2006/07/21 by Stanimir Metchev, Stanimir A. Metchev, Lynne A. Hillenbrand · 2 citations
Physics and Astronomy · #Astronomy #Astrophysics #Astrophysics and Star Formation Studies #Brown dwarf #Effective temperature #Field (mathematics) #Luminosity #Physics #RADIUS #Solar and Space Plasma Dynamics #Stars #Stellar classification #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/507836
published as Astrophys.J.651:1166-1176,2006 · 16 pages, 4 figures, 2 tables. To appear in ApJ November 10, 2006, v651 issue
arxiv created 2006/07/21 · openalex publication_date 2006/11/02 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present the discovery of a brown dwarf companion to the star HD 203030: a G8 V Solar analog with an estimated age between 130 and 400 Myr old G8 V. Separated by 11 9 (487 AU in projection) from its host star, HD 203030B has an estimated mass of 0.023 M ☉ . The K -band spectral type of L7.5 ± 0.5 places HD 203030B near the critical L/T transition in brown dwarfs, which is characterized by the rapid disappearance of dust in substellar photospheres. From a comparative analysis with well-characterized field L/T transition dwarfs, we find that, despite its young age, HD 203030B has a bolometric luminosity similar to the >1 Gyr old field dwarfs. Adopting a radius from current models of substellar evolution, we hence obtain that the effective temperature of HD 203030B is only 1206 K, markedly lower than the ≈1440 K effective temperatures of field L/T transition dwarfs. The temperature discrepancy can be resolved if either (1) the ages of field brown dwarfs have been overestimated by a factor of ≈1.5, leading to underestimated radii, or (2) the lower effective temperature of HD 203030B is related to its young age, implying that the effective temperature at the L/T transition is gravity dependent.