Altarf

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Stern
Altarf (β Cancri)
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation cancer
Right ascension 08 h 16 m 30.92 s
declination + 09 ° 11 ′ 8 ″
Apparent brightness 3.52 mag
Typing
Known exoplanets 1
B − V color index (1.48) 
U − B color index (1.75) 
R − I index (0.80) 
Spectral class K4 III
Variable star type Yes 
Astrometry
Radial velocity (22.94 ± 0.19) km / s
parallax (11.04 ± 0.66)  mas
distance (295 ± 20)  ly
(90)  pc
Proper movement 
Rec. Share: (-48.99 ± 0.97)  mas / a
Dec. portion: (-50.84 ± 0.68)  mas / a
Physical Properties
Dimensions (1.7 ± 0.1)  M ☉
radius (47.2 ± 1.3)  R ☉
Luminosity

(900)  L ☉

Effective temperature (4000)  K.
Metallicity [Fe / H] (-0.29 ± 0.06)
Age (1.85 ± 0.34) bill.  A
Other names
and catalog entries
Bayer name β Cancri
Flamsteed name 17 Cancri
Bonn survey BD + 09 ° 1917
Bright Star Catalog HR 3249 [1]
Henry Draper Catalog HD 69267 [2]
Hipparcos catalog HIP 40526 [3]
SAO catalog SAO 116569 [4]
Tycho catalog TYC 794-1622-1 [5]
2MASS catalog 2MASS J08163090 + 0911080 [6]
Other names Altarf, Tarf, FK5 312

Altarf is the proper name of the star Beta Cancri (β Cancri). It is a giant star of the spectral class K4 (K4IIIBa0.5) and has an apparent magnitude of +3.5 mag. Its distance from the earth is about 300 light years , it is the brightest star in the constellation Cancer .

The star has a very massive companion, beta Cancri b , which weighs around 8 M J and was discovered in 2014 using the radial velocity method. The exoplanet orbits the star at a distance of 1.7 AU with an orbital period of about 600 days.

Web links

Individual evidence

  1. ↑ a b c d e f g h bet Cnc. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 14, 2018 .
  2. ↑ a b c d e f beta Cnc b. In: Extrasolar Planets Encyclopaedia . Retrieved September 14, 2018 .
  3. ^ NSV 3973. In: VSX. AAVSO, accessed September 14, 2018 .
  4. ↑ a b bet Cnc b. In: NASA Exoplanet Archive . Retrieved September 14, 2018 .