Ras Alhague
Double star Ras Alhague (α Ophiuchi) |
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AladinLite | |||||||||||||||||||||||
Observation dates equinox : J2000.0 , epoch : J2000.0 |
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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 |
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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 |
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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
- ↑ a b c Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ NSI 9189th In: VSX. AAVSO, accessed September 29, 2018 .
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ^ A b Hipparcos, the New Reduction (van Leeuwen, 2007)
- ↑ 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 ).
- ↑ 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 .
- ↑ 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 .