Dabih

Double star Dabih (β Capricorni)
β cap in the constellation "Capricorn"
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	Capricorn
Apparent brightness	3.1 mag
Astrometry
parallax	approx. 9.8 mas
distance	approx. 330 ly (approx. 100 pc )
Individual data
Names	β 1 cap; β 2 cap
Observation data:
Right ascension	β 1 cap	20 h 21 m 0.673 s
	β 2 cap	20 h 20 m 46.549 s
declination	β 1 cap	−14 ° 46 ′ 52.98 ″
	β 2 cap	−14 ° 47 ′ 5.63 ″
Apparent brightness	β 1 cap	3.21 mag
	β 2 cap	6.09 mag
Typing:
Spectral class	β 1 cap	K0: II: + A5: N
	β 2 cap	B9 / A0 III / IV
B − V color index	β 1 cap	0.79
	β 2 cap	−0.02
U − B color index	β 1 cap	0.27
Physical Properties:
Dimensions	β 1 cap	10 M ☉
	β 2 cap	8 M ☉
Other names and catalog entries
Bayer name β Capricorni Flamsteed name 9 capricorni Bonn survey BD −15 ° 5629 BD −15 ° 5626 Bright Star Catalog HR 7776 HR 7775 Henry Draper Catalog HD 193495 HD 193452 SAO catalog SAO 163481 SAO 163471 Tycho catalog TYC 5753-2281-1 [1] TYC 5753-2282-1 [2] Hipparcos catalog HIP 100345 HIP 100325 WDS catalog WDS 20210-1447 Further designations: CCDM 20210-1447

Dabih is the proper name of the star Beta Capricorni (β Cap) in the constellation Capricorn . Dabih has an apparent magnitude of 3.1 mag. It is a binary star with the two main components Beta ¹  Capricorni (Dabih Major) and Beta ²  Capricorni (Dabih Minor), each about 330 light years away. Due to their large angular distance of around 3.5 minutes of arc , they can be separated in binoculars and in turn are made up of several stars.

Beta ¹ Capricorni is a complex system with a total brightness of 3.2 mag. The main star is a spectroscopic double star consisting of an orange bright giant with almost four times the mass and 500 times the luminosity of the sun , as well as a somewhat heavier blue-white main sequence star of over four times the mass and 10 times the luminosity of the sun, which orbit each other in just 4 years. The system also contains other weaker stars.

Beta ² Capricorni is also a double star with an overall brightness of 6.1 mag, 14 times weaker than Beta ¹ . The main star is a white giant or sub-giant with five times the mass and 30 times the luminosity of the Sun, which is orbited by a white star about 15 times weaker and three times the solar mass in about 200 years.

Despite the relatively large apparent distance, the different proper movements of the two components and their different parallaxes , the inaccuracy of which allows a difference of up to 80 light years, Beta ¹ and Beta ² Capricorni have so far been considered a common system.

The name Dabih is derived from the old Arabic nameسعد الذابح / saʿd aḏ-ḏābiḥ  / 'luck (star) of the end of the battle' for the star couple Alpha and Beta Capricorni. Beta Capricorni was also occasionally referred to as "Giedi" or "Sadalzabih". According to the “IAU Catalog of Star Names” of the Working Group on Star Names (WGSN) of the IAU for the standardization of star names, the name “Dabih” was only assigned to the lighter Beta ¹ Capricorni in 2016 .

See also

• Beta ¹ Capricorni
• Beta ² Capricorni

Individual evidence

1. ^ ^{A b c} VizieR: Hipparcos, the New Reduction (van Leeuwen, 2007) - The Astrometric Catalog
2. ↑ ^{a b} VizieR: Stellar Photometry in Johnson's 11-color system (Ducati, 2002) - Photometric data in the UBVRIJHKLMN colors
3. ↑ ^{a b} VizieR: Multiple star catalog (MSC) (Tokovinin 1997-1999)
4. ^ D. Adams: The Auspice of the Slaughterer. Retrieved November 30, 2016 . 
5. ↑ Bulletin of the IAU Working Group on Star Names, No. 2. IAU Division C Education, Outreach and Heritage, 2016 ( PDF; 158 kB ).