In the late nineteenth century, Harvard College Observatory director Edward Pickering hired a group of women, later known as the "Harvard Computers," to process astronomical data. Among them was Williamina Fleming, who developed a classification system for stars based on the amount of hydrogen observed in their spectra. Fleming organized the stars alphabetically from A to Q, with "A" stars possessing the most prominent hydrogen lines. While Pickering later modified this system with Annie Jump Cannon to reorganize the categories by stellar temperature rather than hydrogen abundance, Fleming's initial system cataloged over ten thousand stars and established the foundational methodology of spectral analysis. Crucially, Fleming's cataloging relied on examining photographic glass plates rather than observing stars directly through a telescope, a practice that allowed her to identify numerous novae and nebulae.
Based on the text, what is true of Williamina Fleming's stellar classification system?
- AIt was developed primarily to assist other astronomers in identifying novae and nebulae.
- It ordered stars using alphabetical categories that corresponded to the prominence of hydrogen in stellar spectra.Cevap
- CIt required Fleming to make direct telescope observations of more than ten thousand stars.
- DIt categorized stars primarily according to their surface temperatures rather than their hydrogen levels.