Ramírez-Alegría, S.; Herrero, A.; Marín-Franch, A.; Puga, E.; Najarro, F.; Acosta-Pulido, J. A.; Hidalgo, S. L.; Simón-Díaz, S.
Bibliographical reference
Astronomy and Astrophysics, Volume 535, id.A8
Description
Context. The discovery of new massive star clusters and massive stellar
populations in previously known clusters in our Galaxy by means of
infrared studies has changed our view of the Milky Way from an inactive
to an active star-forming machine. Within this scenario, we present a
near-infrared spectrophotometric study of the stellar content of the
compact HII region Sh2-152. Aims: We aim to determine the
distance, extinction, age, and mass of Sh2-152, using for the first time
near-infrared stellar classification for several sources in the region.
Methods: Using our near-infrared (J, H, and KS)
photometry and the colour-magnitude diagram for the cluster field, we
selected 13 bright stars, candidate members of the reddened cluster's
main sequence, for H- and K-spectroscopy and spectral classification.
This near-infrared information was complemented with an optical spectrum
of the ionizing central star to confirm its spectral nature.
Results: From the 13 spectroscopically observed stars, 5 were classified
as B-type, 3 as G-type, 2 were young stellar objects (YSOs), and 3
remained unclassified (because of the poor data quality). The cluster's
extinction varies from AKS = 0.5 to 2.6 mag
(AV = 4.5 to 24 mag) and the distance is estimated to be 3.21
± 0.21 kpc. The age of the cluster is younger than 9.4 Myr and
the lower limit to the total mass of the cluster is (2.45 ± 0.79)
× 103 M&sun;. We compare the number of
ionizing photons emitted from the OB-type stars with the Lyman continuum
photons derived from the radio observations and conclude that both
quantities are consistent for the central region of Sh2-152. In
contrast, the main ionizing source of the lower region remains
unidentified.
Related projects
Milky Way and Nearby Galaxies
The general aim of the project is to research the structure, evolutionary history and formation of galaxies through the study of their resolved stellar populations, both from photometry and spectroscopy. The group research concentrates in the most nearby objects, namely the Local Group galaxies including the Milky Way and M33 under the hypothesis
The study of binary stars is essential to stellar astrophysics. A large number of stars form and evolve within binary systems. Therefore, their study is fundamental to understand stellar and galactic evolution. Particularly relevant is that binary systems are still the best source of precise stellar mass and radius measurements. Research lines
Physical properties and evolution of Massive Stars
This project aims at the searching, observation and analysis of massive stars in nearby galaxies to provide a solid empirical ground to understand their physical properties as a function of those key parameters that gobern their evolution (i.e. mass, spin, metallicity, mass loss, and binary interaction). Massive stars are central objects to
