AM Herculis

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Double star
AM Herculis
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation Hercules
Right ascension 18 h 16 m 13.26 s
declination + 49 ° 52 ′ 4.8 ″
Apparent brightness 12.3 (12.3 to 15.7) mag
Typing
Spectral class D / M4.5
Variable star type AM + E 
Astrometry
parallax (11.40 ± 0.02)  mas
distance (286.0 ± 0.5)  Ly
(88)  pc
Proper movement 
Rec. Share: (−45.96 ± 0.03)  mas / a
Dec. portion: (28.05 ± 0.03)  mas / a
Physical Properties
Dimensions 0.83 / 0.26  M ☉
radius 0.0091 / 0.314  R ☉
Effective temperature 19000/3304  K
Other names
and catalog entries
2MASS catalog 2MASS J18161324 + 4952048 [1]
Other names AM Herculis

AM Herculis is a binary star system consisting of a red dwarf and a white dwarf in the constellation Hercules with a distance of about 290  light years . Together with AN Ursae Majoris, he forms the prototype of the so-called AM Herculis stars , which belong to the cataclysmic variables . The entire system has roughly the same mass as the sun, with the greater part of around 0.8 solar masses falling on the white dwarf and the smaller part of almost 0.3 solar masses falling on the red dwarf.

history

AM Herculis was discovered by Max Wolf in 1923 and entered in the General Catalog of Variable Stars . As an irregular variable star , its brightness fluctuates between 12 and 15. In 1976, the astronomer S. Tapia found that the star's light is linearly and circularly polarized, suggesting a strong magnetic field in the area and revealing that this star system is more complex than assumed by then.

Web links

See also

Individual evidence

  1. ↑ a b c d e AM Her. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed September 14, 2018 .
  2. ↑ a b c AM Her. In: VSX. AAVSO, accessed September 14, 2018 .
  3. ↑ a b c d Goetz, W .: The binary system AM Herculis and the parameters of its components . In: Astronomical News . 312, No. 2, 1991, pp. 103-105. bibcode : 1991AN .... 312..103G .
  4. ^ S. Seliwanow: Communications on changeable - changeable 28.1923 Herculis - M. Wolf - December 1923 . In: Astronomical News . 220, No. 15, 1923, p. 255. bibcode : 1924AN .... 220..249H . doi : 10.1002 / asna.19232201505 .
  5. ^ Tapia, S .: Discovery of a magnetic compact star in the AM Herculis / 3U 1809 + 50 system . In: The Astrophysical Journal Letters . 212, March 15, 1977, pp. L125-L129. bibcode : 1977ApJ ... 212L.125T . doi : 10.1086 / 182390 .
  6. ↑ Hessman, FV, Gansicke, BT, Mattei, JA: The history and source of mass-transfer variations in AM Herculis . In: Astronomy & Astrophysics . 361, September 2000, pp. 952-958. bibcode : 2000A & A ... 361..952H .
  7. ↑ Krzeminski, W., Serkowski, K .: Extremely high circular polarization of AN Ursae Majoris . In: The Astrophysical Journal Letters . 216, Aug 1977, p. L45. bibcode : 1977ApJ ... 216L..45K . doi : 10.1086 / 182506 .