Ras Alhague

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Double star
Ras Alhague (α Ophiuchi)
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Snake bearer
Right ascension 17 h 34 m 56.07 s
declination + 12 ° 33 ′ 36.1 ″
Apparent brightness 2.08 mag
Typing
B − V color index +0.15 
U − B color index +0.10 
R − I index +0.08 
Spectral class A5 III
Variable star type DSCT + GDOR 
Astrometry
Radial velocity (11.7 ± 1.0) km / s
parallax (67.13 ± 1.06)  mas
distance 47.88  ly
14.68  pc  
Visual absolute brightness M vis +1.21 mag
Proper movement 
Rec. Share: (108.07 ± 0.87)  mas / a
Dec. portion: (−221.57 ± 0.80)  mas / a
Physical Properties
Dimensions (2.84 ± 0.19)  M ☉
Effective temperature 8500  K
Other names
and catalog entries
Bayer name α Ophiuchi
Flamsteed name 55 Ophiuchi
Bonn survey BD + 12 ° 3252
Bright Star Catalog HR 6556 [1]
Henry Draper Catalog HD 159561 [2]
Gliese catalog FY 681 [3]
Hipparcos catalog HIP 86032 [4]
SAO catalog SAO 102932 [5]
Tycho catalog TYC 1000-2508-1 [6]
2MASS catalog 2MASS J17345606 + 1233361 [7]
Other names Ras Alhague, FK5  656
annotation
  1. ↑ Calculated from apparent brightness and distance.

Ras Alhague (from arab.رأس الحية raʾs al-ḥayya "head of the serpent"), also Rasalhague or α Ophiuchi (Alpha Ophiuchi ), is a star in the constellation of the Serpent Bearer with an apparent visual magnitude of +2.1 mag. The star forms the northern tip of the constellation and is located about 5 ° southeast of the star Ras Algethi (α Herculis).

Ras Alhague is a binary star system , the main star of which is a giant star of the spectral type A5, which has a mass of about 2.40 solar masses . The companion was discovered through fluctuations in its own motion and has a mass of about 0.85 solar masses and is a main sequence star of the spectral type K 5. The system's orbital period is 8.62 years, the distance between the components about 7 AU . The system is approximately 47.9 light years from Earth. There is evidence that the system is a member of the Ursa Major Stream . However, the current data does not allow a decision on this question.

See also

Web links

Individual evidence

  1. ↑ a b c Hipparcos catalog (ESA 1997)
  2. ↑ a b c Bright Star Catalog
  3. ↑ NSI 9189th In: VSX. AAVSO, accessed September 29, 2018 .
  4. ↑ Pulkovo radial velocities for 35493 HIP stars
  5. ^ A b Hipparcos, the New Reduction (van Leeuwen, 2007)
  6. ↑ a b c d e Sasha Hinkley, John D. Monnier, Ben R. Oppenheimer, Lewis C. Roberts, Michael Ireland, Neil Zimmerman, Douglas Brenner, Rick Burruss et al .: Establishing α Oph as a Prototype Rotator: Improved Astrometric Orbit . In: Institute of Physics IOP (Ed.): The Astrophysical Journal . tape 726 , no. 2 , January 10, 2011, ISSN  0004-637X , p. 104 , doi : 10.1088 / 0004-637X / 726/2/104 ( iop.org ).
  7. ↑ George Gatewood: An Astrometric Study of the Binary Star α Ophiuchi . In: The Astronomical Journal . tape 130/2 , 2005, pp. 809–814 , doi : 10.1086 / 431723 , bibcode : 2005AJ .... 130..809G .
  8. ↑ Jeremy King et al .: Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group . In: The Astronomical Journal . tape 125/4 , 2003, p. 1980–2017 , doi : 10.1086 / 368241 , bibcode : 2003AJ .... 125.1980K .