Are Inner Disc Misalignments Common? ALMA Reveals an Isotropic Outer Disc Inclination Distribution for Young Dipper Stars. (arXiv:1912.01610v1 [astro-ph.EP])

Are Inner Disc Misalignments Common? ALMA Reveals an Isotropic Outer Disc Inclination Distribution for Young Dipper Stars. (arXiv:1912.01610v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+Ansdell_M/0/1/0/all/0/1">M. Ansdell</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaidos_E/0/1/0/all/0/1">E. Gaidos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hedges_C/0/1/0/all/0/1">C. Hedges</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tazzari_M/0/1/0/all/0/1">M. Tazzari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kraus_A/0/1/0/all/0/1">A. L. Kraus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wyatt_M/0/1/0/all/0/1">M. C. Wyatt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kennedy_G/0/1/0/all/0/1">G. M. Kennedy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Williams_J/0/1/0/all/0/1">J. P. Williams</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mann_A/0/1/0/all/0/1">A. W. Mann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Angelo_I/0/1/0/all/0/1">I. Angelo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Duchene_G/0/1/0/all/0/1">G. Duchene</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mamajek_E/0/1/0/all/0/1">E. E. Mamajek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carpenter_J/0/1/0/all/0/1">J. Carpenter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Esplin_T/0/1/0/all/0/1">T. L. Esplin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rizzuto_A/0/1/0/all/0/1">A. C. Rizzuto</a>

Dippers are a common class of young variable star exhibiting day-long
dimmings with depths of up to several tens of percent. A standard explanation
is that dippers host nearly edge-on (70 deg) protoplanetary discs that allow
close-in (< 1 au) dust lifted slightly out of the midplane 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 0-75 deg, above which the occurrence rate declines (likely an observational selection effect due to optically thick disc midplanes 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.

Dippers are a common class of young variable star exhibiting day-long
dimmings with depths of up to several tens of percent. A standard explanation
is that dippers host nearly edge-on (70 deg) protoplanetary discs that allow
close-in (< 1 au) dust lifted slightly out of the midplane 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 0-75 deg, above which the occurrence rate
declines (likely an observational selection effect due to optically thick disc
midplanes 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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