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# The astronomical study of hot gas—gas with a temperature of a million

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The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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Updated on: 01 Aug 2020, 08:18
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New Project RC Butler 2019 - Practice 2 RC Passages Everyday
Passage # 169, Date : 26-APR-2019
This post is a part of New Project RC Butler 2019. Click here for Details

The astronomical study of hot gas—gas with a temperature of a million degrees Kelvin or greater—began with observations of the solar atmosphere. In the 1930s, techniques were developed to perform optical studies of the solar corona during solar eclipses. The detection of highly ionized atoms of iron, calcium, and nickel, as well as an extended gaseous region, implied the presence of gas at temperatures of about a million degrees K. However, detailed study of the solar corona had to await the advent of space astronomy and the chance to observe the sun at ultraviolet and X-ray wavelengths outside the earth’s opaque atmosphere. These wavelengths are crucial for studying hot gas because highly ionized atoms are visible in these regions and because most radiated energy is emitted there.

Recent study of hot gas began with the launching in the 1970s of space observatories which gathered data on ultraviolet and X-ray wavelengths. These observations led to a new picture of the production and evolution of hot gas. Before 1970, direct evidence for the presence of hot gas in large volumes of space was lacking. Although there were theoretical arguments for pervasive interstellar gas, interstellar space in our galaxy was thought to be occupied by gas with a temperature of about 10,000 degrees K. In the 1970s, however, the observatory Copernicus revealed the widespread presence in our galaxy of highly ionized oxygen that could only be produced at high temperatures. At the same time, the Uhuru X-ray satellite discovered emissions from hot gas in the space between galaxies in clusters. Subsequent studies confirmed these findings.

It is believed that interstellar gas is heated through two mechanisms: the motions of stars and matter ejected from them, and gravitational infall. Hot gas has been observed on a smaller scale, between stars in our galaxy, and in largescale structures (clusters of galaxies). On a smaller scale, supernovae, or exploding stars, probably create an interstellar medium of hot gas within galaxies; they may also drive gas out of galaxies. On a larger scale, gravitational infall during which gas slumps toward the center of a galaxy—may play a role in the heating of gas.

1. Which of the following can be inferred from the passage about “recent study of hot gas” (Highlighted)?

(A) It has prompted the rejection of earlier studies of the solar corona.
(B) It has taken place largely outside the earth’s atmosphere.
(C) It has led to full understanding of the production and evolution of hot gas.
(D) It was aimed primarily at gathering data related to the birth and death of stars.
(E) It was hindered by astronomers’ dependence on outdated research techniques.

2. Which of the following is mentioned in the passage as evidence for the presence of hot interstellar gas in our galaxy?

(A) The varying levels of radiation given off by distant stars
(B) The large quantity of ionized atoms detected during solar eclipses
(C) The presence of gas with a temperature of about 10,000 degrees K in our galaxy
(D) The production of highly ionized oxygen in our galaxy
(E) The frequent occurrence of supernovae in our galaxy

3. According to the passage, the Uhuru X-ray satellite has been instrumental in helping to

(A) provide detailed images of the remnants of supernovae in our galaxy
(B) determine the precise sequence of events leading to a supernova
(C) document the widespread presence of hot gas in interstellar space
(D) identify the different types of particles commonly ejected by stars
(E) measure the varying strength of gravitational fields at galactic centers

4. The author suggests that the studies of the solar atmosphere discussed in the first paragraph

(A) conflict with current assumptions about the extent of the gaseous region surrounding the sun
(B) reached conclusions which were overlooked by later studies
(C) were constrained by the technology then available to scientists
(D) confirmed then-current beliefs about the presence of hot gas between stars
(E) are largely irrelevant to recent studies of hot gas

5. Which of the following best describes how the second paragraph relates to the first paragraph?

(A) The second paragraph qualifies a conclusion stated in the first paragraph.
(B) The second paragraph elaborates on developments identified in the first paragraph.
(C) The second paragraph examines in detail the particular studies referred to in the first paragraph.
(D) The second paragraph identifies a more fruitful area of study than that discussed in the first paragraph.
(E) The second paragraph illustrates the degree of speculation involved in the studies mentioned in the first paragraph.

