# Alpha Caeli

Observation data Characteristics Epoch J2000.0      Equinox J2000.0 (ICRS) Alpha Caeli is at lower center. Constellation Caelum A Right ascension 04h 40m 33.7125s Declination −41° 51′ 49.509″[1] Apparent magnitude (V) 4.456 B Right ascension 04h 40m 34.0s Declination −41° 51′ 51″[2] Apparent magnitude (V) 12.5[2] F2V[3] +0.01[4] +0.34[4] M0.5[2] Radial velocity (Rv) –0.6 ± 0.9[5] km/s Proper motion (μ) RA: –141.18[1] mas/yr Dec.: –74.95[1] mas/yr Parallax (π) 49.67 ± 0.53[1] mas Distance 65.7 ± 0.7 ly (20.1 ± 0.2 pc) Absolute magnitude (MV) 3.39[6] Radial velocity (Rv) −0.6 ± 0.9[2] km/s Proper motion (μ) RA: −147[2] mas/yr Dec.: −78[2] mas/yr Mass 1.48[7] M☉ Radius 1.3[8] R☉ Surface gravity (log g) 4.01[3] cgs Temperature 6,991[3] K Metallicity ${\displaystyle {\begin{smallmatrix}\left[{\frac {M}{H}}\right]\ =\ -0.10\end{smallmatrix}}}$[3] Rotational velocity (v sin i) 47.8 ± 2.4[9] km/s Age 0.9 (0.7–1.3) × 109[7] years Mass 0.3[10] M☉ Temperature 3800[10] K A: CCDM J04406-4152A, CD−42°1587, CPD−42°513, FK5 1129, GC 5708, Gl 174.1 A, GJ 9164 A, HD 29875, HIP 21770, HR 1502, IDS 04373-4203 A, SAO 216926.[11] B: CCDM J04406-4152B, CD−42°1587B, CPD−42°513B, Gl 174.1 B, GJ 9164 B, IDS 04373-4203 B.[2] SIMBAD A B

Alpha Caeli (α Cae, α Caeli) is a double star system in the constellation Caelum.

Alpha Caeli A is an F-type main sequence star with a stellar classification of F2V and an apparent magnitude of +4.44. It has 1.48 times the mass of the Sun[7] and 1.3 times the solar radius.[8] The projected rotational velocity at the stellar equator is 47.8 km/s.[9] It is suspected of being a Delta Scuti variable star.[12]

The companion is a spectral class M0.5V red dwarf star with absolute magnitude 9.80.[13] It is a UV Ceti variable star that undergoes random increases in luminosity.[14] This star is currently separated from the primary by an angle of 6.6 arcseconds, which indicates an orbit with a semimajor axis whose expected value is 206 AU.[15]

Alpha Caeli is approximately 65.7 light years from Earth and is an estimated 900 million years old. 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 core 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.[7] 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.[16]

## References

1. ^ a b c d Perryman, M. A. C.; et al. (April 1997). "The HIPPARCOS Catalogue". Astronomy & Astrophysics. 323: L49–L52. Bibcode:1997A&A...323L..49P.
2. GJ 174.1 B -- Flare Star, database entry, SIMBAD. Accessed on line November 5, 2009.
3. ^ a b c d Gray, R. O.; et al. (July 2006). "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample". The Astronomical Journal. 132 (1): 161–170. arXiv:. Bibcode:2006AJ....132..161G. doi:10.1086/504637.
4. ^ a b Johnson, H. L.; Iriarte, B.; Mitchell, R. I.; Wisniewskj, W. Z. (1966). "UBVRIJKL photometry of the bright stars". Communications of the Lunar and Planetary Laboratory. 4 (99). Bibcode:1966CoLPL...4...99J.
5. ^ Evans, D. S. (June 20–24, 1966). "The Revision of the General Catalogue of Radial Velocities". Determination of Radial Velocities and their Applications, Proceedings from IAU Symposium no. 30. University of Toronto: Academic Press. Bibcode:1967IAUS...30...57E. Retrieved 2009-09-24.
6. ^ Reiners, A. (January 2006). "Rotation- and temperature-dependence of stellar latitudinal differential rotation". Astronomy and Astrophysics. 446 (1): 267–277. arXiv:. Bibcode:2006A&A...446..267R. doi:10.1051/0004-6361:20053911.
7. ^ a b c d 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:. Bibcode:2007A&A...475..519H. doi:10.1051/0004-6361:20077221. See the entry for HIP 21770 in the VizieR table with CDS ID V/117A.
8. ^ a b Pasinetti Fracassini, L. E.; Pastori, L.; Covino, S.; Pozzi, A. (February 2001). "Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics". Astronomy and Astrophysics. 367 (2): 521–524. arXiv:. Bibcode:2001A&A...367..521P. doi:10.1051/0004-6361:20000451.
9. ^ a b Reiners, A.; Schmitt, J. H. M. M. (December 2003). "Differential rotation in rapidly rotating F-stars". Astronomy and Astrophysics. 412 (3): 813–819. arXiv:. Bibcode:2003A&A...412..813R. doi:10.1051/0004-6361:20034255.
10. ^ a b Alpha Cae, Stars, Jim Kaler. Accessed on line November 5, 2009.
11. ^ * alf Cae -- Star in double system, database entry, SIMBAD. Accessed on line November 4, 2009.
12. ^ Petit, M. (November 1977). "Etoiles Proches Suspectees de Variabilite". Information Bulletin on Variable Stars. 1362: 1–3. Bibcode:1977IBVS.1362....1P. Retrieved 2009-09-24.
13. ^ Hawley, Suzanne L.; Gizis, John E.; Reid, Neill I. (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. ^ 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.
15. ^ Poveda, A.; et al. (April 1994). "Statistical studies of visual double and multiple stars. II. A catalogue of nearby wide binary and multiple systems". Revista Mexicana Astronomía y Astrofísica. 28 (1): 43–89. Bibcode:1994RMxAA..28...43P. Retrieved 2009-09-24.
16. ^ 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.