A system of classification of stars based on their spectral types, the chief classes (O, B, A, F, G, K, M) forming a series from hot bluish-white stars to cool dull red stars.
- ‘In 1910 Annie Jump Cannon, working under the direction of Pickering, modified the Harvard classification system taking all of the absorption lines into account.’
- ‘Stars are given a Harvard classification according to the dominant element found in their spectra and the classes are ordered according to their surface temperature.’
- ‘In the course of the Harvard classification study, some of the old spectral types were consolidated together, and the types were re-arranged to reflect a steady change in the strengths of representative spectral lines.’
- ‘This spectral sequence is known as the Harvard classification, although it can also be referred to as the MKK system after later development work by Morgan, Keenan and Kelman at Yerkes Observatory.’
- ‘This classification is based on spectral lines sensitive to stellar surface gravity which is related to luminosity, as opposed to the Harvard classification which is based on surface temperature.’
1960s: named after the observatory at Harvard University, where it was devised.
We take a look at several popular, though confusing, punctuation marks.