Astronomy Test Test Questions

Flashcard maker : William Jordan
Emission nebulae is also called
HII region
a solar mass of .08
a brown dwarf is a low mass M star
How much of a stars life is spent in the main sequence?
Where are stars born
in the densest gas in the interstellar medium.
Hydrostatic equilibrium
1. the weight pressing down on a layer of gas in a star must be balanced by the pressure in the gas for the star to be stable. 2. That shows the inner layers of the stars must be hotter because they support more weight.
Absorption line due to interstellar gas
One of the dark lines in some stellar spectra that are formed by interstellar gas.
Stars are born in?
The densest gas in the interstellar medium.
Dust interstellar medium effects Earth how?
Dramatically effects earth’s climate. It will boil away earth’s oceans.
Free Fall collapse.
The earth contraction of a gas cloud to form a star during which internal pressure is too low to resist contraction.
Molecular clouds observation
Spectroscope and use radio, infrared, and x ray telescope.Containing a million solar masses does not contract to form a single humongous star. A very large, cool, cloud of dense gas in which stars are formed.
T Taurin
A young star surrounded by gas and dust, believed to be contracting toward the main sequence. Solar mass objects that have just emerged from their cocoon and are located in the H-R diagram between the birth line and the main sequence.
Orion Neubula
at the center lie four blue/white o and b star known as yhe Trapezium. its the brightest cluster of a few hundred stars.Thesignificance of the orion nebula lies hidden, figuratively, and literally, beyond the visable nebula. the ragion is ripe with star formation.
how are molecular clouds observed?
they are observed by spectroscopy, and use radio, infrared, and x ray telescopes.
The density of a neutron star is
about the same as an atomic nucleus.
Observations from the Compton Gamma Ray Observatory showed that gamma-ray bursters were
located throughout the sky. This told us that
the bursts were not produced among stars in our galaxy.
A gravitational redshift
occurs when light travels out of a gravitational field, loses energy and its
wavelength grows longer
A neutron star is expected to spin rapidly because
they conserved angular momentum when they collapsed.
The slowing of clocks in strongly curved space time is known as
time dilation
In A. D. 1054, Chinese astronomers observed the appearance of a new star, whose location is now
occupied by
a pulsar, a neutron star, and a supernova remnant
Pulsars are believed to slow down because
they are converting energy of rotation into radiation.
An isolated black hole in space would be difficult to detect because
very little matter would be falling into it.
The peculiar system SS 433
is emitting beams of energy and matter, producing a spectrum with both a red and a blue shift, probably contains an accretion disk.
The orbit of the binary pulsar, PSR 1936+16, studied by Taylor and Hulse
is growing smaller, presumably by emitting gravitational waves.
The search for black holes involves searching for
X-ray binaries where the compact companion has a mass in excess of 3 M.
Why don’t all supernova remnants contain pulsars?
The pulsar may be tipped so that the beams do not sweep past Earth.
As material flows into a black hole
the material will experience time dilation and the material will become hotter.
A pulsar requires that a neutron star
rotate rapidly, have a strong magnetic field, and rotate on an axis that is different from the axis of the magnetic field.
Millisecond pulsars that are very old are
believed to be the result of mass transfer from a companion that increases the mass of the pulsar.
The escape velocity of an object depends on
the mass of that object and the distance from the center of the object and the escaping object.
The energy from an AGN is produced by
matter flowing into a supermassive black hole.
In the double-exhaust model, the geometry suggests that the radio lobes are inflated by
jets of excited gas flowing from the central galaxy.
a quasar
emits large amounts of radio energy, but photographically appears to be a
single point of light much like a star
The fact that many radio lobes emit more intensely from the side away from the galaxy suggests that
they are created by jets from the galaxy.
That the radio lobes radiate synchrotron radiation indicates that
high speed electrons are spiraling through a magnetic field.
If the red shifts of quasars arise from the expansion of the universe,
a quasar must be very luminous.
We suspect that quasars are the active centers of galaxies because
quasar fuzz produces stellar spectra.
Mid-sized black holes of a few thousand solar masses have been found in the cores of some
globular clusters.
What was the first evidence that quasars were different from any objects observed before they were
Quasars emitted radio energy like active galaxies, but appeared to be point sources in visible light
Type 2 Seyfert
is observed if our line of sight is parallel to the plane of the dense disk of an active galactic nucleus according to the unified model of active galactic nuclei
A BL Lac object is the same as a
The gravitational lens effect
is observed when light from a distant quasar travels past a massive galaxy
between us and the quasar, and this light is focused to form two or more images of the same quasar
Seyfert galaxies
are more common in close pairs of galaxies than in isolated systems and emit more energy at x-ray, ultraviolet, infrared, or radio wavelengths than normal spiral galaxies
In the unified model of active galactic nuclei, the broad line region in an active galactic nucleus is
composed of clouds of gas and stars moving at very high orbital velocities.
If Hubble’s constant is taken to be 70 km/sec/Mpc, and quasar is found with a radial velocity of 0.95
times the speed of light, how far away is the quasar?
4100 Mpc
The hydrogen Balmer line Hhas a wavelength of 486.1 nm in the laboratory. It is observed in a quasar
at 2430.5 nm, what is the red shift of this quasar?
Type 1
Seyfert galaxies are very luminous at x-ray and ultraviolet wavelengths and have broad
emission lines in their spectra.
1944.4 nm
If the red shift of a quasar were 3, at what wavelength would the 486.1 nm line of hydrogen appear in the quasars spectrum?
unified model
describes blazars, Type 1 Seyferts, Type 2 Seyferts, and radio lobe galaxies as being
produced by a dense disk of gas and a hot accretion disk around a super massive black hole at the core of a galaxy.
blazar or BL Lac object
is observed if our line of sight is along the rotation axis of an active galactic nucleus.
consists of a continuum and a few highly red shifted emission lines of due to hydrogen
Double-lobed radio galaxies appear to be emitting jets of gas and radiation
The radio radiation emitted by a radio lobe is mainly synchrotron radiation.
Seyfert galaxies are spiral galaxies with active cores.
The rapid fluctuations of quasars show that the objects must be very small
Quasar red shifts are usually larger than the red shifts of the visible galaxies.
Some quasars have fuzz around them that produces spectra similar to normal galaxies

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