Astronomy:TOI-1227 b

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TOI-1227 b
Discovery[1]
Discovered byMann et al. (THYME)
Discovery date2022
Transit method
Orbital characteristics
0.0886+0.0054
−0.0057 AU
Orbital period27.4 days
Inclination88.571+0.062
−0.093 °
StarTOI-1227 (Gaia DR2 5842480953772012928)
Physical characteristics
Mean radius0.854+0.067
−0.052 |♃|J}}}}}}


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][lower-alpha 1] 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]

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

TOI-1227
Observation data
Equinox J2000.0]] (ICRS)
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[4] mas/yr
Dec.: −10.6417±0.0807[4] mas/yr
Parallax (π)9.9079 ± 0.0558[4] mas
Distance328.089+1.87
−1.845 ly
(100.641+0.573
−0.566 pc)
Absolute magnitude (MV)11.986[lower-alpha 2]
Details[1]
Mass0.17±0.015 M☉
Radius0.56±0.03 R☉
Luminosity0.0251 L☉
Surface gravity (log g)4.7893±0.0058[4] cgs
Temperature3072±74 K
Rotation1.65±0.04 d
Rotational velocity (v sin i)16.65±0.24 km/s
Age11±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
SIMBADdata

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][lower-alpha 3] The host star shows Lithium in its atmosphere, which should be depleted within 10-200 million years for M-dwarfs.[1]

References

  1. ↑ 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 1.11 1.12 Mann, Andrew W.; Wood, Mackenna L.; Schmidt, Stephen P.; Barber, Madyson G.; Owen, James E.; Tofflemire, Benjamin M.; Newton, Elisabeth R.; Mamajek, Eric E. et al. (2022-04-01). "TESS Hunt for Young and Maturing Exoplanets (THYME). VI. An 11 Myr Giant Planet Transiting a Very-low-mass Star in Lower Centaurus Crux". The Astronomical Journal 163 (4): 156. doi:10.3847/1538-3881/ac511d. ISSN 0004-6256. Bibcode: 2022AJ....163..156M. 
  2. ↑ https://iopscience.iop.org/article/10.3847/1538-4357/ade151
  3. ↑ 3.0 3.1 3.2 3.3 3.4 "TOI-1227". https://simbad.cds.unistra.fr/mobile/object.html?object_name=TOI-1227. 
  4. ↑ 4.0 4.1 4.2 4.3 4.4 "TOI-1227 | NASA Exoplanet Archive". https://exoplanetarchive.ipac.caltech.edu/overview/TOI-1227. 
  5. ↑ 5.0 5.1 Goldman, Bertrand; Röser, Siegfried; Schilbach, Elena; Moór, Attila C.; Henning, Thomas (2018-11-01). "A Large Moving Group within the Lower Centaurus Crux Association". The Astrophysical Journal 868 (1): 32. doi:10.3847/1538-4357/aae64c. ISSN 0004-637X. Bibcode: 2018ApJ...868...32G. 
  6. ↑ Zari, E.; Hashemi, H.; Brown, A. G. A.; Jardine, K.; de Zeeuw, P. T. (2018-12-01). "3D mapping of young stars in the solar neighbourhood with Gaia DR2". Astronomy and Astrophysics 620: A172. doi:10.1051/0004-6361/201834150. ISSN 0004-6361. Bibcode: 2018A&A...620A.172Z. https://ui.adsabs.harvard.edu/abs/2018A&A...620A.172Z. 
  7. ↑ 7.0 7.1 Kerr, Ronan M. P.; Rizzuto, Aaron C.; Kraus, Adam L.; Offner, Stella S. R. (2021-08-01). "Stars with Photometrically Young Gaia Luminosities Around the Solar System (SPYGLASS). I. Mapping Young Stellar Structures and Their Star Formation Histories". The Astrophysical Journal 917 (1): 23. doi:10.3847/1538-4357/ac0251. ISSN 0004-637X. Bibcode: 2021ApJ...917...23K. 
  8. ↑ Boyles, Jason; Lorimer, Duncan R.; Turk, Phil J.; Mnatsakanov, Robert; Lynch, Ryan S.; Ransom, Scott M.; Freire, Paulo C.; Belczynski, Khris (2011-11-20). "Young Radio Pulsars in Galactic Globular Clusters". The Astrophysical Journal 742 (1): 51. doi:10.1088/0004-637X/742/1/51. ISSN 0004-637X. Bibcode: 2011ApJ...742...51B. 
  1. ↑ For comparison, the Solar System is about 4.6 billion years old.
  2. ↑ Calculated using an apparent magnitude of 17 and a distance of 100.641 parsecs[4] in the equation Mapp = Mabs - 5 + 5 * log(distance (parsecs))
  3. ↑ The constellation can be obtained by the right ascension and declination in this website.
  1. ↑ Obtained with a right ascension of  12h 27m 4.31s and a declination of −72° 27′ 6.5″[3] on this website.



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