TOI-270, also known as L 231-32, is a red dwarf star 73.3 light-years (22.5 parsecs) away in the constellation Pictor. It has about 39% the mass and 38% the radius of the Sun, and a temperature of about 3,506 K (3,233 °C; 5,851 °F). TOI-270 hosts a system of three known exoplanets.
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Pictor[1] |
| Right ascension | 04h 33m 39.72001s[2] |
| Declination | −51° 57′ 22.4354″[2] |
| Apparent magnitude (V) | 12.617[3] |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | M3.0V[4] |
| Apparent magnitude (V) | 12.617±0.03[3] |
| Apparent magnitude (R) | 12.147±0.05[3] |
| Apparent magnitude (G) | 11.621±0.003[2] |
| Apparent magnitude (J) | 9.099±0.032[3] |
| Apparent magnitude (H) | 8.531±0.073[3] |
| Apparent magnitude (K) | 8.251±0.029[3] |
| Astrometry | |
| Radial velocity (Rv) | 25.90±0.37[2] km/s |
| Proper motion (μ) | RA: +83.082 mas/yr[2] Dec.: −269.803 mas/yr[2] |
| Parallax (π) | 44.4899 ± 0.0147 mas[2] |
| Distance | 73.31 ± 0.02 ly (22.477 ± 0.007 pc) |
| Details[5] | |
| Mass | 0.386±0.008 M☉ |
| Radius | 0.378±0.011 R☉ |
| Luminosity (bolometric) | 0.0194±0.0019 L☉ |
| Surface gravity (log g) | 4.872±0.026 cgs |
| Temperature | 3506±70 K |
| Metallicity [Fe/H] | −0.20±0.12 dex |
| Other designations | |
| Database references | |
| SIMBAD | data |
Planetary system
editThe three planets of TOI-270 were discovered in 2019 by the transit method with TESS.[4] Their masses have since been measured by both Doppler spectroscopy[5] and transit-timing variations.[6] The innermost planet, TOI-270 b, is a rocky super-Earth, while the two outer planets are mini-Neptunes.[5] TOI-270 b & c orbit near a 5:3 resonance, while TOI-270 c & d orbit near a 2:1 resonance.[4]
Observations of the outermost planet, TOI-270 d, by the Hubble Space Telescope suggest a hydrogen-rich atmosphere with signs of water vapor.[7] TOI-270 c & d are good targets for atmospheric detection with the James Webb Space Telescope.[8]
The James Webb Space Telescope detected methane (CH4), carbon dioxide (CO2) and water vapor in the atmosphere of TOI-270 d.[9] The atmosphere of this planet was also found to be metal-rich, with a mean molecular weight of 5.47+1.25
−1.14 and an atmospheric metal mass fraction (percentage of the mass of metals in the atmosphere) of 58%+8%
−12%.[9] Possible signatures of sulfur dioxide (SO2) and carbon disulfide (CS2) were also found.[9]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 1.48±0.18 M🜨 | 0.03197(22) | 3.3601538(48) | 0.0167(84) | 89.39±0.37° | 1.206±0.039 R🜨 |
| c | 6.20±0.31 M🜨 | 0.04526(31) | 5.6605731(31) | 0.0044(6) | 89.36±0.24° | 2.355±0.064 R🜨 |
| d | 4.20±0.16 M🜨 | 0.07210(50) | 11.379573(13) | 0.0066(20) | 89.73±0.16° | 2.133±0.058 R🜨 |
References
edit- ^ "Finding the constellation which contains given sky coordinates". djm.cc. 2 August 2008.
- ^ 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 "L 231-32". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 18 October 2023.
- ^ a b c Günther, Maximilian N.; Pozuelos, Francisco J.; et al. (July 2019). "A super-Earth and two sub-Neptunes transiting the nearby and quiet M dwarf TOI-270". Nature Astronomy. 3 (12): 1099–1108. arXiv:1903.06107. Bibcode:2019NatAs...3.1099G. doi:10.1038/s41550-019-0845-5. S2CID 256707535.
- ^ a b c d Van Eylen, V.; Astudillo-Defru, N.; et al. (October 2021). "Masses and compositions of three small planets orbiting the nearby M dwarf L231-32 (TOI-270) and the M dwarf radius valley". Monthly Notices of the Royal Astronomical Society. 507 (2): 2154–2173. arXiv:2101.01593. Bibcode:2021MNRAS.507.2154V. doi:10.1093/mnras/stab2143.
- ^ a b Kaye, Laurel; Vissapragada, Shreyas; et al. (March 2022). "Transit Timing Variations in the three-planet system: TOI-270". Monthly Notices of the Royal Astronomical Society. 510 (4): 5464–5485. arXiv:2308.10763. Bibcode:2022MNRAS.510.5464K. doi:10.1093/mnras/stab3483.
- ^ Mikal-Evans, Thomas; Madhusudhan, Nikku; et al. (March 2023). "Hubble Space Telescope Transmission Spectroscopy for the Temperate Sub-Neptune TOI-270 d: A Possible Hydrogen-rich Atmosphere Containing Water Vapor". The Astronomical Journal. 165 (3): 84. arXiv:2211.15576. Bibcode:2023AJ....165...84M. doi:10.3847/1538-3881/aca90b.
- ^ Chouqar, J.; Benkhaldoun, Z.; et al. (June 2020). "Properties of sub-Neptune atmospheres: TOI-270 system". Monthly Notices of the Royal Astronomical Society. 495 (1): 962–970. arXiv:2004.12475. Bibcode:2020MNRAS.495..962C. doi:10.1093/mnras/staa1198.
- ^ a b c Benneke, Björn; Roy, Pierre-Alexis; Coulombe, Louis-Philippe; Radica, Michael; Piaulet, Caroline; Ahrer, Eva-Maria; Pierrehumbert, Raymond; Krissansen-Totton, Joshua; Schlichting, Hilke E. (2024-03-05), JWST Reveals CH$_4$, CO$_2$, and H$_2$O in a Metal-rich Miscible Atmosphere on a Two-Earth-Radius Exoplanet, arXiv:2403.03325
- ^ Reddy, Francis (29 July 2019). "NASA's TESS Mission Scores 'Hat Trick' With 3 New Worlds". NASA. Retrieved 18 October 2023.