6. The passage specifically mentions information relevant to all of the following questions EXCEPT:

(A) In what way does hot gas affect the evolution of stellar systems?
(B) What may result from the migration of gas toward the center of a galaxy?
(C) What effect can the release of energy during a stellar explosion have on interstellar gas?
(D) What evidence have researchers gathered for the presence of hot gas near the sun?
(E) Why is the ability to monitor ultraviolet and X-ray wavelengths necessary for the study of hot gas?

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Last edited by SajjadAhmad on 01 Aug 2020, 08:18, edited 2 times in total.
Updated - Complete topic (861).
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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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26 Apr 2019, 21:17
1
All except question 6 correct in 11 mins, including almost 4 mins to read

Para 1- astronomical study of hot gas, Earlier studies, implied presence of hot gases
Para 2- more detailed study using ultraviolet and X-ray
Para 3- interstellar gas is heated through two mechanisms

1. Which of the following can be inferred from the passage about “recent study of hot gas” (Highlighted)?
(B) It has taken place largely outside the earth’s atmosphere.

However, detailed study of the solar corona had to await the advent of space astronomy and the chance to observe the sun at ultraviolet and X-ray wavelengths outside the earth’s opaque atmosphere.
Recent study of hot gas began with the launching in the 1970s of space observatories which gathered data on ultraviolet and X-ray wavelengths.

2. Which of the following is mentioned in the passage as evidence for the presence of hot interstellar gas in our galaxy?
(D) The production of highly ionized oxygen in our galaxy

In the 1970s, however, the observatory Copernicus revealed the widespread presence in our galaxy of highly ionized oxygen that could only be produced at high temperatures.

3. According to the passage, the Uhuru X-ray satellite has been instrumental in helping to
(C) document the widespread presence of hot gas in interstellar space

the Uhuru X-ray satellite discovered emissions from hot gas in the space between galaxies in clusters. Subsequent studies confirmed these findings.

4. The author suggests that the studies of the solar atmosphere discussed in the first paragraph
(C) were constrained by the technology then available to scientists

However, detailed study of the solar corona had to await the advent of space astronomy and the chance to observe the sun at ultraviolet and X-ray wavelengths outside the earth’s opaque atmosphere.

5. Which of the following best describes how the second paragraph relates to the first paragraph?
(B) The second paragraph elaborates on developments identified in the first paragraph.

However, detailed study of the solar corona had to await the advent of space astronomy and the chance to observe the sun at ultraviolet and X-ray wavelengths outside the earth’s opaque atmosphere. These wavelengths are crucial for studying hot gas because highly ionized atoms are visible in these regions and because most radiated energy is emitted there.

Recent study of hot gas began with the launching in the 1970s of space observatories which gathered data on ultraviolet and X-ray wavelengths.

6. The passage specifically mentions information relevant to all of the following questions EXCEPT:

(A) In what way does hot gas affect the evolution of stellar systems?- correct
(B) What may result from the migration of gas toward the center of a galaxy?- incorrect, On a larger scale, gravitational infall during which gas slumps toward the center of a galaxy—may play a role in the heating of gas.
(C) What effect can the release of energy during a stellar explosion have on interstellar gas?- incorrect, On a smaller scale, supernovae, or exploding stars, probably create an interstellar medium of hot gas within galaxies; they may also drive gas out of galaxies
(D) What evidence have researchers gathered for the presence of hot gas near the sun?- incorrect, The detection of highly ionized atoms of iron, calcium, and nickel, as well as an extended gaseous region, implied the presence of gas at temperatures of about a million degrees K.
(E) Why is the ability to monitor ultraviolet and X-ray wavelengths necessary for the study of hot gas? - incorrect, These wavelengths are crucial for studying hot gas because highly ionized atoms are visible in these regions and because most radiated energy is emitted there.
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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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27 Apr 2019, 05:55
Hi ,

Why is question 1 option C is incorrect?
My understanding: 1) Nothing about evolution of hot gas is stated.
2) Full understanding depends from person to person, so we cannot conclude that it led to full understanding.
Please let me know whether my reasoning is correct.

