scholarly journals Rotation of Early B-type Stars in the Large Magellanic Cloud: The Role of Evolution and Metallicity

2004 ◽  
Vol 21 (3) ◽  
pp. 310-317 ◽  
Author(s):  
Stefan C. Keller
Keyword(s):  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Sequence Stars ◽  
Rapid Rotation ◽  
Field Samples ◽  
General Field ◽  
Galactic Cluster ◽  
The Galaxy

AbstractI present measurements of the projected rotational velocities of a sample of 100 early B-type main-sequence stars in the Large Magellanic Cloud (LMC). This is the first extragalactic study of the distribution of stellar rotational velocities. The sample is drawn from two sources: from the vicinity of the main-sequence turnoff of young clusters (ages 1–3 × 107 yr) and from the general field. I find that the cluster population exhibits significantly more rapid rotation than that seen in the field. I have drawn analogous Galactic cluster and field samples from the literature. Comparison of these samples reveals the same effect. I propose that the observed difference between cluster and field populations can be explained by a scenario of evolutionary enhancement of the surface angular momentum over the main-sequence lifetime. A comparison is made between the cluster and field populations of the LMC and the Galaxy in order to explore the effects of metallicity. This shows that the stars of the LMC are more rapid rotators than their Galactic counterparts.

scholarly journals β Cephei and SPB stars in the Large Magellanic Cloud

2004 ◽  
Vol 193 ◽  
pp. 225-229 ◽  
Author(s):  
Z. Kołaczkowski ◽  
A. Pigulski ◽  
I. Soszyński ◽  
A. Udalski ◽  
M. Szymański ◽  
...  
Keyword(s):  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Progress Report ◽  
Magellanic Cloud ◽  
Main Sequence Stars ◽  
The Galaxy ◽  
Low Order

AbstractThis is a progress report of the study of pulsating main-sequence stars in the LMC. Using the OGLE-II photometry supplemented by the MACHO photometry, we find 64 β Cephei stars in the LMC. Their periods are generally much longer than observed in stars of this type in the Galaxy (the median value is 0.27 d compared with 0.17 d in the Galaxy). In 20 stars with short periods attributable to the β Cephei-type instability, we also find modes with periods longer than ~0.4d. They are likely low-order g modes, which means that in these stars both kinds of variability, β Cephei and SPB, are observed. We also show examples of the multiperiodic SPB stars in the LMC, the first beyond our Galaxy.

Pre-main-sequence stars in the stellar association N 11 in the Large Magellanic Cloud: clustering properties

2009 ◽  
Vol 5 (S266) ◽  
pp. 545-548
Author(s):  
Antonella Vallenari ◽  
Rosanna Sordo ◽  
Emanuela Chiosi
Keyword(s):  
Formation Process ◽  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Sequence Stars ◽  
Stellar Association ◽  
Stellar Objects ◽  
Significant Difference ◽  
Low Metallicity ◽  
Tree Method

AbstractMagellanic Clouds are of extreme importance to study the star-formation process in low-metallicity environments. Here, we discuss the clustering properties of the pre-main-sequence candidates and young embedded stellar objects in N 11, located in the Large Magellanic Cloud. Deep archival HST/ACS photometry is used to derive color–magnitude diagrams of the associations in N 11 and of the foreground field population. These data are complemented by archival infrared Spitzer data which allow detection of young embedded stellar objects. The spatial distribution of the pre-main-sequence candidates and young embedded stellar objects is discussed. The degree of clustering is derived using the minimal-spanning-tree method. No significant difference is found in clustering degree of young blue main-sequence stars and faint pre-main-sequence candidates, suggesting that they might be part of the same formation process.

scholarly journals The study of unclassified B[e] stars and candidates in the Galaxy and Magellanic Clouds†

2019 ◽  
Vol 488 (1) ◽  
pp. 1090-1110 ◽  
Author(s):  
C A H Condori ◽  
M Borges Fernandes ◽  
M Kraus ◽  
D Panoglou ◽  
C A Guerrero
Keyword(s):  
Main Sequence ◽  
Interstellar Extinction ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
Light Curves ◽  
Evolutionary Stage ◽  
The Third ◽  
The Galaxy ◽  
Gaia Dr2

