Summary
LP 890-9, also known as SPECULOOS-2 or TOI-4306, is a high proper motion red dwarf star located 105 light-years (32 pc) away from the Solar System in the constellation of Eridanus. The star has 12% the mass and 15% the radius of the Sun, and a temperature of 2,871 K (2,598 °C; 4,708 °F). It is extremly faint and, with an apparent magnitude of 18, is the faintest star with exoplanets discovered by the Transiting Exoplanet Survey Satellite.[6] As of 2022, it is the second-coolest star found to host a planetary system, after TRAPPIST-1.[3][7]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus[1] |
| Right ascension | 04h 16m 31.16176s[2] |
| Declination | −28° 18′ 52.9543″[2] |
| Apparent magnitude (V) | 18.0±0.2[3] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | M6V[4] |
| Apparent magnitude (V) | 18.0±0.2[3] |
| Apparent magnitude (G) | 15.791±0.003[2] |
| Apparent magnitude (J) | 12.258±0.023[3] |
| Apparent magnitude (H) | 11.692±0.025[3] |
| Apparent magnitude (K) | 11.344±0.023[3] |
| Astrometry | |
| Radial velocity (Rv) | 28.84±2.84[2] km/s |
| Proper motion (μ) | RA: 218.569 mas/yr[2] Dec.: −251.145 mas/yr[2] |
| Parallax (π) | 30.9326 ± 0.0418 mas[2] |
| Distance | 105.4 ± 0.1 ly (32.33 ± 0.04 pc) |
| Absolute magnitude (MV) | 15.45±0.2[note 1] |
| Details[3] | |
| Mass | 0.118±0.002 M☉ |
| Radius | 0.1532+0.0048 −0.0024 R☉ |
| Luminosity (bolometric) | 0.001438±0.000037 L☉ |
| Surface gravity (log g) | 5.139+0.013 −0.028 cgs |
| Temperature | 2871+32 −45 K |
| Metallicity [Fe/H] | −0.028±0.089 dex |
| Age | 7.2+2.2 −3.1 Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
Planetary system edit
In 2022, two exoplanets were discovered in orbit around this star. The first planet, LP 890-9 b, was initially identified using TESS. Further observations using SPECULOOS confirmed this planet and discovered a second planet, LP 890-9 c. Both planets are likely terrestrial planets, somewhat larger than Earth. The outer planet LP 890-9 c orbits within the habitable zone, and is a favorable target for atmospheric characterization using JWST.[3][7]
LP 890-9 c orbits near the inner edge of the conservative habitable zone, and models differ as to whether the planet is more likely to resemble Earth or Venus. Spectra from JWST should make it possible to distinguish between these two scenarios.[4] The planet is tidally locked.[8] While the planet's location in the habitable zone suggests a strong possibility of an Earth-like atmosphere and climate, the planet's large size may count against its habitability. In addition, the planet is close enough to its star that powerful radiation may reduce its habitability.[9]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | <13.2 M🜨 | 0.01875±0.00010 | 2.7299025+0.0000034 −0.0000040 |
— | 89.67+0.22 −0.33° |
1.320+0.053 −0.027 R🜨 |
| c | <25.3 M🜨 | 0.03984±0.00022 | 8.457463±0.000024 | — | 89.287+0.026 −0.047° |
1.367+0.055 −0.039 R🜨 |
See also edit
- Proxima Centauri - Closest star to the Sun, a red dwarf that hosts terrestrial planets with one inside the habitable zone
- Teegarden's Star - A nearby red dwarf with two terrestrial planets in the habitable zone, in the constellation of Aries
- TRAPPIST-1 - An ultra-cool red dwarf in the constellation of Aquarius
- Wolf 359 - A planet hosting nearby ultra-cool red dwarf in the Leo constellation
Notes edit
- ^ The absolute magnitude MV of the star can be calculated from its apparent magnitude mV and distance d using the following equation:
References edit
- ^ "Finding the constellation which contains given sky coordinates". djm.cc. 2 August 2008. Retrieved 7 September 2022.
- ^ a b c d e f 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.
- ^ a b c d e f g h i Delrez, L.; Murray, C. A.; et al. (September 2022). "Two temperate super-Earths transiting a nearby late-type M dwarf". Astronomy & Astrophysics. 667: A59. arXiv:2209.02831. Bibcode:2022A&A...667A..59D. doi:10.1051/0004-6361/202244041. S2CID 252110654.
- ^ a b Kaltenegger, L.; Payne, R. C.; et al. (2023). "Hot Earth or Young Venus? A nearby transiting rocky planet mystery". Monthly Notices of the Royal Astronomical Society: Letters. 524: L10–L14. arXiv:2209.03105. doi:10.1093/mnrasl/slad064.
- ^ "LP 890-9". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 7 September 2022.
- ^ "Planetary Systems". exoplanetarchive.ipac.caltech.edu. Retrieved 2024-02-18.
- ^ a b "SPECULOOS discovers a potentially habitable super-Earth". University of Liège. 7 September 2022. Retrieved 7 September 2022.
- ^ "Two potentially habitable super-Earth planets have been discovered". New Scientist. 2022. Retrieved 8 September 2022.
- ^ "Astronomers spot 2 intriguing alien worlds around ultracool star". Space.com. 7 September 2022. Retrieved 8 September 2022.