Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets

September 2017 • 2017AJ....154..122C

Authors • Christiansen, Jessie L. • Vanderburg, Andrew • Burt, Jennifer • Fulton, B. J. • Batygin, Konstantin • Benneke, Björn • Brewer, John M. • Charbonneau, David • Ciardi, David R. • Collier Cameron, Andrew • Coughlin, Jeffrey L. • Crossfield, Ian J. M. • Dressing, Courtney • Greene, Thomas P. • Howard, Andrew W. • Latham, David W. • Molinari, Emilio • Mortier, Annelies • Mullally, Fergal • Pepe, Francesco • Rice, Ken • Sinukoff, Evan • Sozzetti, Alessandro • Thompson, Susan E. • Udry, Stéphane • Vogt, Steven S. • Barman, Travis S. • Batalha, Natasha E. • Bouchy, François • Buchhave, Lars A. • Butler, R. Paul • Cosentino, Rosario • Dupuy, Trent J. • Ehrenreich, David • Fiorenzano, Aldo • Hansen, Brad M. S. • Henning, Thomas • Hirsch, Lea • Holden, Bradford P. • Isaacson, Howard T. • Johnson, John A. • Knutson, Heather A. • Kosiarek, Molly • López-Morales, Mercedes • Lovis, Christophe • Malavolta, Luca • Mayor, Michel • Micela, Giuseppina • Motalebi, Fatemeh • Petigura, Erik • Phillips, David F. • Piotto, Giampaolo • Rogers, Leslie A. • Sasselov, Dimitar • Schlieder, Joshua E. • Ségransan, Damien • Watson, Christopher A. • Weiss, Lauren M.

Abstract • HD 3167 is a bright (V = 8.9), nearby K0 star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 ± 0.38 {M}\oplus for HD 3167 b, a hot super-Earth with a likely rocky composition ({ρ }b = {5.60}-1.43+2.15 g cm-3), and {9.80}-1.24+1.30 {M}\oplus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement ({ρ }c = {1.97}-0.59+0.94 g cm-3). We explore the possibility of atmospheric composition analysis and determine that planet c is amenable to transmission spectroscopy measurements, and planet b is a potential thermal emission target. We detect a third, non-transiting planet, HD 3167 d, with a period of 8.509 ± 0.045 d (between planets b and c) and a minimum mass of 6.90 ± 0.71 {M}\oplus . We are able to constrain the mutual inclination of planet d with planets b and c: we rule out mutual inclinations below 1.°3 because we do not observe transits of planet d. From 1.°3 to 40°, there are viewing geometries invoking special nodal configurations, which result in planet d not transiting some fraction of the time. From 40° to 60°, Kozai-Lidov oscillations increase the system’s instability, but it can remain stable for up to 100 Myr. Above 60°, the system is unstable. HD 3167 promises to be a fruitful system for further study and a preview of the many exciting systems expected from the upcoming NASA TESS mission.


IPAC Authors


Jessie Christiansen

Associate Scientist


David Ciardi

Senior Scientist


Benjamin Fulton

Assistant Scientist