Jump to content

Alpha Caeli

From Wikipedia, the free encyclopedia
α Caeli
Location of α Caeli in Caelum (circled)
Observation data
Epoch J2000.0      Equinox J2000.0
Constellation Caelum
A
Right ascension 04h 40m 33.71251s[1]
Declination −41° 51′ 49.5045″[1]
Apparent magnitude (V) 4.44 – 4.47[2]
B
Right ascension 04h 40m 33.92449s[3]
Declination −41° 51′ 56.3362″[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) 3.944±0.354[8]
Apparent magnitude (H) 3.654±0.292[8]
Apparent magnitude (K) 3.724±0.324[8]
U−B color index 0.01[9]
B−V color index +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)0.65±0.3[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]
Distance66.48 ± 0.01 ly
(20.382 ± 0.004 pc)[1]
Absolute magnitude (MV)2.93±0.01[12]
B
Absolute magnitude (MV)9.8[13]
Orbit[4]
PrimaryA
CompanionB
Period (P)460,000 days
(1,260 years)
Semi-major axis (a)133.1 AU
Details
A
Mass1.54[14] M☉
Radius1.546[15] R☉
Luminosity5.156[15] L☉
Surface gravity (log g)4.12[1] cgs
Temperature7,002[15] K
Metallicity [Fe/H]−0.06±0.06[14] dex
Rotation1.4[16] days
Rotational velocity (v sin i)47.8±2.4[17] km/s
Age1.5[14] Gyr
B
Radius0.45[18] R☉
Temperature3,355[18] K
Position (relative to A)[19]
ComponentB
Epoch of observation2008
Angular distance6.6″
Other designations
α Caeli, GJ 174.1, GJ 9164, HD 29875, HIP 21770, HR 1502, PPM 308904, WDS J04406-4152, TIC 77263680, TYC 7589-1693-1, GSC 07589-01693, IRAS 04389-4157, 2MASS J04403374-4151495, WISE J044033.59-415150.2[7]
Database references
SIMBADA
B

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 66.48 light-years (20.38 pc) 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

[edit]

Primary

[edit]

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 48 km/s.[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 7000 K,[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 100 μm wavelength, which indicates that it is surrounded by an orbiting debris disk. The disk extends up to a radius of 46 AU from the star and has a temperature of 60 Kelvin (-213 °C). Its mass is estimated to be about 1/11,000 times Earth's mass (M🜨), and was equivalent to about 1/7,100 M🜨 when α Caeli was only 1 million years old.[14]

Companion + Orbit

[edit]

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 133 astronomical units and take 1,300 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

[edit]

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 8.006 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 0.05 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

