GJ 742

Starbox begin
name= [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ%20742 GJ 742] Starbox observe
epoch=J2000.0 (ICRS)
constell=Draco
ra=RA|19|00|10.25 [http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GJ%20742 GJ 742] , entry in SIMBAD. Accessed on line November 5, 2007.]
dec=DEC|+70|39|51.2
appmag_v=13.2 Starbox character
b-v=0.0
class=DA:w Starbox astrometry
prop_mo_ra=105
prop_mo_dec=479
parallax=76
parallax_footnote=
p_error=4 Starbox catalog
names=GJ 742, AC +70 8247, G 260-15, LFT 1446, LHS 3424, LTT 15585, Grw+70 8247, WD 1900+705

GJ 742 is a white dwarf star. Although photographed in the 19th century as part of the Carte du Ciel project, it was not determined to be a white dwarf until observed in 1934 by G. P. Kuiper. [http://adsabs.harvard.edu/abs/1934PASP...46..287K Two New White Dwarfs of Large Parallax] , G. P. Kuiper, "Publications of the Astronomical Society of the Pacific" 46, #273 (October 1934), pp. 287–290.] This makes it the fifth or sixth white dwarf discovered. [The star EGGR 37 was suspected to be a white dwarf by April 1934 ( [http://adsabs.harvard.edu/abs/1934MNRAS..94..508V Some new members of the Hyades cluster] , P. J. van Rhijn and J. J. Raimond, "Monthly Notices of the Royal Astronomical Society" 94 (April 1934), pp. 508–518, at p. 517) but this was not confirmed until 1938 ( [http://adsabs.harvard.edu/abs/1938AN....265..111R Zwei weiße Zwerge unter den physischen Hyadenmigliedern] , Jöran M. Ramberg, "Astronomische Nachrichten" 265 (May 1938), pp. 111–112; see also [http://adsabs.harvard.edu/abs/1941PASP...53..248K List of Known White Dwarfs] , Gerard P. Kuiper, "Publications of the Astronomical Society of the Pacific" 53, #314 (August 1941), pp. 248–252).] At first, its spectrum was thought to be almost featureless, but later observation showed it to have unusual broad, shallow absorption bands. [ [http://adsabs.harvard.edu/abs/1938MWOAR..10....1A Annual Report of the Director of the Mount Wilson Observatory (1937-1938)] , Walter S. Adams and Frederick H. Seahes, "Mount Wilson Observatory Annual Report" 10 (1938), pp. 1–40.] ^{, p. 28;} [ [http://adsabs.harvard.edu/abs/1957ApJ...126...14G Studies of the White Dwarfs. I. Broad Features in White Dwarf Spectra] , Jesse L. Greenstein and Mildred S. Matthews, "Astrophysical Journal" 126 (July 1957), pp. 14–18.] In 1970, when light it emitted was observed to be circularly polarized, it became the first white dwarf known to have a magnetic field. [ [http://adsabs.harvard.edu/abs/1970ApJ...161L..77K Discovery of Circularly Polarized Light from a White Dwarf] , James C. Kemp, John B. Swedlund, J. D. Landstreet, and J. R. P. Angel, "Astrophysical Journal" 161 (August 1970), pp. L77–L79.] In the 1980s it was realized that the unusual absorption bands could be explained as hydrogen absorption lines shifted by the Zeeman effect. [http://adsabs.harvard.edu/abs/1985ApJ...289L..25G Further identifications of hydrogen in Grw +70°8247] , Jesse L. Greenstein, Ronald J. W. Henry, and R. F. O'Connell, "Astrophysical Journal" 289 (February 15, 1985), pp. L25–L29.] [ [http://adsabs.harvard.edu/abs/1985ApJ...292..260A The optical spectrum of hydrogen at 160-350 million gauss in the white dwarf Grw +70°8247] , J. R. P. Angel, James Liebert, and H. S. Stockman, "Astrophysical Journal" 292 (May 1, 1985), pp. 260–266.] [ [http://adsabs.harvard.edu/abs/1988ApJ...327..222W A centered dipole model for the high field magnetic white dwarf GRW +70°8247] , D. T. Wickramasinghe and Lilia Ferrario, "Astrophysical Journal" 327 (April 1, 1988), pp. 222–233.]

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