 Size comparison of XO-4b with Jupiter. | |
| Discovery | |
|---|---|
| Discovered by | McCullough et al. |
| Discovery site | Maui, Hawaii |
| Discovery date | May 19, 2008 |
| Detection method | Transit |
| Orbital characteristics | |
| Semi-major axis | 0.0555 ± 0.00011 AU (8,303,000 ± 16,000 km) |
| Eccentricity | 0.0024 |
| Orbital period (sidereal) | 4.12502 ± 2e-5 d 0.011293 y |
| Inclination | 88.7 ± 1.1 |
| Star | XO-4 |
| Physical characteristics | |
| Mean radius | 1.34 ± 0.048 RJ |
| Mass | 1.72 ± 0.2 MJ |
| Mean density | 0.948 g/cm |
| Surface gravity | 24.8 m/s (2.53 g0) |
| Temperature | ~1333 |
XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx. This planet was found by the transit method by McCullough in May 2008. The planet has mass 1.72 MJ and radius 1.34 RJ. This planet orbits very close to the F-type parent star, as it is typical for transiting planets, classing this planet as Hot Jupiter.
Orbit
It takes only 4.125 days (or 99 hours) to orbit at a distance of 8.3 gigameters (0.0555 AU) away from the star.
The study in 2012, utilizing a Rossiter–McLaughlin effect, have determined the planetary orbit is strongly misaligned with the equatorial plane of the star, misalignment equal to -46.7±8.1°.
Naming
The planet XO-4b is named Hämarik. The name was selected in the NameExoWorlds campaign by Estonia, during the 100th anniversary of the IAU. Hämarik is Estonian for dusk, and was named for a character in a folk tale written by Friedrich Robert Faehlmann.
See also
References
- McCullough, P. R.; et al. (2008). "XO-4b: An Extrasolar Planet Transiting an F5V Star". arXiv:0805.2921 .
- Albrecht, Simon; Winn, Joshua N.; Johnson, John A.; Howard, Andrew W.; Marcy, Geoffrey W.; Butler, R. Paul; Arriagada, Pamela; Crane, Jeffrey D.; Shectman, Stephen A.; Thompson, Ian B.; Hirano, Teruyuki; Bakos, Gaspar; Hartman, Joel D. (2012), "Obliquities of Hot Jupiter host stars: Evidence for tidal interactions and primordial misalignments", The Astrophysical Journal, 757 (1): 18, arXiv:1206.6105, Bibcode:2012ApJ...757...18A, doi:10.1088/0004-637X/757/1/18, S2CID 17174530
- "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.
External links
Media related to XO-4b at Wikimedia Commons
- "XO-4". Exoplanets. Archived from the original on 2016-03-03. Retrieved 2008-08-06.
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