| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Cygnus1 |
| Right ascension | 19h 16m 18.6100s2 |
| Declination | +46° 00′ 18.814″2 |
| Apparent magnitude (V) | 13.988 |
| Characteristics | |
| Evolutionary stage | subgiant2 |
| Spectral type | G1IV |
| Astrometry | |
| Radial velocity (Rv) | 12.18±3.652 km/s |
| Proper motion (μ) | RA: −1.107(15) mas/yr2 Dec.: −13.099(14) mas/yr2 |
| Parallax (π) | 0.8136±0.0118 mas2 |
| Distance | 4,010 ± 60 ly (1,230 ± 20 pc) |
| Details3 | |
| Mass | 1.26+0.03 −0.06 M☉ |
| Radius | 1.66±0.03 R☉ |
| Luminosity | 3.1+0.2 −0.1 L☉ |
| Temperature | 5947±60 K |
| Metallicity [Fe/H] | 0.14±0.04 dex |
| Age | 4.2+1.3 −0.3 Gyr |
| Other designations | |
| KOI-707, KIC 9458613, 2MASS J19161861+4600187, Gaia DR2 21273559237232542724 | |
| Database references | |
| SIMBAD | data |
| Exoplanet Archive | data |
Kepler-33 is a star about 4,000 light-years (1,200 parsecs) in the constellation of Cygnus, with a system of five known planets. Having just begun to evolve off from the main sequence,5 its radius and mass are difficult to ascertain, although data available in 2020 shows its best-fit mass of 1.3M☉ and radius of 1.6R☉ are compatible with a model of a subgiant star.6
Planetary system
The first detections of the candidate four-body planetary system were reported in February 2011.7 On January 26, 2012, the planetary system around the star was confirmed, including a fifth planet.5 However, unlike some other planets confirmed via Kepler, their masses were initially not known, as Doppler spectroscopy measurements were not done before the announcement. Judging by their radii, b may be a large super-Earth or small hot Neptune while the other four are all likely to be the latter. As of 2022, the masses of planets e & f have been measured, with upper limits on the masses of planets c & d. These mass measurements confirm Kepler-33 d, e & f to be low-density, gaseous planets.3
Planets b and c may actually be in a 7:3 resonance, as there is a 0.05 day discrepancy; there is also a small 0.18 day discrepancy between a 5:3 resonance between planets c and d. The other planets do not seem to be in any resonances, though near resonances are 3d:2e and 4e:3f.
The planetary system in its current configuration is highly susceptible to perturbations, therefore assuming stability, no additional giant planets can be located within 30 AU from the parent star.8
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination (°) |
Radius |
|---|---|---|---|---|---|---|
| b | — | 0.0673+0.0004 −0.0012 |
5.66816±0.00005 | <0.2 | >87.0 | 1.54+0.06 −0.05 R🜨 |
| c | <19 M🜨 | 0.1181+0.0008 −0.0020 |
13.17552±0.00005 | <0.05 | >88.6 | 2.73±0.06 R🜨 |
| d | <8.2 M🜨 | 0.165+0.001 −0.003 |
21.77574+0.00006 −0.00004 |
<0.03 | >89.02 | 4.67±0.09 R🜨 |
| e | 6.6+1.1 −1.0 M🜨 |
0.212+0.001 −0.004 |
31.7852±0.0002 | <0.02 | 89.4±0.1 | 3.54+0.09 −0.07 R🜨 |
| f | 8.2+1.6 −1.2 M🜨 |
0.252+0.002 −0.004 |
41.0274±0.0002 | <0.02 | 89.7+0.2 −0.1 |
3.96+0.09 −0.07 R🜨 |
References
References
- Roman, Nancy G. (1987). "Identification of a constellation from a position". Publications of the Astronomical Society of the Pacific. 99 (617): 695. Bibcode:1987PASP...99..695R. doi:10.1086/132034. Constellation record for this object at VizieR.
- 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.
- Sikora, James; Rowe, Jason; et al. (December 2022). "Refining the Masses and Radii of the Star Kepler-33 and its Five Transiting Planets". The Astronomical Journal. 164 (6): 242. arXiv:2211.00703. Bibcode:2022AJ....164..242S. doi:10.3847/1538-3881/ac98c4.
- "Notes for star Kepler-33". Extrasolar Planets Encyclopaedia. Archived from the original on 2012-04-26. Retrieved 2012-02-01.
- Lissauer, Jack J.; Marcy, Geoffrey W.; Rowe, Jason F.; Bryson, Stephen T.; Adams, Elisabeth; Buchhave, Lars A.; Ciardi, David R.; Cochran, William D.; Fabrycky, Daniel C.; Ford, Eric B.; Fressin, Francois; Geary, John; Gilliland, Ronald L.; Holman, Matthew J.; Howell, Steve B.; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David G.; Morehead, Robert C.; Ragozzine, Darin; Seader, Shawn E.; Tanenbaum, Peter G.; Torres, Guillermo; Twicken, Joseph D. (10 May 2012). "Almost All of Kepler's Multiple Planet Candidates are Planets". The Astrophysical Journal. 750 (2): 112. arXiv:1201.5424. Bibcode:2012ApJ...750..112L. doi:10.1088/0004-637X/750/2/112. S2CID 30549908.
- Berger, Travis A.; Huber, Daniel; van Saders, Jennifer L.; Gaidos, Eric; Tayar, Jamie; Kraus, Adam L. (2020), "The Gaia-Kepler Stellar Properties Catalog. I. Homogeneous Fundamental Properties for 186,301 Kepler Stars", The Astronomical Journal, 159 (6): 280, arXiv:2001.07737, Bibcode:2020AJ....159..280B, doi:10.3847/1538-3881/159/6/280, S2CID 210859307
- Ford, Eric B.; Rowe, Jason F.; Fabrycky, Daniel C.; Carter, Joshua A.; Holman, Matthew J.; Lissauer, Jack J.; Ragozzine, Darin; Steffen, Jason H.; Batalha, Natalie M.; Borucki, William J.; Bryson, Steve; Caldwell, Douglas A.; Dunham, Edward W.; Gautier, Thomas N.; Jenkins, Jon M.; Koch, David G.; Li, Jie; Lucas, Philip; Marcy, Geoffrey W.; McCauliff, Sean; Mullally, Fergal R.; Quintana, Elisa; Still, Martin; Tenenbaum, Peter; Thompson, Susan E.; Twicken, Joseph D. (2011), "Transit Timing Observations from Kepler : I. Statistical Analysis of the First Four Months", The Astrophysical Journal Supplement Series, 197 (1): 2, arXiv:1102.0544, Bibcode:2011ApJS..197....2F, doi:10.1088/0067-0049/197/1/2, S2CID 118472942
- Becker, Juliette C.; Adams, Fred C. (2017), "Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems", Monthly Notices of the Royal Astronomical Society, 468 (1): 549–563, arXiv:1702.07714, Bibcode:2017MNRAS.468..549B, doi:10.1093/mnras/stx461, S2CID 119325005