Galactic Astrophysics — MCQs

1. Which component dominates the mass of galaxies?
(A) Gas
(B) Stars
(C) Dark matter
(D) Dust

2. What type of galaxy is the Milky Way classified as?
(A) Elliptical
(B) Irregular
(C) Barred spiral
(D) Lenticular

3. Which galaxy is on a collision course with the Milky Way?
(A) Andromeda (M31)
(B) Triangulum (M33)
(C) Large Magellanic Cloud
(D) Sombrero Galaxy

4. What is the approximate orbital period of the Sun around the Milky Way?
(A) 10 million years
(B) 100 million years
(C) 225 million years
(D) 1 billion years

5. Which component of a spiral galaxy contains the youngest stars?
(A) Bulge
(B) Halo
(C) Spiral arms
(D) Globular clusters

6. The rotation curves of galaxies provide evidence for:
(A) Neutron stars
(B) Cosmic microwave background
(C) Dark matter
(D) Interstellar dust

7. What is the approximate diameter of the Milky Way galaxy?
(A) 10,000 light years
(B) 50,000 light years
(C) 100,000 light years
(D) 1 million light years

8. Which component of the Milky Way hosts old, metal-poor stars?
(A) Spiral arms
(B) Bulge
(C) Halo
(D) Disk

9. What type of galaxies are most common in the universe?
(A) Elliptical
(B) Spiral
(C) Irregular
(D) Lenticular

10. What is the main difference between elliptical and spiral galaxies?
(A) Spirals contain more old stars
(B) Ellipticals lack significant gas and dust
(C) Spirals lack bulges
(D) Ellipticals rotate faster

11. Which galaxy is the nearest major galaxy to the Milky Way?
(A) Triangulum Galaxy
(B) Andromeda Galaxy
(C) Sombrero Galaxy
(D) Whirlpool Galaxy

12. Which galaxies often contain active star-forming regions?
(A) Elliptical galaxies
(B) Spiral galaxies
(C) Dwarf spheroidals
(D) Globular clusters

13. What is the Local Group?
(A) Cluster of globular clusters
(B) Cluster of nearby stars
(C) Cluster of nearby galaxies
(D) Cluster of dark matter halos

14. How many galaxies are in the Local Group approximately?
(A) 2
(B) 10
(C) 50+
(D) 1000+

15. Which is the largest galaxy in the Local Group?
(A) Milky Way
(B) Andromeda
(C) Triangulum
(D) Large Magellanic Cloud

16. What is the primary shape of elliptical galaxies?
(A) Flat disks
(B) Spherical or oval
(C) Barred spirals
(D) Irregular clumps

17. What surrounds most galaxies and extends beyond their visible edges?
(A) Gas halos
(B) Dark matter halos
(C) Globular clusters
(D) Black holes

18. What is the central supermassive black hole of the Milky Way called?
(A) Andromeda A
(B) Sagittarius A*
(C) Triangulum X
(D) Centaurus B

19. Which galaxy type is typically red and dead?
(A) Spiral
(B) Irregular
(C) Elliptical
(D) Barred spiral

20. Starbursts are galaxies that:
(A) Collapse rapidly
(B) Undergo intense star formation
(C) Host active quasars
(D) Lack dark matter

21. What is a dwarf galaxy?
(A) A small star cluster
(B) A galaxy much smaller and fainter than normal galaxies
(C) A galaxy without dark matter
(D) A galaxy that orbits a black hole

22. The Magellanic Clouds are:
(A) Globular clusters
(B) Satellite galaxies of the Milky Way
(C) Star-forming nebulae
(D) Dark matter halos

23. Which galaxy is classified as irregular?
(A) Andromeda
(B) Milky Way
(C) Large Magellanic Cloud
(D) Sombrero Galaxy

24. Which observation led to the discovery of dark matter in galaxies?
(A) Cosmic microwave background
(B) Flat rotation curves
(C) Supernova explosions
(D) Galaxy collisions

25. What is the approximate mass of the Milky Way?
(A) 10⁸ solar masses
(B) 10¹¹ solar masses
(C) 10¹² solar masses
(D) 10¹⁵ solar masses

