Alpha Caeli

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Template:Short description

α Caeli
Template:Location mark
Location of α Caeli in Caelum (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Caelum
A
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 4.44Template:Snd4.47[2]
B
Right ascension Template:RA[3]
Declination Template:DEC[3]
Apparent magnitude (V) 12.5[4]
Characteristics
A
Evolutionary stage main sequence
Spectral type F2V[5]
Apparent magnitude (U) 4.79[6]
Apparent magnitude (B) 4.79[6]
Apparent magnitude (R) 4.11[6]
Apparent magnitude (G) 4.35[7]
Apparent magnitude (I) 3.90[6]
Apparent magnitude (J) Script error: No such module "val".[8]
Apparent magnitude (H) Script error: No such module "val".[8]
Apparent magnitude (K) Script error: No such module "val".[8]
U−B Template:Engvar 0.01[9]
B−V Template:Engvar +0.34[6]
Variable type suspected Delta Scuti[10]
B
Evolutionary stage Red dwarf
Spectral type M0.5V[5]
Variable type Flare star[11]
Astrometry
A
Radial velocity (Rv)Script error: No such module "val".[1] km/s
Proper motion (μ) RA: −139.843 mas/yr[1]
Dec.: −75.677 mas/yr[1]
Parallax (π)49.062±0.00937 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)[1]
Absolute magnitude (MV)Script error: No such module "val".[12]
B
Absolute magnitude (MV)9.8[13]
Orbit[4]
PrimaryA
CompanionB
Period (P)460,000 days
(Script error: No such module "convert". years)
Semi-major axis (a)Script error: No such module "val".
Details
A
Mass1.54[14] Template:Solar mass
Radius1.546[15] Template:Solar radius
Luminosity5.156[15] Template:Solar luminosity
Surface gravity (log g)4.12[1] cgs
Temperature7,002[15] K
Metallicity [Fe/H]Script error: No such module "val".[14] dex
Rotation1.4[16] days
Rotational velocity (v sin i)Script error: No such module "val".[17] km/s
Age1.5[14] Gyr
B
Radius0.45[18] Template:Solar radius
Temperature3,355[18] K
Metallicity [Fe/H]{{{metal_fe2}}} dex
Position (relative to A)[19]
ComponentB
Epoch of observation2008
Angular distance6.6″
Other designations
Template:Odlist[7]
Database references
SIMBADA
B

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Alpha Caeli is a binary star system in the southern constellation Caelum. Its name is a Bayer designation that is Latinized from α Caeli, and abbreviated Alpha Cae or α Cae. With a combined apparent visual magnitude of 4.45,[6] it is only visible to the naked eye in places far from light pollution, but still is the brightest star in the constellation. Parallax measurements by the Gaia spacecraft indicate a distance of Script error: No such module "convert". to Alpha Caeli. It has a relatively low radial velocity, estimated at 0.7 km/s relative to the Sun.[1]

This system consists of an F-type star of magnitude 4.46 and a small red dwarf of magnitude 12.5. As of 2008, they are separated by 6.6" in the sky.[19] A debris disk has been detected around the primary component of the system.

Physical properties

Primary

The primary component (α Caeli A) has a spectral classification of F2V,[5] meaning that it is an ordinary F-type main-sequence star, currently fusing hydrogen into helium at its core. It is estimated to be 1.5 billion years old and has a relatively high rotation rate, spinning at its own axis at a projected rotational velocity of Script error: No such module "val"..[17] This star has 1.54 times the mass[14] and 1.55 times the radius of the Sun.[15] Its photosphere, which is emitting 5 times the solar luminosity, has an effective temperature of Script error: No such module "val".,[15] so it is hotter than the Sun and has a white hue, typical of early F-type stars.[20]

The star is suspected of being a Delta Scuti variable star.[10] The variation in the brightness is of 0.03 magnitudes.[2] It was first suspected to be a variable star by M. Petit in 1979.[21]

It presents a significant infrared excess at the 100Script error: No such module "String".μm wavelength, which indicates that it is surrounded by an orbiting debris disk. The disk extends up to a radius of 46Script error: No such module "String".AU from the star and has a temperature of 60 Kelvin (-213Script error: No such module "String".°C). Its mass is estimated to be about 1/11,000 times Earth's mass (Template:Earth mass), and was equivalent to about Template:Earth mass when α Caeli was only 1 million years old.[14]

Companion + Orbit

The companion (α Caeli B) is a small red dwarf star with spectral class of M0.5V[5] and absolute magnitude 9.80.[13] It is a flare star that undergoes random increases in luminosity.[11] This star was separated from the primary by an angle of 6.6 arcseconds in 2008,[19] but this separation changes over time.[16] They are physically separated by 133Script error: No such module "String".astronomical units and take Script error: No such module "convert".Script error: No such module "String".years to fully orbit each other.[4]

Because of the small angular separation and faintness (12.5m) of the companion, Alpha Caeli B is hard to see with a small telescope.[16]

Motion

Alpha Caeli is approximately 66.5 light years from Earth[1] and is an estimated 1.5 billion years old.[14] The space velocity components of this system are U = 10, V = 6 and W = −10 km/s. It is orbiting the Milky Way galaxy at an average distance of 8.006Script error: No such module "String".kpc from the Galactic Center and with an orbital eccentricity of 0.07. This orbit lies close to the galactic plane, and the system travels no more than 0.05Script error: No such module "String".kpc above or below this plane.[12] Alpha Caeli is probably a member of the Ursa Major moving group of stars that have similar kinematic properties and probably originated from the same star cluster.[22]

The nearest star to Alpha Caeli is LHS 1678, which is 3.4 light-years from it.[23] This is closer than Proxima Centauri is to the Earth at 4.25 ly.

Nearest stars to Alpha Caeli[23]
Name Distance
(light-years)
LHS 1678 3.4
L 447-6 5.9
HD 29220 6.1
SCR J0509-4325 6.5
UPM J0448-3539 7.4

References

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  1. ↑ a b c d e f g h i Template:Cite Gaia DR3
  2. ↑ a b Script error: No such module "citation/CS1".
  3. ↑ a b Template:Cite Gaia DR3
  4. ↑ a b c Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  5. ↑ a b c d Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  6. ↑ a b c d e f Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  7. ↑ a b Template:Cite simbad
  8. ↑ a b c Script error: No such module "citation/CS1".
  9. ↑ Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  10. ↑ a b Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  11. ↑ a b Script error: No such module "Citation/CS1".
  12. ↑ a b Script error: No such module "Citation/CS1". Alpha Caeli's database entry at the VizieR.
  13. ↑ a b Script error: No such module "Citation/CS1".
  14. ↑ a b c d e f Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  15. ↑ a b c d e Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  16. ↑ a b c Script error: No such module "citation/CS1".
  17. ↑ a b Script error: No such module "citation/CS1".
  18. ↑ a b Script error: No such module "Citation/CS1". Alpha Caeli is included as Wo 9164.
  19. ↑ a b c Script error: No such module "Citation/CS1". Alpha Caeli's database entry at VizieR.
  20. ↑ Script error: No such module "citation/CS1".
  21. ↑ Script error: No such module "Citation/CS1".
  22. ↑ Script error: No such module "Citation/CS1".
  23. ↑ a b Script error: No such module "citation/CS1".

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Template:Stars of Caelum

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