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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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28 Apr 2019, 06:50
Official Explanation

Topic and Scope:

Past and more recent astronomical study of hot gas; specifically, how the technology for studying hot gas has improved and what scientists have learned about the gas.

Purpose and Main Idea:

Author shows how study techniques have undergone extensive changes since the 1930s and that, as a result, our knowledge of hot gas has been substantially extended.

Paragraph Structure:

Paragraph 1 defines hot gas and focuses on 1930s studies, which were speculative—scientists lacked technology for more definitive study.
Paragraph 2 moves to the 1970s. The technology has been invented, giving us “a new picture” of hot gas. The paragraph identifies evidence for large volumes of hot gas in space; the observatory Copernicus and satellite Uhuru (circle names like these!) have provided such evidence.
Paragraph 3 speculates about how hot gas may be heated, and draws a distinction between small-scale and large scale masses of gas.

1. Which of the following can be inferred from the passage about “recent study of hot gas” (Highlighted)?

Explanation

The answer to an inference question is generally not explicitly stated in the passage, but will nonetheless be very close to it. (A) is out because earlier studies were not rejected—merely superseded. Checking (B), you find in paragraph 1 the statement that “detailed study...had to await...the chance to observe...outside the earth’s opaque atmosphere.” The next paragraph then discusses recent study. You can infer that recent study has taken place outside the atmosphere. This is the answer—not directly stated but adhering closely to the passage. (C) contradicts the passage with the words “full understanding.” The wording in the last paragraph (“it is believed,” “probably,” and “may”) implies that we lack full understanding. (D) exaggerates a detail in paragraph 3. (E) doesn’t fit the passage’s progression—the studies in the ’70s didn’t use the techniques of the ’30s.

Hope it helps

Priyanka2018 wrote:
Hi ,

Why is question 1 option C is incorrect?
My understanding: 1) Nothing about evolution of hot gas is stated.
2) Full understanding depends from person to person, so we cannot conclude that it led to full understanding.
Please let me know whether my reasoning is correct.

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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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30 Apr 2019, 10:08
can you explain why 5 answer is B, I don't get it
Thanks
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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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06 May 2019, 00:27
1
Official Explanation

5. Which of the following best describes how the second paragraph relates to the first paragraph?

Difficulty Level: 700

Explanation

This question basically asks how the author’s focus changes through the first two paragraphs.
Paragraph 1 discusses the limitations of ‘30s research and explains why new technology was needed.
Paragraph 2 describes how new technology was used in the ‘70s to develop “a new picture” of hot gas.

Checking the choices, (A) is inaccurate. The word “qualifies” means “weakens”; the later studies didn’t conflict with the earlier ones. (Note that the previous question and its choices also picked up on this point.) (B) looks good with “elaborates on developments.” The passage does emphasize development— “elaboration” means refining ideas on the same topic. (C) is faulty because paragraphs 1 and 2 deal with completely different studies. (D) sounds as if the “area of study” changed. The author identifies new technology, but not a more fruitful area of study. (E) mentions the “degree of speculation,” which is incorrect—paragraph 1 cites speculation, but paragraph 2 discusses new knowledge.

lifeforhuskar wrote:
can you explain why 5 answer is B, I don't get it
Thanks

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Re: The astronomical study of hot gas—gas with a temperature of a million  [#permalink]

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01 Aug 2020, 08:19
Bumping up for more discussion.
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Re: The astronomical study of hot gas—gas with a temperature of a million   [#permalink] 01 Aug 2020, 08:19