Evidence of accretion triggered oscillations in the pre-main-sequence interacting binary AK Sco

Pre-main sequence (PMS) binaries are surrounded by circumbinary discs from which matter falls on to both components. The material dragged from the circumbinary disc flows on to each star through independent streams channelled by the variable gravitational field. The action of the bar-like potential...

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Bibliographic Details
Published inMonthly notices of the Royal Astronomical Society. Letters Vol. 429; no. 1; pp. L1 - L4
Main Authors Gómez, de Castro Ana I., López-Santiago, Javier, Talavera, Antonio
Format Journal Article
LanguageEnglish
Published Oxford University Press 11.02.2013
Subjects
circumstellar matter
binaries: close
stars: individual: AK Sco
binaries: spectroscopic
stars: pre-main-sequence
stars: variables: T Tauri, Herbig Ae/Be
accretion, accretion discs
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Summary:Pre-main sequence (PMS) binaries are surrounded by circumbinary discs from which matter falls on to both components. The material dragged from the circumbinary disc flows on to each star through independent streams channelled by the variable gravitational field. The action of the bar-like potential is most prominent in high eccentricity systems made of two equal mass stars. AK Sco is a unique PMS system composed of two F5 stars in an orbit with e = 0.47. Henceforth, it is an ideal laboratory to study matter infall in binaries and its role in orbit circularization. In this Letter, we report the detection of a 1.3 mHz ultra low-frequency oscillation in the ultraviolet light curve at periastron passage. This oscillation lasts 7 ks being most likely fed by the gravitational energy released when the stream's tails spiralling on to each star get in contact at periastron passage enhancing the accretion flow; this unveils a new mechanism for angular momentum loss during PMS evolution and a new type of interacting binary.
ISSN:1745-3925
1745-3933
DOI:10.1093/mnrasl/sls012