AI Velorum

AI Velorum is a variable star in the southern constellation of Vela, abbreviated AI Vel. It is a prototype for a class of high amplitude Delta Scuti variables.[10] The apparent visual magnitude of this star fluctuates around 6.56,[3] which is just bright enough to be dimly visible to the naked eye. The distance to AI Vel is approximately 327 light years based on parallax measurements,[2] and it is drifting further away with a radial velocity of about 9 km/s.[6]

AI Velorum

A light curve for AI Velorum, plotted from TESS data[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Vela
Right ascension 08h 14m 05.146s[2]
Declination −44° 34′ 32.85″[2]
Apparent magnitude (V) 6.56[3] (6.15 to 6.76)[4]
Characteristics
Spectral type A9IV/V[5]
B−V color index 0.18±0.02[3]
Variable type δ Sct[4]
Astrometry
Radial velocity (Rv)9.0±2.4[6] km/s
Proper motion (μ) RA: 26.222 mas/yr[2]
Dec.: 31.094 mas/yr[2]
Parallax (π)9.9703 ± 0.0191 mas[2]
Distance327.1 ± 0.6 ly
(100.3 ± 0.2 pc)
Absolute magnitude (MV)1.61[3]
Details
Mass1.55[7] M☉
Radius2.86[2] R☉
Luminosity20[2] L☉
Surface gravity (log g)3.85±0.14[7] cgs
Temperature7,496±255[7] K
Metallicity [Fe/H]−1.33[2] dex
Rotational velocity (v sin i)18[8] km/s
Age479[7] Myr
Other designations
AI Vel, CD–44°4192, GC 11221, HD 69213, HIP 40330, SAO 219640[9]
Database references
SIMBADdata

The variability of this star was announced by E. Hertzsprung in 1931. He found a period of about 2.67 hours,[11] although he later found that period doubtful. In 1937, F. Zagar found irregular variations in the light curve.[12] T. Walraven classified it as an RR Lyrae star in 1952 and suggested it may have two periods that interfered with each other. The primary period was found to be 2.678 hours while the secondary is 2.069 hours; together their interference creates a beat period of 9.100 hours. The height of the maximum was found to be greater than the depth of the minimum, which may be the result of shockwaves that increase light emission.[13]

As an RR Lyrae variable, AI Velorum should be a low mass, evolved star. However, M. Breger in 1977 noted the period and surface gravity showed a match with Delta Scuti stars of the same period. Together with the space velocity, these indicated it is instead a normal, high mass star belonging to the younger population I.[14] By 1985, there was some evidence for an increase in the second period by one part in 105.[15] At least two additional periodicities were identified by Walraven and associates in 1992.[10]

The stellar classification of AI Vel is A9IV/V,[5] matching a slightly evolved star that is moving away from the main sequence. It is 479 million years old and is estimated to have 1.55 times the mass of the Sun.[7] As a Delta Scuti variable, the brightness of the star ranges in magnitude from 6.15 down to 6.76.[4] Evolutionary models published with Gaia Data Release 3 show it to be approaching the end of its main sequence life.[2]

References
  1. MAST: Barbara A. Mikulski Archive for Space Telescopes, Space Telescope Science Institute, retrieved 10 August 2022.
  2. 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.
  3. Anderson, E.; Francis, Ch. (2012), "XHIP: An extended hipparcos compilation", Astronomy Letters, 38 (5): 331, arXiv:1108.4971, Bibcode:2012AstL...38..331A, doi:10.1134/S1063773712050015, S2CID 119257644.
  4. Samus, N. N.; et al. (2017), "General Catalogue of Variable Stars", Astronomy Reports, 5.1, 61 (1): 80–88, Bibcode:2017ARep...61...80S, doi:10.1134/S1063772917010085, S2CID 125853869.
  5. Houk, N. (1978), "Michigan Catalogue of two dimensional spectral types for the HD stars", Michigan Spectral Survey, 2, Bibcode:1978mcts.book.....H.
  6. Gontcharov, G. A. (November 2006), "Pulkovo Compilation of Radial Velocities for 35495 Hipparcos stars in a common system", Astronomy Letters, 32 (11): 759–771, arXiv:1606.08053, Bibcode:2006AstL...32..759G, doi:10.1134/S1063773706110065, S2CID 119231169.
  7. David, Trevor J.; Hillenbrand, Lynne A. (2015), "The Ages of Early-Type Stars: Strömgren Photometric Methods Calibrated, Validated, Tested, and Applied to Hosts and Prospective Hosts of Directly Imaged Exoplanets", The Astrophysical Journal, 804 (2): 146, arXiv:1501.03154, Bibcode:2015ApJ...804..146D, doi:10.1088/0004-637X/804/2/146, S2CID 33401607.
  8. Rodríguez, E.; et al. (June 2000), "A revised catalogue of δ Sct stars", Astronomy and Astrophysics Supplement, 144 (3): 469–474, Bibcode:2000A&AS..144..469R, doi:10.1051/aas:2000221.
  9. "AI Vel". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2022-08-03.
  10. Walraven, Th.; et al. (January 1992), "Discovery of additional pulsation modes in AI Velorum", Monthly Notices of the Royal Astronomical Society, 254: 59–66, Bibcode:1992MNRAS.254...59W, doi:10.1093/mnras/254.1.59.
  11. Hertzsprung, E. (August 1931), "A new variable star of short period", Bulletin of the Astronomical Institutes of the Netherlands, 6: 147, Bibcode:1931BAN.....6..147H.
  12. van Hoof, A. (June 1937), "Photographic photometry of AI Velorum on Johannesburg plates", Bulletin of the Astronomical Institutes of the Netherlands, 8: 172, Bibcode:1937BAN.....8..172V.
  13. Walraven, Th. (July 1952), "On the light-variation of AI Velorum", Bulletin of the Astronomical Institutes of the Netherlands, 11: 421, Bibcode:1952BAN....11..421W.
  14. Breger, M. (June 1977), "The nature of dwarf cepheids. III. AI Velorum", Publications of the Astronomical Society of the Pacific, 89: 339–344, Bibcode:1977PASP...89..339B, doi:10.1086/130129, S2CID 123575099.
  15. Bates, B.; Halliwell, D. R. (October 1985), "Observations of the light and colour variations of AI Velorum using an acousto-optic filter photometer", Astronomy and Astrophysics, 151: 403–407, Bibcode:1985A&A...151..403B.

Further reading
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