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

January 2025 • 2025AJ....169...47K

Authors • 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 • Winn, Joshua

Abstract • 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 ( , P = 4.47 days) and HD 101581c ( , 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 ( , 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. *This paper includes data gathered with the 6.5 meter Magellan Telescopes located at Las Campanas Observatory, Chile.

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• PDF https://iopscience.iop.org/article/10.3847/1538-3881/ad9266/pdf
• PREPRINT http://arxiv.org/abs/2412.08863
• DATA http://archive.eso.org/bin/ads2eso?2025AJ....169...47K
• DATA https://archive.gemini.edu/searchform/publication=2025AJ....169...47K
• DATA https://doi.org/10.26134/ExoFOP5
• ELECTR https://iopscience.iop.org/article/10.3847/1538-3881/ad9266