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Exam II PHCC
For Professor Guy
44
Astronomy
Graduate
10/08/2012

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Cards

Term
the most comment elements in the universe are?
Definition
helium and hydrogen
Term
what elements account for 98% of the total mass of the universe?
Definition
helium and hydrogen
Term
name the nine planets of our solar system - in correct order outward from the sun
Definition
mercury venus earth mars jupitar saturn uranus neptune pluto
Term
in august 2006, astrophysicists gathered at a conference in Prague, Czech Republic and made a new definition of what constitutes a "major planet." Because of their decision, what planet has been demoted to "minor planet" status?
Definition
pluto
Term
the most probable theory for formation of the sun & solar system is that
Definition
the sun and planets slowly condensed to their present form from a collapsing, rotating nebula of gas and dust cloud
Term
the process of accretion in planetary formation is
Definition
the slow accumulation of solid particles by gravity and collision into larger, solid objects
Term
where is the asteroid belt located in our solar system?
Definition
most asteroids orbit the sun in a belt about 1.5AU wide between orbits of mars and jupiter
Term
the solar system contain heavy elements, formed from an earlier generation of stars. True or false?
Definition
true
Term
strong evidence for the existence of planetary systems in the process of formation around other stars comes from
Definition
periodic wobbling of the positions and spectral line displacements of several nearby stars
Term
in theory, where did all of the hydrogen in the universe come from?
Definition
the big bang
Term
there is very little hydrogen or helium in the inner part of the solar system today. We believe the reason for this is that
Definition
intense radiation from the early sun drove the light elements out of the inner solar system
Term
what are comets?
Definition
comets are chunks of rock and ice. beyond orbit of neptune lies hundreds of millions of these objects.
Term
what is the kupier belt?
Definition
a belt of comets that abound in the million in orbit past pluto out to 50au from sun
Term
color of a body is related to increasing heat; how?
Definition
changes through orange to white then blue
Term
how do we know chemical make-up of a star?
Definition
the science of spectroscopy idetification of atoms by the appearance of their spectra (bright and dark patterns of lines) as separated by a diffraction grating in the instrument called a spectrocope
Term
we plot the intensity of the radiation emitted from an object at a certain temperature versus its wavelength. as we increase the temperature, the wavelength at which the spectrum peaks becomes shorter and shorter. this is an example of
Definition
Wein's Law
Term
Wein's Law states...
Definition
as temperature increases, wavelength emission peaks become shorter and shorter
Term
what is a diffraction grating?
Definition
a piece of glass or plastic w/ thousands of etched parallel grooves
Term
a diffraction grating is the key component of what instrument?
Definition
the spectroscope, an instrument for splitting light rays that produce spectra (patterns of light seen when an element is vaporized into a gas)
Term
the dark absorption lines in the solar spectrum are caused
Definition
by a cooler layer of gas overlying the hot solar surface, which contains many elements including hydrogen, helium, magnesium, calcium, iron, etc.
Term
when astronomers look for evidence of hydrogen gas in the spectra of the Sun, or other stars, the positions of the spectral "lines" due to hydrogen
Definition
will always be in the same characteristic pattern as seen in the laboratory, a pattern unique to hydrogen, but will appear black due to absorption on the cool atmosphere of the air
Term
what does it mean to say - "hydrogen has an emission spectrum"?
Definition
when any element is vaporized here on Earth it will emit bright lines of color that are unique for each element
Term
what evidence do we have that the sun contains the element, iron?
Definition
solar spectra shows absorption in spectral lines that are characteristic of iron & are unique to it
Term
the photosphere is
Definition
visible "surface" layer of the sun
Term
heated interstellar hydrogen gas, near a hot star, will still emit
Definition
spectral lines characteristic of hydrogen
Term
in our sun, a supergranule is?
Definition
an enormous region of rising & falling chromopheric gas.. A typical supergranule gas bubble has a diameter slightly larger than the Earth
Term
the chromosphere is?
Definition
dim layer of less dense gas ABOVE the photosphere. its the middle layer of 3 atmosphere layers of the Sun
Term
the Zeeman Effect is
Definition
splitting of spectral lines emitted by atoms within a magnetic field
Term
solar wind is?
Definition
gas ejected from the corona, breaking force of the sun's gravity & becomes a bubble in space containing the solar system & protecting us from other radiation entering our solar system; called the Heliosphere
Term
the heliosphere is
Definition
protective region containing the sun and planets cradled by the solar wind, which prevents penetration by much of the radiaiton from outside our solar system
Term
what is the name of a small jet of rising gas in the chromosphere of the Sun?
Definition
spicule
Term
what is the Corona?
Definition
uppermost atmosphere of the sun
Term
most of the elements beyond hydrogen & helium in the periodic table in our sun and solar system most probably originated
Definition
from fusion reactions in the centers of earlier stars
Term
most of the weight of our bodies comes from heavy elements such as carbon and oxygen. This fact immediately tells us that
Definition
solar system didn't form directly from material created by the Big Bang
Term
sunspots are what?
Definition
cooler, darker regions of the sun's "surface"
Term
what main physical characteristic do sunspots possess?
Definition
intense magnetic fields
Term
what is the sunspot cycle?
Definition
sunspots come in and go in a 11 year cycle
Term
how hot is the sun? on its surface? in its interior?
Definition
5,800K on surface, 1.5 million degrees kelvin in core
Term
thermonuclear fusion is..
Definition
combining of light nuclei w/ heavy nuclei w/ resultant release of energy
Term
what two elements form the basis of thermonuclear fusion?
Definition
hydrogen and helium
Term
what is thermonuclear fusion?
Definition
fusion of hydrogen into helium, at temperature above 1 million degrees Kelvin, w/ resultant release of EM radiation
Term
the energy source for the Sun is?
Definition
thermonuclear fusion of H & He w/ resultant release of energy
Term
most likely mechanism for formation of solar system?
Definition
is it slowly condensed from a cloud of gas & dust
Term
how can we tell if a star contains a particular element?
Definition
examine the spectra of light emitted by that star
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