HD 17925

HD 17925 is a variable star in the equatorial constellation of Eridanus. It has the Gould designation 32 G. Eridani and the variable star designation EP Eri. The star has a yellow-orange hue and is dimly visible to the naked eye in good seeing conditions with an apparent visual magnitude that varies from 6.03 down to 6.08.^[16] It is located nearby at a distance of 34 light years from the Sun based on parallax,^[2] and is drifting further away with a radial velocity of +18 km/s.^[7] It is a likely member of the Local Association of nearby, co-moving stars.^[12] The spectrum shows a strong abundance of lithium, indicating that it is young star.^[17] This likely makes its point of origin the nearby Scorpio–Centaurus Complex.^[18]

HD 17925

A visual band light curve for EP Eridani, adapted from Cutispoto (1992)[1]
Observation data Epoch J2000      Equinox J2000
Constellation	Eridanus
Right ascension	02h 52m 32.12819s[2]
Declination	−12° 46′ 10.9681″[2]
Apparent magnitude (V)	6.04[3]
Characteristics
Evolutionary stage	Main sequence
Spectral type	K1V[4]
U−B color index	+1.41[5]
B−V color index	+0.86[5]
Variable type	RS CVn[6]
Astrometry
Radial velocity (Rv)	+17.77±0.08[7] km/s
Proper motion (μ)	RA: 397.353[2] mas/yr Dec.: −189.281[2] mas/yr
Parallax (π)	96.5200±0.0258 mas[2]
Distance	33.792 ± 0.009 ly (10.361 ± 0.003 pc)
Absolute magnitude (MV)	5.97[8]
Details
Mass	0.88[9] M☉
Radius	0.85±0.05[10] R☉
Luminosity	0.408±0.005[2] L☉
Surface gravity (log g)	4.58[9] cgs
Temperature	5,225±5[11] K
Metallicity [Fe/H]	+0.10[12] dex
Rotation	6.6 days[12]
Rotational velocity (v sin i)	4.80[13] km/s
Age	100[14] Myr
Other designations
32 G. Eridani, EP Eri, GJ 117, HD 17925, HIP 13402, HR 857, SAO 148647,[15] YPC 599
Database references
SIMBAD	data

The stellar classification of HD 17925 is K1V,^[4] which indicates this is a K-type main-sequence star that is engaged in core hydrogen fusion. It is an active star^[17] that is classified as a RS Canum Venaticorum variable,^[16] showing a rotational modulation with a period of 6.9 days, and has been observed to flare.^[6] The star has an estimated age of 100^[14] million years and is spinning with a projected rotational velocity of 4.8 km/s.^[13] The rotation period of 6.6 days days can be determined from its activity cycle.^[12] The star has 88%^[9] of the mass of the Sun and 85%^[10] of the Sun's radius. It is radiating 41%^[2] of the luminosity of the Sun from its photosphere at an effective temperature of 5,225 K.^[11]

The presence of an unseen companion has been suggested based on variations in the widths of absorption lines in the star's photosphere.^[17] It displays low-amplitude radial velocity variation, which may indicate it is a spectroscopic binary.^[10] However, the binary hypothesis doesn't appear to be consistent with Hipparcos satellite data.^[12] An infrared excess has been detected around this star, most likely indicating the presence of a circumstellar disk at a radius of 17.9 AU. The temperature of this dust is 52 K.^[19]