Law, Nicholas M.
Walter, Frederick M.
AffiliationUniv Arizona, Steward Observ
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PublisherIOP PUBLISHING LTD
CitationAndrei Tokovinin et al 2018 AJ 156 120
Rights© 2018. The American Astronomical Society. All rights reserved.
Collection InformationThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at email@example.com.
AbstractHigh-resolution spectroscopy and speckle interferometry reveal the young star HD 86588 as a quadruple system with a three-tier hierarchy. The 0.'' 3 resolved binary A,B with an estimated period around 300 years contains the 8-yr pair Aa,Abc (also potentially resolvable), where Ab,Ac is a double-lined binary with equal components, for which we compute the spectroscopic orbit. Despite the short period of 2.4058 days, the orbit of Ab,Ac is eccentric (e = 0.086 +/- 0.003). It has a large inclination, but there are no eclipses; only a 4.4 mmag light modulation apparently caused by star spots on the components of this binary is detected with Evryscope. Assuming a moderate extinction of A(v) = 0.5 mag and a parallax of 5.2 mas, we find that the stars are on or close to the main sequence (age >10 Myr) and their masses are from 1 to 1.3 solar. We measure the strength of the lithium line in the visual secondary B which, together with rotation, suggests that the system is younger than 150 Myr. This object is located behind the extension of the Chamaeleon I dark cloud (which explains extinction and interstellar sodium absorption), but apparently does not belong to it. We propose a scenario where the inner orbit has recently acquired its high eccentricity through dynamical interaction with the outer two components; it is now undergoing rapid tidal circularization on a timescale of similar to 1 Myr. Alternatively, the eccentricity could be excited quasi-stationary by the outer component Aa.
VersionFinal published version
SponsorsNational Science Foundation [ATI/1407589, CAREER/1555175]; Spanish Ministerio de Economia y Competitividad (MINECO/FEDER, UE) of ICCUB (Unidad de Excelencia "Maria de Maeztu") [AYA2016-76012-C3-1-P, MDM-2014-0369]