Kepler-13 or KOI-13 is a stellar triple star system consisting of Kepler-13A, around which an orbiting

hot Jupiter Hot Jupiters (sometimes called hot Saturns) are a class of gas giant exoplanets that are inferred to be physically similar to Jupiter (i.e. Jupiter analogue, Jupiter analogues) but that have very short orbital periods (). The close proximity to t ...

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

was discovered with the

Kepler space telescope The Kepler space telescope is a defunct space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orb ...

in 2011, and Kepler-13B a common

proper motion Proper motion is the astrometric measure of changes in the apparent places of stars or other celestial objects as they move relative to the center of mass of the Solar System. It is measured relative to the distant stars or a stable referenc ...

companion star which has an additional star orbiting it.

Stellar system

The multiple nature of the system was discovered in 1904 by

Robert Grant Aitken Robert Grant Aitken (December 31, 1864 – October 29, 1951) was an American astronomer. Early life and education Robert Grant Aitken was born in Jackson, California, to Scottish immigrant Robert Aitken and Wilhelmina Depinau. Aitken atte ...

Lick Observatory The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton (California), Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The ...

. He measured a separation between the A and B components of approximately one

arc second A minute of arc, arcminute (abbreviated as arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of a degree. Since one degree is of a turn, or complete rotation, one arcminute is of a tu ...

and position angle of 281.3° with the 36"

James Lick telescope The James Lick Telescope is a refracting telescope built in 1888. It has a lens, which is in diameter—a major achievement in its day. The instrument remains in operation and public viewing is allowed on a limited basis. Also called the "Gre ...

. The position of the two visual components of the system relative to each other has remained constant since 1904.

Radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

measurements taken with the

SOPHIE échelle spectrograph Sophie is a feminine given name, another version of Sophia, from the Greek word for "wisdom". People with the name Born in the Middle Ages * Sophie, Countess of Bar (c. 1004 or 1018–1093), sovereign Countess of Bar and lady of Mousson * Sop ...

at the

Haute-Provence Observatory The Haute-Provence Observatory (OHP, ) is an astronomical observatory in the southeast of France, about 90 km east of Avignon and 100 km north of Marseille. It was established in 1937 as a national facility for French astronomers. Ast ...

revealed an additional companion orbiting Kepler-13B. This companion has a mass of between 0.4 and 1 times that of the Sun and orbits with a period of 65.831 days with an eccentricity of 0.52

Planetary system

Kepler-13 was identified as one of 1235 planetary candidates with transit-like signatures in the first four months of Kepler data. It was confirmed as a planet by measuring the Doppler beaming effect on the Kepler light curve. The planet that has been confirmed, having a radius of between , is also one of the largest known exoplanets. The planet is likely to be tidally locked to the parent star. In 2015, the planetary nightside temperature was estimated to be equal to 2394 K. The study in 2012, utilizing a

Rossiter–McLaughlin effect The Rossiter–McLaughlin effect is a spectroscopic phenomenon observed when an object moves across the face of a rotating star. The star is seen to undergo a redshift anomaly caused by the obscuration of different parts of its disk. Descriptio ...

, have determined the planetary orbit is mildly misaligned with the equatorial plane of the star, misalignment equal to 24°. The planetary transits are changing in duration over time which is likely caused by the interaction of the planet with its host star. In 2017, Hubble observations by a team of astronomers led by Thomas Beatty revealed that

titanium monoxide Titanium(II) oxide ( Ti O) is an inorganic chemical compound of titanium and oxygen. It can be prepared from titanium dioxide and titanium metal at 1500 °C. It is non-stoichiometric in a range TiO0.7 to TiO1.3 and this is caused by vacancie ...

molecules in the dayside might be carried to the nightside of the planet, where they form clouds and precipitate.

References

{{Sky, 19, 07, 33.107, +, 46, 52, 5.95 Planetary systems with one confirmed planet Planetary transit variables 13 J19075308+4652061 Lyra Durchmusterung objects