| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Lynx |
| Right ascension | 07 21 33.1602 |
| Declination | +58° 16′ 05.110″ |
| Apparent magnitude (V) | 10.674 ± 0.019 |
| Characteristics | |
| Spectral type | F5V |
| Apparent magnitude (B) | 11.240 ± 0.029 |
| Apparent magnitude (V) | 10.674 ± 0.019 |
| Apparent magnitude (J) | 9.667 ± 0.021 |
| Apparent magnitude (H) | 9.476 ± 0.022 |
| Apparent magnitude (K) | 9.406 ± 0.023 |
| Astrometry | |
| Proper motion (μ) | RA: −17.008(12) mas/yr Dec.: 5.463(12) mas/yr |
| Parallax (π) | 3.7812 ± 0.0156 mas |
| Distance | 863 ± 4 ly (264 ± 1 pc) |
| Details | |
| Mass | 1.32 ± 0.02 M☉ |
| Radius | 1.56 ± 0.05 R☉ |
| Temperature | 6397 ± 70 K |
| Metallicity | -0.04 ± 0.03 dex |
| Age | 2.1 ± 0.6 Gyr |
| Other designations | |
| Koit, TYC 3793-1994-1, GSC 03793-01994, 2MASS J07213317+5816051 | |
| Database references | |
| SIMBAD | 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. A search for a binary companion star using adaptive optics at MMT Observatory was negative.
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.
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. It has been named Hämarik, meaning dusk, and referring to a character from the same Faehlmann story featuring Koit.
| 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) | — | — |
Notes
- eccentricity approximately equal to zero is expected theoretically and is consistent with the radial velocities and secondary eclipses timing
References
- 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
- ^ 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.
- ^ McCullough, P. R.; et al. (2008). "XO-4b: An Extrasolar Planet Transiting an F5V Star". arXiv:0805.2921 .
- ^ Cutri; et al. (2003). "2MASS===07213317+5816051". 2MASS All-Sky Catalog of Point Sources. Retrieved 2012-02-25.
- "SIMBAD query result: TYC 3793-1994-1 -- Star". Centre de Données astronomiques de Strasbourg. Retrieved 2009-04-26.
- 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.
- "Approved names". NameExoworlds. Retrieved 2020-01-02.
- "International Astronomical Union | IAU". www.iau.org. Retrieved 2020-01-02.
- "Estonia has been assigned its own star and planet". Estonian World. 20 January 2020. Retrieved 2020-01-20.
- "Estonia has been assigned its own star and planet". Estonian World. 20 January 2020. Retrieved 2020-01-20.
- 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.
- ^ 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.
External links
- "XO-4". Exoplanets. Archived from the original on 2016-03-03. Retrieved 2009-04-28.
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