Star in the constellation Draco
GRW +70 8247 is a white dwarf star located 42 light-years from Earth in the constellation Draco . With a magnitude of about 13 it is visible only through a large telescope .
Properties
Although photographed in the 19th century as part of the Carte du Ciel project, the star was not determined to be a white dwarf until G. P. Kuiper observed it in 1934. This makes it the fifth or sixth white dwarf discovered. At first, its spectrum was thought to be almost featureless, but later observation showed it to have unusual broad, shallow absorption bands . In 1970, when light that it emitted was observed to be circularly polarized , it became the first white dwarf known to have a magnetic field . In the 1980s, it was realized that the unusual absorption bands could be explained as hydrogen absorption lines shifted by the Zeeman effect .
Notes
Stefan–Boltzmann law with a nominal solar effective temperature of 5,772 K :
(
5
,
772
11
,
880
)
4
⋅
10
−
2.88
=
0.00857
R
⊙
{\displaystyle {\sqrt {{\biggl (}{\frac {5,772}{11,880}}{\biggr )}^{4}\cdot 10^{-2.88}}}=0.00857\ R_{\odot }}
References
^ Brown, A. G. A. ; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties" . Astronomy & Astrophysics 616 . A1. arXiv :1804.09365 . Bibcode :2018A&A...616A...1G . doi :10.1051/0004-6361/201833051 .Gaia DR2 record for this source at VizieR .
^ "LAWD 73" . SIMBAD Centre de données astronomiques de Strasbourg . Retrieved November 5, 2007.
Wesemael, F.; Greenstein, J. L.; Liebert, James; Lamontagne, R.; Fontaine, G.; Bergeron, P.; Glaspey, J. W. (1993). "An atlas of optical spectra of white-dwarf stars" . Publications of the Astronomical Society of the Pacific . 105 : 761. Bibcode :1993PASP..105..761W . doi :10.1086/133228 . S2CID 122605705 .
^ Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)" . Catalogue of Eggen's UBV Data . Bibcode :1986EgUBV........0M .
"GJ 742" . Montreal White Dwarf Database . Retrieved 2024-05-30.^ Jesse L. Greenstein, Ronald J. W. Henry, and R. F. O'Connell (February 15, 1985). "Further identifications of hydrogen in Grw +70°8247" . Astrophysical Journal . 289 : L25 – L29. Bibcode :1985ApJ...289L..25G . doi :10.1086/184427 . {{cite journal }}: CS1 maint: multiple names: authors list (link )
^ G. P. Kuiper (October 1934). "Two New White Dwarfs of Large Parallax" . Publications of the Astronomical Society of the Pacific . 46 (273): 287–290. Bibcode :1934PASP...46..287K . doi :10.1086/124496 . S2CID 123421818 .
P. J. van Rhijn and J. J. Raimond (April 1934). "Some new members of the Hyades cluster" . Monthly Notices of the Royal Astronomical Society 94 (6): 508–518, at p. 517. Bibcode :1934MNRAS..94..508V . doi :10.1093/mnras/94.6.508 .
Jöran M. Ramberg (May 1938). "Zwei weiße Zwerge unter den physischen Hyadenmigliedern" . Astronomische Nachrichten (in German). 265 (6–7): 111–112. Bibcode :1938AN....265..111R . doi :10.1002/asna.19382650609 .
Gerard P. Kuiper (August 1941). "List of Known White Dwarfs" . Publications of the Astronomical Society of the Pacific . 53 (314): 248–252. Bibcode :1941PASP...53..248K . doi :10.1086/125335 . S2CID 123040354 .Walter S. Adams and Frederick H. Seahes (1938). "Annual Report of the Director of the Mount Wilson Observatory (1937-1938)" . Mount Wilson Observatory Annual Report . 10 : 28. Bibcode :1938MWOAR..10....1A .
Jesse L. Greenstein and Mildred S. Matthews (July 1957). "Studies of the White Dwarfs. I. Broad Features in White Dwarf Spectra" . Astrophysical Journal . 126 : 14–18. Bibcode :1957ApJ...126...14G . doi :10.1086/146364 .
James C. Kemp, John B. Swedlund, J. D. Landstreet, and J. R. P. Angel (August 1970). "Discovery of Circularly Polarized Light from a White Dwarf" . Astrophysical Journal . 161 : L77 – L79. Bibcode :1970ApJ...161L..77K . doi :10.1086/180574 . {{cite journal }}: CS1 maint: multiple names: authors list (link )
Angel, J.R.P.; Landstreet, J.D.; Oke, J.B. (1972). "The Spectral Dependence of Circular Polarization in Grw+70°8247" . Astrophysical Journal . 171 : L11 – L15. Bibcode :1972ApJ...171L..11A . doi :10.1086/180857 .
J. R. P. Angel, James Liebert, and H. S. Stockman (May 1, 1985). "The optical spectrum of hydrogen at 160-350 million gauss in the white dwarf Grw +70°8247" . Astrophysical Journal . 292 : 260–266. Bibcode :1985ApJ...292..260A . doi :10.1086/163156 . {{cite journal }}: CS1 maint: multiple names: authors list (link )
D. T. Wickramasinghe and Lilia Ferrario (April 1, 1988). "A centered dipole model for the high field magnetic white dwarf GRW +70°8247" . Astrophysical Journal . 327 : 222–233. Bibcode :1988ApJ...327..222W . doi :10.1086/166184 .
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