AB Doradus

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search

Template:Short description Script error: No such module "about".

AB Doradus
Observation data
Epoch J2000      Equinox J2000
Constellation Dorado
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 6.98−7.06[2] / 13.0[3]
Characteristics
AB Dor AC
Spectral type K0V[4] + M8
U−B Template:Engvar +0.37
B−V Template:Engvar Script error: No such module "val".[2]
Variable type Flare star
AB Dor B
Spectral type M5 + M5-6[5]
Astrometry
Radial velocity (Rv)32.40 ± 2.2[6] km/s
Proper motion (μ) RA: 33.16[7] mas/yr
Dec.: 150.83[7] mas/yr
Parallax (π)65.93±0.57 mas[7]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)5.86[8]
Orbit[5]
PrimaryAB Dor Ba
CompanionAB Dor Bb
Period (P)0.986 ± 0.008 yr
Semi-major axis (a)0.052 ± 0.002″
Eccentricity (e)0.6 ± 0.1
Inclination (i)121 ± 5°
Longitude of the node (Ω)270 ± 15°
Periastron epoch (T)2003.68 ± 0.05
Argument of periastron (ω)
(secondary)		54 ± 20°
Orbit[9]
PrimaryAB Dor A
CompanionAB Dor C
Period (P)12.895 yr
Semi-major axis (a)0.304″
Eccentricity (e)0.281
Inclination (i)63.0°
Longitude of the node (Ω)159.2°
Periastron epoch (T)B 1991.822
Argument of periastron (ω)
(secondary)		157.3°
Details
AB Dor A
Mass0.86[10] Template:Solar mass
RadiusScript error: No such module "val".[10] Template:Solar radius
Temperature5,250[11] K
Rotation0.5148 days[11]
Age50[12] Myr
AB Dor C
MassScript error: No such module "val".[13] Template:Solar mass
RadiusTemplate:Solar radius calculator[14]Template:Efn Template:Solar radius
LuminosityScript error: No such module "val".[14] Template:Solar luminosity
TemperatureScript error: No such module "val".[14] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Age25–120[13] Myr
AB Dor Ba
Mass0.28 ± 0.05[5] Template:Solar mass
AB Dor Bb
Mass0.25 ± 0.05[5] Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist
Database references
SIMBADdata
ARICNSdata

Script error: No such module "Check for unknown parameters".

AB Doradus is a pre-main-sequence quadruple[5] star system in the constellation Dorado. The primary is a flare star that shows periodic increases in activity.

File:ABDorLightCurve.png
A visual band light curve for AB Doradus. The main plot shows the long-term variability, and the inset shows the periodic variability (as of Oct/Nov 1989). Adapted from Innis et al. (2008)[2] and Anders (1990).[15]

The primary star in this system spins at a rate 50 times that of the Sun, and consequently has a strong magnetic field.[16] It has a greater number of star spots than 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.[17]

The system has four components consisting of a pair of binary star systems separated by an angle of about 9″.[5] The binary star AB Doradus Ba/Bb orbits the primary AB Doradus A at an average distance of 135 astronomical units (AUs). AB Doradus C is a closer in companion that orbits the primary at a distance of 5.1 AU, and has an orbital period of 11.75 years.

AB Doradus C 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.[18] However, recent evidence indicates that the star may actually be a binary system itself, consisting of two brown dwarfs, AB Doradus Ca/Cb, with 72 and 13 Jupiter masses, respectively.[19]

This system is a member of the eponymous AB Doradus Moving Group, a loose stellar association of about 30 stars that are all approximately the same age and moving in the same general direction.[20] It is likely that all of these stars formed in the same giant molecular cloud.

Notes

Template:Notelist

References

<templatestyles src="Reflist/styles.css" />

  1. ↑ a b Script error: No such module "Citation/CS1".
  2. ↑ a b c Script error: No such module "citation/CS1".
  3. ↑ Template:Cite simbad
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ a b c d e f Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "Citation/CS1".
  7. ↑ a b c Script error: No such module "Citation/CS1".
  8. ↑ Script error: No such module "Citation/CS1".
  9. ↑ Script error: No such module "citation/CS1".
  10. ↑ a b Script error: No such module "citation/CS1".
  11. ↑ a b Script error: No such module "citation/CS1".
  12. ↑ Script error: No such module "Citation/CS1".
  13. ↑ a b Script error: No such module "Citation/CS1".
  14. ↑ a b c Script error: No such module "Citation/CS1".
  15. ↑ Script error: No such module "Citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1". (The AB Dor Picture Gallery Template:Webarchive)
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "Citation/CS1".
  20. ↑ Script error: No such module "Citation/CS1".

Script error: No such module "Check for unknown parameters".

External links

Template:Stars of Dorado

Template:Sister project

Retrieved from "http://debianws.lexgopc.com/wiki143/index.php?title=AB_Doradus&oldid=3411379"