Cepheid variable stars vary because they have reached a point in their evolution
ID: 288371 • Letter: C
Question
Cepheid variable stars vary because
they have reached a point in their evolution where absolute magnitude varies over a period of time .
the distance to them varies as Earth orbits the Sun.
there are clouds in interstellar space that move across them .
they have companion stars that orbit them causing changes in luminosity.
2 points
QUESTION 2
Cepheid variables are valuable as distance markers because they are ________ and their period of brightening is directly related to their ________________
bright; absolute magnitude
bright; apparent magnitude
dim; apparent magnitude
dim; absolute magnitude
2 points
QUESTION 3
Cepheid variable stars are main sequence stars
True
False
2 points
QUESTION 4
Cepheid variable stars can be used to measure distance to galaxies.
True
False
2 points
QUESTION 5
In order to determine whether or not a star is a Cepheid variable I will need to measure____________ in lab.
period of variability and apparent magnitude
absolute and apparent magnitude
distance and absolute magnitude
period of variability and apparent magnitude
a.they have reached a point in their evolution where absolute magnitude varies over a period of time .
b..the distance to them varies as Earth orbits the Sun.
c.there are clouds in interstellar space that move across them .
d.they have companion stars that orbit them causing changes in luminosity.
Explanation / Answer
they have reached a point in their evolution where absolute magnitude varies over a period of time.
Cepheid stars are variable because they pulsate in and out.
bright; apparent magnitude. Measuring their apparent luminosity allows a straightforward calculation of their distance.
False. All stars, late in their lifetime, change from being average stars for their mass ( main sequence stars ) to becoming swollen red giants . Most stars change from the swollen red giant phase to pulsating variable stars before they finally die. thus Cephie stars are yellow stars.
True. Cepheid variable stars can be used to measure larger distances such as the distances between galaxies