XO-4 is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

located approximately 896 light-years away from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

in the

Lynx A lynx is a type of wild cat. Lynx may also refer to: Astronomy * Lynx (constellation) * Lynx (Chinese astronomy) * Lynx X-ray Observatory, a NASA-funded mission concept for a next-generation X-ray space observatory Places Canada * Lynx, Ontar ...

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

. It has a magnitude of about 11 and cannot be seen with the naked eye but is visible through a small

telescope A telescope is a device used to observe distant objects by their emission, absorption, or reflection of electromagnetic radiation. Originally meaning only an optical instrument using lenses, curved mirrors, or a combination of both to observe ...

. 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 Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

, during the 100th anniversary of the

IAU The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach ...

. Koit is Estonian for ''dawn'', and was named for a character in a folk tale written by

Friedrich Robert Faehlmann Friedrich Robert Faehlmann (Fählmann) (31 December 1798 in Ao Manor, Kreis Jerwen – 22 April 1850 in Tartu) was an Estonian writer, medical doctor and philologist active in Livonia, Russian Empire. He was a co-founder of the Learned Estonian ...

Planetary system

One known

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

XO-4b XO-4b is an extrasolar planet approximately 956 light years away in the constellation of Lynx (constellation), Lynx. This planet was found by the transit method by McCullough in May 2008. The planet has mass and radius . This planet orbits very c ...

, which is classified as a

hot jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter but that have very short orbital periods (). The close proximity to their stars and high surface-atmosphere temp ...

, 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.

Notes

References

External links

* F-type main-sequence stars Lynx (constellation) Planetary transit variables Planetary systems with one confirmed planet {{main-star-stub