近日，英国圣安德鲁斯大学Thomas G. Wilson团队报道了红矮星LHS 1903周围的四行星系统中发生了气体耗尽行星的形成。该项研究成果发表在2026年2月12日出版的《科学》杂志上。
小质量系外行星的半径呈现双峰分布，形成由超级地球与次海王星构成的两大族群，两者被称为半径谷的间隙分隔。这一现象可能源于恒星或内部加热导致部分大气层散逸，或是行星诞生之初便缺失原始包层。
研究组利用凌星测光与视向速度测量法，探测并刻画了四颗围绕LHS 1903运行的系外行星——LHS 1903是位于银河系厚盘的一颗红矮星。这些行星的公转周期从2.2天至29.3天不等，在单一行星系统内跨越了半径谷。根据密度推算，LHS 1903 b为岩石行星，LHS 1903 c与LHS 1903 d拥有延展大气层，而距宿主恒星最远的LHS 1903 e则无气体包层，表明其由贫气物质凝聚而成。
附：英文原文
Title: Gas-depleted planet formation occurred in the four-planet system around the red dwarf LHS 1903
Author: Thomas G. Wilson, Anna M. Simpson, Andrew Collier Cameron, Ryan Cloutier, Vardan Adibekyan, Ancy Anna John, Yann Alibert, Manu Stalport, Jo Ann Egger, Andrea Bonfanti, Nicolas Billot, Pascal Guterman, Pierre F. L. Maxted, Attila E. Simon, Sérgio G. Sousa, Malcolm Fridlund, Mathias Beck, Anja Bekkelien, Sébastien Salmon, Valérie Van Grootel, Luca Fossati, Alexander James Mustill, Hugh P. Osborn, Tiziano Zingales, Matthew J. Hooton, Laura Affer, Suzanne Aigrain, Roi Alonso, Guillem Anglada, Alexandros Antoniadis-Karnavas, Tamas Bárczy, David Barrado Navascues, Susana C. C. Barros, Wolfgang Baumjohann, Thomas Beck, Willy Benz, Federico Biondi, Xavier Bonfils, Luca Borsato, Alexis Brandeker, Christopher Broeg, Lars A. Buchhave, Maximilian Buder, Juan Cabrera, Sebastian Carrazco Gaxiola, David Charbonneau, Sébastien Charnoz, David R. Ciardi, Karen A. Collins, Kevin I. Collins, Rosario Cosentino, Szilard Csizmadia, Patricio E. Cubillos, Shweta Dalal, Mario Damasso, James R. A. Davenport, Melvyn B. Davies, Magali Deleuil, Laetitia Delrez, Olivier D. S. Demangeon, Brice-Olivier Demory, Victoria DiTomasso, Diana Dragomir, Courtney D. Dressing, Xavier Dumusque, David Ehrenreich, Anders Erikson, Emma Esparza-Borges, Andrea Fortier, Izuru Fukuda, Akihiko Fukui, Davide Gandolfi, Adriano Ghedina, Steven Giacalone, Holden Gill, Michal Gillon, Yilen Gómez Maqueo Chew, Manuel Güdel, Pere Guerra, Maximilian N. Günther, Nathan Hara, Avet Harutyunyan, Yuya Hayashi, Raphalle D. Haywood, Rae Holcomb, Keith Horne, Sergio Hoyer, Chelsea X. Huang, Masahiro Ikoma, Kate G. Isaak, James A. G. Jackman, Jon M. Jenkins, Eric L. N. Jensen, Daniel Jontof-Hutter, Yugo Kawai, Laszlo L. Kiss, Ben S. Lakeland, Jacques Laskar, David W. Latham, Alain Lecavelier des Etangs, Adrien Leleu, Monika Lendl, Jerome de Leon, Florian Lienhard, Mercedes López-Morales, Christophe Lovis, Michael B. Lund, Rafael Luque, Demetrio Magrin, Luca Malavolta, Aldo F. Martínez Fiorenzano, Andrew W. Mayo, Michel Mayor, Christoph Mordasini, Annelies Mortier, Felipe Murgas, Norio Narita, Valerio Nascimbeni, Belinda A. Nicholson, Gran Olofsson, Roland Ottensamer, Isabella Pagano, Larissa Palethorpe, Enric Pallé, Hannu Parviainen, Marco Pedani, Francesco A. Pepe, Gisbert Peter, Matteo Pinamonti, Giampaolo Piotto, Don Pollacco, Ennio Poretti, Didier Queloz, Samuel N. Quinn, Roberto Ragazzoni, Nicola Rando, David Rapetti, Francesco Ratti, Heike Rauer, Federica Rescigno, Ignasi Ribas, Ken Rice, George R. Ricker, Paul Robertson, Thierry de Roche, Laurence Sabin, Nuno C. Santos, Dimitar D. Sasselov, Arjun B. Savel, Gaetano Scandariato
Issue&Volume: 2026-02-12
Abstract: The radii of small exoplanets form two populations, super-Earths and sub-Neptunes, separated by a gap known as the radius valley. This could be produced by the removal of some atmospheres by stellar or internal heating, or the lack of an initial envelope. We use transit photometry and radial velocity measurements to detect and characterize four exoplanets orbiting LHS 1903, a red dwarf star in the Milky Way’s thick disk. The planets have orbital periods from 2.2 to 29.3 days, and span the radius valley within a single planetary system. The derived densities indicate that LHS 1903 b is rocky, while LHS 1903 c and LHS 1903 d have extended atmospheres. The most distant planet from the host star, LHS 1903 e, has no gaseous envelope, indicating it formed from gas-depleted material.
DOI: adl2348
Source: https://www.science.org/doi/10.1126/science.adl2348