PSU ASTRO 1 - Exam 3 Study Guide Latest

PSU ASTRO 1 - Exam 3 Study Guide Latest Update - Sources with 50 Questions and Verified Correct Answers Golden Ticket to Guaranteed A+ Verified by Professor

A quasar is NOT _____ - CORRECT ANSWER: powered by nuclear fusion.

About how far are we (the Sun & our solar system) from the center of the galaxy? -

CORRECT ANSWER: 25,000ly

Are the stars in our galaxy in danger of being swallowed up by the black hole? -

CORRECT ANSWER: No, virtually all the stars in the galaxy are safe.

Assuming a constant rate of expansion, the age of the Universe equals - CORRECT

ANSWER: 1/Ho

Assuming that expansion rate had always been constant leads to an estimate of about 14 billion years for the age of the universe. If our measurement of the expansion rate were wrong, and the expansion had been slower than we thought, then the actual age

of the universe would be - CORRECT ANSWER: older (but still finite).

Compared to a neutron star, a black hole's density is? - CORRECT ANSWER:

Compared to a white dwarf, a neutron star's density is? - CORRECT ANSWER: •Not all neutron stars are called pulsars because not all neutron stars send this signal in a direction that astronomers can detect them.

Consider that the radius of our galaxy is 50,000 light years (ly). How does the size of the black hole's event horizon (Rs) compare to the size of the galaxy? - CORRECT ANSWER: it less than a billionth the radius of the galaxy — an utterly negligible fraction of the size of the galaxy 1 / 2

Explain how a white dwarf's observable properties (specifically Luminosity & Temp) change over billions of years if it is left alone, and show how its location would change

on an H-R diagram. - CORRECT ANSWER: •White Dwarfs are low-mass stars, and if

they are left alone, they will fade and cool forever.•If mass transfer adds mass to a White Dwarf, it can become, (1) a Nova, or (2) a Supernova

Galaxies all formed at the same time, long ago. If you observe two galaxies at different distances from you, the more distant one will... - CORRECT ANSWER: appear younger

How can we check to see if the expansion rate is actually changing? - CORRECT ANSWER: We look back to different times in the past, to see how the expansion has changed already

How do a white dwarf's observable properties change as it ages, if it is left alone?

Choose the TWO correct answers - CORRECT ANSWER: luminosity decreases

temperature decreases

How does the escape velocity from Earth change if you climb to the top of Mt. Everest?

- CORRECT ANSWER: It decreases a tiny little bit.

How does the radius of the event horizon of a 9 solar mass black hole (BH) compare to

that of a 3 solar mass BH? The 9 solar mass BH is.. - CORRECT ANSWER: 3 times

bigger

How is our Sun moving in the Galaxy? What is its instantaneous direction of motion? - CORRECT ANSWER: perpendicular / tangent to the center; sideways (90 degrees from the center)

How long does it take light to travel from the center of our galaxy to us? - CORRECT

ANSWER: 25,000 years

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