earch science
Population 1 stars
Stars in the disk and arms that have small amounts of heavy elements
absorption lines
a set of dark lines that show frequencies at which light has been absorbed from a star's bright spectrum
Population 2 stars
found in the halo and bulge and contain even smaller traces of heavy elements
Sun composition
hydrogen and helium
emission lines
lines that are made when certain wavelengths of light, or colors, are given off by hot gases
HR diagram
A graph relating the temperature and brightness of stars
red giant
A large, reddish star late in its life cycle
white dwarf
A small, hot, dim star that is the leftover center of an old star
main sequence
a diagonal area on an H-R diagram that includes more than 90 percent of all stars
continuous spectrum
the emission of a continuous range of frequencies of electromagnetic radiation
Population 3 stars
the first generation of stars. They had virtually no metals at all. -The younger universe was hotter on average than it is today. -No cold, dense molecular clouds existed. these are the nebulae that form stars today. -And yet, astronomers see early galaxies of stars! -Population III stars would have been immense, up to several hundred solar masses. -Seeded the very young universe with the first metals formed by fusion in their cores
Photosphere
the visible surface of the sun
