Choose the correct statements concerning spectral classes of stars. (Give ALL correct answers, i.e., B, AC, BCD...) A) Neutral hydrogen lines dominate the spectrum for stars with temperatures around 10,000 K because a lot of the hydrogen is in the n=2 level. B) Hydrogen lines are weak in type O-stars because most of it is completely ionized. C) Oh Be A Fine Guy/Girl Kiss Me, is a mnemonic for remembering spectral classes. D) The spectral sequence has recently been expanded to include L, T, and Y classes. E) K-stars are dominated by lines from ionized helium because they are so hot. F) The spectral types of stars arise primarily as a result of differences in temperature.
Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
- Choose the correct statements concerning spectral classes of stars. (Give ALL correct answers, i.e., B, AC, BCD...)
- A) Neutral hydrogen lines dominate the spectrum for stars with temperatures around 10,000 K because a lot of the hydrogen is in the n=2 level.
- B) Hydrogen lines are weak in type O-stars because most of it is completely ionized.
- C) Oh Be A Fine Guy/Girl Kiss Me, is a mnemonic for remembering spectral classes.
- D) The spectral sequence has recently been expanded to include L, T, and Y classes.
- E) K-stars are dominated by lines from ionized helium because they are so hot.
- F) The spectral types of stars arise primarily as a result of differences in temperature.
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