CX CMa (CX Canis Majoris) is a blue

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

in the

Canis Major Canis Major is a constellation in the Southern Celestial Hemisphere, southern celestial hemisphere. In the second century, it was included in Ptolemy's 48 constellations, and is counted among the 88 modern constellations. Its name is Latin fo ...

constellation. Discovery of this variable is usually credited to German Astronomer

Cuno Hoffmeister Cuno Hoffmeister (2 February 1892 – 2 January 1968) was a German astronomer, observer and discoverer of variable stars, comets and minor planets, and founder of Sonneberg Observatory. Born in Sonneberg in 1892 to Carl and Marie Hoffmeister, Cu ...

in 1931, although this remains uncertain. It is an

eclipsing binary 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 ...

of Algol ( detached) whose magnitude varies between 9.9 and 10.4 with a period of 0.95462500 day (22.911000 hour). The variability was first discovered in 1931. Doubts arose because of scatter in the data and the small amplitude, but the discovery was confirmed by 1949. Its Algol-type light curve exhibits the

O'Connell effect The O'Connell effect is an asymmetry in the photometric light curve of certain close eclipsing binary stars. It was named after the astronomer Daniel Joseph Kelly O'Connell, SJ of Riverview College in New South Wales who in 1951 studied this phe ...

, meaning that there is a magnitude difference between subsequent maxima. The temperature of the secondary star has been estimated at about 10,600 K and its mass at . The spectral type of the secondary star is estimated to be in the B8 to A0 range.

References

{{DEFAULTSORT:CX Canis Majoris B-type main-sequence stars Canis Major Beta Lyrae variables Canis Majoris, CX Durchmusterung objects