Delta Eridani

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**δ Eridani**
Observation data Epoch J2000
Constellation (pronunciation)	Eridanus
Right ascension	03h 43m 14.9s
Declination	-09° 45' 48"
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 (R_v)	-6 km/s
Proper motion (μ)	RA: -91.71 mas/yr Dec.: 742.23 mas/yr
Parallax (π)	110.83 ± 0.82 mas
Distance	29.4 ± 0.2 ly (9.02 ± 0.07 pc)
Absolute magnitude (M_V)	3.75
Details
Mass	1.2 M_☉
Radius	2.3-2.7 R_☉
Surface gravity (log g)	3.9^[1]/– rotation=116 days
Luminosity	2.8 L_☉
Temperature	5,075 K
Metallicity	150% Sun
Age	7.5 × 10⁹ years
Other designations
δ Pavonis, 23 Eridanus, 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.

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.

The name Rana means "the frog" in Latin, and was apparently transferred in the 20th century from another star, Deneb Kaitos, which was also called "Rana Secunda", or second frog.

[edit] References

^ 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.

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.