[edit]
  1. ^ a b c d e f g h i Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  2. ^ a b "VSX : Detail for NSV 16147". AAVSO. Retrieved 2024-06-02.
  3. ^ a b Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
  4. ^ a b c Rodriguez, David R.; et al. (May 2015). "Stellar multiplicity and debris discs: an unbiased sample". Monthly Notices of the Royal Astronomical Society. 449 (3): 3160–3170. arXiv:1503.01320. Bibcode:2015MNRAS.449.3160R. doi:10.1093/mnras/stv483. ISSN 0035-8711. Alpha Caeli's database entry at VizieR.
  5. ^ a b c d Tamazian, V. S.; Malkov, O. Yu. (December 2014). "Catalog of Binary UV Ceti Type Flare Stars". Acta Astronomica. 64 (4): 359–369. Bibcode:2014AcA....64..359T. ISSN 0001-5237. Alpha Caeli's database entry at VizieR.
  6. ^ a b c d e f Ducati, J. R. (2002). "VizieR Online Data Catalog: Catalogue of Stellar Photometry in Johnson's 11-color system". VizieR On-line Data Catalog. 2237. Bibcode:2002yCat.2237....0D. Alpha Caeli's database entry at VizieR.
  7. ^ a b "Alpha Caeli". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved June 1, 2024.
  8. ^ a b c Cutri, R. M.; et al. (June 2003). VizieR Online Data Catalog: 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003). NASA/IPAC. Bibcode:2003tmc..book.....C.
  9. ^ Renson, P.; Manfroid, J. (May 2009). "Catalogue of Ap, HgMn and Am stars". Astronomy and Astrophysics. 498 (3): 961–966. Bibcode:2009A&A...498..961R. doi:10.1051/0004-6361/200810788. ISSN 0004-6361. Alpha Caeli's database entry at VizieR.
  10. ^ a b Hoffleit, D.; Warren Jr., W. H. (November 1995). "VizieR Online Data Catalog: Bright Star Catalogue, 5th Revised Ed. (Hoffleit+, 1991)". VizieR Online Data Catalog. 5050: V/50. Bibcode:1995yCat.5050....0H. Alpha Caeli's database entry at VizieR.
  11. ^ a b Gershberg, R. E.; et al. (November 1999). "Catalogue and bibliography of the UV Cet-type flare stars and related objects in the solar vicinity". Astronomy and Astrophysics Supplement. 139 (3): 555–558. Bibcode:1999A&AS..139..555G. doi:10.1051/aas:1999407.
  12. ^ a b Holmberg, J.; et al. (November 2007). "The Geneva-Copenhagen survey of the Solar neighbourhood II. New uvby calibrations and rediscussion of stellar ages, the G dwarf problem, age-metallicity diagram, and heating mechanisms of the disk". Astronomy and Astrophysics. 475 (2): 519–537. arXiv:0707.1891. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. S2CID 119054949. Alpha Caeli's database entry at the VizieR.
  13. ^ a b Hawley, Suzanne L.; et al. (April 1997). "Erratum: The Palomar/MSU Nearby Star Spectroscopic Survey.II.The Southern M Dwarfs and Investigation of Magnetic Activity". Astronomical Journal. 113: 1458. Bibcode:1997AJ....113.1458H. doi:10.1086/118363.
  14. ^ a b c d e f Gáspár, András; et al. (August 2016). "The Correlation between Metallicity and Debris Disk Mass". The Astrophysical Journal. 826 (2): 171. arXiv:1604.07403. Bibcode:2016ApJ...826..171G. doi:10.3847/0004-637X/826/2/171. ISSN 0004-637X. Alpha Caeli's database entry at VizieR.
  15. ^ a b c d e Schofield, Mathew; et al. (March 2019). "The Asteroseismic Target List for Solar-like Oscillators Observed in 2 minute Cadence with the Transiting Exoplanet Survey Satellite". The Astrophysical Journal Supplement Series. 241 (1): 12. arXiv:1901.10148. Bibcode:2019ApJS..241...12S. doi:10.3847/1538-4365/ab04f5. ISSN 0067-0049. Alpha Caeli's database entry at VizieR.
  16. ^ a b c Kaler, Jim. "Alpha Cae". Stars. Retrieved 2024-06-02.
  17. ^ a b Reiners, A.; Schmitt, J. H. M. M. (December 2003), "Differential rotation in rapidly rotating F-stars", Astronomy and Astrophysics, 412: 813–819, arXiv:astro-ph/0309616, Bibcode:2003A&A...412..813R, doi:10.1051/0004-6361:20034255.
  18. ^ a b Johnson, H. M.; Wright, C. D. (November 1983). "Predicted infrared brightness of stars within 25 parsecs of the sun". The Astrophysical Journal Supplement Series. 53: 643–711. Bibcode:1983ApJS...53..643J. doi:10.1086/190905. ISSN 0067-0049. Alpha Caeli is included as Wo 9164.
  19. ^ a b c Eggleton, P. P.; Tokovinin, A. A. (September 2008). "A catalogue of multiplicity among bright stellar systems". Monthly Notices of the Royal Astronomical Society. 389 (2): 869–879. arXiv:0806.2878. Bibcode:2008MNRAS.389..869E. doi:10.1111/j.1365-2966.2008.13596.x. ISSN 0035-8711. Alpha Caeli's database entry at VizieR.
  20. ^ "The Colour of Stars". Australia National Telescope Facility. March 6, 2024. Retrieved 2024-05-27.
  21. ^ Petit, M. (November 1977). "Etoiles Proches Suspectees de Variabilite". Information Bulletin on Variable Stars. 1362: 1–3. Bibcode:1977IBVS.1362....1P.
  22. ^ King, Jeremy R.; et al. (April 2003). "Stellar Kinematic Groups. II. A Reexamination of the Membership, Activity, and Age of the Ursa Major Group". The Astronomical Journal. 125 (4): 1980–2017. Bibcode:2003AJ....125.1980K. doi:10.1086/368241.
  23. ^ a b "★ Alpha Caeli". Stellar Catalog. Retrieved 2024-04-25.
Retrieved from "https://en.wikipedia.org/w/index.php?title=Alpha_Caeli&oldid=1296451012"