Astronomy Final: Test Two
Which star spends the longest time on the main sequence?
0.5 M
Neutron stars have masses that range from
1.4M®to3.5M®
What is the minimum mass main-sequence star that becomes a Type II supernova?
8M
What prevents white dwarfs from collapsing?
Electron degeneracy pressure
A main sequence star is distinguished by
Hydrogen burning in its core
Which element identifies a T Tauri star?
Lithium
Which of these is smallest?
Neutron stars
What critical event transforms a protostar into a normal main-sequence star?
Nuclear fusion begins in the core.
The bulk of a massive, main sequence star's energy comes from
The CNO cycle
What primarily makes it difficult to observe protostars?
They occur in dusty regions.
A Type I supernova occurs when a white dwarf exceeds a mass of ____.
a) 1.4 M
What happens as a protostar contracts?
a) Its density rises. b) Its temperature rises. c) Its radius decreases. d) Its central pressure rises. e) All of the above are true.
SN 1987A is
a) The only supernova for which the progenitor star has been identified b) The first naked-eye supernova in modern times c) A Type II supernova d) All of the above
In the CNO cycle, carbon is used a catalyst for the fusion of hydrogen to helium. This means that:
carbon facilitates the reaction but is not consumed in it
What mechanism provides the internal pressure inside a neutron star?
degeneracy pressure from neutrons
If you measure the average brightness and pulsation period of a Cepheid variable star, you can also determine its:
distance
Degenerate refers to a state of matter at:
high density
During which phase of the evolution of a low- mass star does it have two separate regions of nuclear burning occurring in its interior?
horizontal branch
A main-sequence star is unique because:
hydrogen burning occurs in its core
The majority of the Sun's energy comes from:
hydrogen fusion
An iron core cannot support a massive main- sequence star because:
iron cannot fuse to make heavier nuclei and produce energy
Dust reddens starlight because:
it preferentially affects light at visible and shorter wavelengths
The most common types of stars in our galaxy are:
low-mass stars
What factor is most important in determining a star's position on the main sequence and subsequent evolution?
mass
A nova is the result of which explosive situation?
mass transfer onto a white dwarf
When two atomic nuclei come together to form a new species of atom, this is called:
nuclear fusion
Where did the iron in your blood come from?
nucleosynthesis that took place in supernova explosions
The energy that fuels the Sun is generated:
only in its core
Massive stars synthesize chemical elements going from helium up to iron:
only in the core of the star
Hydrostatic equilibrium is a balance between:
pressure and gravity
Massive stars explode when they:
run out of nuclear fuel in their core, and the cores collapse
The Hayashi track of a low-mass protostar in the H-R diagram is a path of approximately constant:
temperature
A low-mass main-sequence star's climb up the red giant branch is halted by:
the beginning of helium fusion in the core
What characteristic of a star cluster is used to determine its age?
the color of the main sequence turnoff in the cluster
When radiation from an object passes through the interstellar medium:
the object appears redder and dimmer
Which of the following layers of the Sun makes up the majority of its interior?
the radiative zone
Helium burns in the core of a horizontal branch star via _________ and produces _________.
the triple-alpha reaction; carbon
The main difference between Cepheid stars and RR Lyrae stars is:
their masses
Interior zones of the Sun are distinguished by:
their modes of energy transport
Type I and Type II supernovae are respectively caused by what types of stars?
white dwarfs, massive stars
