MUSE Observations of NGC330 in the Small Magellanic Cloud: Helium Abundance of Bright Main-sequence Stars

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.

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Nonlinear hydrodynamic simulations of radial pulsations in massive stars

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313014993 ◽

2013 ◽

Vol 9 (S301) ◽

pp. 449-450 ◽

Cited By ~ 1

Author(s):

Catherine Lovekin ◽

Joyce A. Guzik

Keyword(s):

Main Sequence ◽

Radial Pulsation ◽

Helium Abundance ◽

Initial Model ◽

Main Sequence Stars ◽

Solar Mass ◽

Dramatic Decrease ◽

Hydrodynamic Simulations ◽

Density Relation ◽

Radial Pulsations

AbstractWe investigate the radial pulsation properties of massive main-sequence stars using both linear and non-linear calculations. Using 20, 40, 60 and 85 solar-mass models evolved by Meynet et al. (1994), we calculate nonlinear hydrodynamic envelope models including the effects of time-dependent convection. Many of these models are massive enough to lose a significant amount of mass as they evolve, which also reveals more helium-rich layers. This allows us to investigate the dependence of pulsation on mass, metallicity and surface helium abundance. We find that as a model loses mass, the periods become longer relative to the period predicted by the period-mean density relation (period × $\sqrt{\overline{\rho}}$ is proportional to a constant, Q) for the initial model. Increased surface helium abundance causes a dramatic decrease in the period relative to that expected from Q, while changing the metallicity had little impact on the expected periods.

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A Preliminary Distance to the Small Magellanic Cloud by the Surface Brightness Technique

International Astronomical Union Colloquium ◽

10.1017/s0252921100116975 ◽

1993 ◽

Vol 139 ◽

pp. 93-93

Author(s):

Thomas G. Barnes ◽

Thomas J. Moffett ◽

Wolfgang P. Gieren

Keyword(s):

Surface Brightness ◽

Main Sequence ◽

Magellanic Cloud ◽

Magellanic Clouds ◽

Distance Modulus ◽

Small Magellanic Cloud ◽

Distance Determination ◽

Intrinsic Interest ◽

Rr Lyrae ◽

Centroid Distance

AbstractWe present a new distance determination to the Small Magellanic Cloud from the surface brightness technique applied to the Cepheid variable HV 829. Although this is a preliminary distance based on only one star, it illustrates the power of the surface brightness technique to extragalactic Cepheid distances, it develops the technique which we will apply to additional SMC and LMC Cepheids, and the distance is of intrinsic interest because of the current controvery concerning distances for the Magellanic Clouds.For HV 829 itself we obtain a distance modulus of 18.91 ± 0.20 mag. From other evidence we infer that HV 829 is slightly in front of the SMC centroid distance. Correcting to the SMC centroid yields a distance to the SMC of 19.05 ± 0.20 mag. We stress that this distance modulus is fully independent of any other distance modulus for the SMC, including those based upon Cepheids. Even so, our result agrees more closely with other, independent Cepheid distances than with RR Lyrae distances and main sequence fitting distances.

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