Exoplanets & Exomoons

The HD 260655 System: Two Rocky Worlds Transiting A Bright M Dwarf At 10 pc

By Keith Cowing
April 21, 2022
Filed under
The HD 260655 System: Two Rocky Worlds Transiting A Bright M Dwarf At 10 pc
TESS target pixel file image of HD 260655 in Sectors 43 (left), 44 (center), and 45 (right) created with tpfplotter (Aller et al. 2020). The electron counts are color-coded. The bordered pixels are used in the simple aperture photometry. The size of the red circles indicates the TESS magnitudes of all nearby stars and host (label #1 with the "×"). The TESS pixel scale is approximately 2100 .

We report the discovery of a multi-planetary system transiting the M0 V dwarf HD 260655 (GJ 239, TOI-4599).

The system consists of at least two transiting planets, namely HD 260655 b, with a period of 2.77 d, a radius of Rb = 1.240±0.023 R⊕, a mass of Mb = 2.14±0.34 M⊕, and a bulk density of ρb = 6.2±1.0 g cm−3, and HD 260655 c, with a period of 5.71 d, a radius of Rc = 1.533+0.051−0.046 R⊕, a mass of Mc = 3.09±0.48 M⊕, and a bulk density of ρc = 4.7+0.9−0.8 g cm−3.

The planets were detected in transit by the TESS mission and confirmed independently with archival and new precise radial velocities obtained with the HIRES and CARMENES instruments since 1998 and 2016, respectively. At a distance of 10 pc, HD 260655 becomes the fourth closest known multi-transiting planet system after HD 219134, LTT 1445 A, and AU Mic. Due to the apparent brightness of the host star (J = 6.7 mag), both planets are among the most suitable rocky worlds known today for atmospheric studies with the JWST, both in transmission and emission.

R. Luque, B. J. Fulton, M. Kunimoto, P. J. Amado, P. Gorrini, S. Dreizler, C. Hellier, G. W. Henry, K. Molaverdikhani, G. Morello, L. Peña-Moñino, M. Pérez-Torres, F. J. Pozuelos, Y. Shan, G. Anglada-Escudé, V. J. S. Béjar, G. Bergond, A. W. Boyle, J. A. Caballero, D. Charbonneau, D. R. Ciardi, S. Dufoer, N. Espinoza, M. Everett, D. Fischer, A. P. Hatzes, Th. Henning, K. Hesse, A. Howard, S. B. Howell, H. Isaacson, S. V. Jeffers, J. M. Jenkins, S. R. Kane, J. Kemmer, S. Khalafinejad, R. C. Kidwell Jr., D. Kossakowski, D. W. Latham, J. Lillo-Box, J. J. Lissauer, D. Montes, J. Orell-Miquel, E. Pallé, D. Pollacco, A. Quirrenbach, S. Reffert, A. Reiners, I. Ribas, G. R. Ricker, L. A. Rogers, J. Sanz-Forcada, M. Schlecker, A. Schweitzer, S. Seager, A. Shporer, K. G. Stassun, S. Stock, L. Tal-Or, E. B. Ting, T. Trifonov, S. Vanaverbeke, R. Vanderspek, J. Villaseñor, J. N. Winn, J. G. Winters

Comments: 24 pages, 17 figures. Submitted to A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
Cite as: arXiv:2204.10261 [astro-ph.EP] (or arXiv:2204.10261v1 [astro-ph.EP] for this version)
Submission history
From: Rafael Luque [
[v1] Thu, 21 Apr 2022 17:01:13 UTC (7,940 KB)

Explorers Club Fellow, ex-NASA Space Station Payload manager/space biologist, Away Teams, Journalist, Lapsed climber, Synaesthete, Na’Vi-Jedi-Freman-Buddhist-mix, ASL, Devon Island and Everest Base Camp veteran, (he/him) 🖖🏻