Transcript: The sequence of stellar spectral classes is also a sequence of photospheric temperature. Going through the stellar sequence, we have O stars with temperatures of 30,000 Kelvin, they are white hot or even blue as seen in the sky, B stars which are also bluish with temperatures of 18,000 degrees Kelvin, blue-white A stars with temperatures of 10,000 Kelvin, white F stars, temperatures of about 7,000 Kelvin, yellowish-white G stars (the Sun is a G star) with temperatures of about 5,500 Kelvin, orangish K stars with temperatures of about 4,000 Kelvin, and the coolest stars of all, orange or reddish M stars with temperatures of only 3,000 Kelvin.