HD 17925
Star in the constellation Eridanus
From Wikipedia, the free encyclopedia
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.[18] 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.[8] It is a likely member of the Local Association of nearby, co-moving stars.[13] The spectrum shows a strong abundance of lithium, indicating that it is young star.[4] This likely makes its point of origin the nearby Scorpio–Centaurus Complex.[19]
  | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus[1] |
| Right ascension | 02h 52m 32.12819s[2] |
| Declination | −12° 46′ 10.9681″[2] |
| Apparent magnitude (V) | 6.04[3] |
| Characteristics | |
| Evolutionary stage | Main sequence[4] |
| Spectral type | K1V[5] |
| U−B color index | +1.41[6] |
| B−V color index | +0.86[6] |
| Variable type | RS CVn[7] |
| Astrometry | |
| Radial velocity (Rv) | +17.77±0.08[8] 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[9] |
| Details | |
| Mass | 0.88[10] M☉ |
| Radius | 0.85±0.05[11] R☉ |
| Luminosity | 0.408±0.005[2] L☉ |
| Surface gravity (log g) | 4.58[10] cgs |
| Temperature | 5,225±5[12] K |
| Metallicity [Fe/H] | +0.10[13] dex |
| Rotation | 6.6 days[13] |
| Rotational velocity (v sin i) | 4.80[14] km/s |
| Age | 100[15] Myr |
| Other designations | |
| 32 G. Eri, EP Eri, BD−13°544, GJ 117, HD 17925, HIP 13402, HR 857, SAO 148647, PLX 599[16][17] | |
| Database references | |
| SIMBAD | data |
The stellar classification of HD 17925 is K1V,[5] which indicates this is a K-type main-sequence star that is engaged in core hydrogen fusion. It is an active star[4] that is classified as a RS Canum Venaticorum variable,[18] showing a rotational modulation with a period of 6.9 days, and has been observed to flare.[7] The star has an estimated age of 100[15] million years and is spinning with a projected rotational velocity of 4.8 km/s.[14] The rotation period of 6.6 days days can be determined from its activity cycle.[13] The star has 88%[10] of the mass of the Sun and 85%[11] 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.[12]
The presence of an unseen companion has been suggested based on variations in the widths of absorption lines in the star's photosphere.[4] It displays low-amplitude radial velocity variation, which may indicate it is a spectroscopic binary.[11] However, the binary hypothesis doesn't appear to be consistent with Hipparcos satellite data.[13] 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.[21]