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Difficulty: EasyIdentifying Primary Purpose and Main Idea

In astrophysics, the precise mechanism governing the formation of massive stars—those with masses exceeding eight solar masses—remained debated for decades. According to the core accretion model, a dense circumstellar disk continuously feeds gas onto a protostellar core until radiation pressure from the growing star halts further inflow. However, early theoretical calculations suggested that intense radiation pressure would blast away surrounding gas and dust before the star could accrete sufficient mass. To resolve this apparent conflict, recent three-dimensional hydrodynamical simulations revealed that accretion disks develop narrow, collimated channels through which radiation escapes, allowing infalling gas to continue accumulating along the equatorial plane. Thus, these simulations demonstrate that core accretion remains a viable framework for massive star formation.

Which of the following best states the primary purpose of the passage?

  1. To explain how recent computational simulations resolve a theoretical obstacle in massive star formation.Answer
  2. B
    To argue that the core accretion model should be completely replaced by a new astrophysical theory.
  3. C
    To detail the specific process by which radiation pressure blasts away surrounding circumstellar gas.
  4. D
    To contrast theoretical calculations with direct empirical telescopic observations of protostars.
  5. E
    To demonstrate that radiation pressure is irrelevant to the growth of protostellar cores.

Answer

The primary purpose of the passage is to explain how recent computational simulations resolve a theoretical obstacle in massive star formation.
The passage follows a classic problem-solution structure: it introduces the core accretion model, explains a potential flaw (radiation pressure blowing away gas), and describes how recent 3D hydrodynamical simulations resolved this issue by showing how gas can continue to fall along the equatorial plane. Therefore, the main purpose is to explain how these simulations resolve a theoretical obstacle in stellar formation.

Step-by-Step Solution

1
Identify the main topic and structural flow of the passage.
The passage begins with the core accretion model, introduces a theoretical conflict involving radiation pressure, and ends with new 3D simulations that resolve this conflict.
Tracking structural transitions reveals the author's core thesis and reason for writing.
2
Evaluate the author's ultimate conclusion.
The author concludes that core accretion 'remains a viable framework' because simulations showed how radiation escapes without stopping gas inflow.
The primary purpose must reflect the main resolution reached at the end of the text.
3
Match the overall narrative to the choice that captures scope and tone accurately.
The statement emphasizing how recent simulations resolve the theoretical obstacle accurately captures the full scope of the passage.
Primary purpose answer choices must encompass the entire scope without overgeneralizing or focusing on minor details.

Key Concept

Identifying Primary Purpose in Scientific Passages
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Topics

Identifying Primary Purpose and Main Idea

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