Radiation astronomy/Oort clouds/Quiz

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Stars closest to the Sun include Barnard's Star (25 April 2014). Credit: NASA/Penn State University.

Oort cloud radiation astronomy is a lecture for the course on the principles of radiation astronomy.

This is a quiz based on the lecture that you are free to take at any time or knowledge level.

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Enjoy learning by doing!

Quiz[edit | edit source]


1 Complete the text:

By comparing astronomical observations with laboratory measurements, astrochemists can infer the


, and

of stars and interstellar clouds.

2 True or False, An hypothesized Oort cloud or protoplanetary disc has been observed around other stars.


3 Which of the following may be characteristic of hydrogen deficiency in stars?

may have been consumed by nucleosynthesis
star formation in a cloud deficient in hydrogen
may point away from a stellar association
may have been formed by white dwarf mergers
may have had transfer of helium from the secondary to the primary
a possible massive convective event

4 Which of the following is not a characteristic of terrestrial X-ray flashes?

antimatter signatures
atmospheric origin
X-ray flashes occur at least 50 times per day globally
X-radiation fountains upward from low cloud-top sources
as high or higher energy X-rays as come from the Sun

5 Which of the following is not a characteristic of terrestrial gamma-ray flashes?

antimatter signatures
atmospheric origin
TGFs occur about 50 times per day globally
gamma radiation fountains downward from high cloud-top sources
higher energy gamma rays than come from the Sun

6 Which of the following is not a characteristic of the heliosphere?

outward speed of the solar wind diminishes to zero
inward pressure from interstellar space is compacting the magnetic field
the solar wind even blows back at us
a 100-fold increase in the intensity of high-energy electrons from elsewhere in the galaxy diffuse into our solar system from outside
the source of heat that brings the coronal cloud near the Sun hot enough to emit X-rays may be the photosphere

7 Complete the text:

Some neutrinos originating from the Sun may be produced by the

reactions occurring in and above the

. Differentiating these coronal cloud-induced neutrinos from the neutrino background and those theorized to be produced within the

of the Sun may someday be possible with neutrino astronomy.

8 Which of the following is not a major source of protons within the solar system?

solar coronal clouds
solar wind
polar coronal holes
coronal mass ejections

9 Complete the text:

The Oort cloud is a hypothesized

cloud of

which may lie roughly

, or nearly a light-year, from the Sun.

10 Which of the following are theoretical radiation astronomy phenomena associated with the Sun?

a core which emits neutrinos
a solar wind which emanates out the polar coronal holes
the barycenter for the solar system
polar coronal holes
coronal clouds
its position

11 Complete the text:

Match up the type of cosmic-ray detector with each of the possibilities below:
visible tracks - A
diffusion cloud chamber - B
bubbles - C
a grid of uninsulated electric wires - D
similar to the Haverah Park experiment - E
fluorescence detectors - F
spark chamber

continuously sensitized to radiation

Pierre Auger Observatory

bubble chamber

Cherenkov detector

expansion cloud chamber


12 Which of the following is likely to apply to a solar binary?

a high relative velocity between the solar system and the cometary medium of a passage through a molecular cloud
none of the captured bodies may localize in the Oort cloud
none of the captured bodies localize near the Sun
some captured bodies may localize near Jupiter
the Jupiter system may be a control group

13 True or False, Super soft X-ray sources have been detected in the Magellanic clouds.


14 True or False, The hot ionized medium (HIM) consists of a coronal cloud which emits X-rays.


15 Which of the following are X-radiation astronomy phenomena associated with the Sun?

a core which emits neutrinos
a solar wind which emanates out the polar coronal holes
the barycenter for the solar system
polar coronal holes
coronal clouds
its position
temperatures at or above 1 MK

16 The first astronomical X-ray source in the constellation Dorado is likely to be which of the following?

the Sun
the Small Magellanic Cloud
Scorpius X-1
the Large Magellanic Cloud
the Crab Nebula

