Which of the following is NOT evidence of the existence of an interstellar medium?
a. extinction of light from distant stars
b. very narrow calcium absorption lines in the spectra of O and B stars
c. reddening of more distant stars
d. dark cloud silhouetted against background stars
e. molecular absorption lines in the spectra of cool stars
E
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Find the average density of a red giant star with a mass of 20 × 10^30 kg (approximately 10 solar masses) and a radius of 150 × 10^9 m (equal to the Earth's distance from the Sun)
a. 1.41 × 10^?4 kg/m3 b. 0.007 kg/m3 c. 1.41 kg/m3 d. 710 kg/m3 e. 1.41 × 10^?3 kg/m3
What is the orbital radius of the n = 3 excited state in the Bohr model of the hydrogen atom? The ground-state radius of the hydrogen atom is 0.529 × 10-10 m
A) 0.476 nm B) 0.159 nm C) 0.381 nm D) 0.548 nm
The photons coming from blackbody radiation create a(n) ____ spectrum
a. absorption b. emission c. Doppler d. continuous e. ionization
The motion of the Sun with respect to the stars is retrograde, i.e., east to west relative to the stars.
Answer the following statement true (T) or false (F)