V830 Tauri
{{Short description|Star in the constellation Taurus}}
{{Starbox begin|name=V830 Tauri}}
{{Starbox image
| image = 250px
| caption = A light curve for V830 Tauri, plotted from TESS data
}}
{{Starbox observe
|epoch=J2000.0
|equinox=J2000.0
|constell=Taurus
}}
{{Starbox character
|type=T Tau
|variable=BY Dra
}}
{{Starbox astrometry
|radial_v = {{val|5.98|11.60}}
|prop_mo_ra = {{val|7.171|0.022}}
|prop_mo_dec = {{val|-21.197|0.017}}
|parallax = 7.6704
|p_error = 0.0165
}}
{{Starbox detail
|mass={{val|1.00|0.05}}
|luminosity=1.2
|radius={{val|2.0|0.2}}
|temperature={{val|4,250|50|fmt=commas}}
|rotational_velocity={{val|30.5|0.5}}
|rotation=2.741 days
|age_myr=~2
}}
{{Starbox catalogue
|names={{odlist|V=V830 Tauri|2MASS=J04331003+2433433|IRAS=C04301+2427}}
}}
{{Starbox reference |Simbad = V830+Tauri}}
{{Starbox end}}
V830 Tauri is a T Tauri star located {{convert|425.2|ly|pc|lk=on}} 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.{{citation|arxiv=1611.02055|year=2016|title=The hot Jupiter of the magnetically active weak-line T Tauri star V830 Tau|doi=10.1093/mnras/stw2904 |last1=Donati |first1=J.-F. |last2=Yu |first2=L. |last3=Moutou |first3=C. |last4=Cameron |first4=A. C. |last5=Malo |first5=L. |last6=Grankin |first6=K. |last7=Hébrard |first7=E. |last8=Hussain |first8=G. A. J. |last9=Vidotto |first9=A. A. |last10=Alencar |first10=S. H. P. |last11=Haywood |first11=R. D. |last12=Bouvier |first12=J. |last13=Petit |first13=P. |last14=Takami |first14=M. |last15=Herczeg |first15=G. J. |last16=Gregory |first16=S. G. |last17=Jardine |first17=M. M. |last18=Morin |first18=J. |author19=the MaTYSSE collaboration |journal=Monthly Notices of the Royal Astronomical Society |volume=465 |issue=3 |pages=3343–3360 |doi-access=free }}
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 {{val|4,250|u=K|fmt=commas}}. For comparison, the Sun's surface temperature is {{val|5,772|u=K|fmt=commas}}.
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
{{OrbitboxPlanet begin
| name = V830 Tauri
| period_unit = day
}}
{{OrbitboxPlanet hypothetical
| exoplanet = b
| mass = 0.77{{±|0.15}}
| radius =
| radius_earth =
| semimajor = 0.057{{±|0.001}}
| period = 4.93{{±|0.05}}
| eccentricity = 0
| inclination = 55
| status=controversial
}}
{{Orbitbox end}}
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.[http://www.ast.obs-mip.fr/article.php3?id_article=1014 Newborn Giant Planet Grazes its Sun], IRAP / OMP Press Release, 2016 Jun 20"'Hot Jupiter' planet orbiting newborn star surprises scientists" CBC News http://www.cbc.ca/news/technology/hot-jupiter-1.3419412"[https://www.theguardian.com/science/2016/jun/20/baby-planets-givel-first-insights-into-planet-and-solar-system-formation-k233b Discovery of 'baby' planets sheds light on planet and solar system formation" The Guardian] The exoplanet has a mass of about 0.77 masses of Jupiter and is orbiting {{val|0.057|ul=AU}} away from its host star with a period of {{val|4.93|ul=days}} and an inclination of {{val|55|ul=deg}}. However, a 2020 study was unable to confirm this planet.{{refn|group=note|Works by Donati claims to detect 0.068km/s radial-velocity planetary signal embedded within 1.2km/s jitter, based only on 27 radial-velocity measurements.}}
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.
Notes
{{reflist|group=note}}
References
{{Reflist|refs=
{{Cite encyclopedia|url=https://exoplanet.eu/catalog/v830_tau_b--3971/|encyclopedia=Extrasolar Planets Encyclopaedia|title=The Extrasolar Planet Encyclopaedia — V830 Tau b|access-date=2017-07-30}}
| access-date=2016-06-22
}}
{{Cite Gaia DR3|147831571737487488}}
{{cite journal |last1=Damasso |first1=M. |last2=Lanza |first2=A. F. |last3=Benatti |first3=S. |last4=Rajpaul |first4=V. M. |last5=Mallonn |first5=M. |last6=Desidera |first6=S. |last7=Biazzo |first7=K. |last8=d'Orazi |first8=V. |last9=Malavolta |first9=L. |last10=Nardiello |first10=D. |last11=Rainer |first11=M. |last12=Borsa |first12=F. |last13=Affer |first13=L. |last14=Bignamini |first14=A. |last15=Bonomo |first15=A. S. |last16=Carleo |first16=I. |last17=Claudi |first17=R. |last18=Cosentino |first18=R. |last19=Covino |first19=E. |last20=Giacobbe |first20=P. |last21=Gratton |first21=R. |last22=Harutyunyan |first22=A. |last23=Knapic |first23=C. |last24=Leto |first24=G. |last25=Maggio |first25=A. |last26=Maldonado |first26=J. |last27=Mancini |first27=L. |last28=Micela |first28=G. |last29=Molinari |first29=E. |last30=Nascimbeni |first30=V. |display-authors=1 |date=October 2020 |title=The GAPS Programme at TNG. XXVII. Reassessment of a young planetary system with HARPS-N: is the hot Jupiter V830 Tau b really there? |journal=Astronomy & Astrophysics |volume=642 |issue= |pages=A133 |doi=10.1051/0004-6361/202038864 |arxiv=2008.09445 |bibcode=2020A&A...642A.133D}}
}}
{{Stars of Taurus}}
{{DEFAULTSORT:V830 Tauri}}
Category:Taurus (constellation)
Category:Pre-main-sequence stars
Category:BY Draconis variables
Category:IRAS catalogue objects