The TESS-Keck Survey. XIII. An Eccentric Hot Neptune with a Similar-Mass
Outer Companion around TOI-1272
Mason G. MacDougall, Erik A. Petigura, Tara Fetherolf, Corey Beard, Jack Lubin, Isabel Angelo, Natalie M. Batalha, Aida Behmard, Sarah Blunt, Casey Brinkman, Ashley Chontos, Ian J. M. Crossfield, Fei Dai, Paul A. Dalba, Courtney Dressing, Benjamin Fulton, Steven Giacalone, Michelle L. Hill, Andrew W. Howard, Daniel Huber, Howard Isaacson, Stephen R. Kane, Molly Kosiarek, Andrew Mayo, Teo Mocnik, Joseph M. Akana Murphy, Daria Pidhorodetska, Alex Polanski, Malena Rice, Paul Robertson, Lee J. Rosenthal, Arpita Roy, Ryan A. Rubenzahl, Nicholas Scarsdale, Emma V. Turtelboom, Dakotah Tyler, Judah Van Zandt, Lauren M. Weiss, Emma Esparza-Borges, Akihiko Fukui, Keisuke Isogai, Kiyoe Kawauchi, Mayuko Mori, Felipe Murgas, Norio Narita, Taku Nishiumi, Enric Palle, Hannu Parviainen, Noriharu Watanabe, Jon M. Jenkins, David W. Latham, George R. Ricker, S. Seager, Roland K. Vanderspek, Joshua N. Winn, Allyson Bieryla, Douglas A. Caldwell, Diana Dragomir, M. M. Fausnaugh, Ismael Mireles, David R. Rodriguez
We report the discovery of an eccentric hot Neptune and a non-transiting
outer planet around TOI-1272. We identified the eccentricity of the inner
planet, with an orbital period of 3.3 d and , based on a mismatch between the observed transit duration and the
expected duration for a circular orbit. Using ground-based radial velocity
measurements from the HIRES instrument at the Keck Observatory, we measured the
mass of TOI-1272b to be . We also confirmed
a high eccentricity of , placing TOI-1272b among the most
eccentric well-characterized sub-Jovians. We used these RV measurements to also
identify a non-transiting outer companion on an 8.7-d orbit with a similar mass
of sin and .
Dynamically stable planet-planet interactions have likely allowed TOI-1272b to
avoid tidal eccentricity decay despite the short circularization timescale
expected for a close-in eccentric Neptune. TOI-1272b also maintains an envelope
mass fraction of despite its high equilibrium
temperature, implying that it may currently be undergoing photoevaporation.
This planet joins a small population of short-period Neptune-like planets
within the "Hot Neptune Desert" with a poorly understood formation pathway.
Comment: Accepted at The Astronomical Journal; 17 pages, 11 figures
Subject: Astrophysics - Earth and Planetary Astrophysics