The radial velocity of a star is close to or far from the observer, which can be measured from the red shift or blue shift of the spectrum. American astronomer Vesta Slipher made a series of measurements from 1902 to 1904, and found that its radial velocity changed periodically. He thinks it is a pair of split binary stars with an orbital period of about 100 days [6]. In 1907, Hans Rudolf announced the preliminary orbit [7], and later, Robert Hollesbeck announced the more accurate orbit [8].

The dim stars in the system were first discovered by Pan Xiaopei and his colleagues using the interferometer between 1988 and 1989. They used the Mark III stellar interferometer of Mount Wilson Observatory in California, and the results of this work were published in 1992 [9]. Because the luminosity of the two stars is different, the spectral lines of this case cannot be distinguished before 1990. The observation results of jocelyn Tomkin, Pan Xiaopei and James K McCarthy from 199 1 to 1994 are published in 1995 [10].

The period of revolution of these two stars is 96.7 days [1 1]. The bigger and brighter star is called the main star, its spectral type is B8IVpMnHg, its mass is about 3.6 solar masses, its surface temperature is about 13800k, and the luminosity measured at each wavelength is about 200 times that of the sun. Smaller and darker companion stars are called secondary stars, with a mass of about 1.8 solar mass, a surface temperature of about 8,500K, and luminosity of all wavelengths is about 10 times that of the sun. It is an early type A star, and its spectral type is estimated as A3V.