FU Tauri is a brown dwarfbinary system in the constellation of Taurus about 429 light years away. The secondary is very close to the lower limit for brown dwarfs and several databases list it as a distant massive exoplanet.
System
The two stars of the FU Tauri system are separated by 5.7″, equivalent to 800 AU at the distance of FU Tauri.[6] The primary is a brown dwarf with a mass of 0.05 M☉, while the secondary has a mass of 0.015 M☉. The secondary mass of 15MJ is close to the dividing line between brown dwarfs and exoplanets, and it is often treated as an exoplanet.[7]
Properties
Both members of the binary are low-mass objects still contracting towards the main sequence. Comparison with theoretical evolutionary tracks gives them ages of one Myr or less. However, the primary is more luminous than expected even for this age and it may be younger than the secondary.[5] The primary has a temperature of 2,838 K, a radius of 1.8 R☉, and a bolometric luminosity of 0.2 L☉. The secondary has a temperature of 2,375 K and a bolometric luminosity of 0.0039 L☉.[5]
^Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1: B/gcvs. Bibcode:2009yCat....102025S.
^Romano, G. (1975). "Observations of T Tau stars and related objects in Taurus dark cloud". Memorie della Societa Astronomica Italiana. 46: 81. Bibcode:1975MmSAI..46...81R.
^Gotz, W. (1961). "Photographische Untersuchungen an RW Aurigae-Sternen in den Dunkelgebieten von Taurus und Orion". Veroeffentlichungen der Sternwarte Sonneberg. 5: 87. Bibcode:1961VeSon...5...87G.