An asymmetric eclipse seen toward the pre-main-sequence binary system V928 Tau
Abstract
K2 observations of the weak-lined T Tauri binary V928 Tau A and B show the detection of a single, asymmetric eclipse, which may be due to a previously unknown substellar companion eclipsing one component of the binary with an orbital period >66 days. Over an interval of about 9 hr, one component of the binary dims by around 60%, returning to its normal brightness about 5 hr later. From modeling of the eclipse shape, we find evidence that the eclipsing companion may be surrounded by a disk or a vast ring system. The modeled disk has a radius of 0.9923 ± 0.0005 R*, with an inclination of 5678 ± 003, a tilt of 4122 ± 005, an impact parameter of −0.2506 ± 0.0002 R*, and an opacity of 1.00. The occulting disk must also move at a transverse velocity of 6.637 ± 0.002 R* day−1, which, depending on whether it orbits V928 Tau A or B, corresponds to approximately 73.53 or 69.26 km s−1. A search in ground-based archival data reveals additional dimming events, some of which suggest periodicity, but no unambiguous period associated with the eclipse observed by K2. We present a new epoch of astrometry that is used to further refine the orbit of the binary, presenting a new lower bound of 67 yr, and constraints on the possible orbital periods of the eclipsing companion. The binary is also separated by 18'' (~2250 au) from the lower-mass CFHT-BD-Tau 7, which is likely associated with V928 Tau A and B. We also present new high-dispersion optical spectroscopy that we use to characterize the unresolved stellar binary.
Citation
van Dam , D M , Kenworthy , M A , David , T J , Mamajek , E E , Hillenbrand , L A , Cody , A M , Howard , A W , Isaacson , H , Ciardi , D R , Rebull , L M , Stauffer , J R , Patel , R , Cameron , A C , Rodriguez , J E , Pojmanski , G , Gonzales , E J , Schlieder , J E , Hambsch , F-J , Dufoer , S , Vanmunster , T , Dubois , F , Vanaverbeke , S , Logie , L , Rau , S & Collaborators , WASP 2020 , ' An asymmetric eclipse seen toward the pre-main-sequence binary system V928 Tau ' , Astronomical Journal , vol. 160 , no. 6 , 285 . https://doi.org/10.3847/1538-3881/abc259
Publication
Astronomical Journal
Status
Peer reviewed
ISSN
0004-6256Type
Journal article
Description
Funding: J.D.and E.E.M.gratefully acknowledge support from the Jet Propulsion Laboratory Exoplanetary Science Initiative and NASA award 17-K2GO6-0030.Collections
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