 A visual band light curve for EP Eridani, adapted from Cutispoto (1992) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Eridanus |
| Right ascension | 02 52 32.12819 |
| Declination | –12° 46′ 10.9681″ |
| Apparent magnitude (V) | 6.04 |
| Characteristics | |
| Evolutionary stage | Main sequence |
| Spectral type | K1V |
| U−B color index | +1.41 |
| B−V color index | +0.86 |
| Variable type | RS CVn |
| Astrometry | |
| Radial velocity (Rv) | +17.77±0.08 km/s |
| Proper motion (μ) | RA: 397.353 mas/yr Dec.: −189.281 mas/yr |
| Parallax (π) | 96.5200 ± 0.0258 mas |
| Distance | 33.792 ± 0.009 ly (10.361 ± 0.003 pc) |
| Absolute magnitude (MV) | 5.97 |
| Details | |
| Mass | 0.88 M☉ |
| Radius | 0.85±0.05 R☉ |
| Luminosity | 0.408±0.005 L☉ |
| Surface gravity (log g) | 4.58 cgs |
| Temperature | 5,225±5 K |
| Metallicity | +0.10 dex |
| Rotation | 6.6 days |
| Rotational velocity (v sin i) | 4.80 km/s |
| Age | 100 Myr |
| Other designations | |
| 32 G. Eridani, EP Eri, GJ 117, HD 17925, HIP 13402, HR 857, SAO 148647, YPC 599 | |
| Database references | |
| SIMBAD | data |
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. It is located nearby at a distance of 34 light years from the Sun based on parallax, and is drifting further away with a radial velocity of +18 km/s. It is a likely member of the Local Association of nearby, co-moving stars. The spectrum shows a strong abundance of lithium, indicating that it is young star. This likely makes its point of origin the nearby Scorpio–Centaurus Complex.
The stellar classification of HD 17925 is K1V, which indicates this is a K-type main-sequence star that is engaged in core hydrogen fusion. It is an active star that is classified as a RS Canum Venaticorum variable, showing a rotational modulation with a period of 6.9 days, and has been observed to flare. The star has an estimated age of 100 million years and is spinning with a projected rotational velocity of 4.8 km/s. The rotation period of 6.6 days days can be determined from its activity cycle. The star has 88% of the mass of the Sun and 85% of the Sun's radius. It is radiating 41% of the luminosity of the Sun from its photosphere at an effective temperature of 5,225 K.
The presence of an unseen companion has been suggested based on variations in the widths of absorption lines in the star's photosphere. It displays low-amplitude radial velocity variation, which may indicate it is a spectroscopic binary. However, the binary hypothesis doesn't appear to be consistent with Hipparcos satellite data. 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.
References
- Cutispoto, G. (November 1992). "Long-term monitoring of active stars. II. UBV (RI)c observations at ESO during January-March 1989". Astronomy and Astrophysics Supplement Series. 95: 397–413. Bibcode:1992A&AS...95..397C.
- ^ Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
- Mermilliod, J.-C. (1986), "Compilation of Eggen's UBV data, transformed to UBV (unpublished)", Catalogue of Eggen's UBV Data. SIMBAD, Bibcode:1986EgUBV........0M.
- ^ Montes, D.; et al. (2001), "Late-type members of young stellar kinematic groups - I. Single stars", Monthly Notices of the Royal Astronomical Society, 328 (1): 45–63, arXiv:astro-ph/0106537, Bibcode:2001MNRAS.328...45M, doi:10.1046/j.1365-8711.2001.04781.x, S2CID 55727428.
- ^ Vieytes, M.; et al. (May 2007), Heinzel, P.; Dorotovič, I.; Rutten, R. J. (eds.), "Chromospheric Activity in K Stars", The Physics of Chromospheric Plasmas. Proceedings of the conference held 9-13 October, 2006 at the University of Coimbra in Coimbra, Portugal, ASP Conference Series, vol. 368, San Francisco: Astronomical Society of the Pacific, p. 265, Bibcode:2007ASPC..368..265V.
- ^ Abbott, B. P.; Pomerance, B. H.; Ambruster, C. W. (March 1995), "UBVRI Photometry of the Solar Neighborhood Pleiades-Age K Dwarfs HD 17925 and HD 1405", Bulletin of the American Astronomical Society, 27: 842, Bibcode:1995AAS...186.2210A.
