CV Serpentis is a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system in the

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

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 Serpens. It is a detached eclipsing binary with an orbital period of 29.7 days. The system includes a Wolf–Rayet (WR) star with the identifier WR 113. The system is located at a distance of approximately 6,700

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 from the Sun 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. It is a member of the Serpens OB2 association of co-moving stars. In 1892, this star was found to be an object of interest based on photographs of its peculiar stellar spectra taken from the

Boyden Station Boyden Observatory is an astronomical research observatory and science education centre located in Maselspoort, north-east of the city of Bloemfontein in Free State, South Africa. The observatory is managed by the Physics Department of the Un ...

in Arequipa, Peru. It was determined to be a carbon-type Wolf–Rayet (WR) star and in 1945 was found to be a

spectroscopic binary A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...

system by W. A. Hiltner. This system was reported to be an eclipsing binary by S. Gaposchkin in 1949, who found a decrease in brightness of 0.14 magnitude during the first eclipse and 0.08 in the second. R. M. Hjellming and W. A. Hiltner in 1963 measured a much deeper primary eclipse with a decrease of about 0.55 magnitude, then in 1970 K. Stępień saw no evidence of eclipsing. L. V. Kuhi and F. Schweizer confirmed this latter result, hypothesizing that it is the result of a changing Wolf-Rayet envelope. This is a double-lined spectroscopic binary system in a near circular orbit, meaning that the spectra of both components is visible. The companion of the WR star is a massive OB star with a

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 O8-9IV. A nebulous double-shell centered on CV Ser was discovered in 1984, spanning angular diameters of and . The diffuse outer ring is incomplete, spanning a radius of at an approximate distance of two kiloparsecs. Variations in the system's light curve continued to be observed, suggesting changes in the outflow from the Wolf-Rayet star. An emission feature in the spectrum of the system was interpreted as a region between the two stars where their

stellar wind A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. D ...

s are colliding, forming a shock region of

plasma Plasma or plasm may refer to: Science * Plasma (physics), one of the four fundamental states of matter * Plasma (mineral), a green translucent silica mineral * Quark–gluon plasma, a state of matter in quantum chromodynamics Biology * Blood pla ...

. The system is expected to evolve into a binary with the OB-star and an

black hole A black hole is a region of spacetime where gravitation, gravity is so strong that nothing, including light or other Electromagnetic radiation, electromagnetic waves, has enough energy to escape it. The theory of general relativity predicts t ...

following a

failed supernova A failed supernova is an astronomical event in time domain astronomy in which a star suddenly brightens as in the early stage of a supernova, but then does not increase to the massive flux of a supernova. They could be counted as a subcategory of ...

where the WR star collapses with little or no visible explosion. The OB star is observed to be rotating rapidly at between 310 and using spectral lines of neutral helium. Observations using ionized helium

absorption line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s show a lower velocity, interpreted as showing an

oblate In Christianity (especially in the Roman Catholic, Orthodox, Anglican and Methodist traditions), an oblate is a person who is specifically dedicated to God or to God's service. Oblates are individuals, either laypersons or clergy, normally livi ...

shape with

gravity darkening Gravity darkening, also referred to as gravity brightening, is an astronomical phenomenon where the poles of a star are brighter than the equator, due to rapid rotation and oblate shape. When a star is oblate, it has a larger radius at its equat ...

causing lower temperatures at the equator. Speckle interferometry has found a companion star from the bright primary and eight magnitudes fainter. The projected separation of is much larger than the maximum possible separation of the Wolf-Rayet and OB pair. If it is found to be at the same distance as the bright spectroscopic pair, it would likely be an F-type

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 ...

star in an orbit with a period around 100,000 years and the lowest-luminosity known companion of any WR star at .

References

Further reading