_version_ 1866915732821901312
author Livingston, John H.
Petigura, Erik A.
David, Trevor J.
Masuda, Kento
Owen, James
Nesvorný, David
Batygin, Konstantin
de Leon, Jerome
Mori, Mayuko
Ikuta, Kai
Fukui, Akihiko
Watanabe, Noriharu
Miquel, Jaume Orell
Murgas, Felipe
Parviainen, Hannu
Korth, Judith
Libotte, Florence
García, Néstor Abreu
Gallardo, Pedro Pablo Meni
Narita, Norio
Pallé, Enric
Tamura, Motohide
Yonehara, Atsunori
Ridden-Harper, Andrew
Bieryla, Allyson
Trani, Alessandro A.
Mamajek, Eric E.
Ciardi, David R.
Gorjian, Varoujan
Hillenbrand, Lynne A.
Rebull, Luisa M.
Newton, Elisabeth R.
Mann, Andrew W.
Vanderburg, Andrew
Stefánsson, Guðmundur
Mahadevan, Suvrath
Cañas, Caleb
Ninan, Joe
Higuera, Jesus
Todorov, Kamen
Désert, Jean-Michel
Pino, Lorenzo
author_facet Livingston, John H.
Petigura, Erik A.
David, Trevor J.
Masuda, Kento
Owen, James
Nesvorný, David
Batygin, Konstantin
de Leon, Jerome
Mori, Mayuko
Ikuta, Kai
Fukui, Akihiko
Watanabe, Noriharu
Miquel, Jaume Orell
Murgas, Felipe
Parviainen, Hannu
Korth, Judith
Libotte, Florence
García, Néstor Abreu
Gallardo, Pedro Pablo Meni
Narita, Norio
Pallé, Enric
Tamura, Motohide
Yonehara, Atsunori
Ridden-Harper, Andrew
Bieryla, Allyson
Trani, Alessandro A.
Mamajek, Eric E.
Ciardi, David R.
Gorjian, Varoujan
Hillenbrand, Lynne A.
Rebull, Luisa M.
Newton, Elisabeth R.
Mann, Andrew W.
Vanderburg, Andrew
Stefánsson, Guðmundur
Mahadevan, Suvrath
Cañas, Caleb
Ninan, Joe
Higuera, Jesus
Todorov, Kamen
Désert, Jean-Michel
Pino, Lorenzo
contents The Galaxy's most common known planetary systems have several Earth-to-Neptune-size planets in compact orbits. At small orbital separations, larger planets are less common than their smaller counterparts by an order of magnitude. The young star V1298 Tau hosts one such compact planetary system, albeit with four planets that are uncommonly large (5 to 10 Earth radii). The planets form a chain of near-resonances that result in transit-timing variations of several hours. Here we present a multi-year campaign to characterize this system with transit-timing variations, a method insensitive to the intense magnetic activity of the star. Through targeted observations, we first resolved the previously unknown orbital period of the outermost planet. The full 9-year baseline from these and archival data then enabled robust determination of the masses and orbital parameters for all four planets. We find the planets have low, sub-Neptune masses and nearly circular orbits, implying a dynamically tranquil history. Their low masses and large radii indicate that the inner planets underwent a period of rapid cooling immediately after dispersal of the protoplanetary disk. Still, they are much less dense than mature planets of comparable size. We predict the planets will contract to 1.5-4.0 Earth radii and join the population of super-Earths and sub-Neptunes that nature produces in abundance.
format Preprint
id arxiv_https___arxiv_org_abs_2601_10598
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A young progenitor for the most common planetary systems in the Galaxy
Livingston, John H.
Petigura, Erik A.
David, Trevor J.
Masuda, Kento
Owen, James
Nesvorný, David
Batygin, Konstantin
de Leon, Jerome
Mori, Mayuko
Ikuta, Kai
Fukui, Akihiko
Watanabe, Noriharu
Miquel, Jaume Orell
Murgas, Felipe
Parviainen, Hannu
Korth, Judith
Libotte, Florence
García, Néstor Abreu
Gallardo, Pedro Pablo Meni
Narita, Norio
Pallé, Enric
Tamura, Motohide
Yonehara, Atsunori
Ridden-Harper, Andrew
Bieryla, Allyson
Trani, Alessandro A.
Mamajek, Eric E.
Ciardi, David R.
Gorjian, Varoujan
Hillenbrand, Lynne A.
Rebull, Luisa M.
Newton, Elisabeth R.
Mann, Andrew W.
Vanderburg, Andrew
Stefánsson, Guðmundur
Mahadevan, Suvrath
Cañas, Caleb
Ninan, Joe
Higuera, Jesus
Todorov, Kamen
Désert, Jean-Michel
Pino, Lorenzo
Earth and Planetary Astrophysics
The Galaxy's most common known planetary systems have several Earth-to-Neptune-size planets in compact orbits. At small orbital separations, larger planets are less common than their smaller counterparts by an order of magnitude. The young star V1298 Tau hosts one such compact planetary system, albeit with four planets that are uncommonly large (5 to 10 Earth radii). The planets form a chain of near-resonances that result in transit-timing variations of several hours. Here we present a multi-year campaign to characterize this system with transit-timing variations, a method insensitive to the intense magnetic activity of the star. Through targeted observations, we first resolved the previously unknown orbital period of the outermost planet. The full 9-year baseline from these and archival data then enabled robust determination of the masses and orbital parameters for all four planets. We find the planets have low, sub-Neptune masses and nearly circular orbits, implying a dynamically tranquil history. Their low masses and large radii indicate that the inner planets underwent a period of rapid cooling immediately after dispersal of the protoplanetary disk. Still, they are much less dense than mature planets of comparable size. We predict the planets will contract to 1.5-4.0 Earth radii and join the population of super-Earths and sub-Neptunes that nature produces in abundance.
title A young progenitor for the most common planetary systems in the Galaxy
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2601.10598