LP 791-18

LP 791-18
Observation data
Epoch J2000      Equinox ICRS
Constellation Crater
Right ascension 11h 02m 45.95462s
Declination −16° 24′ 22.2882″
Apparent magnitude (V) 16.9±0.2
Characteristics
Evolutionary stage Main sequence
Spectral type M6.1±0.7V
Astrometry
Proper motion (μ) RA: -221.291 mas/yr
Dec.: -58.841 mas/yr
Parallax (π)37.5225±0.0392 mas
Distance86.92 ± 0.09 ly
(26.65 ± 0.03 pc)
Details
Mass0.139±0.005 M☉
Radius0.17±0.018 R☉
Temperature2960±55 K
Metallicity [Fe/H]-0.09±0.19 dex
Age0.5±0.064 Gyr
Other designations
LP 791-18, TOI-736, TIC 181804752, 2MASS J11024596-1624222
Database references
SIMBADdata
Exoplanet Archivedata

LP 791-18 (TOI-736) is a cool red dwarf star in the constellation Crater, located 86.92 light-years (26.65 parsecs) away from Earth. The star is one of the smallest known stars to host exoplanets. In 2019 two exoplanets in transit around it were announced by TESS, and a third planet was discovered in Spitzer Space Telescope data in 2023.

Planetary system

Artist's impression of LP 791-18 d, with c in the background

The innermost planet, b, is a super-Earth and the outermost planet, c, is a sub-Neptune. They were discovered together in 2019. The middle planet, d, is an Earth-mass world discovered in 2023. It may potentially be tidally heated by interactions with planet c, which would lead to abundant volcanoes similar to Jupiter's moon Io. As the planet d is in the inner edge of the habitable zone, liquid water could condense on the side of the planet that faces away from the host star.

In 2021 planet c was suggested for atmospheric analysis by the James Webb Space Telescope (JWST). In 2025, by using JWST the atmosphere of planet c was found to be rich in haze and methane (CH4) but without clear evidence for carbon dioxide (CO2), which is unlike that of other temperate sub-Neptune planets including K2-18b and TOI-270d.

The LP 791-18 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination
(°)		 Radius
b — 0.00978±0.00012 0.9479981±0.0000021 — 88.37+0.94
−0.95		 1.212+0.059
−0.058 R🜨
d 0.91±0.19 M🜨 0.01992±0.00014 2.753436±0.000013 0.0011+0.0010
−0.0008		 89.34±0.41 1.032+0.044
−0.043 R🜨
c 7.16±0.65 M🜨 0.02961+0.00035
−0.00036		 4.9899100+0.0000012
−0.0000014		 0.0001±0.0001 89.94±0.05 2.488±0.096 R🜨

Notes

  1. ↑ Planet b: Peterson et al. (2021)
    Semi-major axes: Peterson et al. (2021)
    Planet c: Greklek-McKeon et al. (2025)
    Planet d's mass and eccentricity: Greklek-McKeon et al. (2025); miscellaneous properties from Peterson et al. (2021).

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  3. 1 2 3 4 5 6 Crossfield, Ian J. M.; Waalkes, William; Newton, Elisabeth R.; Narita, Norio; Muirhead, Philip; Ment, Kristo; et al. (2019). "A Super-Earth and Sub-Neptune Transiting the Late-type M Dwarf LP 791-18". The Astrophysical Journal Letters. 883 (1): L16. arXiv:1906.09267. Bibcode:2019ApJ...883L..16C. doi:10.3847/2041-8213/ab3d30.
  4. ↑ "LP 791-18". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 19 May 2023.
  5. 1 2 3 4 5 6 Peterson, Merrin S; Benneke, Björn; Collins, Karen; Piaulet, Caroline; Crossfield, Ian JM; Ali-Dib, Mohamad; et al. (2023). "A temperate Earth-sized planet with tidal heating transiting an M6 star". Nature. 617 (7962): 701–705. Bibcode:2023Natur.617..701P. doi:10.1038/s41586-023-05934-8. hdl:11603/28165. PMID 37198481.
  6. 1 2 Kazmierczak, Jeanette (16 May 2023). "NASA's Spitzer, TESS Find Potentially Volcano-Covered Earth-Size World". NASA. Retrieved 19 May 2023.
  7. ↑ Phillips, Caprice L.; Wang, Ji; Kendrew, Sarah; Greene, Thomas P.; Hu, Renyu; Valenti, Jeff; Panero, Wendy R.; Schulze, Joseph (2021). "Detecting Biosignatures in the Atmospheres of Gas Dwarf Planets with the James Webb Space Telescope". The Astrophysical Journal. 923 (2): 144. arXiv:2109.12132. Bibcode:2021ApJ...923..144P. doi:10.3847/1538-4357/ac29be.
  8. ↑ Roy, Pierre-Alexis; Benneke, Björn; Fournier-Tondreau, Marylou; Coulombe, Louis-Philippe; Piaulet-Ghorayeb, Caroline; Lafrenière, David; Allart, Romain; Cowan, Nicolas B.; Dang, Lisa; Johnstone, Doug; Langeveld, Adam B.; Pelletier, Stefan; Radica, Michael; Taylor, Jake; Albert, Loïc; Doyon, René; Flagg, Laura; Jayawardhana, Ray; MacDonald, Ryan J.; Turner, Jake D. (2025). "Diversity in the haziness and chemistry of temperate sub-Neptunes". Nature Astronomy. arXiv:2512.10876. doi:10.1038/s41550-025-02723-3.
  9. 1 2 Greklek-McKeon, Michael; Knutson, Heather A.; Levine, W. Garrett; Hu, Renyu; Saidel, Morgan; Barrientos, Jonathan Gomez; Batygin, Konstantin; Benneke, Björn (2025-01-30). "Updated Mass, Eccentricity, and Tidal Heating Constraints for the Earth-sized Planet LP 791-18". The Astronomical Journal. 170 (2): 65. arXiv:2501.18700. Bibcode:2025AJ....170...65G. doi:10.3847/1538-3881/addf2d.