A Transiting Super-Earth in the Radius Valley and an Outer Planet Candidate Around HD 307842

July 2023 • 2023AJ....166...32H

Authors • Hua, Xinyan • Wang, Sharon Xuesong • Teske, Johanna K. • Gan, Tianjun • Shporer, Avi • Zhou, George • Stassun, Keivan G. • Rabus, Markus • Howell, Steve B. • Ziegler, Carl • Lissauer, Jack J. • Winn, Joshua N. • Jenkins, Jon M. • Ting, Eric B. • Collins, Karen A. • Mann, Andrew W. • Zhu, Wei • Wang, Su • Butler, R. Paul • Crane, Jeffrey D. • Shectman, Stephen A. • Bouma, Luke G. • Briceño, César • Dragomir, Diana • Fong, William • Law, Nicholas • Medina, Jennifer V. • Quinn, Samuel N. • Ricker, George R. • Schwarz, Richard P. • Seager, Sara • Sefako, Ramotholo • Stockdale, Chris • Vanderspek, Roland • Villaseñor, Joel

Abstract • 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 ${9.67}_{-0.82}^{+0.83}\ {M}_{\oplus }$ . We also report the discovery of an additional planet candidate on an outer orbit that is most likely nontransiting. The possible periods of the planet candidate are approximately 20-63 days, with the corresponding RV semiamplitudes expected to range from 3.2 to 5.4 m s^-1 and minimum masses from 12.6 to 31.1 M _⊕. The radius of the transiting planet (planet b) is ${1.93}_{-0.09}^{+0.11}\ {R}_{\oplus }$ , which results in a mean density of ${7.4}_{-1.2}^{+1.4}\ {\rm{g}}\,{\mathrm{cm}}^{-3}$ suggesting that TOI-784 b is likely to be a rocky planet though it has a comparable radius to a sub-Neptune. We found TOI-784 b is located at the lower edge of the so-called "radius valley" in the radius versus 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 ${88.60^\circ }_{-0.86}^{+0.84}$ and ≤88.°3-89.°2, respectively. More RV observations are needed to determine the period and mass of the second object, and search for additional planets in this system.

Links

• PREPRINT http://arxiv.org/abs/2306.14655
• ELECTR https://doi.org/10.3847/1538-3881/acd751
• SIMBAD https://simbad.u-strasbg.fr/simbad/sim-ref?querymethod=bib&simbo=on&submit=submit+bibcode&bibcode=2023AJ....166...32H
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/acd751/pdf
• DATA https://archive.gemini.edu/searchform/publication=2023AJ....166...32H
• DATA https://doi.org/10.17909/2rfj-4m38
• DATA https://doi.org/10.17909/fwdt-2x66
• DATA https://irsa.ipac.caltech.edu/bibdata/2023/H/2023AJ....166...32H.html