PROFILPELAJAR.COM

Eta Cancri
	Location of η Cancri (circled)
Observation data; Epoch J2000 Equinox J2000
Constellation	Cancer
Right ascension	08h 32m 42.49600s
Declination	20° 26′ 28.1865″
Apparent magnitude (V)	5.34
Characteristics
Spectral type	K3 III
U−B color index	+1.40
B−V color index	+1.25
Astrometry
Radial velocity (Rv)	+22.46 km/s
Proper motion (μ)	RA: −46.33 mas/yr ; Dec.: −44.31 mas/yr
Parallax (π)	10.93 ± 0.40 mas
Distance	300 ± 10 ly ; (91 ± 3 pc)
Absolute magnitude (MV)	+0.44
Details
Mass	1.51 M☉
Radius	17 R☉
Luminosity	87 L☉
Surface gravity (log g)	2.1 cgs
Temperature	4,415±57 K
Metallicity [Fe/H]	0.07±0.21 dex
Rotational velocity (v sin i)	2.7 km/s
Age	3.92 Gyr
Other designations
	η Cnc, 33 Cnc, BD+20° 2109, FK5 321, GC 11687, HD 72292, HIP 41909, HR 3366, SAO 80243
Database references
SIMBAD	data

Eta Cancri, Latinized from η Cancri, is a single,^[8] orange-hued star in the zodiac constellation of Cancer. It is a faint star but visible to the naked eye with an apparent visual magnitude of 5.34.^[2] The annual parallax shift of 10.93^[1] mas as seen from Earth yields a distance estimate of 155 light years from the Sun. It is moving further away with a radial velocity of +22 km/s.^[3]

A stellar classification of K3 III^[2] for Eta Cancri indicates that, at the estimated age of 3.9 billion years old,^[5] it has left the main sequence and become an evolved giant star. The spectrum shows unusually strong absorption lines of cyanogen.^[2] It has 1.5^[5] times the mass of the Sun and has expanded to 17^[6] times the Sun's radius. The star is radiating 87^[5] times the Sun's luminosity from its photosphere at an effective temperature of around 4,415 K.^[5]

In Chinese astronomy, Ghost (Chinese: 鬼宿; pinyin: Guǐ Xiù) refers to an asterism consisting of Theta Cancri, Eta Cancri, Gamma Cancri and Delta Cancri.^[9] Eta Cancri itself is the second star of Ghost (Chinese: 鬼宿二; pinyin: Guǐ Xiù èr), following the designation from its determinative star (θ Cnc) from east to west.

References

^ ^a ^b ^c ^d ^e ^f van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. S2CID 18759600. Vizier catalog entry
^ ^a ^b ^c ^d ^e ^f ^g McClure, R. D. (February 1970). "A photometric investigation of strong-cyanogen stars". Astronomical Journal. 75: 41–52. Bibcode:1970AJ.....75...41M. doi:10.1086/110938.
^ ^a ^b Famaey, B.; et al. (January 2005), "Local kinematics of K and M giants from CORAVEL/Hipparcos/Tycho-2 data. Revisiting the concept of superclusters", Astronomy and Astrophysics, 430 (1): 165–186, arXiv:astro-ph/0409579, Bibcode:2005A&A...430..165F, doi:10.1051/0004-6361:20041272, S2CID 17804304
^ ^a ^b Luck, R. Earle; Heiter, Ulrike (June 2007), "Giants in the Local Region", The Astronomical Journal, 133 (6): 2464–2486, Bibcode:2007AJ....133.2464L, doi:10.1086/513194
^ ^a ^b ^c ^d ^e ^f ^g ^h Luck, R. Earle (September 2015), "Abundances in the Local Region. I. G and K Giants", The Astronomical Journal, 150 (3): 23, arXiv:1507.01466, Bibcode:2015AJ....150...88L, doi:10.1088/0004-6256/150/3/88, S2CID 118505114, 88.
^ ^a ^b ^c ^d Massarotti, Alessandro; et al. (January 2008), "Rotational and radial velocities for a sample of 761 HIPPARCOS giants and the role of binarity", The Astronomical Journal, 135 (1): 209–231, Bibcode:2008AJ....135..209M, doi:10.1088/0004-6256/135/1/209
^ "* eta Cnc". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2015-10-07.
^ Eggleton, P. P.; Tokovinin, A. A. (September 2008), "A catalogue of multiplicity among bright stellar systems", Monthly Notices of the Royal Astronomical Society, 389 (2): 869–879, arXiv:0806.2878, Bibcode:2008MNRAS.389..869E, doi:10.1111/j.1365-2966.2008.13596.x, S2CID 14878976.
^ 陳久金 (2005). Zhōngguó Xīngzuò Shénhuà 中國星座神話 [Chinese Constellation Mythology]. 台灣古籍出版有限公司. p. 394. ISBN 978-986-7332-25-7.