AB Doradus

Starbox begin
name=AB Doradus A/B/C Starbox image


caption = AB Doradus A/B/C Starbox observe
epoch=J2000
ra=RA|05|28|44.828
dec=DEC|−65|26|54.85
appmag_v=6.93/13.0
constell=Dorado Starbox character
class=K1IIIp/dM3-4e/M8
b-v=+0.83
u-b=+0.37
variable=Flare star Starbox astrometry
radial_v=+28.0
prop_mo_ra=32.14
prop_mo_dec=150.97
parallax=66.92
p_error=0.54
absmag_v=6.06 Starbox visbin
name=AB Doradus B
period=
axis=135 AU
eccentricity=
inclination=
node=
periastron= Starbox visbin
name=AB Doradus C
period=11.75
axis=2.3 AU
eccentricity=
inclination=
node=
periastron= Starbox detail
mass=0.76 / ? / 0.089
radius=?
luminosity=?
temperature=?
metal=? % Sun
rotation=0.514d [cite journal | author=M. Jardine, C. A. Collier, J.F. Donati | title=The global magnetic topology of AB Doradus | journal=Monthly Notices of the Royal Astronomical Society | year=2002 | volume=333 | issue=2 | pages=339–346 | url=http://adsabs.harvard.edu/abs/1998RPPh...61...77K | doi=10.1046/j.1365-8711.2002.05394.x ]
age=5 × 10⁷ [cite journal | author=K. L. Luhman, John R. Stauffer, E. E. Mamajek | title=The Age of AB Dor | journal=Astrophysical Journal | year=2005 | volume=628 | pages=L69–L72 | doi=10.1086/432617 ] Starbox catalog
names=AB Dor, CD -65°332, HD 36705, HIP 25647. Starbox reference
Simbad=AB+Doradus

AB Doradus is a pre-main sequence trinary star system in the constellation Dorado. The primary is a flare star that shows periodic increases in activity.

The primary star in this system spins at a rate 50 times that of the Sun, and consequently has a strong magnetic field. [cite web | author=JR Minkel | date = 2001-12-11 | url = http://www.sciam.com/article.cfm?articleID=0000F563-2E41-1C68-B882809EC588ED9F | title = Shimmying Star May Shed Light on Forces at Work in the Sun | publisher = Scientific American | language = English | accessdate = 2006-06-25 ] It has a greater number of star spots than does the Sun. These can cause the luminosity of the star to appear to vary over each orbital cycle. Measurements of the spin rate of this star at its equator have shown that it varies over time due to the effect of this magnetic field. [cite web | author=A. C. Cameron, J.F. Donati | url = http://www.pparc.ac.uk/Nw/Press/rel39_01.asp | title = Christmas Star Does the Twist | publisher = PPARC | language = English | accessdate = 2006-08-25 ( [http://star-www.st-and.ac.uk/~acc4/abdorpix.html The AB Dor Picture Gallery] )]

The system has three components. The binary star AB Doradus B orbits the primary at an average distance of 135 astronomical units (AUs). AB Doradus C, is a close-in companion that orbits the primary at a distance of 2.3 AU, and has an orbital period of 11.75 years. The later star is among the lowest mass stars ever found. At an estimated mass 93 times Jupiter's, it is near the limit of 75-83 Jupiter masses below which it would be classified as a brown dwarf. [cite news | title=Weighing the Smallest Stars | publisher=ESO | date=2005-01-19 | url=http://www.eso.org/outreach/press-rel/pr-2005/pr-02-05.html | accessdate=2006-08-13 ]

This system is a member of the like-named AB Doradus moving group, a loose stellar association of about 30 stars that are all moving in the same general direction and having approximately the same age. [cite journal | author=B. Zuckerman, I. Song, M. S. Bessell | title=The AB Doradus Moving Group | journal=The Astrophysical Journal | year=2005 | volume=613 | issue=1 | pages=L65–L68 | doi=10.1086/425036 ] It is likely that all of these stars formed in the same giant molecular cloud.

References

* http://jumk.de/astronomie/special-stars/ab-doradus.shtml

External links

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