- 1. What is the primary range of radiated output for O-type stars?
A) Visible light
B) Infrared
C) Ultraviolet
D) Radio waves
- 2. What is the approximate frequency of O-type stars among main-sequence stars in the solar neighborhood?
A) 1 in 1,000
B) 1 in 3,000,000
C) 1 in 1,000,000
D) 1 in 100
- 3. Why is the measurement of O-type star spectra often difficult?
A) Distance from Earth
B) Low luminosity
C) Complicated surroundings
D) Excessive cooling
- 4. Which line ratio was formerly used to define O-type spectra?
A) Si IV to O III
B) He II 4541 to He I 4471
C) N IV 4058 to N III 4634
D) He I 4471 to Hydrogen Balmer
- 5. What is the defining spectral type where the He II 4541 and He I 4471 intensities are equal?
A) O7
B) O5
C) O3
D) O9
- 6. What is the modern definition for O-type classification based on?
A) N IV 4058 to N III 4634-40-42
B) He II to Hydrogen Balmer
C) Si IV to C III
D) Neutral helium lines
- 7. Which spectral lines strengthen from O5 to O9?
A) N IV lines
B) He II emission lines
C) Neutral helium lines
D) Hydrogen Balmer lines
- 8. What is the typical velocity of the stellar wind in high-mass O-type stars?
A) 1,000 km/s
B) 2,000 km/s
C) 500 km/s
D) 5,000 km/s
- 9. Why do O-type stars leave the main sequence quickly?
A) They lack helium
B) They burn hydrogen fuel very quickly
C) They have cold cores
D) They have unstable atmospheres
- 10. When was the MKK classification scheme first described?
A) 1971
B) 2000
C) 1978
D) 1943
- 11. Which spectral type was added to the MKK scheme in 1978?
A) O2
B) O3
C) O9.7
D) O4
- 12. Which star is listed as an example spectral standard for O7V?
A) The Sun
B) S Monocerotis
C) Betelgeuse
D) 10 Lacertae
- 13. Which star is listed as an example spectral standard for O9V?
A) 10 Lacertae
B) S Monocerotis
C) Sirius
D) Vega
- 14. What happens to the He I line as spectral types move earlier than O7?
A) It strengthens
B) It weakens
C) It becomes an emission line
D) It disappears immediately
- 15. What is the physical reason O-type stars do not retain extensive atmospheres?
A) Extreme stellar wind velocity
B) High metallic content
C) Excessive ultraviolet radiation
D) Low gravitational pull
- 16. What primary tool is used to split a star's electromagnetic radiation into a spectrum?
A) A specialized telescope lens
B) A radio frequency receiver
C) A digital image sensor
D) A prism or diffraction grating
- 17. What is the primary factor that causes the strength of spectral lines to vary?
A) Temperature of the photosphere
B) Age of the star
C) Velocity of the star
D) Distance from Earth
- 18. What does a spectral class primarily summarize?
A) The rotational speed of the star
B) The total mass of the star
C) The ionization state
D) The chemical age of the star
- 19. Which letter represents the hottest stars in the MK system?
A) O
B) M
C) G
D) A
- 20. Which letter is used to designate white dwarfs?
A) W
B) S
C) D
D) C
- 21. What letters are used to designate brown dwarfs?
A) F, G, and K
B) L, T, and Y
C) W, S, and C
D) O, B, and A
- 22. What do Roman numerals represent in the MK system?
A) The chemical abundance index
B) The number of stellar companions
C) Spectral temperature class
D) Luminosity class
- 23. What does the luminosity class in the MK system distinguish?
A) Young stars from old stars
B) Giant stars from dwarfs
C) Solid surfaces from gaseous surfaces
D) Binary systems from single stars
- 24. What luminosity class is assigned to main-sequence stars?
A) I
B) V
C) IV
D) III
- 25. What is the full spectral class for the Sun?
A) O5I
B) M0III
C) G2V
D) A0V
- 26. What is the approximate surface temperature of the Sun?
A) 5,800 K
B) 2,500 K
C) 3,000 K
D) 10,000 K
- 27. What actual color does a 'yellow' dwarf appear to the human eye?
