Estimation of the Flux at 1450 MHz of OB Stars for FAST and SKA

Radio observation is crucial to understanding the wind mechanism of OB stars but very scarce. This work estimates the flux at 1450 MHz (S _1.4GHz) of about 5000 OB stars identified by the LAMOST spectroscopic survey and confirmed by the Gaia astrometric as well as astrophysical measurements. The calculation is performed under the free-free emission mechanism for wind with the mass-loss rate derived from stellar parameters. The estimated S _1.4GHz distributes from 10^-11 to 10^-3 Jy with the peak at about 10^-8 Jy. This implies that the complete SKA-II can detect more than half of them, and some tens of objects are detectable by FAST without considering source confusion. An array of FAST would increase the detectable sample by 2 orders of magnitude.