Repository logo
 

TESS Hunt for Young and Maturing Exoplanets (THYME). III. A Two-planet System in the 400 Myr Ursa Major Group

Accepted version
Peer-reviewed

Type

Article

Change log

Abstract

Exoplanets can evolve significantly between birth and maturity as their atmospheres, orbits, and structures are shaped by their environment. Young planets ($<1Gyr)offertheopportunitytoprobethesesculptingprocesses.However,mostoftheknownyoungplanetsorbitprohibitivelyfaintstars.WepresentthediscoveryoftwoplanetstransitingHD63433(TOI1726,TIC130181866),ayoungSunlike(M_*=0.99\pm0.03)star.Throughkinematics,lithiumabundance,androtation,weconfirmthatHD63433isamemberoftheUrsaMajormovinggroup(\tau=414\pm23$ Myr). Based on the TESS light curve and updated stellar parameters, the planet radii are 2.15±0.10R and 2.67±0.12R, the orbital periods are 7.11 and 20.55 days, and the orbital eccentricities are lower than abut 0.2. Using HARPS-N velocities, we measure the Rossiter-McLaughlin signal of the inner planet, demonstrating the orbit is prograde. Since the host star is bright (V=6.9), both planets are amenable to transmission spectroscopy, radial velocity measurements of their masses, and more precise determination of the stellar obliquity. This system is therefore poised to play an important role in our understanding of planetary system evolution in the first billion years after formation.

Description

Keywords

5109 Space Sciences, 51 Physical Sciences, 5101 Astronomical Sciences

Journal Title

Astronomical Journal

Conference Name

Journal ISSN

0004-6256
1538-3881

Volume Title

160

Publisher

Institute of Physics Publishing

Rights

All rights reserved