Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars
Kraus, A L
Wyatt, M C
Kennedy, G M
Williams, J P
Mann, A W
Mamajek, E E
Esplin, T L
Rizzuto, A C
AffiliationUniv Arizona, Steward Observ
stars: variables: T Tauri, Herbig Ae/Be
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationM Ansdell, E Gaidos, C Hedges, M Tazzari, A L Kraus, M C Wyatt, G M Kennedy, J P Williams, A W Mann, I Angelo, G Dûchene, E E Mamajek, J Carpenter, T L Esplin, A C Rizzuto, Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars, Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 1, February 2020, Pages 572–588, https://doi.org/10.1093/mnras/stz3361
RightsCopyright © 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.
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AbstractDippers are a common class of young variable star exhibiting day-long dimmings with depths of up to several tens of per cent. A standard explanation is that dippers host nearly edge-on (i(d) approximate to 70 degrees) protoplanetary discs that allow close-in (<1 au) dust lifted slightly out of the mid-plane to partially occult the star. The identification of a face-on dipper disc and growing evidence of inner disc misalignments brings this scenario into question. Thus, we uniformly (re)derive the inclinations of 24 dipper discs resolved with (sub-)mm interferometry from ALMA. We find that dipper disc inclinations are consistent with an isotropic distribution over i(d) approximate to 0-75 degrees, above which the occurrence rate declines (likely an observational selection effect due to optically thick disc mid-planes blocking their host stars). These findings indicate that the dipper phenomenon is unrelated to the outer (>10 au) disc resolved by ALMA and that inner disc misalignments may be common during the protoplanetary phase. More than one mechanism may contribute to the dipper phenomenon, including accretion-driven warps and 'broken' discs caused by inclined (sub-)stellar or planetary companions.
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