CI Tauri is a young star, about 2 million years old, located approximately 500 light years away in the

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 ...

Taurus Taurus is Latin for 'bull' and may refer to: * Taurus (astrology), the astrological sign * Taurus (constellation), one of the constellations of the zodiac * Taurus (mythology), one of two Greek mythological characters named Taurus * ''Bos taurus ...

. It is still accreting material from a debris disk at an unsteady pace, possibly modulated by the eccentric orbital motion of the inner planet. The spectral signatures of compounds of

sulfur Sulfur (or sulphur in British English) is a chemical element with the symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms form cyclic octatomic molecules with a chemical formula ...

were detected from the disk. The magnetic field on the surface of CI Tauri, equal to 0.22 T, is close to average for T Tauri stars.

Planetary system

In 2016 a planet, CI Tauri b, was discovered orbiting CI Tauri on a very tight yet eccentric 9-day orbit. The discovery of CI Tauri b was notable because it is 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 ...

, which are supposed to take a minimum of 10 million years to form, and are often thought to be too close to their parent stars to have formed there. The spectral signature of

carbon monoxide Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simple ...

attributed to the atmosphere of CI Tauri b was detected in 2019.

Additional planets suspected

In 2018 the possible detection of three more planets (inferred by gaps in the protoplanetary disk surrounding the star) was announced. Using the Atacama Large Millimeter Array (ALMA) to look for 'siblings' of CI Tauri b, a team of researchers detected three distinct gaps in the protoplanetary disk which their theoretical modelling suggests are caused by three other planets. The two outer planets are believed to be about the mass of

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

, while the inner planet's mass is around the same as CI Tauri b. Two of the new planets are similarly located to those inferred in the HL Tauri protoplanetary disk. If this discovery is confirmed this would be the most massive collection of

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 ...

s ever detected at this age with its four planets spanning a factor of a thousand in orbital radius. The gaps are visible in wideband photography, but not in the gas spectral lines. These "gaps" may be lower-temperature shadows of dust in the inner disk cast on outer parts rather than true gaps carved by planets.

References

{{DEFAULTSORT:CI Tauri Taurus (constellation) T Tauri stars J04335200+2250301 Planetary systems with one confirmed planet Tauri, CI K-type subgiants