of very young star clusters. We find an anticorrelation between the X-ray luminosity and metallicity of the sub-galactic regions of NGC 922. The different regions have similar stellar population ages, leaving metallicity as the main driver of the anticorrelation. The dependence of the X-ray emission of the different regions in NGC 922 on metallicity is in agreement with similar studies of the integrated X-ray output of galaxies and predictions from X-ray binary population models.

scholarly journals Hyperfast pulsars as the remnants of massive stars ejected from young star clusters

2008 ◽  
Vol 385 (2) ◽  
pp. 929-938 ◽  
Author(s):  
Vasilii V. Gvaramadze ◽  
Alessia Gualandris ◽  
Simon Portegies Zwart
Keyword(s):  
Massive Stars ◽  
Star Clusters ◽  
Young Star ◽  
Young Star Clusters

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 ($V\sim {{24.5}^{m}}-{{20}^{m}}$).

HII regions and young star clusters in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 207-208
Author(s):  
Myung Gyoon Lee
Keyword(s):  
Main Sequence ◽  
Star Clusters ◽  
Hii Regions ◽  
Young Star ◽  
Magellanic Clouds ◽  
Stellar Content ◽  
Ccd Photometry ◽  
Luminosity Functions ◽  
Young Star Clusters ◽  
Mass Functions

Using U BV CCD photometry, the stellar content of HII regions and young star clusters in the Magellanic Clouds has been studied: (1) the reddenings have been determined, and ages of OB associations and young star clusters have been measured; (2) the stellar initial mass functions have been determined by using the main-sequence luminosity functions; and (3) U BV CCD surface photometry of nine young star clusters has been obtained and their structural properties investigated.

scholarly journals HII regions and star formation in the Magellanic Clouds

1991 ◽  
Vol 148 ◽  
pp. 139-144 ◽  
Author(s):  
Robert C. Kennicutt
Keyword(s):  
Star Formation ◽  
Interstellar Medium ◽  
Massive Star ◽  
Massive Stars ◽  
Hii Regions ◽  
Magellanic Clouds ◽  
H Ii Regions ◽  
Distant Galaxies ◽  
Close Range ◽  
Mass Functions

The H II regions in the Magellanic Clouds provide an opportunity to characterize the global star formation properties of a galaxy at close range. They also provide a unique laboratory for testing empirical tracers of the massive star formation rates and initial mass functions in more distant galaxies, and for studying the dynamical interactions between massive stars and the interstellar medium. This paper discusses several current studies in these areas.

scholarly journals Star Clusters in Giant Extragalactic HII Regions

2002 ◽  
Vol 207 ◽  
pp. 439-444
Author(s):  
Yu Zhi-yao
Keyword(s):  
Star Formation ◽  
Key Words ◽  
Star Clusters ◽  
Hii Regions ◽  
Star Cluster ◽  
Continuum Radiation ◽  
Hii Region ◽  
Lyman Continuum ◽  
Formation Efficiency ◽  
The Relationship

In this paper we study the relationship between the star formation efficiency and luminosity of Hα emission, Lyman continuum radiation, and Hβ emission on 35 giant extragalactic HII regions in seven galaxies. Using the observational results we obtain the relationship, and find that the star formation efficiency is correlation with Halpha luminocity, and Lyman continuum luminosity, and Hβ lumonosity, respectively. Key words: external galaxy—giant HII region—star cluster

scholarly journals Constraining star formation timescales with molecular gas and young star clusters

2019 ◽  
Vol 15 (S352) ◽  
pp. 350-352
Author(s):  
Kathryn Grasha ◽  
Daniela Calzetti
Keyword(s):  
Star Formation ◽  
Galaxy Evolution ◽  
Star Clusters ◽  
Young Star ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Multi Wavelength ◽  
Predictive Theory ◽  
Young Star Clusters ◽  
Co Observations

AbstractStar formation provides insight into the physical processes that govern the transformation of gas into stars. A key missing piece in a predictive theory of star formation is the link between scales of individual stars and star clusters up to entire galaxies. LEGUS is now providing the information to test the overall organization and spatial evolution of star formation. We present our latest findings of using star clusters from LEGUS combined with ALMA CO observations to investigate the transition from molecular gas to star formation in local galaxies. This work paves the way for future JWST observations of the embedded phase of star formation, the last missing ingredient to connect young star clusters and their relation with gas reservoirs. Multi-wavelength studies of local galaxies and their stellar and gas components will help shed light on early phases of galaxy evolution and properties of the ISM at high-z.

scholarly journals Summary Talk: What is Happening to Massive Stars in Galaxies?

1986 ◽  
Vol 116 ◽  
pp. 523-528
Author(s):  
J. A. Graham ◽  
Taft E. Armandroff
Keyword(s):  
Star Formation ◽  
Massive Star ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Laboratory Work ◽  
Stellar Systems ◽  
Massive Star Formation ◽  
Formation And Evolution ◽  
Summary Talk

Highlights of the IAU Symposium 116 are reviewed. Some of the general themes running through the meeting are identified. These include:i) the fruitful interaction between observation, laboratory work and theory. ii) the need for understanding and, if possible, correcting for the effects of incompleteness and bias in observing lists. iii) the importance of the Magellanic Clouds, as the nearest independently evolving stellar systems, in the study of massive star formation and evolution in galaxies.

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