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. The apparent visual magnitude of this star fluctuates around 6.56, 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, and it is drifting further away with a radial velocity of about 9 km/s.
The variability of this star was announced by E. Hertzsprung in 1931. He found a period of about 2.67 hours, although he later found that period doubtful. In 1937, F. Zagar found irregular variations in the light curve. 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.
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. By 1985, there was some evidence for an increase in the second period by one part in 105. At least two additional periodicities were identified by Walraven and associates in 1992.
The stellar classification of AI Vel is A9IV/V, 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. As a Delta Scuti variable, the brightness of the star ranges in magnitude from 6.15 down to 6.76. Evolutionary models published with Gaia Data Release 3 show it to be approaching the end of its main sequence life.
References
Further reading
- Guiglion, G.; et al. (February 2013), "Understanding the dynamical structure of pulsating stars: The Baade-Wesselink projection factor of the δ Scuti stars AI Velorum and β Cassiopeiae", Astronomy & Astrophysics, 550: 4, arXiv:1301.2475, Bibcode:2013A&A...550L..10G, doi:10.1051/0004-6361/201220780, S2CID 118666931, L10.
- Guiglion, G.; et al. (December 2012), Boissier, S.; et al. (eds.), "The Baade-Wesselink projection factor of the δ-Scuti stars AI Vel and β Cas", SF2A-2012: Proceedings of the Annual Meeting of the French Society of Astronomy and Astrophysics: 337–342, Bibcode:2012sf2a.conf..337G.
- Guzik, J. A. (December 1993), "Radial and Nonradial Periods and Growth Rates of an AI Velorum Model", Astrophysics and Space Science, 210 (1–2): 321–323, Bibcode:1993Ap&SS.210..321G, doi:10.1007/BF00657916, S2CID 189847932.
- Cox, A. N.; Hodson, S. W. (1980), "A nonlinear study of AI Velorum", Nonradial and nonlinear stellar pulsation; Proceedings of the Workshop, Tucson, Ariz., March 12–16, 1979. (A81-21401 07-90), Lecture Notes in Physics, vol. 125, Berlin: Springer-Verlag, pp. 41–49, Bibcode:1980LNP...125...41C, doi:10.1007/3-540-09994-8_4, ISBN 978-3-540-09994-9, S2CID 118779736.
- Simon, N. R. (April 1979), "On the oscillations of AI Velorum", Astronomy and Astrophysics, 74: 30–37, Bibcode:1979A&A....74...30S.
- Elst, E. W. (November 1975), "V photometric observations of AI Vel", Astronomy and Astrophysics Supplement Series, 22: 221–233, Bibcode:1975A&AS...22..221E.
- Barnes, T. G., III; Moffett, T. J. (January 1975), "Photometric properties and evidence of duplicity for SZ Lyncis", Astronomical Journal, 80: 48–55, Bibcode:1975AJ.....80...48B, doi:10.1086/111712.
{{citation}}: CS1 maint: multiple names: authors list (link) - Petersen, J. O.; Jørgensen, H. E. (March 1972), "Pulsation of models in the lower part of the cepheid instability strip and properties of AI Velorum and delta Scuti stars", Astronomy and Astrophysics, 17: 367, Bibcode:1972A&A....17..367P.
- Walraven, Th. (February 1955), "The pulsations of AI Velorum, SX Phoenicis and RR Lyrae", Bulletin of the Astronomical Institutes of the Netherlands, 12: 223, Bibcode:1955BAN....12..223W.
- Gratton, L. (May 1953), "On the velocity curve of AI Velorum", Bulletin of the Astronomical Institutes of the Netherlands, 12: 31, Bibcode:1953BAN....12...31G.
- Gratton, L.; Lavagnino, C. J. (1953), "Spektrographische Beobachtungen des veränderlichen AI Velorum. Mit 8 Textabbildungen", Zeitschrift für Astrophysik, 32: 69, Bibcode:1953ZA.....32...69G.