A super-massive Neptune-sized planet

Luca Naponiello*, Luigi Mancini, Alessandro Sozzetti, Aldo Stefano Bonomo, Alessandro Morbidelli, Jingyao Dou, Zoe Leinhardt, Katia Biazzo, Patricio E. Cubillos, MATTEO PINAMONTI, Daniele Locci, Antonio Maggio, Mario Damasso, Antonino Francesco Lanza, Jack Lissauer, Karen A. Collins, Philip J. Carter, Eric Jensen, Andrea Bignamini, Walter BoschinLuke Bouma, David R. Ciardi, Rosario Cosentino, Ian Crossfield, Silvano Desidera, Xavier Dumusque, A. F. Martínez Fiorenzano, Akihiko Fukui, Paolo Giacobbe, Crystal L. Gnilka, Adriano Ghedina, Gloria Guilluy, Avet Harutyunyan, Steve B. Howell, Jon Jenkins, Michael B Lund, John Kielkopf, Katie V. Lester, Luca Malavolta, Andrew W. Mann, Rachel Matson, Elisabeth Matthews, Domenico NARDIELLO, Norio Narita, Emanuele Pace, Isabella Pagano, Enric Palle, Marco Pedani, Sara Seager, Joshua E. Schlieder

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

12 Citations (Scopus)

Abstract

Neptune-sized planets exhibit a wide range of compositions and densities, depending on factors related to their formation and evolution history, such as the distance from their host stars and atmospheric escape processes. They can vary from relatively low-density planets with thick hydrogen–helium atmospheres1,2 to higher-density planets with a substantial amount of water or a rocky interior with a thinner atmosphere, such as HD 95338 b (ref. 3), TOI-849 b (ref. 4) and TOI-2196 b (ref. 5). The discovery of exoplanets in the hot-Neptune desert6, a region close to the host stars with a deficit of Neptune-sized planets, provides insights into the formation and evolution of planetary systems, including the existence of this region itself. Here we show observations of the transiting planet TOI-1853 b, which has a radius of 3.46 ± 0.08 Earth radii and orbits a dwarf star every 1.24 days. This planet has a mass of 73.2 ± 2.7 Earth masses, almost twice that of any other Neptune-sized planet known so far, and a density of 9.7 ± 0.8 grams per cubic centimetre. These values place TOI-1853 b in the middle of the Neptunian desert and imply that heavy elements dominate its mass. The properties of TOI-1853 b present a puzzle for conventional theories of planetary formation and evolution, and could be the result of several proto-planet collisions or the final state of an initially high-eccentricity planet that migrated closer to its parent star.
Original languageEnglish
Pages (from-to)255-260
Number of pages6
JournalNature
Early online date31 Aug 2023
DOIs
Publication statusPublished - 12 Oct 2023

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