What did Annie Jump Cannon originally use as a proxy for temperature when formalizing the spectral classification system?
Answer
The visibility and strength of hydrogen lines
When Annie Jump Cannon formalized the system, she organized stars based on the visibility and strength of hydrogen lines, which turned out to be a perfect proxy for surface temperature.
Related Questions
What physical property is fundamental for astronomers sorting stars into the O, B, A, F, G, K, M sequence?Which sequence correctly lists the main spectral classes from hottest to coolest?What temperature range generally defines O-type stars, the hottest class?What spectral characteristic is a key identifier for A-type stars?Which spectral class includes our Sun, and what is its typical color?What feature dominates the spectra of M-type stars?How are finer distinctions made within the OBAFGKM sequence (e.g., between G0 and G5)?What characteristic spectral signature is observed in B-type stars?What is the primary purpose of the Yerkes luminosity classification system, designated by Roman numerals?What did Annie Jump Cannon originally use as a proxy for temperature when formalizing the spectral classification system?