Tau4 Eridani

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τ4 Eridani
Template:Location mark
Location of τ4 Eridani (circled)
Observation data
Epoch J2000.0      Equinox J2000.0 (ICRS)
Constellation Eridanus
τ4 Eridani A
Right ascension Template:RA [1]
Declination Template:DEC [1]
Apparent magnitude (V) 3.57−3.72[2]
τ4 Eridani B
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) 9.5[4]
Characteristics
τ4 Eridani A
Evolutionary stage asymptotic giant branch[5]
Spectral type M3/4 III[6]
U−B Template:Engvar +1.79[7]
B−V Template:Engvar +1.61[7]
Variable type Lb[2]
Astrometry
τ4 Eridani A
Radial velocity (Rv)Script error: No such module "val".[8] km/s
Proper motion (μ) RA: +52.774 mas/yr[1]
Dec.: +32.718 mas/yr[1]
Parallax (π)10.6153±0.3213 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−0.79[9]
τ4 Eridani B
Proper motion (μ) RA: +52.919 mas/yr[3]
Dec.: +34.104 mas/yr[3]
Parallax (π)10.6682±0.1066 mas[3]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Position (relative to A)
ComponentB
Angular distance5.7[4]″
Position angle291[4]°
Projected separation5,800[10] AU
Details
τ4 Eridani A
MassScript error: No such module "val".[11] Template:Solar mass
Radius103[12] Template:Solar radius
Luminosity1,537[13] Template:Solar luminosity
Surface gravity (log g)0.91[14] cgs
Temperature3,652[12] K
τ4 Eridani B
Mass0.9[10] Template:Solar mass
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
τ4 Eridani, τ4 Eri, 16 Eridani, BD−22°584, HD 20720, HIP 15474, HR 1003, SAO 168460[15]
Database references
τ4 Eridani A
SIMBADdata
τ4 Eridani B
SIMBADdata

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Tau4 Eridani (τ4 Eridani, τ4 Eri) is a binary star system in the constellation Eridanus. It is visible to the naked eye with an apparent visual magnitude that varies from 3.57 to 3.72.[2] The distance to this star can be estimated using the parallax method, which yields a value of roughly 300 light years.[1]

File:Tau4EriLightCurve.png
A visual band light curve for Tau4 Eridani, plotted from data published by Tabur et al. (2009)[16]

The primary components ia an evolved red giant star currently on the asymptotic giant branch[5] with a stellar classification of M3/4 III.[6] It is a slow irregular variable star of type Lb, undergoing changes in magnitude over the range 3.57−3.72[2] with a periodicity of 23.8 d.[16] This star has 1.73 times the mass of the Sun[11] and 103 times the radius of the Sun.[12] It shines with 1,537 times the luminosity of the Sun from its photosphere[13] at an effective temperature of 3,650 K.[12]

The secondary is a magnitude 9.5 star at an angular separation of 5.7″ along a position angle of 291°, as of 2013.[4] This angular separation implies a projected separation of 5,800 astronomical units.[10]

References

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  1. ↑ a b c d e Template:Cite Gaia DR3
  2. ↑ a b c d Script error: No such module "citation/CS1".
  3. ↑ a b c d Template:Cite Gaia DR3
  4. ↑ a b c d 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. ↑ a b 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 Script error: No such module "Citation/CS1".
  11. ↑ a b Script error: No such module "Citation/CS1".
  12. ↑ a b c d Script error: No such module "citation/CS1".
  13. ↑ a b Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1". Tau4 Eridani database entry at VizieR.
  15. ↑ Template:Cite simbad
  16. ↑ a b Script error: No such module "citation/CS1".

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Template:Stars of Eridanus

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