Kepler-28 is an M-type main-sequence star about 1,450 light-years (440 parsecs) away in the northern constellation of Cygnus.[2] With an apparent visual magnitude of 15.036,[3] this star is too faint to be seen with the naked eye. It is orbited by two exoplanets.
 Kepler-28 compared to the Sun | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus[1] |
| Right ascension | 19h 28m 32.8905s[2] |
| Declination | +42° 25′ 45.959″[2] |
| Apparent magnitude (V) | 15.036[3] |
| Characteristics | |
| Spectral type | M0V[4] |
| Astrometry | |
| Radial velocity (Rv) | −26.99±6.00[2] km/s |
| Proper motion (μ) | RA: −0.463(21) mas/yr[2] Dec.: 11.691(21) mas/yr[2] |
| Parallax (π) | 2.2537 ± 0.0185 mas[2] |
| Distance | 1,450 ± 10 ly (444 ± 4 pc) |
| Details | |
| Mass | 0.684±0.026[5] M☉ |
| Radius | 0.664±0.013[5] R☉ |
| Temperature | 4499±75[5] K |
| Metallicity [Fe/H] | −0.17±0.11[4] dex |
| Rotation | 17.951±0.016 days[6] |
| Rotational velocity (v sin i) | 0.6[3] km/s |
| Age | 2.2[7] Gyr |
| Other designations | |
| Database references | |
| SIMBAD | data |
| KIC | data |
Planetary system
editThe two transiting planets of Kepler-28 were discovered in 2011 using the Kepler space telescope, and were confirmed in early 2012.[9] They are both warm sub-Neptune gas planets.[7] The planetary parameters were updated in 2023, with lower values for all of mass, radius, and density compared to previous estimates.[5]
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | 1.63+0.51 −0.40 M🜨 |
0.062 | 5.91213(17) | <0.08 | — | 1.959+0.043 −0.042 R🜨 |
| c | 2.06+0.70 −0.52 M🜨 |
0.081 | 8.98597(27) | 0.017+0.023 −0.014 |
— | 1.857±0.042 R🜨 |
References
edit- ^ "Cygnus – constellation boundary", The Constellations, International Astronomical Union, retrieved 2011-12-15
- ^ 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 Kepler-28b, NASA Ames Research Center, archived from the original on 2012-05-03, retrieved 2011-12-06
- ^ a b c Muirhead, Philip S.; Hamren, Katherine; et al. (May 2012). "Characterizing the Cool Kepler Objects of Interests. New Effective Temperatures, Metallicities, Masses, and Radii of Low-mass Kepler Planet-candidate Host Stars". The Astrophysical Journal Letters. 750 (2): L37. arXiv:1109.1819. Bibcode:2012ApJ...750L..37M. doi:10.1088/2041-8205/750/2/L37.
- ^ a b c d e Leleu, A.; Delisle, J.-B.; et al. (January 2023). "Removing biases on the density of sub-Neptunes characterised via transit timing variations. Update on the mass-radius relationship of 34 Kepler planets". Astronomy & Astrophysics. 669: A117. arXiv:2207.07456. Bibcode:2023A&A...669A.117L. doi:10.1051/0004-6361/202244132.
- ^ McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv:1308.1845. Bibcode:2013ApJ...775L..11M. doi:10.1088/2041-8205/775/1/L11.
- ^ a b Cubillos, Patricio; Erkaev, Nikolai V.; Juvan, Ines; Fossati, Luca; Johnstone, Colin P.; Lammer, Helmut; Lendl, Monika; Odert, Petra; Kislyakova, Kristina G. (2016), "An overabundance of low-density Neptune-like planets", Monthly Notices of the Royal Astronomical Society, 466 (2): 1868–1879, arXiv:1611.09236, Bibcode:2017MNRAS.466.1868C, doi:10.1093/mnras/stw3103, S2CID 119408956
- ^ "Kepler-28". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 10 January 2017.
- ^ Steffen, Jason H.; Fabrycky, Daniel C.; Ford, Eric B.; Carter, Joshua A.; Desert, Jean-Michel; Fressin, Francois; Holman, Matthew J.; Lissauer, Jack J.; Moorhead, Althea V.; Rowe, Jason F.; Ragozzine, Darin; Welsh, William F.; Batalha, Natalie M.; Borucki, William J.; Buchhave, Lars A.; Bryson, Steve; Caldwell, Douglas A.; Charbonneau, David; Ciardi, David R.; Cochran, William D.; Endl, Michael; Everett, Mark E.; Gautier III, Thomas N.; Gilliland, Ron L.; Girouard, Forrest R.; Jenkins, Jon M.; Horch, Elliott; Howell, Steve B.; Isaacson, Howard; et al. (2012), Transit Timing Observations from Kepler: III. Confirmation of 4 Multiple Planet Systems by a Fourier-Domain Study of Anti-correlated Transit Timing Variations, arXiv:1201.5412, Bibcode:2012MNRAS.421.2342S, doi:10.1111/j.1365-2966.2012.20467.x, S2CID 11898578