Eclipsing binary DI Herculis (DI Her) is known to exhibit anomalously slow apsidal precession, below the rate predicted by the general relativity. Recent measurements of the Rossiter-McLauglin effect indicate that stellar spins in DI Her are almost orthogonal to the orbital angular momentum, which explains the anomalous precession in agreement with the earlier theoretical suggestion by Shakura. However, these measurements yield only the projections of the spin-orbit angles onto the sky plane, leaving the spin projection onto our line of sight unconstrained. Here we describe a method of determining the full three-dimensional spin orientation of the binary components relying on the use of the gravity darkening effect, which is significant for the rapidly rotating stars in DI Her. Gravity darkening gives rise to nonuniform brightness distribution over the stellar surface, the pattern of which depends on the stellar spin orientation. Using archival photometric data obtained during multiple eclipses spread over several decades we are able to constrain the unknown spin angles in DI Her with this method, finding that spin axes of both stars lie close to the plane of the sky. Our procedure fully accounts for the precession of stellar spins over the long time span of observations.
The EBLM project XVI. Moderate spin-orbit misalignment of the low mass eclipsing binary EBLM J0021-16
Tufts University（塔夫茨大学）；University of Birmingham（伯明翰大学）；Massachusetts Institute of Technology（麻省理工学院）；Michigan State University（密歇根州立大学）；University of Leeds（利兹大学）；Keele University（基尔大学）；The Ohio State University（俄亥俄州立大学）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Observatoire Astronomique de l’Université de Genève（日内瓦大学天文台）；Universität Bonn, Argelander-Institut für Astronomie（波恩大学阿尔兰德尔天文学研究所）
Tidal effects on brown dwarfs: Application to the eclipsing binary 2MASSJ05352184-0546085 - The anomalous temperature reversal in the context of tidal heating
The EBLM Project XVIII. 3D Obliquities of Five Low-Mass Eclipsing Binaries
Tufts University（塔夫茨大学）；University of Birmingham（伯明翰大学）；Massachusetts Institute of Technology（麻省理工学院）；Michigan State University（密歇根州立大学）；University of Leeds（利兹大学）；Keele University（基尔大学）；The Ohio State University（俄亥俄州立大学）；Jet Propulsion Laboratory, California Institute of Technology（加州理工学院喷气推进实验室）；Observatoire Astronomique de l’Université de Genève（日内瓦大学天文台）
