Exploring the Cosmos - Class Test 1 - Galaxies and Large Scale Structure
1. Our Sun is situated
in a globular cluster in the galactic disc about half of its radius from the centre.
in the disc of the galaxy about two thirds of its radius from the centre.
in the disc of the galaxy close to the edge of the disc.
in a globular cluster in the halo of the galaxy.
2. Neutral hydrogen can be detected by astronomers because
it reflects blue light from nearby stars.
it forms dark clouds in the disc of a spiral galaxy.
it glows with a bright blue colour.
it radiates a sharp 21 cm radio signal.
3. Our Sun and solar system are
moving directly towards a supermassive black hole at the centre of the Galaxy and will merge into the centre in 240 million years.
stationary in our Galaxy.
rotating about the centre of the Galaxy once every million years.
rotating around the centre of the Galaxy once every 240 million years.
4. Recent observations have shown that there is much invisible matter in the outer regions of our Galaxy.
The missing invisible material is likely to be completely accounted for by a large number of planets around stars.
The evidence has come from theoretical studies of black hole formation.
The observations have involved measurement of the velocities of stars in the spiral arms of the Galaxy.
The current estimate is that around 50% of the mass of the Galaxy is in this invisible form.
5. The disk component of a spiral galaxy includes which of the following parts?
Bulge
Halo
Globular clusters
Spiral arms
6. By observing what astronomical objects was it first found that the Solar System is not located in the centre of the Milky Way?
Absorption nebulae
Black holes
Globular clusters
Cepheids
7. Our Sun is situated
in the disc of the galaxy close to the edge of the disc.
in a globular cluster in the galactic disc about half of its radius from the centre.
in a globular cluster in the halo of the galaxy.
in the disc of the galaxy about two thirds of its radius from the centre.
8. Of the stars in our galaxy
those in the spherical component move in circular orbits that have random orientations.
those in the spherical component move in elliptical orbits that have a random orientation.
those in the nucleus orbit the centre in the opposite direction to those in the disc component.
those in the disc component move in circular orbits that have random orientations.
9. The approximate position of the centre of the Milky Way galaxy was first found, using optical telescopes, by
looking for the central bulge.
measuring the position of visible open star clusters.
observing stars moving round the massive black hole in the centre.
measuring the position of visible globular clusters.
10. The diameter of the Milky Way Galaxy is
about 25 to 30 pc.
about 25 to 30 kpc.
about 250 to 300 pc.
about 25 to 30 Mpc.
11. Population II stars are
"metal" rich and typically found in the disc of a spiral galaxy.
"metal" rich and typically found in the disc of a spiral galaxy.
"metal" poor and typically found in the disc of a spiral galaxy.
"metal" poor and typically found in the nucleus and halo of a spiral galaxy.
12. Recent observations have shown that there is much invisible matter in the outer regions of our Galaxy.
The current estimate is that around 50% of the mass of the Galaxy is in this invisible form.
The evidence has come from theoretical studies of black hole formation.
The missing invisible material is likely to be completely accounted for by a large number of planets around stars.
The observations have involved measurement of the velocities of stars in the spiral arms of the Galaxy.
13. Several different measurements indicated that our galaxy is a spiral galaxy. Which of the following observations does not give evidence for the presence of spiral arms?
Location of CO clouds within the galaxy
Infra-red measurements of the dust density in the Milky Way
Location of nearby Globular clusters
Location of nearby O and B stars
14. The existence of dark matter was proposed to explain...
the formation of galaxies with extremely luminous galactic centres (active galaxies).
the observation of strong sources of x-rays and radio waves at the galactic centre.
the flat region of the rotation curve far from the galactic centre.
the shape of the orbits of halo stars and globular clusters.
15. In a galaxy such as ours, extremely young Population I stars are predominantly found...
in the halo.
in the disc component.
in the nuclear bulge.
in the spiral arms.
16. Globular clusters...
are usually found in the discs of galaxies and contain population I stars.
are usually found in the halos of galaxies and contain population I stars.
are usually found in the halos of galaxies and contain population II stars.
are usually found in the discs of galaxies and contain population II stars.
17. The approximate position of the centre of the Milky Way galaxy was first found, using optical telescopes, by...
looking for the central bulge.
measuring the position of visible globular clusters.
measuring the position of visible open star clusters.
observing stars moving round the massive black hole in the centre.
18. Gas and dust in the interstellar medium (ISM) is often seen in diffuse clouds called nebulae.
Reflection nebulae show up as pink, due to the reflection by dust of light coming from nearby stars.
The difference in colour between emission and reflection nebulae arises from the Doppler effect and is due to their differing motion relative to us.
The Pleiades is an example of an emission nebula.
The gas in emission nebulae typically emits pink light when it is excited by high energy light from nearby stars.
19. The speed of stars as they orbit in a nearby spiral galaxy can be measured by...
using the red or blue shift of the spectrum from different parts of the disc.
observing them for a long period and measuring the change in their position.
measuring the infra red spectrum from them.
determining their spectral class.
20. Star clusters in our Galaxy that are...
globular clusters mainly contain hot, young stars.
open clusters typically contain up to a few thousand stars.
globular clusters mainly lie in the disk region.
open clusters typically occupy a volume of about 1 kpc across.
21. Which of the following processes does not contribute to the formation of 'metals' (elements heavier than Hydrogen and Helium)?
Emission nebulae
Planetary nebulae
Type 2 Supernovae
Type 1a Supernovae
22. Today we know that the Milky Way has two disc components. Which of the following statements is correct?
The stars of the two disc components move in opposite direction around the galactic centre.
The stars of the thin disk have a stronger oscillatory motion than stars in the thick disc.
The stars in the thick disc have an iron to oxygen ratio that suggests they were formed later than the thin disk.
The stars in the thin disc have an iron to oxygen ratio that suggests they were formed later than the thick disk.
23. Interstellar medium can be classified in four different categories, each of which has different densities. Which of the following statements is wrong?
Very hot coronal gas has lower density than inter-cloud media.
Very hot coronal gases have higher density than diffuse gas clouds.
Inter-cloud media have a lower density than diffuse gas clouds.
Dark giant molecular clouds are denser than diffuse gas clouds.
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