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Massive star evolution at low metallicity is closely connected to many fields in high-redshift astrophysics, but poorly understood. The Small Magellanic Cloud (SMC) is a unique laboratory to study this because of its metallicity of 0.2 Zsol, its proximity, and because it is currently forming stars. We used a spectral type catalog in combination with GAIA magnitudes to calculate temperatures and luminosities of bright SMC stars. By comparing these with literature studies, we tested the validity of our method, and using GAIA data, we estimated the completeness of stars in the catalog as a function of luminosity. This allowed us to obtain a nearly complete view of the most luminous stars in the SMC. When then compared with stellar evolution predictions. We also calculated the extinction distribution, the ionizing photon production rate, and the star formation rate. Our results imply that the SMS hosts only 30 very luminous main-sequence stars (M > 40 Msol; L > 10^5 Lsol), which are far fewer than expected from the number of stars in the luminosity range 3*10^4 < L/Lsol < 3*10^5 and from the typically quoted star formation rate in the SMC. Even more striking, we find that for masses above M > 20 Msol, stars in the first half of their hydrogen-burning phase are almost absent. This mirrors a qualitatively similar peculiarity that is known for the Milky Way and Large Magellanic Cloud. This amounts to a lack of hydrogen-burning counterparts of helium-burning stars, which is more pronounced for higher luminosities. We argue that a declining star formation rate or a steep initial mass function are unlikely to be the sole explanations for the dearth of young bright stars. Instead, many of these stars might be embedded in their birth clouds, although observational evidence for this is weak. We discuss implications for cosmic reionization and the top end of the initial mass function.
Using archival Spitzer Space Telescope data, we identified for the first time a dozen runaway OB stars in the Small Magellanic Cloud (SMC) through the detection of their bow shocks. The geometry of detected bow shocks allows us to infer the direction
We present new observations of 34 YSO candidates in the SMC. The anchor of the analysis is a set of Spitzer-IRS spectra, supplemented by groundbased 3-5 micron spectra, Spitzer and NIR photometry, optical spectroscopy and radio data. The sources SEDs
High spatial resolution imaging with the Hubble Space Telescope allowed us to resolve the compact HII, region N81 lying in the Small Magellanic Cloud (SMC). We show the presence of a tight cluster of newborn massive stars embedded in this nebular ``b
We present radial velocities for 2045 stars in the Small Magellanic Cloud (SMC), obtained from the 2dF survey by Evans et al. (2004). The great majority of these stars are of OBA type, tracing the dynamics of the young stellar population. Dividing th
Understanding the evolutionary history of the Magellanic Clouds requires an in-depth exploration and characterization of the stellar content in their outer regions, which ultimately are key to tracing the epochs and nature of past interactions. We pr