Astronomy:XO-4

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Short description: Star in the constellation Lynx
XO-4 / Koit
Observation data
Equinox J2000.0]] (ICRS)
Constellation Lynx[1]
Right ascension  07h 21m 33.1602s[2]
Declination +58° 16′ 05.112″[2]
Apparent magnitude (V) 10.674 ± 0.019[3]
Characteristics
Spectral type F5V[3]
Apparent magnitude (B) 11.240 ± 0.029[3]
Apparent magnitude (V) 10.674 ± 0.019[3]
Apparent magnitude (J) 9.667 ± 0.021[4]
Apparent magnitude (H) 9.476 ± 0.022[4]
Apparent magnitude (K) 9.406 ± 0.023[4]
Astrometry
Proper motion (μ) RA: −16.989±0.056[2] mas/yr
Dec.: 5.310±0.050[2] mas/yr
Parallax (π)3.6392 ± 0.0385[2] mas
Distance896 ± 9 ly
(275 ± 3 pc)
Details
Mass1.32 ± 0.02[3] M☉
Radius1.56 ± 0.05[3] R☉
Temperature6397 ± 70[3] K
Metallicity [Fe/H]-0.04 ± 0.03[3] dex
Age2.1 ± 0.6[3] Gyr
Other designations
Koit, TYC 3793-1994-1, GSC 03793-01994, 2MASS J07213317+5816051[5]
Database references
SIMBADdata

XO-4 is a star located approximately 896 light-years away from Earth in the Lynx constellation. It has a magnitude of about 11 and cannot be seen with the naked eye but is visible through a small telescope.[3] A search for a binary companion star using adaptive optics at MMT Observatory was negative.[6]

The star XO-4 is named Koit. The name was selected in the NameExoWorlds campaign by Estonia, during the 100th anniversary of the IAU. Koit is Estonian for dawn, and was named for a character in a folk tale written by Friedrich Robert Faehlmann.[7][8][9]

Planetary system

One known exoplanet, XO-4b, which is classified as a hot jupiter, orbits XO-4. This exoplanet was discovered in 2008 by the XO Telescope project using the transit method.[3] It has been named Hämarik, meaning dusk, and referring to a character from the same Faehlmann story featuring Koit.[10]

The XO-4 planetary system[3][11][12]
Companion
(in order from star) 		Mass Semimajor axis
(AU) 		Orbital period
(days) 		Eccentricity Inclination Radius
b / Hämarik 1.72 ± 0.20 MJ 0.0552 ± 0.0003 4.1250823 ± 0.0000039 0(assumed) [note 1] — —

Notes

  1. ↑ eccentricity approximately equal to zero is expected theoretically and is consistent with the radial velocities and secondary eclipses timing[3][12]

References

  1. ↑ Roman, Nancy G. (1987). "Identification of a Constellation From a Position". Publications of the Astronomical Society of the Pacific 99 (617): 695–699. doi:10.1086/132034. Bibcode: 1987PASP...99..695R.  Vizier query form
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Brown, A. G. A. (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics 616: A1. doi:10.1051/0004-6361/201833051. Bibcode: 2018A&A...616A...1G.  Gaia DR2 record for this source at VizieR.
  3. ↑ 3.00 3.01 3.02 3.03 3.04 3.05 3.06 3.07 3.08 3.09 3.10 3.11 3.12 McCullough, P. R. et al. (2008). XO-4b: An Extrasolar Planet Transiting an F5V Star. Bibcode: 2008arXiv0805.2921M. 
  4. ↑ 4.0 4.1 4.2 Cutri (2003). "2MASS===07213317+5816051". 2MASS All-Sky Catalog of Point Sources. http://vizier.u-strasbg.fr/viz-bin/VizieR-S?2MASS%20J07213317%2b5816051. 
  5. ↑ "SIMBAD query result: TYC 3793-1994-1 -- Star". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?Ident=TYC3793-1994-1. 
  6. ↑ Adams, E. R. et al. (2013). "Adaptive Optics Images. II. 12 Kepler Objects of Interest and 15 Confirmed Transiting Planets". The Astronomical Journal 146 (1): 9. doi:10.1088/0004-6256/146/1/9. Bibcode: 2013AJ....146....9A. 
  7. ↑ "Approved names" (in en). http://www.nameexoworlds.iau.org/final-results. 
  8. ↑ "International Astronomical Union | IAU". https://www.iau.org/news/pressreleases/detail/iau1912/. 
  9. ↑ "Estonia has been assigned its own star and planet" (in en). 20 January 2020. https://estonianworld.com/knowledge/estonia-has-been-assigned-its-own-star-and-planet. 
  10. ↑ "Estonia has been assigned its own star and planet" (in en). 20 January 2020. https://estonianworld.com/knowledge/estonia-has-been-assigned-its-own-star-and-planet. 
  11. ↑ Narita, Norio et al. (2010). "The Rossiter-McLaughlin Effect of the Transiting Exoplanet XO-4b". Publications of the Astronomical Society of Japan 62 (6): L61–L65. doi:10.1093/pasj/62.6.l61. Bibcode: 2010PASJ...62L..61N. https://academic.oup.com/pasj/article/62/6/L61/1501821. 
  12. ↑ 12.0 12.1 Todorov, Kamen O. et al. (2012). "Warm Spitzer Observations of Three Hot Exoplanets: XO-4b, HAT-P-6b, and HAT-P-8b". The Astrophysical Journal 746 (1): 111. doi:10.1088/0004-637X/746/1/111. Bibcode: 2012ApJ...746..111T. 

External links

Coordinates: Sky map 07h 21m 33.1657s, +58° 16′ 05.005″




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