HD 139664

HD 139664 is a single^[9] star in the southern constellation of Lupus. It has the Bayer designation g Lupi; HD 139664 is the star's identifier from the Henry Draper Catalogue.^[8] It has a yellow-white hue and is visible to the naked eye with an apparent visual magnitude of 4.64. The star is located at a distance of 57 light years from the Sun based on parallax, and it is drifting closer with a radial velocity of −7 km/s.^[2] It is a member of the Hercules-Lyra association of co-moving stars.^[10][2]

HD 139664

ACS image of debris disk around HD 139664 Credit: NASA/ESA
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Lupus
Right ascension	15h 41m 11.3768s[1]
Declination	−44° 39′ 40.342″[1]
Apparent magnitude (V)	4.64[2]
Characteristics
Evolutionary stage	main sequence[1]
Spectral type	F3/5V[3]
U−B color index	−0.03[4]
B−V color index	+0.413[2]
R−I color index	+0.20[4]
Astrometry
Radial velocity (Rv)	−7.08±0.03[2] km/s
Proper motion (μ)	RA: −169.106[1] mas/yr Dec.: −266.391[1] mas/yr
Parallax (π)	57.4759±0.1312 mas[1]
Distance	56.7 ± 0.1 ly (17.40 ± 0.04 pc)
Absolute magnitude (MV)	3.57[5]
Details
Mass	1.368±0.026[2] M☉
Radius	1.26[6] R☉
Luminosity	3.31[7] L☉
Surface gravity (log g)	4.29[7] cgs
Temperature	6,704±63[7] K
Rotation	0.719 d
Rotational velocity (v sin i)	71.6[2] km/s
Age	1.11±1.40[7] Gyr
Other designations
g Lupi, CD−44°10310, CPD−44°7529, GC 21070, GJ 594, HD 139664, HIP 76829, HR 5825, SAO 226064, PPM 320883, LTT 6256, NLTT 40843[8]
Database references
SIMBAD	data

This is an F-type main-sequence star with a stellar classification of F3/5V,^[3] which indicates it is generating energy through core hydrogen fusion. The estimated age is poorly constrained at around one billion years,^[7] but the age of the Hercules-Lyra association to which it belongs is 257±46 million years.^[11] It has a moderately high rate of spin, showing a projected rotational velocity of 71.6 km/s.^[2] The star has 1.37^[2] times the mass of the Sun and 1.26^[6] times the Sun's radius. It is radiating 3.31 times the luminosity of the Sun from its photosphere at an effective temperature of 6,704 K.^[7]

Debris disk

millimetre image of the disk with the REASONS survey^[12]

A debris disk has been imaged around this star using the coronagraphic mode of the ACS instrument on the Hubble Space Telescope. The disk appears to have a dust maximum at 83 AU from the star and a sharp outer boundary at 109 AU. These features may be caused by gravitational perturbations from planets orbiting the star.^[13]