KOI-74

KOI-74 (KIC 6889235) is an eclipsing binary star in the constellation of Cygnus. The primary star is an A-type main-sequence star with a temperature of 9,400 K (9,130 °C; 16,460 °F). It lies in the field of view of the Kepler Mission and was determined to have a companion object in orbit around it which is smaller and hotter than the main star.^[4]

KOI-74

A light curve for KOI-74, adapted from van Kerkwijk et al. (2010)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Cygnus
Right ascension	19h 53m 17.811s[2]
Declination	+42° 23′ 18.52″[2]
Apparent magnitude (V)	10.715[3]
Characteristics
Spectral type	A1V[1]
B−V color index	0.154[3]
Details
Mass	2.22+0.10 −0.14[1] M☉
Radius	1.90+0.04 −0.05[1] R☉
Luminosity	25.6 ± 2.4[1] L☉
Temperature	9400 ± 150[1] K
Other designations
KIC 6889235, 2MASS J19531781+4223185, GSC2.3 N2J3000844
Database references
SIMBAD	data
KIC	data

KOI-74b

KOI-74b is a hot compact object orbiting KOI-74. It was discovered in 2010 by the Kepler Mission and came to attention because of its small size (its radius is only 4.3% of the solar radius) and high temperature of 13,000 K (12,700 °C; 22,900 °F).^[4] The orbit of KOI-74b around the main star takes 5.18875 days to complete. Analysis of relativistic boosting of light in the Kepler data indicates that it is likely to be a low mass white dwarf of approximately 0.22 solar masses, resulting from an earlier phase of mass transfer in a binary system when the object underwent its giant phase.^[1]

See also

• KOI-81, a similar system also discovered by the Kepler Mission.
• Kepler Object of Interest, stars observed to have transits by the Kepler Mission

References

1. van Kerkwijk, Marten H.; Rappaport, Saul A.; Breton, René P.; Justham, Stephen; Podsiadlowski, Philipp; Han, Zhanwen (2010). "Observations of Doppler Boosting in Kepler Light Curves". The Astrophysical Journal. 715 (1): 51–58. arXiv:1001.4539. Bibcode:2010ApJ...715...51V. doi:10.1088/0004-637X/715/1/51. S2CID 15893663.
2. "KOI-74". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2010-06-19.
3. "GSC2.3 N2J3000844". Guide Star Catalog 2.3. 2008. Retrieved 2010-06-19.
4. Rowe, Jason F.; Borucki, William J.; Koch, David; Howell, Steve B.; Basri, Gibor; Batalha, Natalie; Brown, Timothy M.; Caldwell, Douglas; Cochran, William D.; Dunham, Edward; Dupree, Andrea K.; Fortney, Jonathan J.; Gautier, Thomas N.; Gilliland, Ronald L.; Jenkins, Jon; Latham, David W.; Lissauer, Jack J.; Marcy, Geoff; Monet, David G.; Sasselov, Dimitar; Welsh, William F. (2010). "Kepler Observations of Transiting Hot Compact Objects". The Astrophysical Journal Letters. 713 (2): L150–L154. arXiv:1001.3420. Bibcode:2010ApJ...713L.150R. doi:10.1088/2041-8205/713/2/L150. S2CID 118578253.