A) Blue
B) Yellow
C) White
D) Green
- 28. What color do 'red' dwarfs actually appear to be?
A) A deep shade of yellow/orange
B) Deep purple
C) Bright red
D) Pure white
- 29. Which of the following colors are generally not seen in stars under typical viewing conditions?
A) Red, orange, or yellow
B) Green, cyan, indigo, or violet
C) Red and infrared
D) Blue and white
- 30. What does the UBV system use for classification?
A) Color indices
B) Surface temperature
C) Absolute mass
D) Ionization energy
- 31. What does the abbreviation 'MK' stand for?
A) Main-sequence Kinetic
B) Morgan–Keenan
C) Molecular Kelvin
D) Mass-Klassification
- 32. Which luminosity class represents hypergiants?
A) II
B) III
C) V
D) 0 or Ia+
- 33. Who developed the Harvard spectral classification system?
A) Ejnar Hertzsprung
B) Annie Jump Cannon
C) Meghnad Saha
D) Cecilia Payne
- 34. What is the spectral classification of the Sun?
A) A0
B) G2
C) M5
D) O9.7
- 35. Who derived a theory of ionization that explained stellar spectra?
A) Annie Jump Cannon
B) Henry Draper
C) Meghnad Saha
D) Cecilia Payne
- 36. Who demonstrated that the O-B-A-F-G-K-M sequence is a temperature sequence?
A) Annie Jump Cannon
B) Cecilia Payne
C) Ejnar Hertzsprung
D) Meghnad Saha
- 37. Are fractional numbers allowed in the Harvard spectral classification?
A) Only for O-type stars
B) No
C) Yes
D) Only for M-type stars
- 38. What was the Harvard classification based on before its physical basis was fully understood?
A) Atomic weight
B) Spectral characteristics
C) Chemical composition
D) Surface gravity
- 39. Which observatory is associated with the developers of the Morgan-Keenan system?
A) Mauna Kea Observatory
B) Harvard Observatory
C) Yerkes Observatory
D) Palomar Observatory
- 40. What phenomenon causes greater pressure broadening of spectral lines in denser stars?
A) Increased magnetic fields
B) Greater stellar radius
C) Lower surface temperature
D) Higher surface gravity
- 41. Which roman numeral is used for sub-dwarf stars?
A) V
B) IV
C) VI
D) VII
- 42. Which luminosity class is now rarely used for white dwarfs?
A) I
B) VII
C) V
D) III
- 43. What designation is given to extreme V stars with strong He II λ4686 absorption?
A) Vz
B) Vn
C) Ve
D) Vb
- 44. Who created the Secchi classes in the 1860s and 1870s?
A) Williamina Fleming
B) Annie Jump Cannon
C) Edward C. Pickering
D) Angelo Secchi
- 45. By what year had Angelo Secchi developed three classes of stellar spectra?
A) 1880
B) 1890
C) 1875
D) 1866
- 46. What system began to supersede the Secchi classes in the late 1890s?
A) The Henry Draper memorial catalogue
B) The Yerkes luminosity classes
C) The neutron star classification
D) The Harvard classification
- 47. Who funded the creation of the Harvard Plate Stacks?
A) Mary Anna Draper
B) Antonia Maury
C) Edward C. Pickering
D) Williamina Fleming
- 48. Who was the director of the Harvard College Observatory who hired the Harvard Computers?
A) Edward C. Pickering
B) Angelo Secchi
C) Williamina Fleming
D) Henry Draper
- 49. In what year was the first edition of the Henry Draper Memorial Catalogue of Stellar Spectra published?
A) 1899
B) 1866
C) 1890
D) 1905
- 50. Who is credited with classifying over 10,000 stars in the first Henry Draper catalogue?
A) Mary Anna Draper
B) Antonia Maury
C) Williamina Fleming
D) Annie Jump Cannon
- 51. How many variable stars did Williamina Fleming discover?
A) Less than 50
B) More than 200
C) 1,000
D) Exactly 10
- 52. What letter was used in the original Henry Draper catalogue for stars that did not fit into other classes?
