Delta Eridani

Delta Eridani
Observation data
Epoch J2000      Equinox J2000
Constellation Eridanus
Right ascension 03h 43m 14.90s[1]
Declination –09° 45′ 48.2″[1]
Apparent magnitude (V) 3.54
Characteristics
Spectral type K0 IV
U−B color index 0.69
B−V color index 0.92
Variable type Suspected
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] cgs
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. Rana was referenced as a guide star in "Sky Captain and the World of Tomorrow"[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.

See also

References

  1. 1 2 3 4 5 van Leeuwen, F. (2007). "HIP 17378". Hipparcos, the New Reduction. Retrieved 2009-12-11.
  2. 1 2 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. 1 2 3 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:1002.4268Freely accessible, 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. 1 2 Piau, L.; et al. (February 2011), "Surface convection and red-giant radius measurements", Astronomy and Astrophysics, 526: A100, arXiv:1010.3649Freely accessible, 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.

Sources

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