Intriguing detection of 12 CO molecular emission in a classical Be star

COCHETTI, Y. R.; ARIAS, M. L.; KRAUS, M.; CIDALE, L. S.; TORRES, A. F.; GRANADA, A.; MARYEVA, O. V.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2021

0004-6361

Context. In the group of B stars with spectroscopic peculiarities, we can find the Be and the B[e] stars. The Be stars are early-typerapid rotators that present as their principal characteristic emission lines of hydrogen and singly ionized metals, due to the presenceof a gaseous envelope. The B[e] stars present in their spectra heterogeneous features that reveal the presence of regions with verydifferent properties in a gaseous and dusty envelope.Aims. Our goal is to study the evolution of the disks around peculiar B stars through the variability of their physical properties anddynamical structure, as well as to set constraints to different models and disk forming mechanisms.Methods. Throughout the last decade, we have carried out temporal monitoring of a sample of objects in the near infrared usingspectroscopic facilities at the Gemini and Las Campanas Observatories. In the present work, we focus on the classical Be star 12 Vul,for which also optical spectra have been collected quasi-simultaneously.Results. We observed variability in the hydrogen line profiles of 12 Vul, attributed to dissipating and building-up processes of thecircumstellar envelope. Also, we found that this Be star presented the 12CO band heads in emission in one observation. The emissionof this molecule has not been previously reported in a Be star, while it is a common feature among B[e] stars. We obtained parametersto describe the 12CO emitting region and proposed different scenarios to explain this intriguing emission.