HD 142250 (HR 5910, HIP 77900) is a star in the constellationScorpius. It has a visual apparent magnitude of 6.1, being visible to the naked eye only in excellent seeing conditions. From parallax measurements, it is located 486 light-years (149 parsecs) away from Earth. This distance, together with the star's proper motion, indicate that HIP 77900 is a member of the Upper Scorpius subgroup of the Scorpius–Centaurus association, the nearest OB association to the Sun.[11] This subgroup is the youngest of the three of the association, with an estimated age of 11 million years.[9]
Stars in young stellar associations are frequent targets for direct imaging searches for sub-stellar objects, because these objects lose luminosity with time. A 2013 article, using data from the Pan-STARRS and UKIDSSsurveys and follow up observations with the IRTF telescope, presented the discovery of an object of spectral type M9 and effective temperature of 2400 ± 150 K separated from HIP 77900 by 21.8 arcseconds, or more than 3200 ± 300 AU at the system's distance. Its mass, estimated from evolutionary models and assuming an age of 10 million years, is 20+7 −3Jupiter masses, so the object is probably a low mass brown dwarf. The physical association between the two bodies has not been confirmed through common proper motion observation, but is considered likely given the proximity of the two objects in the sky and that the probable brown dwarf shows signs of youth.[7]
A 2023 survey, using data from the Gaia spacecraft, refined the parameters of this substellar companion.[12] It was found to have a mass of 21±1 MJ, a temperature of 2,507+16 −5K and to be separated from HIP 77900 by a distance of 3,319±28 AU. It is now included in the NASA Exoplanet Archive since its mass is below their upper mass limit of 30MJ.[13][14]
^ abde Geus, E. J.; de Zeeuw, P. T.; Lub, J. (June 1989). "Physical parameters of stars in the Scorpio-Centaurus OB association". Astronomy and Astrophysics. 216 (1–2): 44–61. Bibcode:1989A&A...216...44D.
^ abPecaut, Mark J.; Mamajek, Eric E.; Bubar, Eric J. (February 2012). "A Revised Age for Upper Scorpius and the Star Formation History among the F-type Members of the Scorpius–Centaurus OB Association". The Astrophysical Journal. 746 (2): article 154, 22 pp. arXiv:1112.1695. Bibcode:2012ApJ...746..154P. doi:10.1088/0004-637X/746/2/154. S2CID118461108.
^"HD 142250 -- Star". SIMBAD. Centre de Données astronomiques de Strasbourg. Retrieved 2018-04-17.