6. It was later realized that the strength of a star's absorption lines can be predicted if the star's surface temperatu

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6 It Was Later Realized That The Strength Of A Star S Absorption Lines Can Be Predicted If The Star S Surface Temperatu 1 (134.32 KiB) Viewed 24 times

6 It Was Later Realized That The Strength Of A Star S Absorption Lines Can Be Predicted If The Star S Surface Temperatu 2 (55.18 KiB) Viewed 24 times

It was later realized that the strength of a star's absorption lines can be predicted if the star's
surface temperature is known. This is because the heat of a star can excite electrons up to higher
energy levels. For example, most hydrogen atoms in very hot stars are ionized (the electron
leaves the atom completely,) and thus show very weak Balmer Series absorption lines. Cool
stars keep most of their electrons in the 1st energy level. The medium temperature stars show the
strongest Balmer lines because most of their electrons start in the 2nd energy level.
Therefore, it is more intuitive to classify stars based on their temperature rather than on their
Balmer lines alone. Astronomers reordered the classification sequence such that the hottest stars
came first, but they retained the letters originally assigned to each star based on their Balmer line
strengths.
6. It was later realized that the strength of a star's absorption lines can be predicted if the star's surface temperature is known. This is because the heat of a star can excite electrons up to higher energy levels. For example, most hydrogen atoms in very hot stars are ionized (the electron leaves the atom completely,) and thus show very weak Balmer Series absorption lines. Cool stars keep most of their electrons in the 1s energy level. The medium temperature stars show the strongest Balmer lines because most of their electrons start in the 2nd energy level. Therefore, it is more intuitive to classify stars based on their temperature rather than on their Balmer lines alone. Astronomers reordered the classification sequence such that the hottest stars came first, but they retained the letters originally assigned to each star based on their Balmer line strengths. a) Reorder the classification sequence by listing the panel numbers from hottest star to coolest star in the first column of Table 4. b) In the second column of Table 4, write down the letter you assigned each panel in Table 2. CONGRATULATIONS, YOU JUST OBTAINED THE (NON-ALPHABETICAL) STELLAR CLASSIFICATION SEQUENCE USED BY ASTRONOMERS.
Panel Number hottest star to coolest Table 4 Corresponding Spectral Class (Letter Designation from Table 2) hottest coolest