Two Earth-size Planets and an Earth-size Candidate Transiting the nearby Star HD 101581

Kunimoto, Michelle, Lin, Zifan, Millholland, Sarah, Venner, Alexander, Hinkel, Natalie R., Shporer, Avi, Vanderburg, Andrew, Bailey, Jeremy, Brahm, Rafael, Burt, Jennifer A., Butler, R. Paul, Carter, Brad, Ciardi, David R., Collins, Karen A., Collins, Kevin I., Colón, Knicole D., Crane, Jeffrey D., Daylan, Tansu, Díaz, Matías R., Doty, John P., Feng, Fabo, Guenther, Eike W., Horner, Jonathan, Howell, Steve B., Janik, Jan, Jones, Hugh R. A., Kabáth, Petr, Kanodia, Shubham, Littlefield, Colin, Osborn, Hugh P., O’Toole, Simon, Paegert, Martin, Pintr, Pavel, Schwarz, Richard P., Shectman, Steve, Srdoc, Gregor, Stassun, Keivan G., Teske, Johanna K., Twicken, Joseph D., Vanzi, Leonardo, Wang, Sharon X., Wittenmyer, Robert A., Jenkins, Jon M., Ricker, George R., Seager, Sara and Winn, Joshua (2025) Two Earth-size Planets and an Earth-size Candidate Transiting the nearby Star HD 101581. The Astronomical Journal, 169 (1): 47. pp. 1-19. ISSN 0004-6256

Copy

We report the validation of multiple planets transiting the nearby (d = 12.8 pc) K5V dwarf HD 101581 (GJ 435, TOI–6276, TIC 397362481). This system consists of at least two Earth-size planets whose orbits are near a mutual 4:3 mean-motion resonance, HD 101581 b ( Rp=0.956−0.061+0.063R⊕ , P = 4.47 days) and HD 101581c ( Rp=0.990−0.070+0.070R⊕ , P = 6.21 days). Both planets were discovered in Sectors 63 and 64 TESS observations and statistically validated with supporting ground-based follow-up. We also identify a signal that probably originates from a third transiting planet, TOI-6276.03 ( Rp=0.982−0.098+0.114R⊕ , P = 7.87 days). These planets are remarkably uniform in size and their orbits are evenly spaced, representing a prime example of the “peas-in-a-pod” architecture seen in other compact multiplanet systems. At V = 7.77, HD 101581 is the brightest star known to host multiple transiting planets smaller than 1.5 R ⊕. HD 101581 is a promising system for atmospheric characterization and comparative planetology of small planets.

Item Type	Article
Additional information	© 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/
Keywords	exoplanet dynamics, exoplanets, transit photometry, exoplanet systems, astronomy and astrophysics, space and planetary science
Date Deposited	15 May 2025 15:47
Last Modified	31 May 2025 00:46