QUESTION 1 A certain pulsar is pulsing in radio waves 7.333 times per second. Wh

Question

QUESTION 1

A certain pulsar is pulsing in radio waves 7.333 times per second. Why?
      
A. It is eclipsed by a companion 7.333 times per second.
      
B. It's a mystery; no one really knows.
      
C. A jet ejects energy and particles from a hot spot 7.333 times per second.
      
D. It rotates 7.333 times per second.

QUESTION 2

An O-star has a surface temperature significantly hotter than that of the Sun. Therefore, compared to the Sun,
      
A. it emits at about the same wavelengths as the Sun (similar peak) but it is much brighter.
      
B. it emits at about the same wavelengths as the Sun (similar peak) but it is much fainter.
      
C. its emission peaks in the infrared part of the spectrum.
      
D. its emission peaks at smaller wavelengths than that of the Sun.

QUESTION 3

Astronauts traveling through the disk of any spiral galaxy would spend most of their time in?
      
empty space-a pure vacuum
      
A. rarefied clouds of atomic hydrogen
      
B. star clusters
      
C. hot bubbles of ionized hydrogen
      
D. cool, dense clouds of molecular hydrogen

Explanation / Answer

answer- the pulsar is neutron star star that emit electromagnetic radiation (radiowave, X ray and gamma rays).it is highly magnetized and rotating star. it pulse .radiowave 7.333 times per second because it is rotated 7.333 times per second.(option D). the beam of radiowave is generated from the magnetic axis of the pulsar.

answer- the surface temperature of the O star is hotter than sun.the surface temperature of the O star is 30000 K. there is presence of Helium II absroption lines. these star located in the active star formation their temperature is higher than sun because it emits at about same wavelengthas the sun but it more brighter than sun (option A)

answer- astronauts travelling through disk of any spiral galaxy would spent more time in cool dense cloud of molecular hydrogen (option D) the centre of the disc is surrounded by the dust and gas surround it

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