Radiation astronomy/First astronomical X-ray source/Quiz

First astronomical X-ray source is a lecture for the advanced course on X-ray astronomy. You are free to take this quiz based on the lecture at any time. Once you’ve read and studied the lecture itself, the links contained within the lecture, listed under See also, External links and in the {{principles of radiation astronomy}} template, you should have adequate background to achieve 100 %.

X-ray emission from Hyakutake is seen by the ROSAT satellite. Credit: NASA.

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Enjoy learning by doing!



1 Object identification:

What "mystery object" made a sudden appearance on February 21, 2006, and was observed to have an X-ray glow around it by the X-ray observatory satellite XMM Newton in early August 2006?

2 Yes or No, An X-ray may have a wavelength as long as 10 nm.


3 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

4 Which of the following may be a type of X-ray binary?

a dwarf planet
a member of the Oort belt
a soft X-ray transient
the polar regions (North and South) of Jupiter
an X-ray burster
Hercules X-1
an X-ray emitting Be star

5 Complete the text:

publication in print contains the identification of all of the first X-ray sources discovered for each of the 88 (or 89) constellations.

6 True or False, The Sun is an X-ray source in the constellation Lupus.


7 A natural X-ray source has been detected by an X-ray counter at a site on the ground (Earth) from what astronomical X-ray source?

the Sun
the ionosphere
the diffuse X-ray background
Serpens X-1
the Moon

8 Which of the following is associated with the diffuse X-ray background?

the Sun
rather consistently observed over a wide range of energies
an Aitoff-Hammer equal-area map in galactic coordinates
an isotropic X-ray background flux was obtained in 1956
an early high-energy end was obtained by instruments on board Ranger 3
super soft X-rays are absorbed by galactic neutral hydrogen

9 True or False, A professional astronomer holding an X-ray detector in their hands while working on the International Space Station is a primary astronomical X-ray source.


10 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

11 Which of the following is associated with the Sun as a possible first X-ray source?

lofting an X-ray detector with a V-2 rocket from White Sands Proving Grounds on August 5, 1948
in the late 1930s, "the presence of a very hot, tenuous gas surrounding the Sun ... was inferred indirectly from optical coronal lines of highly ionized species"
early theoretical estimates of black body radiation from the solar corona
“extensive 1/4 keV emission in the Galactic halo”
its overall redness has decreased
ionizing radiation that may originate deep within the Sun does not reach the bottom of a sunspot

12 True or False, The bottom of a sunspot ~400 km deep is cooler than the bottom of the photosphere.


13 Which of the following is not an astronomical X-ray source?

the planet Mercury
traces of the element gold in the Sun’s photosphere
the solar wind
Cepheus X-1
nucleosynthesis near the surface of the Sun
lightning on Jupiter

14 A first X-ray source located roughly 9000 light years away in the constellation Scorpius is

15 True or False, Alpha Apodis is a known (SIMBAD) X-ray source.


16 Complete the text:

A well-known black hole (or black hole candidate) and galactic X-ray source in the constellation Cygnus is


17 Which of the following is not an astronomical X-ray source?

Comet Lulin
the Moon
Carina X-1
Centaurus X-2
EZ Aquarii

18 True or False, Cassiopeia X-1 was first detected during a June 16, 1964, Aerobee sounding rocket flight.


19 Of the discovery of the first extrasolar X-ray source, the instrumentation had been designed for an attempt to observe X-rays from the

20 Complete the text:

A non-SI unit of spectral X-ray flux density is called the


21 True or False, A high-mass X-ray binary designation indicates that the X-ray source is a high-mass neutron star.


22 Complete the text:

An X-ray binary star exhibiting periodic and rapid increases in luminosity (typically a factor of 10 or greater) peaked in the X-ray regime is called an


23 True or False, The flux density or monochromatic flux,  , of a source is the integral of the spectral radiance,  , over the source solid angle:




  1. The first astronomical X-ray source may have been the Earth.

See alsoEdit

External linksEdit

{{Radiation astronomy resources}}{{History of science resources}}