V533 Herculis was a nova visible to the naked eye, which occurred in 1963 in the

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 first constellati ...

Hercules Hercules (, ) is the Roman equivalent of the Greek divine hero Heracles, son of Jupiter and the mortal Alcmena. In classical mythology, Hercules is famous for his strength and for his numerous far-ranging adventures. The Romans adapted the Gr ...

. The nova was discovered by the Swedish amateur astronomer Elis Dahlgren on 6 February 1963, and independently by an American amateur, Leslie Peltier, on 7 February 1963. Both reported it to be a 4th magnitude star. Subsequent examination of pre-discovery images, taken by the Baker-Nunn satellite tracking group at the Tokyo Observatory, showed that the star had begun its nova event as early as 18:36 UT on 26 January 1963, when it had an magnitude of 8. It had attained its peak brightness, magnitude 3, by 17:38 UT on 30 January 1968. All novae are binary stars, with a "donor" star transferring matter to a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

. In the case of V533 Herculis, the pair's orbital period is 3.43 hours. Thorstensen and Taylor analysed spectra of the star in its quiescent state, and concluded that it is a non-eclipsing SW Sextantis variable, implying that the donor star is a

red dwarf A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...

. Knigge derived a mass of 0.225 M_⊙, and a radius of 0.333 R_⊙, for the donor star. V533HerNebulaExpanding

Images of V533 Herculis taken with the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

show a faint, approximately circular shell (

nebula A nebula (; or nebulas) is a distinct luminescent part of interstellar medium, which can consist of ionized, neutral, or molecular hydrogen and also cosmic dust. Nebulae are often star-forming regions, such as in the Pillars of Creation in ...

) with a diameter of 10±1.4 arc seconds, surrounding the star. The shell is expanding at 850±150 km/sec. Santamaria ''et al.'' obtained similar results by comparing images of the shell taken in 1993 and 2018. They found that by 2018 the slightly elliptical shell had major and minor axis of 16.8×15.2 arc seconds, and it was expanding at a rate of 0.152×0.139 arc seconds per year, implying a physical expansion rate of 850×770 km/sec. V533HerLocation

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{{DEFAULTSORT:V533 Herculis Novae Hercules (constellation) 1963 in science Herculis, V533