Read the following passage carefully:
1. About twice every century, one of the massive stars in our galaxy blows itself apart in a
supernova explosion that sends massive quantities of radiation and matter into space and
generates shock waves that sweep through the arms of the galaxy. The shock waves heat the
interstellar gas, evaporate small clouds, and compress larger ones to the point at which they
collapse under their own gravity to form new stars. The general picture that has been developed
for the supernova explosion and its aftermath goes something like this. Throughout its evolution,
a star is much like a leaky balloon. It keeps its equilibrium figure through a balance of internal
pressure against the tendency to collapse under its own weight. The pressure is generated by
nuclear reactions in the core of the star which must continually supply energy to balance the
energy that leaks out in the form of radiation. Eventually the nuclear fuel is exhausted, and the
pressure drops in the core. With nothing to hold it up, the matter in the center of the star
collapses inward, creating higher and higher densities and temperatures, until the nuclei and
electrons are fused into a super-dense lump of matter known as a neutron star.
2. As the overlying layers rain down on the surface of the neutron star, the temperature rises, until
with a blinding flash of radiation, the collapse is reversed. A thermonuclear shock wave runs
through the now expanding stellar envelope, fusing lighter elements into heavier ones and
producing a brilliant visual outburst that can be as intense as the light of 10 billion suns. The
shell of matter thrown off by the explosion plows through the surrounding gas, producing an
expanding bubble of hot gas, with gas temperatures in the millions of degrees. This gas will emit
most of its energy at X-ray wavelengths, so it is not surprising that X-ray observatories have
provided some of the most useful insights into the nature of the supernova phenomenon. More
than twenty supernova remnants have now been detected in X-Ray Studies.
3. Recent discoveries of meteorites with anomalous concentrations of certain isotopes indicate
that a supernova might have precipitated the birth of our solar system more than four and a half
billion years ago. Although the cloud that collapsed to form the Sun and the planets was
composed primarily of hydrogen and helium, it also contained carbon, nitrogen, and oxygen,
elements essential for life as we know it.
4. Elements heavier than helium are manufactured deep in the interior of stars and would, for the
most part, remain there if it were not for the cataclysmic supernova explosions that blow giant
stars apart. Additionally, supernovas produce clouds of high-energy particles called cosmic
rays. These high-energy particles continually bombard the Earth and are responsible for many
of the genetic mutations that are the driving force of the evolution of species.According to the passage all of the following are true of supernovas EXCEPT that they
(a) are extremely bright
(b) are an explosion of some sort
(c) emit large quantities of X-rays
(d) are caused by the collision of large galaxies
Answers
Answer:
Read the following passage carefully:
1. About twice every century, one of the massive stars in our galaxy blows itself apart in a
supernova explosion that sends massive quantities of radiation and matter into space and
generates shock waves that sweep through the arms of the galaxy. The shock waves heat the
interstellar gas, evaporate small clouds, and compress larger ones to the point at which they
collapse under their own gravity to form new stars. The general picture that has been developed
for the supernova explosion and its aftermath goes something like this. Throughout its evolution,
a star is much like a leaky balloon. It keeps its equilibrium figure through a balance of internal
pressure against the tendency to collapse under its own weight. The pressure is generated by
nuclear reactions in the core of the star which must continually supply energy to balance the
energy that leaks out in the form of radiation. Eventually the nuclear fuel is exhausted, and the
pressure drops in the core. With nothing to hold it up, the matter in the center of the star
collapses inward, creating higher and higher densities and temperatures, until the nuclei and
electrons are fused into a super-dense lump of matter known as a neutron star.
2. As the overlying layers rain down on the surface of the neutron star, the temperature rises, until
with a blinding flash of radiation, the collapse is reversed. A thermonuclear shock wave runs
through the now expanding stellar envelope, fusing lighter elements into heavier ones and
producing a brilliant visual outburst that can be as intense as the light of 10 billion suns. The
shell of matter thrown off by the explosion plows through the surrounding gas, producing an
expanding bubble of hot gas, with gas temperatures in the millions of degrees. This gas will emit
most of its energy at X-ray wavelengths, so it is not surprising that X-ray observatories have
provided some of the most useful insights into the nature of the supernova phenomenon. More
than twenty supernova remnants have now been detected in X-Ray Studies.
3. Recent discoveries of meteorites with anomalous concentrations of certain isotopes indicate
that a supernova might have precipitated the birth of our solar system more than four and a half
billion years ago. Although the cloud that collapsed to form the Sun and the planets was
composed primarily of hydrogen and helium, it also contained carbon, nitrogen, and oxygen,
elements essential for life as we know it.
4. Elements heavier than helium are manufactured deep in the interior of stars and would, for the
most part, remain there if it were not for the cataclysmic supernova explosions that blow giant
stars apart. Additionally, supernovas produce clouds of high-energy particles called cosmic
rays. These high-energy particles continually bombard the Earth and are responsible for many
of the genetic mutations that are the driving force of the evolution of species.According to the passage all of the following are true of supernovas EXCEPT that they
(a) are extremely bright
(b) are an explosion of some sort
(c) emit large quantities of X-rays
(d) are caused by the collision of large galaxies
The correct answer is d)
- A supernova is a massive star exploding. It usually occurs in the last evolutionary stage of star.
- It is an explosion
- Upon the explosion the star emits luminous light.
- The supernova emits a number of rays including visible light when they blow off, x rays, ultraviolet rays and huge amount of neutrinos (subatomic particles that do not interact with matter).
- A supernova explodes within 100 seconds and when the star explodes it leaves behind a remnant usually a white dwarf or black hole.
- A star explodes in a supernova once every 50 years. A supernova has an impact that could wipe out galaxies and the planets inside them.
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