Delta Eridani
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Observation data Epoch J2000 Equinox J2000 | |
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Constellation | Eridanus |
Right ascension | 03h 43m 14.90088s[1] |
Declination | –09° 45′ 48.2084″[1] |
Apparent magnitude (V) | 3.51 - 3.56[2] |
Characteristics | |
Evolutionary stage | Subgiant |
Spectral type | K0 IV[3] |
U−B color index | +0.69[4] |
B−V color index | +0.92[4] |
Astrometry | |
Radial velocity (Rv) | −6.28±0.09[5] km/s |
Proper motion (μ) | RA: −93.16[1] mas/yr Dec.: +743.64[1] mas/yr |
Parallax (π) | 110.61 ± 0.29 mas[1] |
Distance | 29.49 ± 0.08 ly (9.04 ± 0.02 pc) |
Absolute magnitude (MV) | 3.77[6] |
Details[7] | |
Mass | 1.33±0.07[8] M☉ |
Radius | 2.35±0.01 R☉ |
Luminosity | 3.17±0.09 L☉ |
Surface gravity (log g) | 3.66±0.1 cgs |
Temperature | 5,027±48 K |
Metallicity [Fe/H] | +0.07±0.03 dex |
Rotational velocity (v sin i) | 0.7±0.6[8] km/s |
Age | 6.194[9] Gyr |
Other designations | |
Database references | |
SIMBAD | data |
Delta Eridani, which is Latinized from δ Eridani, is the fifth-brightest star in the constellation of Eridanus.
The star is visible to the naked eye and has been observed to vary slightly in brightness between magnitudes 3.51 and 3.56,[2] although subsequent observations did not bear this out.[11] It is relatively near to the Sun, with a distance of about 29.5 light years as determined from parallax.[1] The star is drifting closer with a radial velocity of −6 km/s.[5]
Delta Eridani is sometimes called Rana:[12] Rana means "the frog" in Latin, but derivation of this name is uncertain. The name was approved by the International Astronomic Union on 4 April 2022.[13]
Characteristics
The stellar classification of this star is K0 IV,[3] matching a subgiant star that has exhausted its core hydrogen. This has caused the star to expand and become cooler than a comparable main sequence star. Stellar modelling indicates it is near the end of the subgiant stage and about to transition into a giant. It is an estimated six[9] billion years old with 33% more mass than the Sun.[8] The star has 2.35 times the size of the Sun and is radiating three times the Sun's luminosity from its photosphere at an effective temperature of 5,022 K.[7]
Delta Eridani is catalogued as a suspected RS Canum Venaticorum variable in 1983,[14] but the activity level for the star is very low that this is considered a mistake.[15] A low projected rotational velocity of under 1 km/s and the lack of radial velocity variation suggests that this star is being viewed from nearly pole-on. However, an examination of the star using interferometry does not detect the presence of a companion at the expected distance.[9]
Chinese name
In Chinese, 天苑 (Tiān Yuàn), meaning Celestial Meadows, refers to an asterism consisting of δ Eridani, γ Eridani, π Eridani, ε Eridani, ζ Eridani, η Eridani, π Ceti, τ1 Eridani, τ2 Eridani, τ3 Eridani, τ4 Eridani, τ5 Eridani, τ6 Eridani, τ7 Eridani, τ8 Eridani and τ9 Eridani.[16] Consequently, the Chinese name for δ Eridani itself is 天苑三 (Tiān Yuàn sān, English: the Third Star of Celestial Meadows.)[17]
See also
References
- ^ a b c d e f van Leeuwen, F. (2007). "HIP 17378". Hipparcos, the New Reduction. Retrieved 2009-12-11.
- ^ a b 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.
- ^ a b Spinrad, Hyron; Taylor, Benjamin J. (1969). "Scanner Abundance Studies. I. an Investigation of Supermetallicity in Late-Type Evolved Stars". Astrophysical Journal. 157: 1279. Bibcode:1969ApJ...157.1279S. doi:10.1086/150154.
