AU Mic b is the Youngest Planet to have a Spin-Orbit Alignment Measurement. (arXiv:2006.13675v2 [astro-ph.EP] UPDATED)

AU Mic b is the Youngest Planet to have a Spin-Orbit Alignment Measurement. (arXiv:2006.13675v2 [astro-ph.EP] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Addison_B/0/1/0/all/0/1">Brett C. Addison</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horner_J/0/1/0/all/0/1">Jonathan Horner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wittenmyer_R/0/1/0/all/0/1">Robert A. Wittenmyer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Heitzmann_A/0/1/0/all/0/1">Alexis Heitzmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Plavchan_P/0/1/0/all/0/1">Peter Plavchan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wright_D/0/1/0/all/0/1">Duncan J. Wright</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nicholson_B/0/1/0/all/0/1">Belinda A. Nicholson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marshall_J/0/1/0/all/0/1">Jonathan P. Marshall</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Clark_J/0/1/0/all/0/1">Jake T. Clark</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gunther_M/0/1/0/all/0/1">Maximilian N. Gunther</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kane_S/0/1/0/all/0/1">Stephen R. Kane</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hirano_T/0/1/0/all/0/1">Teruyuki Hirano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_S/0/1/0/all/0/1">Songhu Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kielkopf_J/0/1/0/all/0/1">John Kielkopf</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shporer_A/0/1/0/all/0/1">Avi Shporer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tinney_C/0/1/0/all/0/1">C.G. Tinney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_H/0/1/0/all/0/1">Hui Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ballard_S/0/1/0/all/0/1">Sarah Ballard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bowler_B/0/1/0/all/0/1">Brendan P. Bowler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mengel_M/0/1/0/all/0/1">Matthew W. Mengel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Okumura_J/0/1/0/all/0/1">Jack Okumura</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaidos_E/0/1/0/all/0/1">Eric Gaidos</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_X/0/1/0/all/0/1">Xian-Yu Wang</a>

We report measurements of the sky-projected spin-orbit angle for AU,Mic,b,
a Neptune-size planet orbiting a very young ($sim20$,Myr) nearby pre-main
sequence M dwarf star which also hosts a bright, edge-on, debris disk. The
planet was recently discovered from preliminary analysis of radial velocity
observations and confirmed to be transiting its host star from photometric data
from the NASA’s textit{TESS} mission. We obtained radial velocity measurements
of AU,Mic over the course of two partially observable transits and one full
transit of planet b from high-resolution spectroscopic observations made with
the {textsc{Minerva}}-Australis telescope array. Only a marginal detection of
the Rossiter–McLaughlin effect signal was obtained from the radial velocities,
in part due to AU Mic being an extremely active star and the lack of full
transit coverage plus sufficient out-of-transit baseline. As such, a precise
determination of the obliquity for AU,Mic,b is not possible in this study and
we find a sky-projected spin-orbit angle of $lambda =
47{^{+26}_{-54}}^{circ}$. This result is consistent with both the planet’s
orbit being aligned or highly misaligned with the spin-axis of its host star.
Our measurement independently agrees with, but is far less precise than
observations carried out on other instruments around the same time that measure
a low obliquity orbit for the planet. AU,Mic is the youngest exoplanetary
system for which the projected spin-orbit angle has been measured, making it a
key data point in the study of the formation and migration of exoplanets —
particularly given that the system is also host to a bright debris disk.

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