NEID Rossiter-McLaughlin Measurement of TOI-1268b: A Young Warm Saturn Aligned with Its Cool Host Star
Creators: name: Dong, Jiayin
name: Huang, Chelsea X.
name: Zhou, George
name: Dawson, Rebekah I.
name: Stefánsson, Gudmundur K.
name: Bender, Chad F.
name: Blake, Cullen H.
name: Ford, Eric B.
name: Halverson, Samuel
name: Kanodia, Shubham
name: Mahadevan, Suvrath
name: McElwain, Michael W.
name: Ninan, Joe P.
name: Robertson, Paul
name: Roy, Arpita
name: Schwab, Christian
name: Stevens, Daniel J.
name: Terrien, Ryan C.
name: Vanderburg, Andrew
name: Kraus, Adam L.
name: Douglas, Stephanie
name: Newton, Elisabeth
name: Rampalli, Rayna
name: Krolikowski, Daniel M.
name: Collins, Karen A.
name: Rodriguez, Joseph E.
name: Feliz, Dax L.
name: Srdoc, Gregor
name: Ziegler, Carl
name: Barkaoui, Khalid
name: Pozuelos, Francisco J.
name: Jehin, Emmanuel
name: Gillon, Michaël
name: Benkhaldoun, Zouhair
name: Lewin, Pablo
name: Forés-Toribio, Raquel
name: Muñoz, Jose A.
name: McLeod, Kim K.
name: Özyurt, Fiona Powers
name: Horta, Ferran Grau
name: Murgas, Felipe
name: Latham, David W.
name: Quinn, Samuel N.
name: Bieryla, Allyson
name: Howell, Steve B.
name: Gnilka, Crystal L.
name: Ciardi, David R.
name: Lund, Michael B.
name: Dressing, Courtney D.
name: Giacalone, Steven
name: Savel, Arjun B.
name: Strakhov, Ivan A.
name: Belinski, Alexander A.
name: Ricker, George R.
name: Seager, S.
name: Winn, Joshua N.
name: Jenkins, Jon M.
name: Torres, Guillermo
name: Paegert, Martin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Earth and Planetary Astrophysics (astro-ph.EP)
subject: Solar and Stellar Astrophysics (astro-ph.SR)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: Close-in gas giants present a surprising range of stellar obliquity, the angle between a planet's orbital axis and its host star's spin axis. It is unclear whether the obliquities reflect the planets' dynamical history (e.g., aligned for in situ formation or disk migration versus misaligned for high-eccentricity tidal migration) or whether other mechanisms (e.g., primordial misalignment or planet-star interactions) are more important in sculpting the obliquity distribution. Here we present the stellar obliquity measurement of TOI-1268 (TIC-142394656, $V_{\rm mag} {\sim} 10.9$), a young K-type dwarf hosting an 8.2-day period, Saturn-sized planet. TOI-1268's lithium abundance and rotation period suggest the system age between the ages of Pleiades cluster (${\sim}120$ Myr) and Praesepe cluster (${\sim}670$ Myr). Using the newly commissioned NEID spectrograph, we constrain the stellar obliquity of TOI-1268 via the Rossiter-McLaughlin (RM) effect from both radial velocity (RV) and Doppler Tomography (DT) signals. The 3$σ$ upper bounds of the projected stellar obliquity $|λ|$ from both models are below 60$^\circ$. The large host star separation ($a/R_\star {\sim} 17$), combined with the system's young age, makes it unlikely that the planet has realigned its host star. The stellar obliquity measurement of TOI-1268 probes the architecture of a young gas giant beyond the reach of tidal realignment ($a/R_\star {\gtrsim} 10$) and reveals an aligned or slightly misaligned system.
description: 14 pages, 6 figures, 1 table, accepted for publication in ApJL; see independent work by Subjak et al. for RV follow-up of TOI-1268