17 Leporis

17 Leporis is a binary star system in the southern constellation of Lepus.[7] It has an overall apparent visual magnitude which varies between 4.82 and 5.06,[3] making it luminous enough to be visible to the naked eye as a faint star. The variable star designation for this system is SS Leporis, while 17 Leporis is the Flamsteed designation. Parallax measurements yield a distance estimate of around 910 light years from the Sun. The system is moving further away from the Earth with a heliocentric radial velocity of +18.7 km/s.[6]

17 Leporis

A light curve for SS Leporis, plotted from Hipparcos data[1]
Observation data Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation	Lepus
Right ascension	06h 04m 59.12945s[2]
Declination	−16° 29′ 03.9692″[2]
Apparent magnitude (V)	4.82 to 5.06[3]
Characteristics
Spectral type	A1V + M6III[4]
U−B color index	+0.12 (combined)[5]
B−V color index	+0.24 (combined)[5]
R−I color index	+0.52 (combined)[5]
Variable type	Z And[3]
Astrometry
Radial velocity (Rv)	+18.74±0.10 (center of mass)[6] km/s
Proper motion (μ)	RA: −5.955[2] mas/yr Dec.: −3.680[2] mas/yr
Parallax (π)	3.5742 ± 0.0992 mas[2]
Distance	910 ± 30 ly (280 ± 8 pc)
Orbit[6]
Period (P)	260.34±1.80 d
Semi-major axis (a)	4.492±0.014 mas[4]
Eccentricity (e)	0.005±0.003[4]
Inclination (i)	143.7±0.5[4]°
Longitude of the node (Ω)	162.2±0.7[4]°
Periastron epoch (T)	2,448,528.78±0.37 HJD
Argument of periastron (ω) (secondary)	203.7±0.4°
Semi-amplitude (K1) (primary)	6.1±1.0 km/s
Semi-amplitude (K2) (secondary)	21.32±0.21 km/s
Details
A-type star
Mass	2.71±0.27[4] M☉
Radius	18[7] R☉
Luminosity	1,900[7] L☉
Surface gravity (log g)	2.0[7] cgs
Temperature	9,000[7] K
M giant
Mass	1.30±0.33[4] M☉
Radius	66.7±3.3[4] R☉
Luminosity	1,200[7] L☉
Surface gravity (log g)	1.0[7] cgs
Temperature	3,250[7] K
Other designations
17 Lep, SS Lep, BD−16°1349, HD 41511, HIP 28816, HR 2148, SAO 151093[8]
Database references
SIMBAD	data

This is a double-lined spectroscopic binary system with an orbital period of 260 days and an eccentricity of 0.005.[6] The spectrum reveals the pair to consist of an A-type main-sequence star with a stellar classification of A1 V, and a red giant with a class of M6III. The close pair form a symbiotic binary with ongoing mass transfer from the giant to the hotter component. The giant does not appear to be filling its Roche lobe, so the mass transfer is coming from stellar wind off the giant. The pair are surrounded by a shell and a dusty circumbinary disk, with the former obliterating the lines from the A-type star.[4]