GJ 440
GJ 440 (or Gliese 440) (also known by the designation WD 1142-645) is a white dwarf star located 15 light years from the solar system.[5] According to a 2009 paper, it is the fourth closest known white dwarf to the Sun (after Sirius B, Procyon B, and van Maanen's star.)[6]
White dwarfs are no longer generating energy at their cores through nuclear fusion, and instead are steadily radiating away their remaining heat. GJ 440 has a DQ spectral classification, indicating that it is a rare type of white dwarf which displays evidence of atomic or molecular carbon in its spectrum.[7]
GJ 440 has only 75% of the Sun's mass, but it is the remnant of a massive main sequence star that had an estimated 4.4 solar masses.[8] While it was on the main sequence, it probably was a spectral class B star (in the range B4-B9).[9] Most of the star's original mass was shed after it passed into the asymptotic giant branch stage, just prior to becoming a white dwarf.
A survey with the Hubble Space Telescope revealed no visible orbiting companions, at least down to the limit of detection.[3]
GJ 440 may be a member of the Wolf 219 moving group, which has seven possible members. These stars share a similar motion through space, which may indicate a common origin.[10] This group has an estimated space velocity of 160 km/s and is following a highly eccentric orbit through the Milky Way galaxy.[11]
References
- ^ "Constellation boundaries". Centre de Données astronomiques de Strasbourg. http://vizier.u-strasbg.fr/vizier/VizieR/constellations.htx. Retrieved 2007-07-16.
- ^ a b c d e f g h i "SIMBAD query result: GJ 440 -- White Dwarf". Centre de Données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=GJ+440. Retrieved 2007-07-16.
- ^ a b Daniel J. Schroeder et al. (February 2000). "A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2". The Astronomical Journal 119 (2): 906–922. Bibcode 2000AJ....119..906S. doi:10.1086/301227.
- ^ a b c d e Table 2, P. Bergeron, S. K. Leggett, and María Teresa Ruiz (April 2001). "Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements". Astrophysical Journal Supplement Series 133 (2): 413–449. arXiv:astro-ph/0011286. Bibcode 2001ApJS..133..413B. doi:10.1086/320356.
- ^ Henry, Todd J.; Walkowicz, Lucianne M.; Barto, Todd C.; Golimowski, David A. (April 2002). "The Solar Neighborhood. VI. New Southern Nearby Stars Identified by Optical Spectroscopy". The Astronomical Journal 123 (4): 2002–2009. arXiv:astro-ph/0112496. Bibcode 2002AJ....123.2002H. doi:10.1086/339315.
- ^ Table 1, "The White Dwarfs Within 20 Parsecs of the Sun: Kinematics and Statistics", Edward M. Sion et al., The Astronomical Journal 138, #6 (December 2009), pp. 1681-1689, doi:10.1088/0004-6256/138/6/1681, Bibcode: 2009AJ....138.1681S.
- ^ Kawaler, S.; Dahlstrom, M. (2000). "White Dwarf Stars". American Scientist 88 (6): 498. Bibcode 2000AmSci..88..498K. doi:10.1511/2000.6.498. http://www.americanscientist.org/template/AssetDetail/assetid/23825. Retrieved 2007-07-19.
- ^ Burleigh, M. R.; Clarke, F. J.; Hodgkin, S. T. (April 2002). "Imaging planets around nearby white dwarfs". Monthly Notices of the Royal Astronomical Society 331 (4): L41–L45. arXiv:astro-ph/0202194. Bibcode 2002MNRAS.331L..41B. doi:10.1046/j.1365-8711.2002.05417.x.
- ^ Siess, Lionel (2000). "Computation of Isochrones". Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles. http://astropc0.ulb.ac.be/~siess/server/iso.html. Retrieved 2007-03-24.
- ^ Eggen, O. J.; Greenstein, J. L. (1965). "Spectra, colors, luminosities, and motions of the white dwarfs". Astrophysical Journal 141: 83–108. Bibcode 1965ApJ...141...83E. doi:10.1086/148091. — see table 5.
- ^ Bell, R. A. (1962). "Observations of some southern white dwarfs". The Observatory 82: 68–71. Bibcode 1962Obs....82...68B.
External links
|
← Star systems within 15–20 light-years →
|
|
|
|
|
|
|
Altair ( 16.69 ± 0.04 ly; 1 star)
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
DQ
|
Gliese 440 ( 15.09 ± 0.08 ly; 1 star) • GJ 1221 ( 19.80 ± 0.30 ly; 1 star)‡ |
|
|
|
|
|
|
In left column are stellar classes of primary members of star systems. ‡Distance error margin extends out of declared distance interval. Bold are systems containing at least one component with absolute magnitude of +8.5 or brighter. Italic are systems possibly located within declared distance interval, but probably not.
|
|