Alphard

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Stern
Alphard (α Hydrae)
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Water snake
Right ascension 09 h 27 m 35.24 s
declination -08 ° 39 ′ 31 ″
Apparent brightness 1.99 likes
Typing
B − V color index +1.44 
U − B color index +1.72 
R − I index +0.77 
Spectral class K3 III
Astrometry
Radial velocity (−4.7 ± 0.1) km / s
parallax (18.09 ± 0.18)  mas
distance (180.3 ± 1.8)  ly
(55.28 ± 0.55)  pc  
Visual absolute brightness M vis −1.72 mag
Proper movement 
Rec. Share: (−15.23 ± 0.19)  mas / a
Dec. portion: (34.37 ± 0.13)  mas / a
Physical Properties
Dimensions (4 to 5)  M ☉
radius (55.7)  R ☉
Luminosity

(950)  L ☉

Effective temperature ≈ 4000  K
Rotation time <17 km / s
Other names
and catalog entries
Bayer name α hydrae
Flamsteed name 30 hydrae
Bonn survey BD -8 ° 2680
Bright Star Catalog HR 3748 [1]
Henry Draper Catalog HD 81797 [2]
Hipparcos catalog HIP 46390 [3]
SAO catalog SAO 136871 [4]
Tycho catalog TYC 5460-1592-1 [5]
2MASS catalog 2MASS J09273524-0839308 [6]
Other names FK5 354
annotation
  1. ↑ Calculated from apparent brightness and distance.

Alphard (from the Arabic الفردal-fard "the single person") is the name of the star α Hydrae (Alpha Hydrae), the brightest star of the constellation Water Snake . The star is also called "Cor Hydrae" in the sense of "dragon heart". Alphard has an apparent magnitude of +1.98  mag and is 180 light years away. Alphard is an orange-red giant star of the spectral type K3 with an absolute brightness of −1.8 mag. Alphard has about 400 times the luminosity of our sun. Its surface temperature is 4000 Kelvin . With a diameter that exceeds that of the Sun by 40.8 times, it belongs to the orange-red giant stars. He is one of the bright giants . Alphard has an optical companion (optical double star ) at a distance of 281 "at 153 °, a blue star 10th magnitude, without any physical reference.

See also

Web links

Individual evidence

  1. ↑ a b c Hipparcos catalog (ESA 1997)
  2. ↑ a b c Bright Star Catalog
  3. ↑ Pulkovo radial velocities for 35493 HIP stars
  4. ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
  5. ↑ a b c P Cruzalèbes, A Jorissen, Y Rabbia, S Sacuto, A Chiavassa, E Pasquato, B Plez, K Eriksson, A Spang, O Chesneau: Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI / AMBER . In: Monthly Notices of the Royal Astronomical Society . 434, 2013, p. 437. arxiv : 1306.3288 . bibcode : 2013MNRAS.434..437C . doi : 10.1093 / mnras / stt1037 .
  6. ↑ Robert Burnham Jr., Burnham's Celestial Handbook Vol. II , Dover Publications, New York 2nd rev. 1978, p. 1012