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- GD_356 abstract "GD 356 is a white dwarf in the constellation of Draco showing an unusual emission of circular polarised light. The star is 65 light years from earth. The class of this white dwarf is DAe meaning that it has a cool helium rich atmosphere. This star exhibits emission lines showing the Zeeman effect in the hydrogen Balmer spectrum. GD 356 belongs to a class of high field magnetic white dwarfs (HFMWD), but it is unique in that the split lines are purely emission lines with no absorption. The emission region appears to be due to a heated upper layer in the photosphere in which the magnetic field is uniform to within 10%. The emission can be produced by an atmosphere at 7500K in a gravity field of 106 ms−2 and a magnetic field of 13 megaGauss. The magnetically split emission lines, Hα and Hβ, are circularly polarised. One explanation is that it is caused by a large electric current flowing between the poles of the star and a highly conducting planet. Other explanations such as being due to Bondi-Hoyle accretion or due to a corona are ruled out by the lack of radio and X-ray emissions. Accretion of gas at a low rate over a broad area of the star, only results in heating at levels high in the atmosphere and not down to the opacity depth of 1.0 as observed with these lines.The spectrum does not vary over periods of hours or days. This indicates that the rotation axis must match the magnetic dipole axis. The power radiated by the emission lines is 1027 erg s−1. Overall light from the white dwarf varies by 0.2% smoothly over a period of 117 minutes. Explanations given for the variation are a dark spot rotating with the star. This could be near the rotation pole when viewed nearly edge on, or could be on the equator with the pole pointing roughly towards Earth.Other catalog names for this are LP137-43, Gr329 and WD1639+537.".
- GD_356 wikiPageID "36104002".
- GD_356 wikiPageRevisionID "601547521".
- GD_356 absmagV "13.43".
- GD_356 ageGyr "About 2.1".
- GD_356 appmag "~14.0".
- GD_356 appmag "~14.369".
- GD_356 appmag "~14.479".
- GD_356 appmag "~14.493".
- GD_356 appmag "~15.06".
- GD_356 appmag "~15.1".
- GD_356 appmag "~15.39".
- GD_356 appmag1Passband "B".
- GD_356 appmag2Passband "V".
- GD_356 appmag3Passband "R".
- GD_356 appmag4Passband "I".
- GD_356 appmag5Passband "J".
- GD_356 appmag6Passband "H".
- GD_356 appmag7Passband "K".
- GD_356 appmagV "15.06".
- GD_356 aricns "2194".
- GD_356 bV "+0.33".
- GD_356 class "DC7".
- GD_356 constell Draco_(constellation).
- GD_356 distLy "65".
- GD_356 distPc "21.1".
- GD_356 epoch Epoch_(astronomy).
- GD_356 gravity "8".
- GD_356 hasPhotoCollection GD_356.
- GD_356 mass "0.67".
- GD_356 pError "3.5".
- GD_356 parallax "545.4".
- GD_356 propMoDec "-0.2".
- GD_356 propMoRa "-0.125".
- GD_356 radialV "25".
- GD_356 rotation "6900.0".
- GD_356 temperature "7510".
- GD_356 uB "-0.52".
- GD_356 variable "6900.0".
- GD_356 subject Category:Draco_(constellation).
- GD_356 subject Category:Emission-line_stars.
- GD_356 subject Category:White_dwarfs.
- GD_356 type CelestialBody.
- GD_356 type Star.
- GD_356 type PhysicalBody.
- GD_356 comment "GD 356 is a white dwarf in the constellation of Draco showing an unusual emission of circular polarised light. The star is 65 light years from earth. The class of this white dwarf is DAe meaning that it has a cool helium rich atmosphere. This star exhibits emission lines showing the Zeeman effect in the hydrogen Balmer spectrum. GD 356 belongs to a class of high field magnetic white dwarfs (HFMWD), but it is unique in that the split lines are purely emission lines with no absorption.".
- GD_356 label "GD 356".
- GD_356 sameAs m.0j_5xtr.
- GD_356 sameAs Q5174473.
- GD_356 sameAs Q5174473.
- GD_356 wasDerivedFrom GD_356?oldid=601547521.
- GD_356 isPrimaryTopicOf GD_356.
- GD_356 name "GD 356".