<P> The spectrum of VY CMa is that of a luminous class M star . The hydrogen lines have P Cygni profiles . The spectrum is dominated by TiO bands whose strength suggests a classification of M5 . The H line is not seen and there are unusual emission lines of neutral sodium and calcium . The luminosity class as determined from different spectral features varies from bright giant (II) to bright supergiant (Ia), with a compromise being given as M5eIbp . Early attempts at classification were confused by the interpretation of surrounding nebulosity as companion stars . </P> <P> The derived spectral class varies depending on the features examined . The spectral features also vary over time . It is considered to be unambiguously cooler than M2 and is usually classified between M3 and M4 . Classes as extreme as M2. 5 and M5 have been given . The luminosity class is likewise confused and often given only as I . </P> <P> VY Canis Majoris is a high - luminosity M star with an effective temperature of about 3,500 K, placing it at the upper - right hand corner of the Hertzsprung--Russell diagram and meaning it is a highly evolved star . During its main sequence, it would have been an O - type star with a mass of 15 to 35 M . </P> <P> In 2006, University of Minnesota Professor Roberta M. Humphreys used the spectral energy distribution distance of VY Canis Majoris to calculate its luminosity . Since most of the radiation coming from the star is reprocessed by the dust in the surrounding cloud, she integrated the total fluxes over the entire nebula and showed that VY Canis Majoris has a luminosity of 7005560000000000000 ♠ 5.6 × 10 L . </P>

What is the temperature of vy canis majoris