V2052 Ophiuchi, also known as HR 6684, is a star about 920

light year A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distance, astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by t ...

s from Earth in the constellation

Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...

. It is a 5th-

magnitude Magnitude may refer to: Mathematics *Euclidean vector, a quantity defined by both its magnitude and its direction *Magnitude (mathematics), the relative size of an object *Norm (mathematics), a term for the size or length of a vector *Order of ...

star, making it faintly visible to the

naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...

of an observer far from

city lights ''City Lights'' is a 1931 American synchronized sound film, sound romance film, romantic comedy drama, comedy-drama film written, produced, directed by, and starring Charlie Chaplin. While the film has no audible dialog, it was released with a ...

. V2052 Ophiuchi is a

Beta Cephei variable Beta Cephei variables, also known as Beta Canis Majoris stars, are variable stars that exhibit small rapid variations in their brightness due to pulsations of the stars' surfaces, thought due to the unusual properties of iron at temperatures of 200 ...

(β Cep) star, varying slightly in brightness from magnitude 5.81 to 5.84 over a period of about 3.4 hours. In 1972, Mikolaj Jerzykiewicz announced that HR 6684 is a variable star, based on his observations using the 0.6 meter Air Force Telescope on

Mauna Kea Mauna Kea (, ; abbreviation for ''Mauna a Wākea''); is a dormant Shield volcano, shield volcano on the Hawaii (island), island of Hawaii. Its peak is above sea level, making it the List of U.S. states by elevation, highest point in Hawaii a ...

. He classified the star as a β Cep variable with period of 0.13989 days, He further noted that if confirmed, it would be the least luminous and shortest period β Cep star known up to that date.

Spectroscopic Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectrosc ...

and photometric observations by D. Harold McNamara and Bruce Bills in 1973 confirmed Jerzykiewicz's results. In 1973, HR 6684 was given the

variable star designation In astronomy, a variable-star designation is a unique identifier given to variable stars. It extends the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constellation in whic ...

V2052 Ophiuchi. In 1994, Henryk Cugier ''et al.'' determined that V2052 Ophiuchi pulsated primarily in the fundamental (l=0) radial mode. A much less powerful non-radial pulsation mode was identified in 2003. Ultraviolet observations by the

TD-1A TD-1A, or Thor-Delta 1A (or just TD-1), was a European astrophysical research satellite which was launched in 1972. Operated by the European Space Research Organisation, TD-1A made astronomical surveys primarily in the ultraviolet, but also using ...

satellite show that throughout its pulsation cycle, the temperature of V2052 Ophiuchi varies by , and its radius changes by . Observations at the Pic du Midi Observatory showed that V2052 Ophiuchi has a dipole magnetic field, the axis of which is offset from the star's center, and there are helium spots on the surface near the magnetic poles. V2052 Ophiuchi is a type of

chemically peculiar star In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual Metallicity, metal abundances, at least in their surface layers. Classification Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) ...

known as a helium-strong star. Its surface is over-abundant in helium, and under-abundant in oxygen, perhaps due to its magnetic field differentially effecting the diffusion of elements in its atmosphere.

References

{{DEFAULTSORT:V2052 Ophiuchi Ophiuchus 87812 163472 Ophiuchi, V2052 6684 Beta Cephei variables Helium-weak stars