Gliese 569

Gliese 569 is a star in the constellation Boötes. It is orbited by a pair of brown dwarfs. The system lies 32.45 light years away.

Gliese 569

An ultraviolet band light curve for a flare on CE Boötis, adapted from Hansen and Veeder (1977)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Boötes
Gliese 569 A
Right ascension	14h 54m 29.2362s[2]
Declination	+16° 06′ 03.798″[2]
Apparent magnitude (V)	10.15[3]
Gliese 569 B
Right ascension	14h 54m 29.7686s[4]
Declination	+16° 06′ 05.627″[4]
Characteristics
Gliese 569 A
Evolutionary stage	main-sequence star
Spectral type	M3
Apparent magnitude (g)	9.12[2]
Variable type	Flare star[5]
Gliese 569 B
Spectral type	M8.5+M9[6]
Apparent magnitude (g)	15.32[4]
Astrometry
A
Radial velocity (Rv)	−8.00±0.17 km/s
Proper motion (μ)	RA: +279.12±0.02 mas/yr[2] Dec.: −117.91±0.02 mas/yr[2]
Parallax (π)	100.5243±0.0210 mas[2]
Distance	32.446 ± 0.007 ly (9.948 ± 0.002 pc)
Orbit[7]
Primary	Gliese 569 Ba
Companion	Gliese 569 Bb
Period (P)	863.7±4.2 d
Semi-major axis (a)	0.89±0.02 AU
Eccentricity (e)	0.312±0.007
Inclination (i)	32.4±1.3°
Details
Gliese 569 A
Mass	0.48[8] M☉
Radius	0.43[8] R☉
Luminosity	0.034±0.008[9] L☉
Temperature	3,649±79[9] K
Rotation	14.7[8] days
Age	<700[6] Myr
Gliese 569 Ba
Mass	0.081±0.010[10] M☉
Radius	0.119±0.020[11] R☉
Luminosity	4.5+0.8 −0.7×10−4[11] L☉
Surface gravity (log g)	4.5[11] cgs
Temperature	2,440±100[11] K
Rotational velocity (v sin i)	19[6] km/s
Age	<700[6] Myr
Gliese 569 Bb
Mass	0.059±0.007[10] M☉
Radius	0.102±0.020[11] R☉
Luminosity	2.6+0.5 −0.4×10−4[11] L☉
Surface gravity (log g)	4.5[11] cgs
Temperature	2,305±100[11] K
Rotational velocity (v sin i)	6[6] km/s
Age	<700[6] Myr
Other designations
Gliese 569, BD+16 2708, G 136-28, GSC 01478-00495, HIP 72944, 2MASS J14542923+1606039, TYC 1478-495-1, CE Boötis, WDS J14545+1606[12]
Database references
SIMBAD	Gliese 569 A
	Gliese 569 B

System

The primary star GJ 569A is orbited by the much fainter (3.7 magnitudes) secondary GJ 659B at a projected separation of 5.92 arcseconds, discovered in 1988.^[13] The star GJ 569B (BD+16 2708B) itself is a close binary system of two high-mass brown dwarfs in a 2.4-year orbit,^[14] and a small (0.538±0.048) magnitude difference between components.^[15] The orbital plane of close binary GJ 569Ba and GJ 569Bb is expected to precess at timescales of about 100 thousand years due to the gravitational influence of GJ 569A.^[6]

Properties

The primary star Gliese 569A is a flare star.^[1] The star was given its variable star designation, CE Boötis, in 1975.^[16] The nature of the brown dwarf binary Gliese 569B is highly uncertain, and it was even suspected Gliese 569Ba itself may be either a low-mass star or a binary object. But with a mass about 8-9% that of the Sun means it may possibly be a binary of two extremely low mass ultra-cool dwarf stars that are extremely dim, dim enough to look like a brown dwarf.^[7] Both brown dwarfs are weakly variable, likely due to starspot activity.^[14]