The TESS-keck survey. III. A stellar obliquity measurement of TOI-1726 c

Fei Dai, Arpita Roy, Benjamin Fulton, Paul Robertson, Lea Hirsch, Howard Isaacson, Simon Albrecht, Andrew W. Mann, Martti H. Kristiansen, Natalie M. Batalha, Corey Beard, Aida Behmard, Ashley Chontos, Ian J.M. Crossfield, Paul A. Dalba, Courtney Dressing, Steven Giacalone, Michelle Hill, Andrew W. Howard, Daniel HuberStephen R. Kane, Molly Kosiarek, Jack Lubin, Andrew Mayo, Teo Mocnik, Joseph M. Akana Murphy, Erik A. Petigura, Lee Rosenthal, Ryan A. Rubenzahl, Nicholas Scarsdale, Lauren M. Weiss, Judah van Zandt, George R. Ricker, Roland Vanderspek, David W. Latham, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Douglas A. Caldwell, David Charbonneau, Tansu Daylan, Maximilian N. Günther, Edward Morgan, Samuel N. Quinn, Mark E. Rose, Jeffrey C. Smith

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


We report the measurement of a spectroscopic transit of TOI-1726c, one of two planets transiting a G-type star with V = 6.9 in the Ursa Major Moving Group (∼400 Myr). With a precise age constraint from cluster membership, TOI-1726 provides a great opportunity to test various obliquity excitation scenarios that operate on different timescales. By modeling the Rossiter-McLaughlin (RM) effect, we derived a sky-projected obliquity of -1-+3235∘. This result rules out a polar/retrograde orbit and is consistent with an aligned orbit for planet c. Considering the previously reported, similarly prograde RM measurement of planet b and the transiting nature of both planets, TOI-1726 tentatively conforms to the overall picture that compact multitransiting planetary systems tend to have coplanar, likely aligned orbits. TOI-1726 is also a great atmospheric target for understanding differential atmospheric loss of sub-Neptune planets (planet b 2.2 R☉ and c 2.7 R☉ both likely underwent photoevaporation). The coplanar geometry points to a dynamically cold history of the system that simplifies any future modeling of atmospheric escape.

Original languageEnglish (US)
Article numberabb3bd
JournalAstronomical Journal
Issue number4
StatePublished - Oct 2020

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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