ABSTRACT We investigated 12 unclassified B[e] stars or candidates, 8 from the Galaxy, 2 from the Large Magellanic Cloud (LMC), and 2 from the Small Magellanic Cloud (SMC). Based on the analysis of high-resolution spectroscopic (FEROS) and photometric data, we confirmed the presence of the B[e] phenomenon for all objects of our sample, except for one (IRAS 07455-3143). We derived their effective temperature, spectral type, luminosity class, interstellar extinction and, using the distances from Gaia DR2, we obtained their bolometric magnitude, luminosity, and radius. Modelling of the forbidden lines present in the FEROS spectra revealed information about the kinematics and geometry of the circumstellar medium of these objects. In addition, we analysed the light curves of four stars, finding their most probable periods. The evolutionary stage of 11 stars of our sample is suggested from their position on the HR diagram, taking into account evolutionary tracks of stars with solar, LMC, and SMC metallicities. As results, we identified B and B[e] supergiants, B[e] stars probably at the main sequence or close to its end, post-AGB and HAeB[e] candidates, and A[e] stars in the main sequence or in the pre-main sequence. However, our most remarkable results are the identification of the third A[e] supergiant (ARDB 54, the first one in the LMC), and of an ‘LBV impostor’ in the SMC (LHA 115-N82).

scholarly journals Low mass pre-main sequence stars in the Large Magellanic Cloud

2006 ◽  
Vol 446 (3) ◽  
pp. 955-969 ◽  
Author(s):  
M. Romaniello ◽  
S. Scuderi ◽  
N. Panagia ◽  
R. M. Salerno ◽  
C. Blanco
Keyword(s):  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Sequence Stars ◽  
Low Mass

scholarly journals Pre-main-sequence Stars in the SMC and LMC

1999 ◽  
Vol 190 ◽  
pp. 366-367 ◽  
Author(s):  
Wolfgang Brandner ◽  
Eva K. Grebel ◽  
Hans Zinnecker ◽  
Bernhard Brandl
Keyword(s):  
Stellar Population ◽  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Magellanic Clouds ◽  
High Mass ◽  
Main Sequence Stars ◽  
Intermediate Mass ◽  
First Results ◽  
Low Mass

We present first results of a survey for pre-main-sequence stars in the Magellanic Clouds. Our search concentrated on NGC 346, the most prominent OB association in the Small Magellanic Cloud, and on the 30 Dor starburst cluster in the Large Magellanic Cloud. The identification of the young low- to intermediate-mass stellar population in the SMC and LMC allows us to study whether or not these populations formed simultaneously with high-mass stars, and to what an extent lower metallicity affects the low-mass IMF. We can also evaluate the duration of star formation in a starburst region.

scholarly journals Main-Sequence Stars and the Star Formation History of the Outer Disk in the Large Magellanic Cloud

1996 ◽  
Vol 466 ◽  
pp. 732 ◽  
Author(s):  
J. S. Gallagher ◽  
J. R. Mould ◽  
E. de Feijter ◽  
J. Holtzman ◽  
B. Stappers ◽  
...  
Keyword(s):  
Star Formation ◽  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Star Formation History ◽  
Main Sequence Stars ◽  
Outer Disk ◽  
Formation History ◽  
History Of

scholarly journals Revisiting the Hunter diagram with the Geneva Stellar Evolution Code

2014 ◽  
Vol 9 (S307) ◽  
pp. 142-143
Author(s):  
R. Simoniello ◽  
G. Meynet ◽  
S. Ekström ◽  
C. Georgy ◽  
A. Granada
Keyword(s):  
Chemical Composition ◽  
Stellar Evolution ◽  
Initial Velocity ◽  
Main Sequence ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Main Sequence Stars ◽  
Star Evolution ◽  
Initial Chemical Composition ◽  
Stellar Masses

AbstractWe produced a model grid of rotating main and post-main sequence stars with the Geneva Stellar Evolution Code (GENEC). The initial chemical composition is tailored to compare with observations of early OB type stars in the Large Magellanic Cloud (LMC) and the grid covers stellar masses in the range of 7 ≤ M/M⊙ ≤ 15 and initial velocity between 0 km s−1 ≤ v sin(i) ≤ 300 km s−1. The model grid has been used to determine the changes in the surface Nitrogen abundances during the star evolution and the results have been compared with observations.

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