Teide 1 and the Discovery of Brown Dwarfs
In 1995, after many years of intense observational efforts, brown dwarfs were finally discovered in a star cluster and also orbiting a star. The work that led to the discovery and characterization of the brown dwarf Teide 1 is described here. This very red object was detected in optical images of the central region of the Pleiades cluster obtained by our group with the IAC80 telescope (Teide Observatory, Tenerife) in January 1994. Follow-up spectroscopy in December 1994 with the 4.2 m William Herschel Telescope (Roque de los Muchachos Observatory, La Palma) confirmed its cool nature. Teide 1 was one of the coolest objects known at that time and the coolest found in a star cluster. The location, photometric and spectroscopic properties, the measured proper motion and kinematics fully supported membership in the young Pleiades cluster and set strong constraints on its age. According to evolutionary models the low luminosity and cool atmospheric temperature of such a young object implied a mass significantly below the minimum required for stable hydrogen burning. On 22 May 1995, we submitted to Nature a manuscript reporting the discovery of Teide 1. By the time of the publication, on 14 September 1995, we had already extended the survey and found other similar objects in the Pleiades cluster, among them, Calar 3. Evidence for full preservation of lithium in the atmospheres of these two brown dwarfs was obtained with the Keck telescope on 20–21 November 2005. These early findings suggested the existence of a large number of brown dwarfs in the Pleiades and indicated by extrapolation that billions of these objects could populate our Galaxy. Subsequent surveys have confirmed such a numerous population of brown dwarfs. Remarkably, the nearest brown dwarf to the Sun may still remain undetected.
KeywordsStar Cluster Solar Neighbourhood Carbon Star Tauri Star Brown Dwarf
During more than 20 years, I have had the great pleasure and privilege to collaborate with many colleagues sharing their interest and efforts to study low-mass stars and brown dwarfs. I wish to thank all for their dedication and invaluable contributions to these studies. My thanks go to M. R. Zapatero Osorio, E. Martín and A. Magazzù for providing photographic material. I also want to give special thanks to the Instituto de Astrofísica de Canarias and Spanish Academic authorities that have continuously supported substellar research throughout many years and hopefully will continue doing so.
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