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4 Lacertae is a single star in the northern constellation
Lacerta Lacerta is one of the 88 modern constellations defined by the International Astronomical Union. Its name is Latin for lizard. A small, faint constellation, it was defined in 1687 by the astronomer Johannes Hevelius. Its brightest stars form a "W" ...
, located about 1,900  light years away. This object visible to the naked eye as a white-hued star with an
apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's lig ...
of 4.55. It is moving closer to the Earth with a heliocentric radial velocity of −26 km/s. This star is a suspected member of the Lac OB1 association. This is a
supergiant Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spa ...
star with a stellar classification of A0 Ib. The surface abundances show evidence of material that has been processed via the
CNO cycle The CNO cycle (for carbon–nitrogen–oxygen; sometimes called Bethe–Weizsäcker cycle after Hans Albrecht Bethe and Carl Friedrich von Weizsäcker) is one of the two known sets of fusion reactions by which stars convert hydrogen to helium, ...
at the core. It has ten times the mass of the Sun and has expanded to about 59 times the Sun's radius. The star is around 25 million years old and is spinning with a
projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulg ...
of 28 km/s.


References

{{DEFAULTSORT:4 Lacertae A-type supergiants Lacerta (constellation) J22243097+4928351 Durchmusterung objects Lacertae, 04 212593 110609 8541