V830 Tauri

V830 Tauri is a T Tauri star located 425.2 ly away from the Sun in the constellation Taurus. 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 strong flare activity, with three flares detected during a 91-day observation period in 2016.

Characteristics
V830 Tauri is an M-type star. The star has a mass of roughly 1 solar mass, but has a radius of 2 solar radii, due to the star's age, which means that it hasn't fully contracted yet to become a main-sequence star. (It will likely be on the main sequence portion of its lifetime for about 10 billion years, much like the Sun.) It has a surface temperature of $5.98$. For comparison, the Sun's surface temperature is $7.171$.

V830 Tauri is a weak-lined T Tauri star, a pre-main sequence star that has a surrounding disc producing emission lines in its spectrum. It is also classified as a BY Draconis variable, 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.

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 of about 0.77 masses of Jupiter and is orbiting $-21.197$ away from its host star with a period of $1$ and an inclination of $2$. However, a 2020 study was unable to confirm this planet.

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 Sun. Its mass is about 70% that of Jupiter, and, because it is orbiting very close to its parent star, it is classified as a hot Jupiter.

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.