Study Of The OB Stars From LAMOST Data

Massive stars which are usually a mass greater than 8M? are the main reason for the addition and reionizations of elements in the universe,they play an important role in the evolution of their host galaxies.As massive stars,OB stars have an important influence on galaxy media,element abundance,star formation and evolution of galaxies in the universe mainly by ultraviolet radiation,stellar winds loss and eventually nuclear collapse the nova bomb.In addition,OB stars have the characteristics of short life,and it is also an important probe to study the distribution of star formation and distribution of molecular cloud.At present,internationally known galaxy OB stars mainly come from the sun's neighborhood and their number are limited,thus more OB stars are important for studying the structure of the galaxy,star formation,and the physics of stars associated with massive stars.This work is based on the LAMOST DR4 huge star spectrum data,a study of the Milky Way OB stars spectrum characteristics and spatial distribution,the development of the spectral index method based on accurate spectrum that is calculated.We successfully selected 11,676 OB stars by using the method,including 59 O stars and 11,627 B stars.they are repeated inspection by the human eye.It has been proved that our spectral index method can effectively eliminate a large number of not OB samples and greatly improve the working efficiency.Because of the time,we can't use our eyes to complete the spectrum and photometric classification of all OB stars.At present,we only selected 1,505 OB stars from them,and the detailed spectral type and photometric identification were identified by the eyes.The sample of OB stars maximum cover the spectrum from O4-B9 all the spectral type and luminosity,for the next step,we will give all 11,676 OB stars of spectral type and luminosity type classification by using the method of machine learning.This paper consists of six parts.In the first part,we introduce the Harvard classification system and classification of MK,spectrum characteristics of O type star and B type star,the research significance and purpose of OB stars;In the second part,we introduce the LAMOST survey and the dataset that were used in this paper;In the third part,we give the research method and the selection of spectral index.In the fourth part,the spectral of OB stars and catalogue of OB stars that we get are introduced;we give the parameter's analysis and the spatial distribution of OB stars in section five;The last part gives the summary of this article.