TOI-1075 b: A Dense, Massive, Ultra-short-period Hot Super-Earth Straddling the Radius Gap

February 2023 • 2023AJ....165...47E

Authors • Essack, Zahra • Shporer, Avi • Burt, Jennifer A. • Seager, Sara • Cambioni, Saverio • Lin, Zifan • Collins, Karen A. • Mamajek, Eric E. • Stassun, Keivan G. • Ricker, George R. • Vanderspek, Roland • Latham, David W. • Winn, Joshua N. • Jenkins, Jon M. • Butler, R. Paul • Charbonneau, David • Collins, Kevin I. • Crane, Jeffrey D. • Gan, Tianjun • Hellier, Coel • Howell, Steve B. • Irwin, Jonathan • Mann, Andrew W. • Ramadhan, Ali • Shectman, Stephen A. • Teske, Johanna K. • Yee, Samuel W. • Mireles, Ismael • Quintana, Elisa V. • Tenenbaum, Peter • Torres, Guillermo • Furlan, Elise

Abstract • Populating the exoplanet mass-radius diagram in order to identify the underlying relationship that governs planet composition is driving an interdisciplinary effort within the exoplanet community. The discovery of hot super-Earths-a high-temperature, short-period subset of the super-Earth planet population-has presented many unresolved questions concerning the formation, evolution, and composition of rocky planets. We report the discovery of a transiting, ultra-short-period hot super-Earth orbiting TOI-1075 (TIC351601843), a nearby (d = 61.4 pc) late-K/early-M-dwarf star, using data from the Transiting Exoplanet Survey Satellite. The newly discovered planet has a radius of 1.791 ${}_{-0.081}^{+0.116}$ R _⊕ and an orbital period of 0.605 day (14.5 hr). We precisely measure the planet mass to be 9.95 ${}_{-1.30}^{+1.36}$ M _⊕ using radial velocity measurements obtained with the Planet Finder Spectrograph mounted on the Magellan II telescope. Our radial velocity data also show a long-term trend, suggesting an additional planet in the system. While TOI-1075 b is expected to have a substantial H/He atmosphere given its size relative to the radius gap, its high density ( ${9.32}_{-1.85}^{+2.05}$ g cm^-3) is likely inconsistent with this possibility. We explore TOI-1075 b's location relative to the M-dwarf radius valley, evaluate the planet's prospects for atmospheric characterization, and discuss potential planet formation mechanisms. Studying the TOI-1075 system in the broader context of ultra-short-period planetary systems is necessary for testing planet formation and evolution theories and density-enhancing mechanisms and for future atmospheric and surface characterization studies via emission spectroscopy with the JWST.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2023AJ....165...47E
• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ac9c5b/pdf
• PREPRINT http://arxiv.org/abs/2210.14901
• DATA https://archive.gemini.edu/searchform/publication=2023AJ....165...47E
• DATA https://irsa.ipac.caltech.edu/bibdata/2023/E/2023AJ....165...47E.html
• ELECTR https://doi.org/10.3847/1538-3881/ac9c5b