Bibcode
Herbst, W.; Hessman, F.; Boudreault, S.; Pintado, O.; Mundt, R.; Rodríguez-Ledesma, M. V.
Bibliographical reference
Astronomy and Astrophysics, Volume 551, id.A44, 6 pp.
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3
2013
Journal
Citations
5
Refereed citations
5
Description
Aims: We present the spectroscopic characterization of the
unusual high-amplitude very low mass pre-main-sequence periodic variable
CHS 7797. Methods: This study is based on optical
medium-resolution (R = 2200) spectroscopy in the 6450 - 8600 Å
range, carried out with GMOS-GEMINI -S in March 2011. Observations of
CHS 7797 have been carried out at two distinct phases of the 17.8 d
period, namely at maximum (I ≈ 17.4 mag) and four days before maximum
(I ≈ 18.5 mag). Four different spectral indices were used for the
spectral classification at these two phases, all of them well-suited for
spectral classification of young and obscured late M dwarfs. In
addition, the gravity-sensitive Na I (8183/8195 Å) and K I
(7665/7699 Å) doublet lines were used to confirm the young age of
CHS 7797. Results: From the spectrum obtained at maximum light we
derived a spectral type (SpT) of M 6.05 ± 0.25, while for the
spectrum taken four days before maximum the derived SpT is M 5.75
± 0.25. The derived SpTs confirm that CHS 7797 has a mass in the
stellar-substellar boundary mass range. In addition, the small
differences in the derived SpTs at the two observed phases may provide
indirect hints that CHS 7797 is a binary system of similar mass
components surrounded by a tilted circumbinary disk, a system similar to
KH 15D.
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Our goal is to study the processes that lead to the formation of low mass stars, brown dwarfs and planets and to characterize the physical properties of these objects in various evolutionary stages. Low mass stars and brown dwarfs are likely the most numerous type of objects in our Galaxy but due to their low intrinsic luminosity they are not so
Rafael
Rebolo López