Wilbert Smith Archives Files Box 1136 11 1136-11-p011

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ge We would therefore expect about 30 billion stars to have one or more planets, Now, we can reject certain classes of stars as candidates for habitable planets, because their lifetimes are too short (these are stars of high mass). Others can be rejected because of variabil- ity in light output, a characteristic that would make evolutionary de- velopment of life much more difficult, In fact if we select only those stars similar to the sun (whose peak of radiation energy coincides with a region...