Astronomy: Sun Structure and Activity; Stellar Parallax; Life Cycle of Stars.
The Sun contains about ___ of the mass in our solar system.
99%
Approximately how old is the Sun?
45 billion years
A star has a parallax of 0.5 arc sec. Calculate the distance to the star in parsecs.
d=1/0.5= 2 parsecs
The parallax of a star is inversely related to its
distance
The luminosity of the Sun results from its
energy emission
1 parsec is about equal to ____ light year(s)
3.26
The temperature of the Photosphere is
Cooler than the core and corona
Fusion occurs in the Sun's
Core
If the star has a parallax of ____ arc seconds, then its distance is _____
0.25; 4 parsecs
Alpha Centauri has a parallax of 0.74 arc sec. What is the approximate distance to Alpha Centauriin
1.35 par sec
What is the approximate diameter of the Sun?
1.4 million km
Parallax is useful for measuring the distance of stars up to about ____ light year(s) from Earth.
100
Which of the following stars is most likely to have a degenerate helium core at some point?
A star that is the same mass as our Sun.
Which of the following star's would be most likely to spend the longest time on the main sequence?
A star with 1.2 solar masses
When the helium and hydrogen shells around a low mass star's core begins burning, the star will become which of the following?
AGB Giant
The parallax of nearby stars are produced by
Earth's revolution around the Sun
A low mass star will end its life as which of the following?
Black Dwarf
What will be the final state of the Sun?
Black Dwark
In the last stage of stellar evolution following a supernova, stars too massive to form neutron stars may form a
Black hole
Sunspots are _____ regions of the Sun's surface.
Cooler
About 25% of the Sun is composed of hydrogen
False
Astronomers have calculated the parallax angles of millions of stars.
False
What will happen to a low mass star on the HR diagram after it begins ejecting its envelope near the end of its life?
It will move to the left, appearing hotter as the core is exposed.
As a low mass star begins ejecting material near the end of its life, it forms what?
Planetary nebula
Describe the sun's rotation
Since the Sun is not solid, it rotates at different rates, faster at the equator and slower at the poles.
How does distance affect parallax?
The nearest stars have the largest parallax angles, while those of distant stars are too small to measure.
Which statement best describes the Sun's hydrostatic equilibrium?
The outward push of the Sun's internal pressure balances the inward force of gravity
Galileo's observation of the motion of Sunspots provided evidence for which of the following?
The rotation of the Sun
Different parts of the Sun rotate at different speeds
True
Nearby stars have large parallax angles.
True
A red giant is formed when
a star begins burning its hydrogen shell
Which is NOT true about a protostar?
it generates pressure by fusing hydrogen
Which phrase best describes the Sun's age in its stellar life cycle?
middle aged
The part of the Sun that emits visible light and is typically seen from Earth is the:
photosphere
