First stellar spectroscopy in Leo P

Evans, C. J.; Castro, N.; Gonzalez, O. A.; Garcia, M.; Bastian, N.; Cioni, M.-R. L.; Clark, J. S.; Davies, B.; Ferguson, A. M. N.; Kamann, S.; Lennon, D. J.; Patrick, L. R.; Vink, J. S.; Weisz, D. R.
Referencia bibliográfica

Astronomy and Astrophysics, Volume 622, id.A129, 11 pp.

Fecha de publicación:
2
2019
Número de autores
14
Número de autores del IAC
2
Número de citas
29
Número de citas referidas
22
Descripción
We present the first stellar spectroscopy in the low-luminosity (MV ˜ -9.3 mag), dwarf galaxy Leo P. Its significantly low oxygen abundance (3% solar) and relative proximity (˜1.6 Mpc) make it a unique galaxy in which to investigate the properties of massive stars with near-primordial compositions akin to those in the early Universe. From our VLT-MUSE spectroscopy we find the first direct evidence for an O-type star in the prominent H II region, providing an important test case to investigate the potential environmental dependence of the upper end of the initial mass function in the dwarf galaxy regime. We classify 14 further sources as massive stars (and 17 more as candidate massive stars), most likely B-type objects. From comparisons with published evolutionary models we argue that the absolute visual magnitudes of massive stars in very metal-poor systems such as Leo P and I Zw 18 may be fainter by ˜0.5 mag compared to Galactic stars. We also present spectroscopy of two carbon stars identified previously as candidate asymptotic-giant-branch stars. Two of three further candidate asymptotic-giant-branch stars display Ca II absorption, confirming them as cool, evolved stars; we also recover Ca II absorption in the stacked data of the next brightest 16 stars in the upper red giant branch. These discoveries will provide targets for future observations to investigate the physical properties of these objects and to calibrate evolutionary models of luminous stars at such low metallicity. The MUSE data also reveal two 100 pc-scale ring structures in Hα emission, with the H II region located on the northern edge of the southern ring. Lastly, we report serendipitous observations of 20 galaxies, with redshifts ranging from z = 0.39, to a close pair of star-forming galaxies at z = 2.5.
Proyectos relacionados
Physical properties and evolution of massive stars
Propiedades Físicas y Evolución de Estrellas Masivas
Las estrellas masivas son objetos claves para la Astrofísica. Estas estrellas nacen con más de 8 masas solares, lo que las condena a morir como Supernovas. Durante su rápida evolución liberan, a través de fuertes vientos estelares, gran cantidad de material procesado en su núcleo y, en determinadas fases evolutivas, emiten gran cantidad de
Sergio
Simón Díaz