Masses for 664 single-lined hot subdwarf stars identified in LAMOST were calculated by comparing synthetic fluxes from spectral energy distribution with observed fluxes from a Virtual Observatory service. Three groups of hot subdwarf stars were selected from the whole sample according to their parallax precision to study the mass distributions. We found that He-poor sdB/sdOB stars present a wide mass distribution from 0.1 to 1.0M_{sun} with a sharp mass peak at around 0.46M{sun}, which is consistent with canonical binary model prediction. He-rich sdB/sdOB/sdO stars present a much flatter mass distribution than He-poor sdB/sdOB stars and with a mass peak at around 0.42M{sun}. By comparing the observed mass distributions to the predictions of different formation scenarios, we concluded that the binary merger channel, including two helium white dwarfs (He-WDs) and He-WD + main-sequence mergers, cannot be the only main formation channel for He-rich hot subdwarfs, and other formation channels, such as the surviving companions from Type Ia supernovae, could also make impacts on producing this special population, especially for He-rich hot subdwarfs with masses less than 0.44M{sun}. He-poor sdO stars also present a flatter mass distribution with an inconspicuous peak mass at 0.18M{sun}. The similar mass-{Delta}RV_max distribution between He-poor sdB/sdOB and sdO stars supports the scenario that He-poor sdO stars could be the subsequent evolution stage of He-poor sdB/sdOB stars.

Cone search capability for table J/ApJ/953/122/table1 (Main parameters for the 664 hot subdwarfs selected in this study)