AI Velorum is a

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

in the southern

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

of Vela, abbreviated AI Vel. It is a prototype for a class of high

amplitude The amplitude of a periodic variable is a measure of its change in a single period (such as time or spatial period). The amplitude of a non-periodic signal is its magnitude compared with a reference value. There are various definitions of amplit ...

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 year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s based on

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements, and it is drifting further away with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of about 9 km/s. The variability of this star was announced by E. Hertzsprung in 1931. He found a period of about , 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 while the secondary is ; together their interference creates a beat period of . The height of the maximum was found to be greater than the depth of the minimum, which may be the result of

shockwave In physics, a shock wave (also spelled shockwave), or shock, is a type of propagating disturbance that moves faster than the local speed of sound in the medium. Like an ordinary wave, a shock wave carries energy and can propagate through a me ...

s 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 In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction grati ...

of AI Vel is A9IV/V, matching a slightly

evolved Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation t ...

star that is moving away from the

main sequence In astronomy, the main sequence is a continuous and distinctive band of stars that appears on plots of stellar color versus brightness. These color-magnitude plots are known as Hertzsprung–Russell diagrams after their co-developers, Ejnar Her ...

. It is 479 million years old and is estimated to have 1.55 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

. 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 The ''Gaia'' catalogues are star catalogues created using the results obtained by ''Gaia'' space telescope. The catalogues are released in stages that will contain increasing amounts of information; the early releases also miss some stars, especia ...

show it to be approaching the end of its main sequence life.

References

Further reading