Massive stars in the SDSS-IV/APOGEE SURVEY. I- OB stars

TL;DR

This study demonstrates that APOGEE near-infrared spectroscopy can effectively classify OB stars, including newly identified ones, aligning well with traditional optical methods, thus enabling the study of obscured massive stars in the Galaxy.

Contribution

Developed a semi-empirical near-infrared spectral classification method for OB stars, validated with new classifications consistent with optical spectra.

Findings

Spectral classifications agree with optical results.

APOGEE can classify obscured OB stars.

Method successfully identified four new OB stars.

Abstract

In this work we make use of DR14 APOGEE spectroscopic data to study a sample of 92 known OB stars. We developed a near-infrared semi-empirical spectral classification method that was successfully used in case of four new exemplars, previously classified as later B-type stars. Our results agree well with those determined independently from ECHELLE optical spectra, being in line with the spectral types derived from the "canonical" MK blue optical system. This confirms that the APOGEE spectrograph can also be used as a powerful tool in surveys aiming to unveil and study large number of moderately and highly obscured OB stars still hidden in the Galaxy.