Measuring the Cosmos
The star Aldebaran (α Tauri) has a parallax of 0.050”.
Notice that 0.050 = 1/20. Its distance from the Sun is
what is 20 PC.
The flow of energy by the process of absorption and ree-
mission of photons is called
what is RADIATION.
As a star is forming by the condensing of gases, the gases
what is HEAT UP AS THEY FALL.
The Sun is a middle-aged, main sequence star that is
estimated to be ——————————– years old.
what is 5 BILLION
Why does hydrogen fusion occur only in a main-sequence
star’s center?
what is
ONLY NEAR THE CENTER IS THERE
ENOUGH TEMPERATURE AND PRES-
SURE.
The rungs of the modern cosmic distance ladder start
with —————– within the solar system and continue
with —————– for the nearby stars up to about 100
parsecs.
What is
RADAR RANGING; STELLAR PARAL-
LAX
The proton-proton chain involves
what is NUCLEAR FUSION.
A star is considered to begin its main sequence life when
what is NUCLEAR REACTIONS START.
Hydrostatic equilibrium requires a balance between
what is PRESSURE AND GRAVITY.
The Sun will at some time in the future become
(a) a red giant.
(b) a white dwarf.
(c) a black dwarf.
what is all of the above
The use of (trigonometric) stellar parallax in determining
the distances to stars (with ground telescopes) is
what is
LIMITED TO STARS CLOSER THAN A
FEW HUNDRED PARSECS.
The flow of energy by the movement of heated gas is
called
what is CONVECTION.
The contraction of an interstellar cloud to become a star
is caused by
what is GRAVITATIONAL FORCES.
Why do stars of great mass live longer on the main se-
quence than stars of smaller mass?
The massive stars have more hydrogen fuel.
(b) The massive stars burn their fuel more slowly.
(c) The massive stars go through many stages of fusion.
(d) [More than one of the above.]
(e) none of the above
what is
[NONE OF THE ABOVE; THE STATE-
MENT IN THE QUESTION IS FALSE.]
Some supernovae occur when the Chandrasekhar limit
is exceeded in a white dwarf. In this case, the energy
producing the explosion is
what is RUNAWAY NUCLEAR FUSION.
The parallax of a given star is measured by an observer on
the planet Saturn, which has an approximate semimajor
axis aSaturn = 10 AU. The resulting parallax will be
—————————- the “standard” parallax measured
from the Earth.
what is 10 TIMES BIGGER
The proton-proton chain converts
what is
HYDROGEN INTO HELIUM AND EN-
ERGY.
An evolutionary track on an HR diagram reveals
what is
THE CHANGES THAT OCCUR IN A
STAR’S LIFE.
Compared to a young star of the same mass, an older
star contains
what is
GREATER AMOUNTS OF ELEMENTS
HEAVIER THAN HYDROGEN.
Which type of supernovae have hydrogen lines in their
spectra?
what is
TYPE II (FROM THE LATE EVOLUTION
OF SINGLE STARS)
As the distances of the stars increase, the value of the
parallax angle
what is DECREASES.
If the rate of hydrogen fusion within the Sun were some-
how to increase, the core would
what is
EXPAND AND THEREFORE TEND TO
SLOW THE FUSION.
The source of energy of protostars is
what is GRAVITATIONAL.
An important principle of stellar evolution is that the
properties and evolution of stars depend mainly on
what is MASS.
The Chandrasekhar limit is the dividing line between —
———– and ————–; it is about ——— solar masses.
Likewise, the Oppenheimer-Volkoff limit is the dividing
line between neutron stars and black holes; it is about
——— solar masses.
WHITE DWARFS; NEUTRON STARS;
1.4; 2 to 3