HD 17925

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]
Distance33.792 ± 0.009 ly
(10.361 ± 0.003 pc)
Absolute magnitude (MV)5.97[8]
Details
Mass0.88[9] M☉
Radius0.85±0.05[10] R☉
Luminosity0.408±0.005[2] L☉
Surface gravity (log g)4.58[9] cgs
Temperature5,225±5[11] K
Metallicity [Fe/H]+0.10[12] dex
Rotation6.6 days[12]
Rotational velocity (v sin i)4.80[13] km/s
Age100[14] Myr
Other designations
32 G. Eridani, EP Eri, GJ 117, HD 17925, HIP 13402, HR 857, SAO 148647,[15] YPC 599
Database references
SIMBADdata

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]

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]

  1. ^ Cite error: The named reference Cutispoto was invoked but never defined (see the help page).
  2. ^ a b c d e f g h Cite error: The named reference GaiaDR3 was invoked but never defined (see the help page).
  3. ^ Cite error: The named reference MERMILLIOD was invoked but never defined (see the help page).
  4. ^ a b Cite error: The named reference montes 2001 was invoked but never defined (see the help page).
  5. ^ a b Cite error: The named reference Vieytes_et_al_2007 was invoked but never defined (see the help page).
  6. ^ a b Cite error: The named reference baas27_842 was invoked but never defined (see the help page).
  7. ^ a b Cite error: The named reference mnras349_1_1069 was invoked but never defined (see the help page).
  8. ^ Cite error: The named reference Holmberg2009 was invoked but never defined (see the help page).
  9. ^ a b c Cite error: The named reference Luck2018 was invoked but never defined (see the help page).
  10. ^ a b c Cite error: The named reference Ambruster_et_al_2003 was invoked but never defined (see the help page).
  11. ^ a b Cite error: The named reference aaa411_3_559 was invoked but never defined (see the help page).
  12. ^ a b c d e Cite error: The named reference aaa521_A12 was invoked but never defined (see the help page).
  13. ^ a b Cite error: The named reference aa547_A106 was invoked but never defined (see the help page).
  14. ^ a b Cite error: The named reference apj687 was invoked but never defined (see the help page).
  15. ^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
  16. ^ a b Cite error: The named reference Samus_et_al_2017 was invoked but never defined (see the help page).
  17. ^ a b c Cite error: The named reference Pandey_Singh_2008 was invoked but never defined (see the help page).
  18. ^ Cite error: The named reference aa218_1_L9 was invoked but never defined (see the help page).
  19. ^ Cite error: The named reference aa555_A11 was invoked but never defined (see the help page).