GJ 3090 b: one of the most favourable mini-Neptune for atmospheric characterisation

J. M. Almenara, X. Bonfils, J. F. Otegi, O. Attia, M. Turbet, N. Astudillo-Defru, K. A. Collins, A. S. Polanski, V. Bourrier, C. Hellier, C. Ziegler, F. Bouchy, C. Briceno, D. Charbonneau, M. Cointepas, K. I. Collins, I. Crossfield, X. Delfosse, R. F. Diaz, C. DornJ. P. Doty, T. Forveille, G. Gaisné, T. Gan, R. Helled, K. Hesse, J. M. Jenkins, E. L.N. Jensen, D. W. Latham, N. Law, A. W. Mann, S. Mao, B. McLean, F. Murgas, G. Myers, S. Seager, A. Shporer, T. G. Tan, J. D. Twicken, J. Winn

Research output: Contribution to journalArticlepeer-review


The report discusses the discovery of a mini-Neptune planet, GJ 3090 b (TOI-177.01), orbiting a bright M2 dwarf star every 2.9 days, located 22 pc away. This discovery was made by the Transiting Exoplanet Survey Satellite and confirmed using the High Accuracy Radial velocity Planet Searcher. The study eliminated the possibility of nearby eclipsing binaries through seeing-limited photometry and speckle imaging. Additional transits were observed using various telescopes. The star was characterized having a certain mass and radius, while the planet GJ 3090 b was found to have a mass of 3.34 ± 0.72 ME and a radius of 2.13 ± 0.11 RE. Its low density suggests the presence of volatiles, placing it near a transitional zone between super-Earths and mini-Neptunes known as the radius valley. A detailed analysis suggests the planet's atmosphere isn't pure H-He, but rather has a heavy mean molecular weight. The transmission spectroscopy indicates GJ 3090 b as a favorable candidate for atmospheric characterization, making it a valuable probe for studying the transition between super-Earths and mini-Neptunes. Another potential planet with a 13-day orbital period was also identified, but its transits were not detected.
Original languageEnglish
Article numberA91
JournalAstronomy and Astrophysics
StatePublished - Sep 1 2022

ASJC Scopus Subject Areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Planetary systems
  • Stars: individual: GJ 3090
  • Techniques: photometric
  • Techniques: radial velocities

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