17 What may be the first astronomical source of the rocky objects in the solar system?

the solar wind
the diffuse X-ray background
Mount Redoubt in Alaska
the asteroid belt
the former protoplanetary disc around the Sun
the Oort cloud
the Kuiper belt

18 Which of the following are the differences between a star and an astronomical yellow source?

a star may emit predominantly green rays
an astronomical yellow source is spherical
a yellow star is an astronomical yellow source
a star with nuclear fusion in its chromosphere emits neutrinos, but a yellow source with no nuclear fusion ongoing does not
a yellow source may be cloud like
an astronomical yellow source my be a rocky object

19 Which of the following are radiation astronomy phenomena associated with the gaseous-object Neptune?

Voyager 2
blue rays
neutron emission
polar coronal holes
meteor emission

20 Neutrinos detected from the solar octant may be from nucleosynthesis within the coronal cloud in the near vicinity of the Sun or perhaps from nucleosynthesis occurring within what theoretical interior structure of the Sun?

21 Complete the text:

Match up the observatory facility with the observatory:
Ondrejov Observatory - A
Okayama Astrophysical Observatory - B
Orbiting Astronomical Observatory - C
Metsähovi Radio Observatory - D
Tortugas Mountain Planetary Observatory - E
Pierre Auger Observatory - F
Observed quasar 3C 454.3 in the spring of 2005.

A solar telescope.

Detector components.

Data on AG Peg were obtained with the ultraviolet broad-band photometers on the second one.

The 0.6 m monitors cloud decks and equatorial activity.

A 188 cm telescope.


22 Which of the following is not a characteristic of the X-ray continuum?

Bragg peaks
may arise from an X-ray jet
may arise from the coronal cloud of an accretion disc
a power-law spectrum
a thermal emission at the lowest energies

23 The Sun is a natural X-ray source because X-rays originate from what astronomical X-ray source?

a coronal cloud about the Sun
the diffuse X-ray background
the photosphere
nucleosynthesis in the center of the Sun

24 Complete the text:

Match up the item letter with each of the cosmogonic possibilities below:
interior models of the giant planets - A
high interest for cosmogony, geophysics and nuclear physics - B
hierarchical accumulation - C
clouds and globular clusters - D
cosmic helium abundance - E
deuterium fusion - F
a large deficiency of light elements - G
after galactic sized systems had collapsed - H
the motions of hydrogen

fornation of luminous quasars

stars with an initial mass less than the solar mass

rotating liquid drops

primordial is less than 26 per cent

a solar mixture of elements dominated by hydrogen and helium gas

around 13 Jupiter masses

smaller rocky objects


25 The use of the principle of line of sight allows what phenomenon to be determined?

the Moon is closer to the Earth than the Sun
the planet Mercury is nearer to the Earth than Venus
any cumulus cloud overhead follows the Sun across the sky
the plane of the Earth's orbit around the Sun is in the plane of the galaxy
the surface of the photosphere of the Sun is hotter than the surface of Mars
lightning always precedes rain

26 Which of the following may be true regarding the interacting galaxies of UGC 9618?

the pair of galaxies appear to be interacting rather than a mere galaxy double
a lack of luminous sources at any wavelength in the interaction volume
asymmetry is approximately centered on the interaction volume
a common origin originally between them
the large X-ray output surrounding primarily the more central portion of the edge-on galaxy suggests a very high temperature galactic coronal cloud
the infrared portion of the composite image with ultraviolet strongly suggests that the edge-on galaxy is much cooler in general than the face-on galaxy
orange and yellow astronomy reveal that the edge-on galaxy may be composed of older or cooler stars
VV340A appears to be more than 33 % involved in the interaction

27 True or False, If the energy of the incoming electrons is 700 MeV and the flux is 8.48 x 104 e- cm-2 s-1, then the interstellar electron influx is sufficient to heat the photosphere to its effective temperature and heat the coronal clouds to at least a few MK.


Hypotheses[edit | edit source]

  1. Questions leaning more on theoretical development may be better.

See also[edit | edit source]

External links[edit | edit source]

{{Radiation astronomy resources}}