Alpha Pictoris

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Template:Short description

α Pictoris
Template:Location mark
Location of α Pictoris (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Pictor
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 3.27[2]
Characteristics
Spectral type A8 Vn kA6[3]
U−B Template:Engvar +0.13[2]
B−V Template:Engvar +0.21[2]
Astrometry
Radial velocity (Rv)+20.6[4] km/s
Proper motion (μ) RA: −66.07[1] mas/yr
Dec.: +242.97[1] mas/yr
Parallax (π)33.78±1.78 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)0.86[5]
Orbit[6]
Period (P)Template:Val days
Semi-major axis (a)3.25 AUTemplate:Efn
Eccentricity (e)Template:Val
Inclination (i)Template:Val°
Longitude of the node (Ω)Template:Val°
Periastron epoch (T)Template:Val BJD
Argument of periastron (ω)
(secondary)		Template:Val°
Details
A
MassTemplate:Val[6] Template:Solar mass
Radius3.55[7] Template:Solar radius
LuminosityTemplate:Val[8] Template:Solar luminosity
Surface gravity (log g)3.48[9] cgs
TemperatureTemplate:Val[8] K
Metallicity [Fe/H]−0.11[3] dex
Rotational velocity (v sin i)206[10] km/s
Age660[11][12] Myr
B
MassTemplate:Val[6] Template:Solar mass
TemperatureTemplate:Val[6] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
CD−61°1478, Gl 248, HD 50241, HIP 32607, HR 2550, LTT 2656, SAO 249647.[13]
Database references
SIMBADdata

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Alpha Pictoris (α Pic, α Pictoris) is the brightest star in the southern constellation of Pictor. It has an apparent visual magnitude of 3.27,[2] which is bright enough to be viewed from urban areas in the southern hemisphere. This is actually a binary star system, whose components complete an orbit every three years and seven months.[6] It is close enough for its distance to be measured using parallax shifts, which yields a value of roughly Template:Convert from the Sun, with a 5% margin of error.[1] Alpha Pictoris has the distinction of being the south pole star of the planet Mercury.[14]

Properties

With an estimated age of 660 million years,[11][12] the primary component is a relatively young Lambda Boötis star.[15] The stellar classification of A8 Vn kA6[3] shows this peculiarity, with the kA6 notation indicating weaker than normal calcium K-lines in the spectrum. The 'n' following the main sequence luminosity class of V indicates the absorption lines in the spectrum are broad and nebulous. This is caused by the rapid spin of the star, which has a high projected rotational velocity of 206 km/s.[10] Spectroscopy shows narrow, time-varying absorption features being caused by circumstellar gas moving toward the star. This is not the result of interstellar matter, but a shell of gas along the orbital plane. Alpha Pictoris is categorized as a rapidly rotating shell star that may have recently ejected mass from its outer atmosphere.[9][16]

Alpha Pictoris A is larger than the Sun, with a 60% greater mass[6] and a 355% greater radius.[7] It is radiating 40 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of Template:Val.[8] At this heat, the star glows with the white hue of an A-type star.[17] It is also one of the brightest known Delta Scuti variables.[18] The space velocity components of this star in the galactic coordinate system are U = -22, V = -20 and W = -9 km/s.[19]

Data from the Hipparcos mission uncovered the presence of a binary companion[15] with a companion orbiting at a semimajor axis of around 3.25 AU, or three times the distance from Earth to the Sun.[6] Alpha Pictoris is an X-ray source, which is unusual for an A-type star since stellar models don't predict them to have magnetic dynamos. This emission may instead be originating from the companion.[9][20]

Notes

Template:Notelist

References

Template:Reflist

Template:Stars of Pictor

  1. ↑ a b c d e f Cite error: Invalid <ref> tag; no text was provided for refs named aaa474_2_653
  2. ↑ a b c d Cite error: Invalid <ref> tag; no text was provided for refs named clpl4_99
  3. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named aj132_1_161
  4. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named gcsr
  5. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aaa361_614
  6. ↑ a b c d e f g Cite error: Invalid <ref> tag; no text was provided for refs named Dholakia2024
  7. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named tycho-gaia
  8. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named Zorec2012
  9. ↑ a b c Cite error: Invalid <ref> tag; no text was provided for refs named aaa408
  10. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named aaa463
  11. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named apj653
  12. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named apj546
  13. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named SIMBAD
  14. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named moore2007
  15. ↑ a b Cite error: Invalid <ref> tag; no text was provided for refs named apjss173
  16. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named apj676
  17. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named csiro
  18. ↑ Script error: No such module "Citation/CS1".
  19. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named cns1969
  20. ↑ Cite error: Invalid <ref> tag; no text was provided for refs named aaa475_2_677
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