The Gran Canarias Telescopio (GTC) allows you to observe previously never seen details of several stars and brown dwarfs in the Orionis sigma cluster

Members of the Consolider-GTC collaboration, including CAB researcher José Antonio Caballero, have managed to confirm data related to the characteristics of ten low-mass stars and brown dwarfs thanks to observations made with the instrument OSIRIS, installed in the Gran Telescopio CANARIAS (GTC). The data were taken on different observation nights during the month of March 2012. OSIRIS obtained low resolution spectra of these objects in the young open star cluster of Sigma Orionis, close to the famous Horsehead Nebula.

The objective of this program was to take advantage of the nights in which the conditions are not optimal for other observation programs (such as a high "seeing" or presence of dense clouds) in order to obtain high quality spectra from sources variables without known classification that were relatively bright for a 10-meter type telescope. Some of the spectra obtained during one of the observation nights were captured while the rest of La Palma's telescopes were not operational. & Nbsp;

With this work we have managed to reveal detailed data of seven objects, such as their spectral classification or the intensity of the lithium lines in absorption, and of hydrogen and calcium in emission. While the spectral type is an indicator of temperature and mass, the mentioned spectral lines are markers of extreme youth and accretion, which is the violent fall of material on the surface of the star from a disk that surrounds it. All the stars and brown dwarfs fulfilled a requirement: that they were known variable objects in the optician or in X-rays. Some of the characterized objects have turned out to be very interesting, like the Mayrit brown dwarf 1196092, which has characteristics that until recently were believed exclusive of certain type of young and active stars called T Tauri. & nbsp;

This study is part of two projects: one is the spectroscopic study with OSIRIS / GTC of little-known variable sources, and the another is the Mayrit project, whose objective is to catalog in detail all the bodies belonging to the Sigma cluster Orionis, which is a true laboratory of star formation. All stars and brown dwarfs in this catalog have the name Mayrit and a number that indicates their position in the cluster. Mayrit is the word that evolved to give name to the city of Madrid. & Nbsp;

Despite the numerous works carried out previously, many of them made by Spanish astronomers, there are still dozens of stars from low mass and brown dwarfs in Sigma Orionis without detailed spectroscopic characterization. Some of them may even be accreting material or have discs not yet detected, discs in which planets may be forming.

This study has been developed by José Antonio Caballero, researcher at the Astrobiology Center (CSIC-INTA), and Consolider-GTC member of the PLANETAS-IAC team; Antonio Cabrera-Lavers, researcher at the Institute of Astrophysics of the Canary Islands (IAC), astronomer of support of the GTC and member Consolider-GTC of the EAST team; David García Álvarez, GTC support astronomer and IAC researcher; and Sergio Pascual, researcher at the Department of Astrophysics and Atmospheric Sciences of the Faculty of Physics of the Complutense University of Madrid (UCM), and Consolider-GTC member of the GALAXIAS-UCM team.


Fuente: UCC CAB


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