TOI-561
TOI-561 is an old, metal-poor, Sun-like star, known to have multiple small planets. It is an orange dwarf, estimated to be 10.5 billion years old, and about 79% the mass and 85% the radius of Sol, Earth's sun.
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Hercules |
| Right ascension | 09h 52m 44.1851s |
| Declination | 06° 12′ 58.921″ |
| Apparent magnitude (V) | 10.25 |
| Characteristics | |
| Evolutionary stage | main sequence |
| Spectral type | G9V |
| Astrometry | |
| Proper motion (μ) | RA: 124.612 mas/yr Dec.: −61.279 mas/yr |
| Parallax (π) | 11.8342 ± 0.0208 mas |
| Distance | 275.6 ± 0.5 ly (84.5 ± 0.1 pc) |
| Details | |
| Mass | 0.785±0.018 M☉ |
| Radius | 0.849±0.007 R☉ |
| Luminosity | 0.522±0.017 L☉ |
| Surface gravity (log g) | 4.50±0.12 cgs |
| Temperature | 5,372±70 K |
| Metallicity [Fe/H] | −0.40±0.05 dex |
| Rotational velocity (v sin i) | <2 km/s |
| Age | 10±3 Gyr |
| Other designations | |
2MASS J09524454+0612589, TYC 243-1528-1, GSC 00243-01528, Gaia DR2 3850421005290172416 | |
| Database references | |
| SIMBAD | data |
In January 2021, a team led by Lauren Weiss of the University of Hawaii at Manoa announced that, using data from NASA's Transiting Exoplanet Survey Satellite, they had found a Super-Earth in a very close orbit, as well as two outer Sub-Neptunes. The innermost planet, TOI-561 b, orbits in under one Earth day. Another team led by Gaia Lacedelli of the University of Padua independently announced the discovery in a paper published in December 2020. However, the two papers disagree on the structure of the system. While the innermost two planets were confirmed from TESS data by both papers, Weiss proposes only a single third planet in a 16.3-day orbit, while Lacedelli argues that the system instead contains two further planets, in wider orbits of 25.6 and 77 days.