Astronomy:KOI-74

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Short description: Binary star in the constellation Cygnus
KOI-74
KOI-74LightCurve.png
A light curve for KOI-74, adapted from van Kerkwijk et al. (2010)[1]
Observation data
Equinox J2000.0]] (ICRS)
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
Mass2.22+0.10−0.14[1] M
Radius1.90+0.04−0.05[1] R
Luminosity25.6 ± 2.4[1] L
Temperature9400 ± 150[1] K
Other designations
KIC 6889235, 2MASS J19531781+4223185, GSC2.3 N2J3000844
Database references
SIMBADdata
KICdata

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-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. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 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. doi:10.1088/0004-637X/715/1/51. Bibcode2010ApJ...715...51V. 
  2. 2.0 2.1 "KOI-74". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=KOI-74. 
  3. 3.0 3.1 "GSC2.3 N2J3000844". Guide Star Catalog 2.3. 2008. http://gsss.stsci.edu/webservices/GSC2/GSC2DataReturn.aspx?RAH=&RAM=&RAS=&DSN=+&DD=&DM=&DS=&EQ=2000&SIZE=&SRCH=Radius&FORMAT=HTML&CAT=GSC23&HSTID=N2J3000844&GSC1ID=&RA=&DEC=&R1=&R2=&M1=&M2=&N=&CL=. 
  4. 4.0 4.1 Rowe, Jason F.; Borucki, William J.; Koch, David; Howell, Steve B.; Basri, Gibor; Batalha, Natalie; Brown, Timothy M.; Caldwell, Douglas et al. (2010). "Kepler Observations of Transiting Hot Compact Objects". The Astrophysical Journal Letters 713 (2): L150–L154. doi:10.1088/2041-8205/713/2/L150. Bibcode2010ApJ...713L.150R. 

Coordinates: Sky map 19h 53m 17.81s, +42° 23′ 18.5″