WR 1 is a Wolf-Rayet star located around 10,300 light years away from

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in the constellation of Cassiopeia. It is only slightly more than twice the size of the sun, but due to a temperature over 100,000 K it is over 758,000 times as luminous as the sun. Although WR 1 has been recognised as a Wolf-Rayet star since the 19th century, the WR 1 designation does not indicate that it was the first to be discovered. Ordered by

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the March equinox to the (hour circle of the) point in question above the earth. When paired w ...

, WR 1 is the first star in the Seventh Catalogue of galactic Wolf-Rayet stars. WR 1 is a member of the nitrogen sequence of WR stars and has a spectrum with He_II lines much stronger than He_I lines, and N_V emission more than twice the strength of N_III, leading to the assignment of a WN4 spectral type. The spectrum has particularly wide He_II, leading to the equivalent classifications of WN4-b (for broad) or WN4-s (for strong). The spectrum also includes C_IV and N_IV, but no hydrogen lines at all, indicating that WR 1 has already expelled all of its hydrogen through its powerful solar winds. WR 1 is slightly

variable Variable may refer to: * Variable (computer science), a symbolic name associated with a value and whose associated value may be changed * Variable (mathematics), a symbol that represents a quantity in a mathematical expression, as used in many ...

and given the

variable star designation In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the constell ...

V863 Cassiopeiae. The total amplitude of the variations is only 0.09 magnitudes at visual wavelengths. The variations are well-defined with a period of 16.9 days, but the light curve is not sinusoidal and its shape may vary. The variations have been ascribed to a dense asymmetric

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 ...

and co-rotating interacting regions in ejected material. It has been suggested that the variability and an infrared excess could be due to a cool companion, but WR 1 is now considered to be a single star. The WN-b subclass of Wolf-Rayet star are generally thought to be all single, in contrast with the WN-A subclass which have narrow emission on a stronger continuum and are thought to be binary systems with a more conventional hot luminous star. WR 1 is a possible member of the Cassiopeia OB7

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at a distance of around , although its

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parallax suggests it is more distant. Interstellar extinction is calculated to be 2.1 magnitudes, and at the bolometric luminosity would be . A temperature of is derived from fitting the spectrum, giving a radius of .

References

{{Stars of Cassiopeia Cassiopeia (constellation) Wolf–Rayet stars Cassiopeiae, V863 Durchmusterung objects 004004 003415 TIC objects