We present a catalog of 166 spectroscopically identified hot subdwarf stars from LAMOST DR1 , 44 of which show the characteristics of cool companions in their optical spectra .
Atmospheric parameters of 122 non-composite spectra subdwarf stars were measured by fitting the profiles of hydrogen ( H ) and helium ( He ) lines with synthetic spectra from non-LTE model atmospheres .
Most of the sdB stars scatter near the Extreme Horizontal Branch in the T _ { eff } - \log { g } diagram and two well defined groups can be outlined .
A clustering of He-enriched sdO stars appears near T _ { eff } = 45 000 K and \log ( g ) = 5.8 .
The sdB population separates into several nearly parallel sequences in the T _ { eff } - { He } abundance diagram with clumps corresponding to those in the T _ { eff } - \log { g } diagram .
Over 38 000 K ( sdO ) stars show abundance extremes , they are either He-rich or He-deficient and we observe only a few stars in the -1 < \log ( y ) < 0 abundance range .
With increasing temperature these extremes become less prominent and the He abundance approaches to \log ( y ) \sim - 0.5 .
A unique property of our sample is that it covers a large range in apparent magnitudes and galactic latitudes , therefore it contains a mix of stars from different populations and galactic environments .
Our results are consistent with the findings of Hirsch ( 2009 ) and we conclude that He-rich and He-deficient sdB stars ( \log ( y ) < 1 ) probably origin from different populations .
We also find that most sdO and sdB stars lie in a narrow strip in the luminosity and helium abundance plane , which suggests that these atmospheric parameters are correlated .