Chemical Composition of Young Stars in the Leading Arm of the Magellanic System
- Key Lab. of Optical Astronomy, National Astronomical Observatories, CAS, 20A Datun Road, Chaoyang District, 100012 Beijing (China)
- Instituto de Astronomía, Universidad Católica del Norte, Av. Angomos 0610, Antofagasta (Chile)
- Department of Physics, Southern Connecticut State University, 501 Crescent Street, New Haven, CT 06515 (United States)
- Departamento de Astronomia Universidad de Chile, Camino El Observatorio #1515, Las Condes, Santiago (Chile)
- 14 Dunn Rd, Hamden, Connecticut, CT 06518 (United States)
- Institute of Physics, Southern Federal University, Stachki st/194, 344090, Rostov-on-Don (Russian Federation)
- Centro de Investigaciones de Astronomiá, Apartado Postal 264, Mérida 5101-A (Venezuela, Bolivarian Republic of)
Chemical abundances of eight O- and B-type stars are determined from high-resolution spectra obtained with the MIKE instrument on the Magellan 6.5 m Clay telescope. The sample is selected from 42 candidates for membership in the Leading Arm (LA) of the Magellanic System. Stellar parameters are measured by two independent grids of model atmospheres and analysis procedures, confirming the consistency of the stellar parameter results. Abundances of seven elements (He, C, N, O, Mg, Si, and S) are determined for the stars, as are their radial velocities and estimates of distances and ages. Among the seven B-type stars analyzed, the five that have radial velocities compatible with membership of the LA have an average [Mg/H] of −0.42 ± 0.16, significantly lower than the average of the remaining two, [Mg/H] = −0.07±0.06, which are kinematical members of the Galactic disk. Among the five LA members, four have individual [Mg/H] abundance compatible with that in the LMC. Within errors, we cannot exclude the possibility that one of these stars has an [Mg/H] consistent with the more metal-poor, SMC-like material. The remaining fifth star has an [Mg/H] close to Milky Way values. Distances to the LA members indicate that they are at the edge of the Galactic disk, while ages are of the order of ∼50–70 Myr, lower than the dynamical age of the LA, suggesting a single star-forming episode in the LA. V {sub LSR} of the LA members decreases with decreasing Magellanic longitude, confirming the results of previous LA gas studies.
- OSTI ID:
- 22663961
- Journal Information:
- Astrophysical Journal, Vol. 835, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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