Friday, April 12, 2013

Answer To Question 233

A233: The HD (Henry Draper) number is an identifying number assigned to the strs in the Henry Draper catalog. In this system, every star is classified by its stellar spectrum. This sytem is named for the astronomer Henry Draper, but was cataloged by Annie J. Cannon (225,300 stars), and later extended by Margaret W. Mayall. For example, the star Vega is HD 172167 (the spectral type is not in the HD number).

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