- ^ a b Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
- ^ a b Jofré, E.; et al. (2015). "Stellar parameters and chemical abundances of 223 evolved stars with and without planets". Astronomy & Astrophysics. 574: A50. arXiv:1410.6422. Bibcode:2015A&A...574A..50J. doi:10.1051/0004-6361/201424474. S2CID 53666931.
- ^ Pizzolato, N.; et al. (September 2000). "Evolution of X-ray activity of 1-3 Msun late-type stars in early post-main-sequence phases". Astronomy and Astrophysics. 361: 614–628. Bibcode:2000A&A...361..614P.
- ^ a b Rains, Adam D.; et al. (April 2020). "Precision angular diameters for 16 southern stars with VLTI/PIONIER". Monthly Notices of the Royal Astronomical Society. 493 (2): 2377–2394. arXiv:2004.02343. Bibcode:2020MNRAS.493.2377R. doi:10.1093/mnras/staa282.
- ^ a b c Bruntt, H.; et al. (July 2010). "Accurate fundamental parameters for 23 bright solar-type stars". Monthly Notices of the Royal Astronomical Society. 405 (3): 1907–1923. arXiv:1002.4268. Bibcode:2010MNRAS.405.1907B. doi:10.1111/j.1365-2966.2010.16575.x. S2CID 118495267.
- ^ a b c Thévenin, F.; et al. (June 2005). "VLTI/VINCI diameter constraints on the evolutionary status of δ Eri, ξ Hya, η Boo". Astronomy and Astrophysics. 436 (1): 253–262. arXiv:astro-ph/0501420. Bibcode:2005A&A...436..253T. doi:10.1051/0004-6361:20042075. S2CID 118169489.
- ^ "Del Eri". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2021-01-11.
- ^ Eaton, J. A.; Poe, C. H. (April 1985). "Limits on the Variability of epsilon Eridani and delta Eridani". Information Bulletin on Variable Stars. 2712: 1. Bibcode:1985IBVS.2712....1E.
- ^ Bečvář, A. (1951). Atlas Coeli Skalnaté Pleso II - Katalog 1950.0. Přírodovědecké Vydavatelstrí. p. 277. Retrieved 27 May 2019.
- ^ "Naming Stars".
- ^ Fisher, G. F.; et al. (January 1983). "Delta Eridani: a Very Bright New Variable Star". Information Bulletin on Variable Stars. 2259: 1. Bibcode:1983IBVS.2259....1F.
- ^ Laliotis, Katherine; Burt, Jennifer A.; Mamajek, Eric E.; Li, Zhexing; Perdelwitz, Volker; Zhao, Jinglin; Butler, R. Paul; Holden, Bradford; Rosenthal, Lee; Fulton, B. J.; Feng, Fabo; Kane, Stephen R.; Bailey, Jeremy; Carter, Brad; Crane, Jeffrey D.; Furlan, Elise; Gnilka, Crystal L.; Howell, Steve B.; Laughlin, Gregory; Shectman, Stephen A.; Teske, Johanna K.; Tinney, C. G.; Vogt, Steven S.; Wang, Sharon Xuesong; Wittenmyer, Robert A. (2023-04-01). "Doppler Constraints on Planetary Companions to Nearby Sun-like Stars: An Archival Radial Velocity Survey of Southern Targets for Proposed NASA Direct Imaging Missions*". The Astronomical Journal. 165 (4): 176. arXiv:2302.10310. Bibcode:2023AJ....165..176L. doi:10.3847/1538-3881/acc067. ISSN 0004-6256.
- ^ (in Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ^ (in Chinese) 香港太空館 - 研究資源 - 亮星中英對照表 Archived January 30, 2011, at the Wayback Machine, Hong Kong Space Museum. Accessed on line November 23, 2010.
External links
- Kaler, James B. "RANA (Delta Eridani)". STARS. Retrieved 2021-01-11.
- "Rana". SolStation Company. Retrieved 2021-01-11.
- nStars entry
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