An Earth-sized Planet on the Verge of Tidal Disruption
Fei Dai, Andrew W. Howard, Samuel Halverson, J. Orell-Miquel, Ε. Πάλλη, Howard Isaacson, Benjamin J. Fulton, Ellen M. Price, Mykhaylo Plotnykov, Leslie A. Rogers, Diana Valencia, Kimberly Paragas, Michael Greklek-McKeon, Jonathan Gomez Barrientos, Heather A. Knutson, Erik A. Petigura, Lauren M. Weiss, Rena A. Lee, Casey L. Brinkman, Daniel Huber, Gumundur Stefánsson, K. Masuda, Steven Giacalone, Cicero X. Lu, Edwin S. Kite, Renyu Hu, Eric Gaidos, Michael Zhang, Ryan A. Rubenzahl, Joshua N. Winn, Te Han, Corey Beard, Rae Holcomb, Aaron Householder, Gregory J. Gilbert, Jack Lubin, J. M. Joel Ong, Alex S. Polanski, Nicholas Saunders, Judah Van Zandt, Samuel W. Yee, Jingwen Zhang, Jon K. Zink, B. Holden, Ashley Baker, Max Brodheim, Ian J. M. Crossfield, William Deich, Jerry Edelstein, Steven R. Gibson, Grant M. Hill, Sharon R. Jelinsky, Marc Kassis, Russ R. Laher, Kyle Lanclos, Scott Lilley, Joel Payne, Kodi Rider, Paul Robertson, Arpita Roy, Christian Schwab, Abby P. Shaum, Martin M. Sirk, Chris Smith, Adam Vandenberg, Josh Walawender, Sharon X. Wang, S. X. Wang, Edward Wishnow, Jason T. Wright, Sherry Yeh, J. A. Caballero, J. C. Morales, F. Murgas, E. Nagel, A. Reiners, A. Schweitzer, H. M. Tabernero, M. Zechmeister, Alton Spencer, David R. Ciardi, Catherine A. Clark, Michael B. Lund, Douglas A. Caldwell, Karen A. Collins, Richard P. Schwarz, Khalid Barkaoui, Cristilyn N. Watkins, Avi Shporer, Norio Narita, Akihiko Fukui, Gregor Srdoč, David W. Latham, Jon M. Jenkins, G. Ricker, Sara Seager, R. Vanderspek
Abstract
Abstract TOI-6255 b (GJ 4256) is an Earth-sized planet (1.079 ± 0.065 R ⊕ ) with an orbital period of only 5.7 hr. With the newly commissioned Keck Planet Finder and CARMENES spectrographs, we determine the planet’s mass to be 1.44 ± 0.14 M ⊕ . The planet is just outside the Roche limit, with P orb / P Roche = 1.13 ± 0.10. The strong tidal force likely deforms the planet into a triaxial ellipsoid with a long axis that is ∼10% longer than the short axis. Assuming a reduced stellar tidal quality factor <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>Q</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>⋆</mml:mo> </mml:mrow> <mml:mrow> <mml:mo accent="true">′</mml:mo> </mml:mrow> </mml:msubsup> <mml:mo>≈</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:msup> </mml:math> , we predict that tidal orbital decay will cause TOI-6255 to reach the Roche limit in roughly 400 Myr. Such tidal disruptions may produce the possible signatures of planet engulfment that have been seen on stars with anomalously high refractory elemental abundances compared to their conatal binary companions. TOI-6255 b is also a favorable target for searching for star–planet magnetic interactions, which might cause interior melting and hasten orbital decay. TOI-6255 b is a top target (with an Emission Spectroscopy Metric of about 24) for phase-curve observations with the James Webb Space Telescope.