Gliese 521

Gliese 521 is a double star in the northern constellation of Canes Venatici. The system is located at a distance of 43.6 light-years from the Sun based on parallax measurements, but is drawing closer with a radial velocity of −65.6 km/s.^[5] It is predicted to come as close as 15.70 light-years from the Sun in 176,900 years.^[9] This star is too faint to be visible to the naked eye, having an apparent visual magnitude of +10.26^[3] and an absolute magnitude of 10.24.^[5]

Gliese 521

Observation data Epoch J2000      Equinox J2000
Constellation	Canes Venatici[1]
Right ascension	13h 39m 24.10228s[2]
Declination	+46° 11′ 11.3631″[2]
Apparent magnitude (V)	+10.26[3]
Characteristics
Spectral type	M1V[4]
Apparent magnitude (J)	7.05[3]
Apparent magnitude (H)	6.51[3]
Apparent magnitude (K)	6.26[3]
Astrometry
Radial velocity (Rv)	−65.72±0.15[2] km/s
Proper motion (μ)	RA: −42.332±0.012 mas/yr[2] Dec.: 389.167±0.014 mas/yr[2]
Parallax (π)	74.7985±0.0153 mas[2]
Distance	43.605 ± 0.009 ly (13.369 ± 0.003 pc)
Absolute magnitude (MV)	10.243[5]
Details
Mass	0.506±0.021 M☉[3] 0.47±0.05[6] M☉
Radius	0.619±0.030 R☉[5] 0.47±0.05[6] R☉
Luminosity	0.033+0.008 −0.007[6] L☉
Surface gravity (log g)	4.79±0.04[6] cgs
Temperature	3,493±50[5] K
Metallicity [Fe/H]	−0.34 dex[3] −0.09±0.09[6] dex
Rotation	49.5±3.5 d[7]
Rotational velocity (v sin i)	0.85[5] km/s
Other designations
BD+46 1889, GJ 521, HIP 66625, SAO 44697, WDS 13394+4611, LTT 13979, TYC 3463-00063-1, 2MASS J13392410+4611114[8]
Database references
SIMBAD	data

The primary is an M-type main-sequence star with a stellar classification of M1V.^[4] It is only about half the size and mass of the Sun. The star is rotating slowly with a projected rotational velocity of 0.85 km/s^[5] and a rotation period of roughly 49.5 days.^[7] The star has a lower metal-content compared to the Sun. It is radiating just 3%^[6] of the luminosity of the Sun from its photosphere at an effective temperature of 3,493 K.^[5]

A faint stellar companion was announced by E. Jódar and associates in 2013. The companion has an angular separation of 521 mas along a position angle of 352.1°±1.4° from the primary. This is equivalent to a projected separation of 7.24±0.14 AU.^[10]

Search for planets

According to Marcy & Benitz (1989)^[11] detected a possible periodicity of 510 days, inferring the possible presence of a massive planetary object with minimum mass of 12 times that of Jupiter in highly eccentric orbit (e=0.6). So far the planet has not been confirmed. A radial velocity study of the star during the period 2013–2017 initially found a promising signal, but this disappeared when additional data was collected and was instead attributed to magnetic activity.^[12]

See also

• Gliese 806