Pr0211

Pr0211 (sometimes written Pr 0211, also 2MASS J08421149+1916373) is a Sun-like late G or early K-type main-sequence star in the Beehive Cluster, or Praesepe, located 600 light-years away in the constellation Cancer. It is rotationally variable and has a rotation period of 7.97 days,^[5] with its spin axis at an inclination of 76°±11° to the plane of the sky.^[4] Pr0211 hosts two known exoplanets, and was the first multi-planet system to be discovered in an open cluster.^[3][4]

Pr0211

Observation data Epoch J2000      Equinox J2000
Constellation	Cancer
Right ascension	08h 42m 11.49887s[1]
Declination	+19° 16′ 37.2375″[1]
Apparent magnitude (V)	12.143[2]
Characteristics
Evolutionary stage	Main sequence
Spectral type	K1V[2] or late G[3]
Apparent magnitude (G)	11.926±0.003[1]
Apparent magnitude (J)	10.660±0.022[2]
Apparent magnitude (H)	10.242±0.019[2]
Apparent magnitude (K)	10.173±0.016[2]
Astrometry
Radial velocity (Rv)	35.37±0.42[1] km/s
Proper motion (μ)	RA: -36.820 mas/yr[1] Dec.: -12.384 mas/yr[1]
Parallax (π)	5.4387±0.0184 mas[1]
Distance	600 ± 2 ly (183.9 ± 0.6 pc)
Details[4]
Mass	0.935±0.013 M☉
Radius	0.827±0.012 R☉
Surface gravity (log g)	4.51±0.05 cgs
Temperature	5300±30 K
Metallicity [Fe/H]	0.18±0.02 dex
Rotation	7.97 days[5]
Rotational velocity (v sin i)	5.1±0.3 km/s
Age	578±12 or 790±30 Myr
Other designations
Pr0211, EPIC 211936827, TIC 175291727, 2MASS J08421149+1916373, NGC 2632 JC 278[2]
Database references
SIMBAD	data
Exoplanet Archive	data

Pr0211 forms a binary star system with a K-type main-sequence star known as NGC 2632 JC 280 or 2MASS J08421285+1916040.^[6][7][8]

Planetary system

Pr0211 b is a gas giant exoplanet, specifically a hot Jupiter, orbiting around Pr0211. Pr0211 b along with Pr0201 b are notable for being the first exoplanets discovered in the Beehive Cluster.^[9][10] Pr0211 b and Pr0201 b were discovered in 2012 by Sam Quinn^[9][10][3] and his colleagues while observing 53 stars in the Beehive Cluster using the 1.5 metres (4.9 ft; 1.6 yd) telescope at the University of Georgia in the United States.^[9]

Pr0211 c is a gas giant exoplanet orbiting around Pr0211.^[11] Pr0211 c was discovered in 2016 by Luca Malavolta^[11][4] and his colleagues while observing its host star with the HARPS-N spectrograph on the 3.6 metres (12 ft; 3.9 yd) Italian Telescopio Nazionale Galileo (TNG) in La Palma, and the Tillinghast Reflector Echelle Spectrograph (TRES) mounted at the 1.5 metres (4.9 ft; 1.6 yd) telescope at the University of Georgia in the United States.

The Pr0211 planetary system^[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥1.88±0.03 MJ	0.03176±0.00015	2.14610±0.00003	0.011+0.012 −0.008	—	—
c	≥7.79±0.33 MJ	5.5+3.0 −1.4	4850+4560 −1750	0.71±0.11	—	—