GRW +70 8247

	GRW +70 8247
Observationsdata; Epok: J2000.0
Stjärnbild	Draken
Rektascension	19t 00m 10,2534s
Deklination	+70° 39′ 51,418″
Skenbar magnitud ()	+13,19
Stjärntyp
Spektraltyp	DAP4.5
U–B	-0,85
B–V	+0,05
Astrometri
Egenrörelse (µ)	RA: +85,774 mas/år; Dek.: +505,050 mas/år
Parallax ()	77,6525 ± 0,0317
Avstånd	42,00 ± 0,02 lå (12,878 ± 0,005 pc)
Andra beteckningar
	GJ 742, AC +70 8247, G 260-15, LFT 1446, LHS 3424, LTT 15585, Grw+70 8247, WD 1900+705, G 260-15GJ 742LHS, 3424LSPM J1900+7039, 2MASS J19001024+7039512, NLTT 47348, PLX 4440U, SNO-B1.0 1606-00125381, uvby98 980260015, WD 1900+706, WD 1900+705, WD 1900+70, WISEA J190010.44+703956.7, Gaia EDR3 2262849634963004416, Gaia DR2 2262849634963004416,

GRW +70 8247 är en ensam stjärna i den mellersta delen av stjärnbilden Draken. Den har en skenbar magnitud av ca 13,19^[2] och kräver ett stort teleskop för att kunna observeras. Baserat på parallaxenligt Gaia Data Release 2 på ca 77,7 mas,^[1] beräknas den befinna sig på ett avstånd på ca 42 ljusår (ca 12,9 parsek) från solen.

Egenskaper

GRW +70 8247 är en vit dvärg av spektralklass DAP4.5^[3] Även om stjärnan fotograferades på 1800-talet som en del av Cartes du Ciel-projektet, var den inte fastställd att vara en vit dvärg förrän Gerard Kuiper observerade den 1934.^[7] Detta gör den till den femte eller sjätte vita dvärgen som upptäckts (stjärnan EGGR 37 misstänktes vara en vit dvärg i april 1934,^[8] men detta bekräftades inte förrän 1938^[9]^[10]). Först trodde man att dess spektrum var nästan funktionslöst,^[7] men senare observationer visade sig att den hade ovanliga breda, grunda absorptionsband.^[11]^[12] År 1970, när ljus som den avgav observerades vara cirkulärt polariserat, blev det den första vita dvärgen som var känd för att ha ett magnetfält.^[13]^[14] På 1980-talet insåg man att de ovanliga absorptionsbanden kunde förklaras som väte absorptionslinjer förskjutna av Zeemaneffekten.^[7]^[15]^[16]

Referenser

Den här artikeln är helt eller delvis baserad på material från engelskspråkiga Wikipedia, GRW +70 8247, 10 april 2021.

Noter

^ [a b c d e] 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.
^ [a b c] "LAWD 73". SIMBAD. Centre de données astronomiques de Strasbourg. Hämtad 5 november 2007.
^ [a b] 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.
^ [a b] Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.
^ [a b] 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.
^ GJ 742 (unistra.fr) Hämtad 2022-08-03.
^ [a b c] G. P. Kuiper (October 1934). "Two New White Dwarfs of Large Parallax". Publications of the Astronomical Society of the Pacific. 46 (273): 287–290.
^ 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: 508–518, at p. 517.
^ Jöran M. Ramberg (May 1938). "Zwei weiße Zwerge unter den physischen Hyadenmigliedern". Astronomische Nachrichten (in German). 265: 111–112.
^ See also Gerard P. Kuiper (August 1941). "List of Known White Dwarfs". Publications of the Astronomical Society of the Pacific. 53 (314): 248–252.
^ 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.
^ 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.
^ 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.
^ 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.
^ 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.

[A-1] [a b c d e] 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.

[B-2] [a b c] "LAWD 73". SIMBAD. Centre de données astronomiques de Strasbourg. Hämtad 5 november 2007.

[C-3] [a b] 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.

[D-4] [a b] Mermilliod, J.-C. (1986). "Compilation of Eggen's UBV data, transformed to UBV (unpublished)". Catalogue of Eggen's UBV Data. Bibcode:1986EgUBV........0M.

[E-5] [a b] 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.

[SIMBAD-6] GJ 742 (unistra.fr) Hämtad 2022-08-03.

[F-7] [a b c] G. P. Kuiper (October 1934). "Two New White Dwarfs of Large Parallax". Publications of the Astronomical Society of the Pacific. 46 (273): 287–290.

[G-8] 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: 508–518, at p. 517.

[H-9] Jöran M. Ramberg (May 1938). "Zwei weiße Zwerge unter den physischen Hyadenmigliedern". Astronomische Nachrichten (in German). 265: 111–112.

[I-10] See also Gerard P. Kuiper (August 1941). "List of Known White Dwarfs". Publications of the Astronomical Society of the Pacific. 53 (314): 248–252.

[J-11] 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.

[K-12] 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.

[L-13] 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.

[M-14] 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.

[N-15] 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.

[O-16] 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.

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