XO-4

Last updated
XO-4 / Koit
Observation data
Epoch J2000       Equinox J2000
Constellation Lynx [1]
Right ascension 07h 21m 33.1602s [2]
Declination +58° 16′ 05.110″ [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
Radial velocity (Rv)1.74±0.33 [2] km/s
Proper motion (μ)RA: −17.008(12) mas/yr [2]
Dec.: 5.463(12) mas/yr [2]
Parallax (π)3.7812±0.0156  mas [2]
Distance 863 ± 4  ly
(264 ± 1  pc)
Details [3] [5]
Mass 1.32±0.02  M☉
Radius 1.56±0.05  R☉
Surface gravity (log g)4.18±0.07  cgs
Temperature 6397±70  K
Metallicity [Fe/H]−0.04±0.03  dex
Rotational velocity (v sin i)8.8±0.5 km/s
Age 2.1±0.6  Gyr
Other designations
Koit, TOI-1721, TIC 51234631, TYC 3793-1994-1, GSC 03793-01994, 2MASS J07213317+5816051 [6]
Database references
SIMBAD data
Exoplanet Archive data

XO-4 is a star located approximately 863 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. [7]

Contents

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. [8] [9] [10]

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 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. [11] The planetary orbit is misaligned with the stellar rotation. [12]

The XO-4 planetary system [5] [note 1]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b / Hämarik 1.612+0.027
−0.028  MJ 		0.05524+0.00027
−0.00028		4.1250823(39)<0.003988.7±1.1 ° 1.34±0.05  RJ

Notes

  1. ↑ eccentricity approximately equal to zero is expected theoretically and is consistent with the radial velocities and secondary eclipse timing [3] [13]

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. Bibcode:1987PASP...99..695R. doi: 10.1086/132034 . Vizier query form
  2. 1 2 3 4 5 6 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.
  3. 1 2 3 4 5 6 7 McCullough, P. R.; et al. (2008). "XO-4b: An Extrasolar Planet Transiting an F5V Star". arXiv: 0805.2921 [astro-ph].
  4. 1 2 3 Cutri; et al. (2003). "2MASS===07213317+5816051". 2MASS All-Sky Catalog of Point Sources. Retrieved 2012-02-25.
  5. 1 2 Bonomo, A. S.; Desidera, S.; et al. (June 2017). "The GAPS Programme with HARPS-N at TNG. XIV. Investigating giant planet migration history via improved eccentricity and mass determination for 231 transiting planets". Astronomy & Astrophysics . 602: A107. arXiv: 1704.00373 . Bibcode:2017A&A...602A.107B. doi:10.1051/0004-6361/201629882.
  6. ↑ "SIMBAD query result: TYC 3793-1994-1 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-04-26.
  7. ↑ 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. arXiv: 1305.6548 . Bibcode:2013AJ....146....9A. doi:10.1088/0004-6256/146/1/9. S2CID   119117620.
  8. ↑ "Approved names". NameExoworlds. Retrieved 2020-01-02.
  9. ↑ "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
  10. ↑ "Estonia has been assigned its own star and planet". Estonian World. 20 January 2020. Retrieved 2020-01-20.
  11. ↑ "Estonia has been assigned its own star and planet". Estonian World. 20 January 2020. Retrieved 2020-01-20.
  12. ↑ 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. arXiv: 1008.3803 . Bibcode:2010PASJ...62L..61N. doi:10.1093/pasj/62.6.l61. S2CID   2967944.
  13. 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. arXiv: 1111.5858 . Bibcode:2012ApJ...746..111T. doi:10.1088/0004-637X/746/1/111. S2CID   119200344.
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