PSU ASTRO 1 - EXAM 3 STUDY GUIDE
QUESTIONS WITH CORRECT ANSWERS
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
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.
Which statement is necessarily true?
A. Every pulsar is a neutron
star
B. Every neutron star is a
pulsar
C. both - CORRECT ANSWER-A. Every pulsar is a neutron
star
Compared to a neutron star, a black hole's density is? - CORRECT ANSWER-
If our Sun were suddenly compressed to a black hole (BH) of the Sun's same mass, Earth would... -
CORRECT ANSWER-maintain the same orbit
What happens to as you get closer and closer to the center of a black hole (BH)? - CORRECT ANSWER-It
increases without bound
How long does it take light to travel from the center of our galaxy to us? - CORRECT ANSWER-25,000
years
PSU ASTRO 1 - Exam 3 Study Guide QUESTIONS WITH CORRECT ANSWERS
, About how far are we (the Sun & our solar system) from the center of the galaxy? - CORRECT ANSWER-
25,000ly
If you observe two galaxies at different distances from you (2 billion ly and 6 billion ly), the more distant
one will - CORRECT ANSWER-appear younger.
If a distant galaxy is 2x10^3 Mpc away, how fast is it receding from us? (use H0 = 70 km/s/Mpc) -
CORRECT ANSWER-1.4x105 km/s
If a galaxy were receding from us at 3x10^5 km/s*, how far away would it be?
(use H0 = 70 km/s/Mpc) - CORRECT ANSWER-3/7 x 10^4 Mpc
Imagine that you are in Galaxy 1 and you observe that both Galaxies 2 and 3 are moving away from you.
How would Galaxy 3 describe the motion of Galaxy 2? - CORRECT ANSWER-"Galaxy 2 is moving away
from 3."
Imagine that you are in Galaxy 1 and you observe that both Galaxies 2 and 3 are moving away from you.
How would Galaxy 2 see the other galaxies moving? - CORRECT ANSWER-"Galaxy 2 is moving away from
3."
Using H0=70, we get T0=__ billion years. But if the true value of H0 turned out to be smaller than 70, the
Universe would be - CORRECT ANSWER-older than 14 billion years.
Is it possible to measure, in a practical way, whether the Hubble constant is changing with time? -
CORRECT ANSWER-Yes
Which are more likely to collide? - CORRECT ANSWER-galaxies within a cluster?
PSU ASTRO 1 - Exam 3 Study Guide QUESTIONS WITH CORRECT ANSWERS
QUESTIONS WITH CORRECT ANSWERS
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
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.
Which statement is necessarily true?
A. Every pulsar is a neutron
star
B. Every neutron star is a
pulsar
C. both - CORRECT ANSWER-A. Every pulsar is a neutron
star
Compared to a neutron star, a black hole's density is? - CORRECT ANSWER-
If our Sun were suddenly compressed to a black hole (BH) of the Sun's same mass, Earth would... -
CORRECT ANSWER-maintain the same orbit
What happens to as you get closer and closer to the center of a black hole (BH)? - CORRECT ANSWER-It
increases without bound
How long does it take light to travel from the center of our galaxy to us? - CORRECT ANSWER-25,000
years
PSU ASTRO 1 - Exam 3 Study Guide QUESTIONS WITH CORRECT ANSWERS
, About how far are we (the Sun & our solar system) from the center of the galaxy? - CORRECT ANSWER-
25,000ly
If you observe two galaxies at different distances from you (2 billion ly and 6 billion ly), the more distant
one will - CORRECT ANSWER-appear younger.
If a distant galaxy is 2x10^3 Mpc away, how fast is it receding from us? (use H0 = 70 km/s/Mpc) -
CORRECT ANSWER-1.4x105 km/s
If a galaxy were receding from us at 3x10^5 km/s*, how far away would it be?
(use H0 = 70 km/s/Mpc) - CORRECT ANSWER-3/7 x 10^4 Mpc
Imagine that you are in Galaxy 1 and you observe that both Galaxies 2 and 3 are moving away from you.
How would Galaxy 3 describe the motion of Galaxy 2? - CORRECT ANSWER-"Galaxy 2 is moving away
from 3."
Imagine that you are in Galaxy 1 and you observe that both Galaxies 2 and 3 are moving away from you.
How would Galaxy 2 see the other galaxies moving? - CORRECT ANSWER-"Galaxy 2 is moving away from
3."
Using H0=70, we get T0=__ billion years. But if the true value of H0 turned out to be smaller than 70, the
Universe would be - CORRECT ANSWER-older than 14 billion years.
Is it possible to measure, in a practical way, whether the Hubble constant is changing with time? -
CORRECT ANSWER-Yes
Which are more likely to collide? - CORRECT ANSWER-galaxies within a cluster?
PSU ASTRO 1 - Exam 3 Study Guide QUESTIONS WITH CORRECT ANSWERS
