HR 465

Database links to HR 465

Star HR 465
AladinLite
Observation dates equinox :  J2000.0 , epoch : J2000.0
Constellation	Andromeda
Right ascension	1 h 38 m 31.82 s
declination	+ 45 ° 23 ′ 58.9 ″
Apparent brightness	6.4 mag
Typing
B − V color index	+0.04
U − B color index	−0.10
Spectral class	A2 pe
Variable star type	α 2 CVn
Astrometry
Radial velocity	−0.3 km / s
parallax	6.23  mas
distance	524  ly 161  pc
Visual absolute brightness M vis	+0.68 mag
Physical Properties
Dimensions	2.47  M ☉
radius	2.6  R ☉
Luminosity	52  L ☉
Effective temperature	10,723  K
Metallicity [Fe / H]	+0.86 dex
Other names and catalog entries
Bonn survey BD + 44 ° 341 Henry Draper Catalog HD 9996 [1] Hipparcos catalog HIP 7651 [2] SAO catalog SAO 37393 [3] Tycho catalog TYC 3278-2505-1 [4] 2MASS catalog 2MASS J01383183 + 4523589 [5] Other names GY Andromedae

HR 465 ( HD 9996 , GY Andromedae , GY And) is a variable star in the constellation Andromeda . Its distance is approximately 524 light years .

nomenclature

The part of the name HR denotes the H arvard R evised star catalog. The successor to this catalog is now the Bright Star catalog .

The name part GY follows the rules for naming variable stars and says that GY Andromedae is the 207th variable star discovered in the constellation Andromeda.

properties

HR 465 is a variable star of the type α ² Canum Venaticorum . Its brightness fluctuates between 6.27 and 6.41 mag.

The star belongs to the spectral class A 2 pe. pe (Latin: pe culiaris = peculiar) identifies him as a group member of the CP stars .

The star's magnetic activity shows an unusually long period of 23 years.

The spectrum of its emitted light has some special features. So it shows spectral lines of chromium and europium . Its most striking characteristic, however, are the spectral lines of the chemical element promethium . Promethium belongs to the group of lanthanides and is radioactive. Probably it is created by the fission of elements of some transuranic elements in the outer shell of the star.

Binary star system

Between 1927 and 1935, the Canadian astronomer William Edmund Harper measured the star's radial velocity at the Dominion Astrophysical Observatory . He came to the conclusion that this could be a spectroscopic binary star. In 1958, the American astronomer Horace W. Babcock confirmed Harper's conjecture. The orbital period (duration of a common orbit) is 273 days with a considerable eccentricity of 0.47. The distance between the two stars is at least 0.25 AU (about 3.74 × 10 ⁷ km).

Individual evidence

1. ↑ ABT HA and MORRELL NI: The relation between rotational velocities and spectral peculiarities among A-type stars. Astrophys. J., July 1995, accessed July 3, 2018 . 
2. ↑ SIMBAD - V * GY and. In: SIMBAD. Retrieved July 3, 2018 . 
3. ↑ GY Andromedae - HD9996 - HIP7651. August 27, 2017, accessed on August 27, 2017 . 
4. ↑ Anonymous : "Michigan astronomers discover promethium in star", in: Eos Trans. AGU , 1971 , 52  (1), p. 10; Abstract ; doi : 10.1029 / EO052i001p00010-01 .
5. ^ MF Aller: "Promethium in the star HR 465", in: Sky & Telescope , 1971 , 41 , pp. 220-222.
6. ^ DN Davis: "The Possible Identification of Promethium in S Stars", in: Astrophysical Journal , 1971 , 167 , pp. 327-330; Full text .
7. ^ SC Wolff, ND Morrison: "Remarks on the Proposed Identification of Promethium in HR 465", in: Astrophysical Journal , 1972 , 175 , pp. 473-475; Full text .
8. ^ CR Cowley, MF Aller: "Comments on the Identification of Promethium in HR 465", in: Astrophysical Journal , 1972 , 175 , pp. 477-480: Volltext .
9. ↑ O. Havnes, EPJ van den Heuvel, MF Aller, CR Cowley: "Is there promethium in HR 465?", In: Astronomy and Astrophysics , 1972 , 19 , pp 283-286; Full text .
10. ↑ R. Mitalas, JM Marlborough: "Some tests and consequences of the identification of promethium in HR 465," in the Astrophysical Journal , 1973 , 181 , pp 475-480; Full text .