Luminosity effects in O4-type stars in the near infrared domain

FERRERO, G; BARBÁ, R H; GAMEN, R; GIUDICI MICHILINI, F.; MORRELL, N I

Viedma

Congreso; Reunión Anual de la AAA; 2019

UNRN + AAA

The study of spectral morphology is a powerful tool for understanding the fundamental properties of stars. The spectral classification scheme for O starswas recently revised and a new set of spectroscopic standard stars was proposed for all subtypes from O2 to B0, and for all luminosity classes. Given that the vast majority of the Galactic O stars lie in regions where the interstellar absorption in the optical bands is very high, it is necessary to extend the atlas to wavelengths in the near infrared (NIR). Four years ago, we started to gather data in order to build a spectroscopic atlas of high-quality observations in the NIR (0.85−2.5μm). The observations were carried out with the GNIRS (Gemini North, Hawaii) and FIRE (Las Campanas, Chile) spectrographs. We present here our first results that include a comparison among the spectra of four O4 type standard stars of different luminosity classes in the NIR Y and J-bands.The aforementioned bands are potentially suitable for the development of spectral classification criteria. The line He II λ1.012 μm located there would allow us to make luminosity class classification.