Alpha Fornacis

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Template:Short description

Alpha Fornacis
File:Fornax constellation map.png
Location of α Fornacis (upper left).
Observation data
Epoch J2000      Equinox J2000
Constellation Fornax[1]
Right ascension Template:RA[2]
Declination Template:DEC[2]
Apparent magnitude (V) 3.80[3] (3.98/7.19)[4]
Characteristics
Spectral type F6V + G7V[5]
U−B Template:Engvar +0.082[6]
B−V Template:Engvar +0.581[6]
Astrometry
Radial velocity (Rv)−20.5[7] km/s
Proper motion (μ) RA: +359.565[2] mas/yr
Dec.: +619.186[2] mas/yr
Parallax (π)71.4337±0.1320 mas[2]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)3.08[8]
Orbit[9]
Period (P)Script error: No such module "val". yr
Semi-major axis (a)Script error: No such module "val".″
Eccentricity (e)Script error: No such module "val".
Inclination (i)Script error: No such module "val".°
Longitude of the node (Ω)Script error: No such module "val".°
Periastron epoch (T)Script error: No such module "val".
Argument of periastron (ω)
(secondary)		Script error: No such module "val".°
Details
α For A
MassScript error: No such module "val".[10] Template:Solar mass
RadiusScript error: No such module "val".[11] Template:Solar radius
LuminosityScript error: No such module "val".[11] Template:Solar luminosity
Surface gravity (log g)4.27[10] cgs
Temperature6,240[10] K
Metallicity [Fe/H]−0.20[10] dex
Rotational velocity (v sin i)3.9[11] km/s
Age2.9[12] Gyr
α For B
Mass0.78[13] Template:Solar mass
Temperature5,040[13] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[14]
Database references
SIMBADdata

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Alpha Fornacis (α Fornacis, abbreviated Alpha For, α For) is a triple star[13] system in the southern constellation of Fornax. It is the brightest star in the constellation and the only one brighter than magnitude 4.0. Based on parallax measurements obtained during the Gaia mission, it is 45.66 light-years distant.

Its three components are designated Alpha Fornacis A (officially named Dalim Template:IPAc-en),[15] Alpha Fornacis Ba and Alpha Fornacis Bb.

Nomenclature

α Fornacis (Latinised to Alpha Fornacis) is the system's Bayer designation. The designations of the three components as Alpha Fornacis A, Ba and Bb derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star systems, and adopted by the International Astronomical Union (IAU).[16] Formerly it was designated as the 12th of Eridanus (12 Eri) by Flamsteed.[17]

Indigenous Arabs had named both Alpha Eridani and Fomalhaut ظَلِيم al-ẓalīm, a local word for 'ostrich'. Later, Arabian astronomer would transfer the appellation to Theta Eridani, as they could not see those other stars from their location.[18] In recent times, Italian astronomer Giuseppe Piazzi applied it with the spelling Dalim to his "III 13" (= α For) in his Palermo Catalogue,[19][20][21] and Elijah Burritt labeled it Fornacis in his Atlas.[22]

In 2016, the IAU organized a Working Group on Star Names (WGSN)[23] to catalog and standardize proper names for stars. The WGSN decided to attribute proper names to individual stars rather than entire multiple systems.[24] It approved the name Dalim for the component Alpha Fornacis A on 5 September 2017 and it is now so included in the List of IAU-approved Star Names.[15]

Properties

Alpha Fornacis has a high proper motion[14] and the system displays an excess of infrared emission, which may indicate the presence of circumstellar material such as a debris disk.[25] The space velocity components of this star are (U, V, W) = (−35, +20, +30) km/s.[26] Approximately 350,000 years ago, Alpha Fornacis experienced a close encounter with the A-type main-sequence star Nu Horologii. The two came within an estimated Script error: No such module "convert". of each other, and both stars have debris disks.[27]

Alpha Fornacis A has a stellar classification of F6V, where the luminosity class V suggests this is a main sequence star.[5] It is a fairly old star which has sometimes been considered to be a subgiant,[28] although evolutionary models place it towards the end of its main sequence life.[2] It has 33% more mass than the Sun and is an estimated 2.9 billion years old.[10][12]

The secondary, Alpha Fornacis B, has been identified as a blue straggler, and has likely accumulated material from a third star in the past. It is a strong source of X-rays and is 78% as massive as the Sun.[29] Such a third star, designated Alpha Fornacis Bb, was detected in 2016. Alpha Fornacis Ba is enriched in barium relative to star A, suggesting that its companion is likely a white dwarf.[13]

References

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  1. ↑ Template:Cite constellation
  2. ↑ a b c d e f Template:Cite Gaia DR3
  3. ↑ Template:Cite XHIP
  4. ↑ Script error: No such module "citation/CS1".
  5. ↑ a b Script error: No such module "Citation/CS1".
  6. ↑ a b Script error: No such module "Citation/CS1".
  7. ↑ 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 c d e Script error: No such module "Citation/CS1".
  11. ↑ a b c Script error: No such module "Citation/CS1".
  12. ↑ a b Script error: No such module "Citation/CS1". See VizierR catalogue V/130.
  13. ↑ a b c d Script error: No such module "Citation/CS1".
  14. ↑ a b Script error: No such module "citation/CS1".
  15. ↑ a b Script error: No such module "citation/CS1".
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ Script error: No such module "citation/CS1".
  20. ↑ Script error: No such module "citation/CS1".
  21. ↑ Script error: No such module "citation/CS1".
  22. ↑ Script error: No such module "citation/CS1". plate III.
  23. ↑ Script error: No such module "citation/CS1".
  24. ↑ Script error: No such module "citation/CS1".
  25. ↑ Script error: No such module "Citation/CS1".
  26. ↑ Script error: No such module "Citation/CS1".
  27. ↑ Script error: No such module "citation/CS1".
  28. ↑ Script error: No such module "Citation/CS1".
  29. ↑ Script error: No such module "Citation/CS1".

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External links

Template:Stars of Fornax

Template:Authority control

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