Infrared properties of OH/IR stars. I. Near infrared observation and some physical parameters of OH/IR stars

We present near infrared observations of 59 Type II OH/IR stars with their IRAS data. Using different color-color diagrams, some properties of OH/IR stars are analysed. Some physical parameters are statistically derived by fitting the infrared photometric data with a ''double blackbody model'', and a correlation between color temperatures and periods is found for Type II OH/IR stars. Several possible correlations are found between the evolutionary status of OH/IR stars and their near infrared properties, and we try to describe an evolutionary scheme for the OH/IR stars.