TOI-663: A newly discovered multi-planet system with three transiting mini-Neptunes orbiting an early M star

M. Cointepas, F. Bouchy, J. M. Almenara, X. Bonfils, N. Astudillo-Defru, H. Knierim, M. Stalport, L. Mignon, N. Grieves, J. Bean, M. Brady, J. Burt, B. L. Canto Martins, K. A. Collins, J. H. Livingston, X. Delfosse, J. R. de Medeiros, B. O. Demory, C. Dorn, T. ForveilleA. Fukui, T. Gan, Y. Gómez Maqueo Chew, S. Halverson, R. Helled, I. Helm, T. Hirano, K. Horne, S. B. Howell, K. Isogai, D. Kasper, K. Kawauchi, J. H. Livingston, B. Massey, R. A. Matson, F. Murgas, N. Narita, E. Palle, H. M. Relles, L. Sabin, N. Schanche, R. P. Schwarz, A. Seifahrt, A. Shporer, G. Stefansson, J. Sturmer, M. Tamura, T. G. Tan, J. D. Twicken, N. Watanabe, R. D. Wells, F. P. Wilkin, G. R. Ricker, S. Seager, J. N. Winn, J. M. Jenkins

Research output: Contribution to journalArticlepeer-review

Abstract

We present the detection of three exoplanets orbiting the early M dwarf TOI-663 (TIC 54962195; V = 13.7 mag, J = 10.4 mag, R* = 0.512 ± 0.015 R, M* = 0.514 ± 0.012 M, d = 64 pc). TOI-663 b, c, and d, with respective radii of 2.27 ± 0.10 R+, 2.26 ± 0.10 R+, and 1.92 ± 0.13 R+ and masses of 4.45 ± 0.65 M+, 3.65 ± 0.97 M+, and <5.2 M+ at 99%, are located just above the radius valley that separates rocky and volatile-rich exoplanets. The planet candidates are identified in two TESS sectors and are validated with ground-based photometric follow-up, precise radial-velocity measurements, and high-resolution imaging. We used the software package juliet to jointly model the photometric and radial-velocity datasets, with Gaussian processes applied to correct for systematics. The three planets discovered in the TOI-663 system are low-mass mini-Neptunes with radii significantly larger than those of rocky analogs, implying that volatiles, such as water, must predominate. In addition to this internal structure analysis, we also performed a dynamical analysis that confirmed the stability of the system. The three exoplanets in the TOI-663 system, similarly to other sub-Neptunes orbiting M dwarfs, have been found to have lower densities than planets of similar sizes orbiting stars of different spectral types.

Original languageEnglish (US)
Article numberA19
JournalAstronomy and Astrophysics
Volume685
DOIs
StatePublished - May 1 2024

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • planets and satellites: detection
  • stars: low-mass
  • techniques: photometric
  • techniques: radial velocities

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