We report the discovery of four transiting F-M binary systems with companions between 0.1 and 0.2 M<SUB>☉</SUB> in mass by the HATSouth survey. These systems have been characterized via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters and equating spectroscopic primary star rotation velocity with spin-orbit synchronization. These new very low mass companions are HATS550-016B (0.110_-0.006^+0.005 M_odot , 0.147_-0.004^+0.003 R_odot ), HATS551-019B (0.17_-0.01^+0.01 M_odot , 0.18_-0.01^+0.01 R_odot ), HATS551-021B (0.132_-0.005^+0.014 M_odot , 0.154_-0.008^+0.006 R_odot ) and HATS553-001B (0.20_-0.02^+0.01 M_odot , 0.22_-0.01^+0.01 R_odot ). We examine our sample in the context of the radius anomaly for fully convective low-mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5 per cent systematic deviation between the measured radii and theoretical isochrone models.
Zhou, G., Bayliss, D., Hartman, J.d., Bakos, G.a., Penev, K., Csubry, Z., et al. (2014). The mass-radius relationship for very low mass stars: Four new discoveries from the HATSouth Survey. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 437(3), 2831-2844 [10.1093/mnras/stt2100].
The mass-radius relationship for very low mass stars: Four new discoveries from the HATSouth Survey
Mancini L.;
2014-01-01
Abstract
We report the discovery of four transiting F-M binary systems with companions between 0.1 and 0.2 M☉ in mass by the HATSouth survey. These systems have been characterized via a global analysis of the HATSouth discovery data, combined with high-resolution radial velocities and accurate transit photometry observations. We determined the masses and radii of the component stars using a combination of two methods: isochrone fitting of spectroscopic primary star parameters and equating spectroscopic primary star rotation velocity with spin-orbit synchronization. These new very low mass companions are HATS550-016B (0.110_-0.006^+0.005 M_odot , 0.147_-0.004^+0.003 R_odot ), HATS551-019B (0.17_-0.01^+0.01 M_odot , 0.18_-0.01^+0.01 R_odot ), HATS551-021B (0.132_-0.005^+0.014 M_odot , 0.154_-0.008^+0.006 R_odot ) and HATS553-001B (0.20_-0.02^+0.01 M_odot , 0.22_-0.01^+0.01 R_odot ). We examine our sample in the context of the radius anomaly for fully convective low-mass stars. Combining our sample with the 13 other well-studied very low mass stars, we find a tentative 5 per cent systematic deviation between the measured radii and theoretical isochrone models.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
