<Tr> <Th> h </Th> <Td> WR stars with emission lines due to hydrogen . </Td> </Tr> <Tr> <Th> ha </Th> <Td> WR stars with hydrogen emissions seen on both absorption and emission . </Td> </Tr> <Tr> <Th> He wk </Th> <Td> Weak Helium lines </Td> </Tr> <Tr> <Th> k </Th> <Td> Spectra with interstellar absorption features </Td> </Tr>

From hottest to coolest the order of the spectral types of stars is