J/AJ/162/137 Minerva-Australis radial velocity of AU Mic (Addison+, 2021)
The youngest planet to have a spin-orbit alignment measurement AU Mic b.
Addison B.C., Horner J., Wittenmyer R.A., Heitzmann A., Plavchan P.,
Wright D.J., Nicholson B.A., Marshall J.P., Clark J.T., Gunther M.N.,
Kane S.R., Hirano T., Wang S., Kielkopf J., Shporer A., Tinney C.G.,
Zhang H., Ballard S., Bedding T., Bowler B.P., Mengel M.W., Okumura J.,
Gaidos E., Wang X.-Y.
<Astron. J., 162, 137-137 (2021)>
=2021AJ....162..137A 2021AJ....162..137A (SIMBAD/NED BibCode)
ADC_Keywords: Exoplanets; Stars, M-type; Radial velocities; Spectra, optical
Keywords: Exoplanets; Hot Neptunes; Exoplanet astronomy; Radial velocity
Exoplanet detection methods; Dynamical evolution
Abstract:
We report measurements of the sky-projected spin-orbit angle for AU
Mic b, a Neptune-size planet orbiting a very young (∼20Myr) 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 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
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 λ=47-54+26deg . 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.
Description:
We carried out the spectroscopic observations of three AU Mic b
transits using the Minerva-Australis facility. Minerva-Australis
consists of an array of four independently operated 0.7m CDK700
telescopes situated at the Mount Kent Observatory in Queensland,
Australia. Each telescope simultaneously feeds stellar light via fiber
optic cables to a single KiwiSpec R4-100 high-resolution (R=80000)
spectrograph with wavelength coverage from 480-620nm.
Objects:
------------------------------------------------------
RA (2000) DE Designation(s) (Period)
------------------------------------------------------
20 45 09.53 -31 20 27.2 AU Mic = V* AU Mic (P=4.8d)
------------------------------------------------------
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 25 147 Minerva-Australis radial velocities for AU Mic
for the three transit observations (unbinned)
table2.dat 23 57 Minerva-Australis telescope binned radial
velocities for the three transit observations
--------------------------------------------------------------------------------
See also:
III/150 : Perkins Revised MK Types for the Cooler Stars (Keenan+ 1989)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/529/A75 : Limb-darkening coefficients (Claret+, 2011)
J/A+A/532/A10 : RACE-OC project. II. (Messina+, 2011)
J/ApJS/200/15 : HARPS-TERRA project. I. (Anglada-Escude+, 2012)
J/AJ/158/56 : Stellar parameters of M and K dwarfs (Houdebine+, 2019)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2458635/2458746] Barycentric Julian Date
16- 20 I5 m/s RVel [-5453/-4410] Radial Velocity
22- 23 I2 m/s e_RVel [17/73] Uncertainty in RVel
25- 25 I1 --- Fib [3/6] Fiber used
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 14 F14.6 d BJD [2458635/2458746] Barycentric Julian Date
16- 20 I5 m/s RVel [-5389/-4466] Radial Velocity
22- 23 I2 m/s e_RVel [14/35] Uncertainty in RVel
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 13-Dec-2021