V830 Tauri is a

T Tauri star T Tauri stars (TTS) are a class of variable stars that are less than about ten million years old. This class is named after the prototype, T Tauri, a young star in the Taurus star-forming region. They are found near molecular clouds and ide ...

located away from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

in the constellation

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 tauru ...

. This star is very young, with an age of only 2 million years, compared to the Sun's age, which is 4.6 billion years. Typical for a young stars, it exhibits a strong flare activity, with three flared detected in 91-days observation period in 2016.

Characteristics

V830 Tauri is an

M-type star In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the ...

. The star has a mass of roughly 1 solar mass, but has a radius of 2

solar radii Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3: :1\,R_ = 6.957\tim ...

, due to the star's age, which means that it hasn't fully contracted yet to become a

main-sequence star In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Hert ...

. It has a surface temperature of . For comparison, the Sun's surface temperature is . V830 Tauri is a

, a pre-main sequence star that has a surrounding disc producing emission lines in its spectrum. It is classified as a weak-lined T Tauri star. It is also classified as a

BY Draconis variable BY Draconis variables are variable stars of late spectral types, usually K or M, and typically belong to the main sequence. The name comes from the archetype for this category of variable star system, BY Draconis. They exhibit variations in thei ...

, cool stars with starspots and chromospheric activity that vary in brightness as they rotate. The variable period of 2.74 days matches the rotation period. V830 Tauri is a

T Tauri T Tauri is a variable star in the constellation Taurus, the prototype of the T Tauri stars. It was discovered in October 1852 by John Russell Hind. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri, but i ...

star that is the same mass of the Sun, but twice the radius. It has a surface temperature of 4250 ± 50 K. In comparison, the Sun has a surface temperature of 5778 K. The star's age is estimated to be about 2 million years old, which makes it a very young star. For comparison, the Sun is 4.6 billion years old. The star has not yet fully contracted to become a main sequence star, which ties in with its bloated radius but similar mass to the Sun. Given its mass, it will likely be on the main sequence portion of its lifetime for about 10 billion years, much like the Sun.

Planetary system

On June 20, 2016, an exoplanet was found around V830 Tauri via radial velocity. It is one of, if not the youngest exoplanet ever found, with an age of only about 2 million years. The exoplanet has a

mass Mass is an intrinsic property of a body. It was traditionally believed to be related to the quantity of matter in a physical body, until the discovery of the atom and particle physics. It was found that different atoms and different eleme ...

of about 0.77 masses of

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousandth t ...

and is orbiting away from its host star with a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of and an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

of . However, a 2020 study was unable to confirm this planet.Planet V830 Tau b on exoplanet.eu
/ref> V830 Tauri b orbits its parent star every 4.93 days at a distance of 0.057 AU from its parent star. This is about 7x closer to the host star than the planet Mercury is to the

. Its mass is about 70% that of

, and, because it is orbiting very close to its parent star, it 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 tem ...

. Previously, before the discovery of V830 Tauri b (and a slightly older planet named K2-33b, with an age around 5-10 million years), TW Hya b was discovered and disproven and PTFO 8-8695 b / CVSO 30 b was discovered with an age equally young and an orbit even closer. The yet unconfirmed objects are pending confirmation. The discovery of V830 Tauri b, K2-33b and PTFO 8-8695 b / CVSO 30 b suggests that the formation and migration of close-in giant planets can occur on a timescale of only a few million years. The new discoveries support planet-disc interactions as the most likely mechanism for efficiently producing young hot Jupiters.

Notes

References

{{DEFAULTSORT:V830 Tauri Taurus (constellation) Pre-main-sequence stars BY Draconis variables T Tauri stars J04331003+2433433 IRAS catalogue objects M-type stars Hypothetical planetary systems Tauri, V830