We report the confirmation of a TESS-discovered transiting super-Earth planet orbiting a mid-G star, HD 307842 (TOI-784). The planet has a period of 2.8 days, and the radial velocity (RV) measurements constrain the mass to be 9.67+0.83/-0.82 [Earth Masses]. We also report the discovery of an additional planet candidate on an outer orbit that is most likely non-transiting. The possible periods of the planet candidate are approximately 20 to 63 days, with the corresponding RV semi-amplitudes expected to range from 3.2 to 5.4 m/s and minimum masses from 12.6 to 31.1 [Earth Masses]. The radius of the transiting planet (planet b) is 1.93+0.11/-0.09 [Earth Radii], which results in a mean density of 7.4+1.4/-1.2 g/cm^3 suggesting that TOI-784b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784b is located at the lower edge of the so-called ``radius valley'' in the radius vs. insolation plane, which is consistent with the photoevaporation or core-powered mass loss prediction. The TESS data did not reveal any significant transit signal of the planet candidate, and our analysis shows that the orbital inclinations of planet b and the planet candidate are 88.60+0.84/-0.86 degrees and <= 88.3-89.2 degrees, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.
@article{arxiv.2306.14655,
title = {A Transiting Super-Earth in the Radius Valley and An Outer Planet Candidate Around HD 307842},
author = {Xinyan Hua and Sharon Xuesong Wang and Johanna K. Teske and Tianjun Gan and Avi Shporer and George Zhou and Keivan G. Stassun and Markus Rabus and Steve B. Howell and Carl Ziegler and Jack J. Lissauer and Joshua N. Winn and Jon M. Jenkins and Eric B. Ting and Karen A. Collins and Andrew W. Mann and Wei Zhu and Su Wang and R. Paul Butler and Jeffrey D. Crane and Stephen A. Shectman and Luke G. Bouma and Cesar Briceno and Diana Dragomir and William Fong and Nicholas Law and Jennifer V. Medina and Samuel N. Quinn and George R. Ricker and Richard P. Schwarz and Sara Seager and Ramotholo Sefako and Chris Stockdale and Roland Vanderspek and Joel Villasenor},
journal= {arXiv preprint arXiv:2306.14655},
year = {2023}
}
Comments
30 pages, 21 figures, accepted for publication in AJ