A) Q
B) P
C) A
D) O
- 53. In what year was Antonia Maury's Harvard system published?
A) 1901
B) 1912
C) 1890
D) 1897
- 54. How many spectral types did Antonia Maury's 1897 system include?
A) Forty-eight
B) Twelve
C) Ten
D) Twenty-two
- 55. What notation did Antonia Maury use for her spectral types?
A) Greek symbols
B) Arabic numerals
C) Lowercase letters
D) Roman numerals
- 56. What does the lowercase letter 'b' represent in Antonia Maury's spectral classification?
A) Average width
B) Hazy
C) Bright
D) Sharp
- 57. What does the lowercase letter 'c' represent in Antonia Maury's spectral classification?
A) Average width
B) Sharp
C) Clear
D) Hazy
- 58. How many star analyses were included in Maury's 1897 catalogue?
A) 100
B) 681
C) 1,000
D) 4,800
- 59. Which system was introduced in 1901 by Annie Jump Cannon?
A) The lettered types system
B) The Mount Wilson system
C) The Roman numeral system
D) The Secchi system
- 60. What did the letter 'P' represent in Annie Jump Cannon's system?
A) Primary stars
B) Peculiar spectra
C) Protostars
D) Planetary nebulae
- 61. What did the letter 'Q' represent in Annie Jump Cannon's system?
A) Quasars
B) Planetary nebulae
C) Peculiar spectra
D) Quiet stars
- 62. In what year was the modern form of the Harvard classification system established?
A) 1912
B) 1920
C) 1901
D) 1897
- 63. What does the 'sd' notation stand for in the Mount Wilson system?
A) Supergiant
B) Small dwarf
C) Subdwarf
D) Standard dwarf
- 64. What does the 'd' notation stand for in the Mount Wilson system?
A) Double star
B) Dwarf
C) Dark star
D) Dense star
- 65. What does the 'sg' notation stand for in the Mount Wilson system?
A) Supergiant
B) Small giant
C) Subgiant
D) Secondary giant
- 66. What does the 'c' notation stand for in the Mount Wilson system?
A) Common star
B) Supergiant
C) Center star
D) Compact star
- 67. What is the stellar classification system based on?
A) Age of the star
B) Type specimens
C) Chemical composition
D) Distance from Earth
- 68. In stellar nomenclature, what does 'early' signify?
A) Hotter
B) Brighter
C) Younger
D) Larger
- 69. In stellar nomenclature, what does 'late' signify?
A) Fainter
B) Cooler
C) Older
D) Smaller
- 70. What does a higher Arabic numeral following a class letter indicate in relative terms?
A) Bright
B) Early
C) Late
D) Massive
- 71. What does a lower Arabic numeral following a class letter indicate in relative terms?
A) Late
B) Dim
C) Cold
D) Early
- 72. The terms 'early' and 'late' originate from a model based on what process?
A) Gravitational contraction
B) Nuclear fusion
C) Stellar accretion
D) Supernova explosion
- 73. What nineteenth-century mechanism was thought to power stars?
A) Thermal expansion
B) Radiative pressure
C) Nuclear fission
D) Kelvin–Helmholtz mechanism
- 74. What process is now known to actually power main-sequence stars?
A) Gravitational contraction
B) Nuclear fusion
C) Radioactive decay
D) Chemical combustion
- 75. What is the primary color of B-type stars?
A) White
B) Red
C) Yellow
D) Blue
- 76. At which B-type subclass is the neutral helium line most prominent?
A) B0
B) B8
C) B2
D) B5
- 77. Which element is used to classify B-type supergiants?
A) Silicon
B) Helium
C) Magnesium
D) Iron
- 78. In what structures are B-type stars typically found?
A) Globular clusters
B) Planetary nebulae
C) OB associations
D) Black holes
- 79. What is the closest B-type star to the solar neighborhood?
A) Alnilam
B) Regulus
C) Alkaid
D) Rigel
- 80. What property of Be stars is described as 'curiously rapid'?
A) Orbital velocity
B) Pulsation rate
C) Rotation
D) Expansion rate
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