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What is the name of the temperature scale that places zero at the point where all atomic and molecular motion ceases
A jar filled with gas is placed directly in front of a second jar filled with gas. Using a spectroscope to look at one jar through the other you observe dark spectral lines. The jar closes to you contains
the cooler gas
The two forms of EM radiation that experience the least atmospheric opacity are
light and radio waves
the observes spectral lines of a star are all shifted towards the red end of the spectrum. Which statement is true?
this is an example of the Doppler effect
Medium A blocks more of a certain wavelength of radiation that medium B. Medium A has a higher
The angular resolution of an 8 inch diameter telescope is ____ greater than that of a 2 inch diameter telescope
the amount of diffraction and thus the resolution of the scope depends on
the brightness of the object
what is the resolution of a telescope?
its ability to distinguish two adjacent objects close together in the sky
compared to a 5 inch prime focus reflector, a 5 inch Newtonian reflector will
have the same light gathering power
Green light has a shorter WL than orange light. In a 5 inch telescope, green light will
provide better angular resolution than orange light
What problem does adaptive optics correct
Turbulence on the earths atmosphere that creates twinkling
What is the meaning of the solar constant?
the amount of energy the Earth receives per unit area and unit time
What two energy transport mechanisms, in order from outside the core to the surface, are found in
From inside out, which is in the correct order for the structure of the Sun?
radiative zone, convective zone, chromosphere
As the Sun rotates, an individual sunspot can be tracked across its face. From eastern to western
limb, this takes about
Sunspots are dark splotches on the Sun. Which statement is true?
they are extremely hot, but cooler than the surrounding areas of the sun
While observing the Sun, you note a large number of sunspots. What can you conclude?
There are likely to be an above average number of flares and prominences.
In the proton-proton cycle, the helium atom and neutrino have less mass than the original
hydrogen. What happens to the "lost" mass?
It is converted to energy.
Which is the net result of the proton-proton chain?
4 protons = 1 helium 4 + 2 neutrinos + gamma rays
Hydrogen "burning" by fusion reactions occurs only in the deep interior of the Sun (and
other stars), because
this is the only place in the Sun where
the requisite conditions of high temperature and high density occur
What happens to the positrons produced by the nuclear reactions in the core of the Sun?
they collide with electrons, producing energy
Which statement about stellar motion is incorrect?
proper motion is measured in intervals of 6 months
If Vega is apparent magnitude zero, and Deneb first magnitude, then
vega must be 2.5x more luminous than deneb
Two stars both have parallaxes of 0.023", but star A has apparent magnitude +2.3, while star B is
magnitude +7.3. Which statement is true?
star A is both 100x brighter and more luminous than star B
What can be said with certainty about a red star and a blue star?
the blue star is hotter than the red star
In the H-R diagram, what are the two most important types of data plotted?
spectral classes and absolute magnitudes
apparent angular movement of a nearby star against the background stars as a consequence of
its motion in space is known as
The speed of a star, measured in a direction perpendicular to the line of sight from the Earth to the
star, is known as
Suppose that two identical stars (having the same total light output or luminosity) are located such
that star A is at a distance of 5 pc and star B is at a distance of 25 pc. How will star B appear,
1/25 as bright
Light, leaving a point source, spreads out so that the apparent brightness, I , of light per unit area
varies with distance d according to which law (μ means "proportional to")?
A) I µ 1/d 2
What happens to light passing through even thin clouds of dust?
It dims and reddens the light of all more distant stars.
Which statement about dark dust clouds is true?
They can be penetrated only with longer wavelengths such as radio and infrared.
Some regions along the plane of the Milky Way appear dark because
stars in that region are hidden by dark dust particles.
The density of interstellar dust is very low, yet it still blocks starlight because
the dust particles are about the same size as the light waves they absorb.
What two things are needed to create an emission nebulae?
hot stars and interstellar gas, particularly hydrogen
A large gas cloud in the interstellar medium that contains several type O and B stars would appear
to us as
an emission nebulae
Neutral hydrogen atoms are best studied from their energy given off as
21-cm waves in the radio region.
Which of these is not a consequence of dust in the interstellar medium?
red light from the emission nebulae
It is important to study interstellar dust because
A) there is almost as much mass between the stars as therre is in them.
B) this is where stars are formed.
C) old stars expel their matter here when they die.
D) all of the above.
What is true of emission nebula?
A) they are often part of much larger interstellar clouds.
B) their temperature can exceed that of our sun.
C) they are bigger than earth.
D) they produce an emission spectrum.
E) All of the above.
When an electron in hydrogen changes its spin from the same to the opposite direction as the
emits radio wave photon
Which statement about the stages of starbirth is false?
*A) nuclear reactions begin in the core by stage 4.*
B) The T-Tauri wind is prevalent in stage 5.
C) By stage 3, the star has formed a photosphere.
D) At stage 1, only the cloud exists.
E) By stage 7, the star has reached the main sequence.
The single most important determinant of the temperature, density, radius, luminosity,
and pace of evolution of a protostar is its
Why are star clusters ideal "laboratories" for stellar evolution?
Their stars are all about the same age, composition, and distance from us.
Which is characteristic of globular star clusters?
old age and hundreds of thousands of stars, only about 50 pc wide
How long does it take an M-type star to reach the main sequence, compared to a
about twenty times longer
A fragment of a collapsing gas cloud that comes to equilibrium with a central
temperature of 4 million K will become a
Why are the majority of stars in the sky in the main sequence phase of their lives?
This is the longest-lasting phase in each star's life.
Which of the following statements about the rate of stellar evolution is true?
The more massive the original star, the faster the evolution.
Within a globular cluster, what would you expect to find in the population of stars?
many red giants, white dwarfs, and dim red stars but no bright blue stars or dust
What is the importance of nebular clouds that surround newly forming stars?
They add mass to the star during formation.
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