26. The thin disk of the Milky Way contains:
(A) Young stars and gas
(B) Only old stars
(C) Only globular clusters
(D) Only black holes

27. Galactic bulges are dominated by:
(A) Young stars
(B) Old stars
(C) Molecular clouds
(D) Dark matter only

28. The Tully–Fisher relation connects:
(A) Galaxy rotation speed and luminosity
(B) Galaxy age and metallicity
(C) Galaxy size and mass
(D) Galaxy color and star formation rate

29. What is an active galactic nucleus (AGN)?
(A) Region of intense star formation
(B) Central black hole accreting matter
(C) Dark matter core
(D) Globular cluster in bulge

30. What is a quasar?
(A) A type of spiral galaxy
(B) An extremely luminous AGN
(C) A faint dwarf elliptical
(D) A neutron star system

31. What is a lenticular galaxy?
(A) A spiral without arms
(B) A galaxy with irregular shape
(C) A starburst galaxy
(D) A dwarf galaxy

32. Which galaxy type dominates galaxy clusters?
(A) Spiral
(B) Elliptical
(C) Lenticular
(D) Irregular

33. Which part of the Milky Way contains globular clusters?
(A) Disk
(B) Halo
(C) Bulge
(D) Spiral arms

34. What is the stellar population in the thick disk of the Milky Way?
(A) Young, metal-rich
(B) Old, metal-poor
(C) Old, metal-rich
(D) Primordial hydrogen only

35. Which effect explains the red color of elliptical galaxies?
(A) Presence of dust
(B) Lack of young blue stars
(C) High metallicity only
(D) Strong gravitational lensing

36. What is a galactic merger?
(A) Two star clusters colliding
(B) Two galaxies colliding and combining
(C) A galaxy collapsing into a black hole
(D) Satellite galaxies escaping

37. What structure results from repeated galaxy mergers?
(A) Spiral galaxy
(B) Elliptical galaxy
(C) Lenticular galaxy
(D) Irregular galaxy

38. What is the main source of X-rays in elliptical galaxies?
(A) Supernovae
(B) Hot interstellar gas
(C) Blackbody radiation from stars
(D) Cold molecular clouds

39. What is a galactic halo primarily composed of?
(A) Dust
(B) Gas
(C) Dark matter and old stars
(D) Only young stars

40. Which is the most luminous type of galaxy?
(A) Irregular galaxies
(B) Starburst galaxies
(C) cD galaxies
(D) Dwarf spheroidals

41. Which galaxies are common satellites of larger spirals?
(A) Ellipticals
(B) Dwarf galaxies
(C) Lenticulars
(D) Starbursts

42. What is galactic cannibalism?
(A) When a galaxy absorbs smaller galaxies
(B) When stars eat planets
(C) When dark matter collapses
(D) When black holes merge

43. What evidence suggests the Milky Way is barred?
(A) Infrared mapping of the bulge
(B) Star counts in halo
(C) Globular cluster distribution
(D) Gas rotation speed

44. Which galaxies often host quasars?
(A) Dwarf irregulars
(B) Massive ellipticals
(C) Spiral galaxies only
(D) Low-surface-brightness galaxies

45. The spiral arms of galaxies are thought to be:
(A) Solid structures
(B) Density waves
(C) Regions of only dark matter
(D) Magnetic fields

46. Which satellite galaxies are closest to the Milky Way?
(A) Andromeda satellites
(B) Magellanic Clouds
(C) Triangulum satellites
(D) Sculptor dwarf

47. What is the Virgo Cluster?
(A) Cluster of stars
(B) Cluster of galaxies
(C) Cluster of globulars
(D) Cluster of black holes

48. What is intracluster medium in galaxy clusters?
(A) Cold molecular gas
(B) Hot, X-ray emitting gas
(C) Neutrino background
(D) Dark matter streams

49. What happens during ram-pressure stripping in galaxies?
(A) Gas is removed due to motion through cluster medium
(B) Stars are stripped from disk
(C) Dark matter is lost
(D) Galaxy rotates faster

50. What is the ultimate fate of most galaxies in the distant future?
(A) Continuous star formation
(B) Red, dead galaxies dominated by old stars
(C) Becoming quasars
(D) Evaporation of dark matter halos