TOI-1227 b
Young exoplanet orbiting the red dwarf TOI-1227
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TOI-1227 b is one of the youngest transiting exoplanets discovered (as of September 2022), alongside K2-33b and HIP 67522 b. The exoplanet TOI-1227 b is 5–12 million years old[2][a] and currently 9.6 R🜨 large. It will become a 3-5 R🜨 planet in about 1 billion years, because the planet is still contracting. TOI-1227 b orbits its host star every 27.36 days.[1]
| Discovery[1] | |
|---|---|
| Discovered by | Mann et al. (THYME) |
| Discovery date | 2022 |
| Transit method | |
| Orbital characteristics | |
| 0.0886+0.0054 −0.0057 AU | |
| 27.4 days | |
| Inclination | 88.571+0.062 −0.093 ° |
| Star | TOI-1227 (Gaia DR2 5842480953772012928) |
| Physical characteristics | |
| 0.854+0.067 −0.052 RJ | |
Characteristics
TOI-1227 b has a size that is 85% that of Jupiter, or 9.6 times that of Earth. No other Jupiter-sized planet was detected around mid- to late M-dwarfs, despite the deep transits such a planet would create. The researchers find that the planet is still hot from its formation and this heat, combined with a hydrogen-dominated primary atmosphere makes the atmosphere of TOI-1227 b inflated. Evolutionary models suggest that TOI-1227 b will eventually evolve into a sub-Neptune within the next billion years.[1]
Future research
Radial velocity follow-up to determine the mass of TOI-1227 b is not possible in the optical, but might be possible in the near-infrared. A less challenging follow-up would be the measurement of the Spin-Orbit-Alignment via the Rossiter–McLaughlin effect.[1]
Host star
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Musca[note 1] |
| Right ascension | 12h 27m 4.31s[3] |
| Declination | −72° 27′ 6.5″[3] |
| Apparent magnitude (V) | 17±1.133[4] |
| Characteristics | |
| Evolutionary stage | Pre-main sequence star[1] |
| Spectral type | M4.5V-M5V[1] |
| Astrometry | |
| Radial velocity (Rv) | 13.3±0.3[1] km/s |
| Proper motion (μ) | RA: −40.2658±0.0972 mas/yr[4] Dec.: −10.6417±0.0807 mas/yr[4] |
| Parallax (π) | 9.9079±0.0558 mas[4] |
| Distance | 328.089+1.87 −1.845 ly (100.641+0.573 −0.566 pc)[4] |
| Absolute magnitude (MV) | 11.986[b] |
| Details[1] | |
| Mass | 0.17±0.015 M☉ |
| Radius | 0.56±0.03 R☉ |
| Luminosity | 0.0251 L☉ |
| Surface gravity (log g) | 4.7893±0.0058[4] cgs |
| Temperature | 3072±74 K |
| Rotation | 1.65±0.04 d |
| Rotational velocity (v sin i) | 16.65±0.24 km/s |
| Age | 11±2 Myr |
| Other designations | |
| 2MASS J12270432-7227064, Gaia DR2 5842480953772012928, Gaia DR3 5842480953772012928, TIC 360156606, TOI-1227, UCAC4 088-032065, WISE J122704.24-722706.5, WISEA J122704.22-722706.5[3] | |
| Database references | |
| SIMBAD | data |
TOI-1227 was first identified as a pre-main-sequence star (PMS star) with the Gaia satellite.[5][6][7] Without this prior identification as a PMS star the exoplanet signal of TOI-1227 b would have been disregarded as an eclipsing binary due to the V-shape of the transit signal.[1]
The star is located north of the globular cluster NGC 4372, but it is much closer to earth than this cluster of stars, at a distance of about 101 parsecs (330 light-years).[1] NGC 4372 is 5,800 parsecs (19,000 ly) away.[8]
The host star TOI-1227 is part of a subgroup of the Lower Centaurus Crux OB association, sometimes called B,[7] A0[5] and called Musca group by the scientists that discovered TOI-1227 b. This group was called Musca after the constellation Musca in which most of its members are located.[1]
TOI-1227 has a spectral type of M4.5V to M5V, a mass 17% of the Sun and a radius 56% of the Sun. The host star is relative faint for a TOI with a visual magnitude of about 17.[1] The right ascension of 12h 27m 4.31s and the declination −72° 27′ 6.5″ implies that it is located in the Musca constellation.[3][c] The host star shows Lithium in its atmosphere, which should be depleted within 10-200 million years for M-dwarfs.[1]