Kraus, Stefan, Le Bouquin, Jean-Baptiste, Kreplin, Alexander, Davies, Claire L., Hone, Edward, Monnier, John D., Gardner, Tyler, Kennedy, Grant M. and Hinkley, Sasha (2020) Spin–orbit alignment of the β pictoris planetary system. The Astrophysical Journal Letters, 897 (1). L8. doi:10.3847/2041-8213/ab9d27

PDF WRAP-Spin–orbit-alignment-β-pictoris-planetary-system-Grant-2020.pdf - Accepted Version Embargoed item. Restricted access to Repository staff only until 29 June 2021. Contact author directly, specifying your specific needs. - Requires a PDF viewer. Available under License Creative Commons Attribution Non-commercial No Derivatives. Download (2623Kb)

Request Changes to record.

Abstract

A crucial diagnostic that can tell us about processes involved in the formation and dynamical evolution of planetary systems is the angle between the rotation axis of a star and a planet's orbital angular momentum vector ("spin-orbit" alignment or "obliquity"). Here we present the first spin-orbit alignment measurement for a wide-separation exoplanetary system, namely on the directly imaged planet β Pictoris b. We use VLTI/GRAVITY spectro-interferometry with an astrometric accuracy of 1 μas (microarcsecond) in the Brγ photospheric absorption line to measure the photocenter displacement associated with the stellar rotation. Taking inclination constraints from astroseismology into account, we constrain the three-dimensional orientation of the stellar spin axis and find that β Pic b orbits its host star on a prograde orbit. The angular momentum vectors of the stellar photosphere, the planet, and the outer debris disk are well aligned with mutual inclinations ≤3° ± 5°, which indicates that β Pic b formed in a system without significant primordial misalignments. Our results demonstrate the potential of infrared interferometry to measure the spin-orbit alignment for wide-separation planetary systems, probing a highly complementary regime to the parameter space accessible with the Rossiter-McLaughlin effect. If the low obliquity is confirmed by measurements on a larger sample of wide-separation planets, it would lend support to theories that explain the obliquity in Hot Jupiter systems with dynamical scattering and the Kozai-Lidov mechanism.

Item Type:	Journal Article
Subjects:	Q Science > QB Astronomy
Divisions:	Faculty of Science > Physics
Library of Congress Subject Headings (LCSH):	Stars -- Rotation, Planetary systems , Planets -- Orbits, Astroseismology
Journal or Publication Title:	The Astrophysical Journal Letters
Publisher:	Institute of Physics Publishing, Inc.
ISSN:	2041-8205
Official Date:	29 June 2020
Dates:	Date Event 29 June 2020 Published 16 June 2020 Accepted
Date of first compliant deposit:	30 November 2020
Volume:	897
Number:	1
Article Number:	L8
DOI:	10.3847/2041-8213/ab9d27
Status:	Peer Reviewed
Publication Status:	Published
Publisher Statement:	"This is an author-created, un-copyedited version of an article accepted for publication/published in The Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at http://dx.doi.org/10.3847/2041-8213/ab9d27 ”
Access rights to Published version:	Restricted or Subscription Access
RIOXX Funder/Project Grant:	Project/Grant ID RIOXX Funder Name Funder ID 639889 European Research Council http://dx.doi.org/10.13039/501100000781 nsf-ast1506540 National Science Foundation http://dx.doi.org/10.13039/501100008982 NNX16AD43G [NASA] National Aeronautics and Space Administration http://dx.doi.org/10.13039/100000104 UNSPECIFIED Royal Society http://dx.doi.org/10.13039/501100000288
Open Access Version:	ArXiv

Request changes or add full text files to a record

Repository staff actions (login required)

View Item