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Delta Eridani

Delta Eridani
Observation data
Epoch J2000     &n bsp;Equinox J2000
ConstellationEridanus
Right ascension03h 43m 14.90s[1]
Declination–09° 45′ 48.2″[1]
Apparent magnitude (V)3.54
Characteristics
Spectral typeK0 IV
U−B color index0.69
B−V color index0.92
Variable typeSuspected
Astrometry
Radial velocity (Rv)–6 km/s
Proper motion (μ)RA: –93.16 ± 0.29[1] mas/yr
Dec.: +743.64 ± 0.22[1] mas/yr
Parallax (π)110.61 ± 0.29[1] mas
Distance29.49 ± 0.08 ly
(9.04 ± 0.02 pc)
Absolute magnitude (MV)3.77[2]
Details
Mass1.33 ± 0.07[3] M☉
Radius2.327 ± 0.029[3] R☉
Luminosity3.00 ± 0.12[3] L☉
Surface gravity (log g)3.9[4]
Temperature5,055[5] K
Metallicity [Fe/H]0.13[5] dex
Rotational velocity (v sin i)1.0[2] km/s
Other designations
δ Eridani, 23 Eridani, HD 23249, HR 1136, BD-10°728, GCTP 788, GJ 150, LHS 1581, and HIP 17378.

Delta Eridani (δ Eri, δ Eridani) is a 3.54 magnitude star in the constellation of Eridanus. It is also called Rana. The name Rana means "the frog" in Latin[6]

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.[7] Consequently, δ Eridani itself is known as 天苑三 (Tiān Yuàn sān, English: the Third Star of Celestial Meadows.)[8]

Structure

This star is relatively near to the Sun, at a measured distance of about 29 light years. It is sometime listed as a RS Canum Venaticorum-type variable star, but this is likely to be an error. (It is currently a suspected variable.) Rana is a sub-giant star that is near the end of its hydrogen-burning cycle and is now consuming helium. This has caused the star to expand and become hotter than a comparable main sequence star. As a sub-giant star it is subject to pulsations in its atmosphere.

Radial velocity surveys of this star have thus far failed to discern any gas giants in orbit.

References

  1. ^ a b c d e van Leeuwen, F. (2007). "HIP 17378". Hipparcos, the New Reduction. Retrieved 2009-12-11. 
  2. ^ a b Pizzolato, N.; Maggio, A.; Sciortino, S. (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 
  3. ^ 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 
  4. ^ Morell, O.; Kallander, D.; Butcher, H. R (1999). "The age of the Galaxy from thorium in G dwarfs, a re-analysis". Astronomy and Astrophysics 259 (2): 543–548. Bibcode:1992A&A...259..543M. 
  5. ^ a b Piau, L. et al. (February 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics 526: A100, arXiv:1010.3649, Bibcode:2011A&A...526A.100P, doi:10.1051/0004-6361/201014442 
  6. ^ Constellations of Words - Eridanus (Rana)
  7. ^ (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.
  8. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.
  • Fisher, G. F., Hall, D. S., Henry, G. W., Landis, H. J., Renner, T. R., and Shore, S. N., "Delta Eridani: A Very Bright New Variable Star,", Information Bulletin on Variable Stars, No. 2259, 1983.
  • Eaton, J. A.; Poe, C. H., "Limits on the Variability of epsilon Eridani and delta Eridani", Information Bulletin on Variable Stars, 2712, 1985.

External links

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