GJ 440

Starbox begin
name= [http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=GJ+440 GJ 440] Starbox observe
epoch=J2000.0 (ICRS)
ra=RA|11|45|42.9205cite web
url=http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=GJ+440
title=SIMBAD query result: GJ 440 -- White Dwarf
publisher=Centre de Données astronomiques de Strasbourg
accessdate=2007-07-16 ]
dec=DEC|−64|50|29.459
appmag_v=11.50
constell=Musca [cite web
url =http://vizier.u-strasbg.fr/vizier/VizieR/constellations.htx
title =Constellation boundaries
publisher =Centre de Données astronomiques de Strasbourg
accessdate = 2007-07-16 ] Starbox character
class=DQ6
b-v=+0.19
u-b=-0.59
variable= Starbox astrometry
radial_v=
prop_mo_ra=2665.25
prop_mo_dec=-346.19
parallax=216.40
p_error=2.11
parallax_footnote=
absmag_v= Starbox detail
mass=0.75 ± 0.03
radius=
luminosity=0.0005
temperature=8,500 ± 300Table 2, cite journal
author = P. Bergeron, S. K. Leggett, and María Teresa Ruiz
title = Photometric and Spectroscopic Analysis of Cool White Dwarfs with Trigonometric Parallax Measurements
journal=Astrophysical Journal Supplement Series
year=2001 | month = April | volume = 133 | issue = 2 | pages=413–449
url=http://adsabs.harvard.edu/abs/2001ApJS..133..413B
doi=10.1086/320356
accessdate=2007-11-05 ]
gravity=8.27 ± 0.05
metal=
rotation=
age=(as white dwarf)
1.44·10⁹ Starbox catalog
names=WD 1142-645, GJ 440, LHS 43, LTT 4364, L 145-141, HIP 57367.

GJ 440 (also known by the designation WD 1142-645) is a white dwarf star located 15 light years from the solar system. [cite journal
author=Henry, Todd J.; Walkowicz, Lucianne M.; Barto, Todd C.; Golimowski, David A.
title=The Solar Neighborhood. VI. New Southern Nearby Stars Identified by Optical Spectroscopy
journal=The Astronomical Journal
year=2002 | month=April | volume=123 | issue=4 | pages=2002–2009
doi=10.1086/339315
url=http://adsabs.harvard.edu/abs/2002AJ....123.2002H
accessdate=2007-07-16] 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. [cite journal
author=Kawaler, S.; Dahlstrom, M. | title=White Dwarf Stars
journal=American Scientist
year=2000 | volume=88 | issue=6 | pages=498
url=http://www.americanscientist.org/template/AssetDetail/assetid/23825
accessdate=2007-07-19 | doi=10.1511/2000.6.498 ]

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.cite journal
author=Burleigh, M. R.; Clarke, F. J.; Hodgkin, S. T.
title=Imaging planets around nearby white dwarfs
journal=Monthly Notices of the Royal Astronomical Society
year=2002 | month=April | volume=331 | issue=4 | pages=L41–L45
url=http://adsabs.harvard.edu/abs/2002MNRAS.331L..41B
doi=10.1046/j.1365-8711.2002.05417.x
accessdate=2007-07-16] While it was on the main sequence, it probably was a spectral class B star (in the range B4-B9). [cite web
last = Siess | first = Lionel | year = 2000
url = http://astropc0.ulb.ac.be/~siess/server/iso.html
title = Computation of Isochrones
publisher = Institut d'Astronomie et d'Astrophysique, Université libre de Bruxelles
accessdate = 2007-03-24] 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.cite journal
author=Daniel J. Schroeder "et al."
title=A Search for Faint Companions to Nearby Stars Using the Wide Field Planetary Camera 2
journal=The Astronomical Journal
year=2000 | month=February | volume=119 | issue=2 | pages=906–922
doi=10.1086/301227
url=http://adsabs.harvard.edu/abs/2000AJ....119..906S
accessdate=2007-07-16 ]

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. [cite journal
author=Eggen, O. J.; Greenstein, J. L.
title=Spectra, colors, luminosities, and motions of the white dwarfs
journal=Astrophysical Journal
year=1965 | volume=141 | pages=83–108
url=http://adsabs.harvard.edu/abs/1965ApJ...141...83E
accessdate=2007-07-16
doi=10.1086/148091 — see table 5.] This group has an estimated space velocity of 160 km/s and is following a highly eccentric orbit through the Milky Way galaxy. [cite journal
last=Bell |first=R. A.
title=Observations of some southern white dwarfs
journal=The Observatory
year=1962 | volume=82 | pages=68–71
url=http://adsabs.harvard.edu/abs/1962Obs....82...68B
accessdate=2007-07-16 ]

References

External links

* [http://www.stellar-database.com/Scripts/search_star.exe?Catalog=Gl&CatNo=440 CC 658]