- ^ Karataș, Yüksel; Bilir, Selçuk; Eker, Zeki; Demircan, Osman; Liebert, James; Hawley, Suzanne L.; Fraser, Oliver J.; Covey, Kevin R.; Lowrance, Patrick; Kirkpatrick, J. Davy; Burgasser, Adam J. (2004). "Kinematics of chromospherically active binaries and evidence of an orbital period decrease in binary evolution". Monthly Notices of the Royal Astronomical Society. 349 (3): 1069–1092. arXiv:astro-ph/0404219. Bibcode:2004MNRAS.349.1069K. doi:10.1111/j.1365-2966.2004.07588.x. S2CID 15290475.
- Holmberg, J.; et al. (July 2009), "The Geneva-Copenhagen survey of the solar neighbourhood. III. Improved distances, ages, and kinematics", Astronomy and Astrophysics, 501 (3): 941–947, arXiv:0811.3982, Bibcode:2009A&A...501..941H, doi:10.1051/0004-6361/200811191, S2CID 118577511.
- ^ Luck, R. Earle (March 2018), "Abundances in the Local Region. III. Southern F, G, and K Dwarfs", The Astronomical Journal, 155 (3): 31, Bibcode:2018AJ....155..111L, doi:10.3847/1538-3881/aaa9b5, S2CID 125765376, 111.
- ^ Ambruster, C. W.; et al. (October 2003), Brown, A.; Harper, G. M.; Ayres, T. R. (eds.), "The Radii of Solar Neighborhood ZAMS Stars", The Future of Cool-Star Astrophysics: 12th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (2001 July 30 - August 3), vol. 12, pp. 912–915, Bibcode:2003csss...12..912A.
- ^ Kovtyukh, V. V.; et al. (2003), "High precision effective temperatures for 181 F-K dwarfs from line-depth ratios", Astronomy and Astrophysics, 411 (3): 559–564, arXiv:astro-ph/0308429, Bibcode:2003A&A...411..559K, doi:10.1051/0004-6361:20031378, S2CID 18478960.
- ^ Maldonado, J.; et al. (October 2010), "A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups", Astronomy and Astrophysics, 521: A12, arXiv:1007.1132, Bibcode:2010A&A...521A..12M, doi:10.1051/0004-6361/201014948, S2CID 119209183.
- ^ Mishenina, T. V.; et al. (November 2012), "Activity and the Li abundances in the FGK dwarfs", Astronomy & Astrophysics, 547: 8, arXiv:1210.6843, Bibcode:2012A&A...547A.106M, doi:10.1051/0004-6361/201118412, S2CID 119287319, A106.
- ^ Mamajek, Eric E.; Hillenbrand, Lynne A. (November 2008), "Improved Age Estimation for Solar-Type Dwarfs Using Activity-Rotation Diagnostics", The Astrophysical Journal, 687 (2): 1264–1293, arXiv:0807.1686, Bibcode:2008ApJ...687.1264M, doi:10.1086/591785, S2CID 27151456.
- "HD 17925", SIMBAD, Centre de données astronomiques de Strasbourg, retrieved 2021-01-11.
- ^ Samus', N. N; et al. (2017), "General catalogue of variable stars", Astronomy Reports, GCVS 5.1, 61 (1): 80, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
- ^ Pandey, J. C.; Singh, K. P. (July 2008), "A study of X-ray flares - I. Active late-type dwarfs", Monthly Notices of the Royal Astronomical Society, 387 (4): 1627−1648, arXiv:0805.3882, Bibcode:2008MNRAS.387.1627P, doi:10.1111/j.1365-2966.2008.13342.x, S2CID 18111371.
- Cayrel de Strobel, G.; Cayrel, R. (July 1989), "Strong lithium in the very nearby K-dwarf HD 17925", Astronomy and Astrophysics, 218 (1–2): L9–L12, Bibcode:1989A&A...218L...9C
- Eiroa, C.; et al. (July 2013), "DUst around NEarby Stars. The survey observational results", Astronomy & Astrophysics, 555: A11, arXiv:1305.0155, Bibcode:2013A&A...555A..11E, doi:10.1051/0004-6361/201321050, S2CID 377244.
Further reading
- Christian, D. J.; Mathioudakis, M.; Jevremović, D. (October 2008), "Li in the Atmosphere of GJ 117 Revisited", The Astrophysical Journal, 686 (1): 542–547, arXiv:0807.3693, Bibcode:2008ApJ...686..542C, doi:10.1086/591727, S2CID 346207
{{citation}}: CS1 maint: multiple names: authors list (link)
