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Journal Articles Monthly Notices of the Royal Astronomical Society Year : 2020

Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars

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M. Ansdell
  • Function : Author
E. Gaidos
  • Function : Author
C. Hedges
  • Function : Author
M. Tazzari
  • Function : Author
A. L. Kraus
  • Function : Author
M. C. Wyatt
  • Function : Author
G. M. Kennedy
  • Function : Author
J. P. Williams
  • Function : Author
A. W. Mann
  • Function : Author
I. Angelo
  • Function : Author
E. E. Mamajek
  • Function : Author
J. Carpenter
  • Function : Author
T. L. Esplin
  • Function : Author
A. C. Rizzuto
  • Function : Author

Abstract

Dippers 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 (Id ≈ 70°) 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 Id ≈ 0-75°, 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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insu-03705221 , version 1 (27-06-2022)

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Attribution - CC BY 4.0

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M. Ansdell, E. Gaidos, C. Hedges, M. Tazzari, A. L. Kraus, et al.. Are inner disc misalignments common? ALMA reveals an isotropic outer disc inclination distribution for young dipper stars. Monthly Notices of the Royal Astronomical Society, 2020, 492, pp.572-588. ⟨10.1093/mnras/stz3361⟩. ⟨insu-03705221⟩
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