Examkin

Question

Difficulty: MediumIdentifying Core Claims and Hypotheses

### The Solar Corona Heating Problem

The Sun’s surface, the photosphere, has a temperature of approximately 5,800 K5,800\text{ K}, while the corona, the outermost layer of the solar atmosphere, reaches temperatures of over 1,000,000 K1,000,000\text{ K}. Because heat normally flows from hotter to cooler regions, this temperature inversion is a major puzzle in astrophysics. Two scientists propose different hypotheses to explain how energy is transported to heat the corona.

Scientist 1
Energy is transported from the photosphere to the corona by magnetic waves called Alfvén waves. These are low-frequency transverse waves that propagate along magnetic field lines. Convection in the photosphere shakes the magnetic field lines, generating these waves. As the Alfv��n waves travel outward through the solar atmosphere into regions of lower plasma density, they become unstable, dissipate, and transfer their electromagnetic energy directly to the coronal plasma as thermal energy. The heating is continuous and occurs globally across all magnetic field structures.

Scientist 2
Energy is transported and released in the corona through a process called magnetic reconnection. The Sun's magnetic field lines are continuously twisted and sheared by the motion of photospheric plasma. When oppositely directed magnetic field lines are forced together, they rapidly break and reconnect, releasing stored magnetic energy. This energy release occurs in sudden, localized bursts called nanoflares. The cumulative effect of millions of these tiny, impulsive nanoflares occurring throughout the corona provides the energy necessary to maintain the high coronal temperature.

According to Scientist 1, which of the following is a necessary condition for Alfvén waves to transfer thermal energy to the solar corona?

  1. The waves must propagate into regions of decreasing plasma density to become unstable and dissipate.Answer
  2. B
    Opposing magnetic field lines must be forced together, break, and reconnect.
  3. C
    The waves must remain stable and maintain a constant frequency as they cross regions of high plasma density.
  4. D
    The magnetic field lines must be twisted and sheared by the continuous motion of nanoflares.

Answer

The waves must propagate into regions of decreasing plasma density to become unstable and dissipate.
The correct answer is correct because Scientist 1 states that Alfvén waves transfer energy to the coronal plasma as thermal energy only when they travel into regions of lower (decreasing) plasma density and become unstable. This matches the assertion that they must propagate into regions of decreasing plasma density to become unstable and dissipate.

Step-by-Step Solution

1
Identify the scientist and the specific process referenced in the question.
The question asks about the condition required for energy transfer via Alfvén waves under Scientist 1's hypothesis.
This directs focus to the text block for Scientist 1.
2
Locate the explanation of how Alfvén waves transfer thermal energy within Scientist 1's text.
Scientist 1 states: 'As the Alfvén waves travel outward through the solar atmosphere into regions of lower plasma density, they become unstable, dissipate, and transfer their electromagnetic energy directly to the coronal plasma as thermal energy.'
This establishes that traveling into lower (decreasing) density is the trigger for instability, dissipation, and subsequent heat transfer.
3
Match this finding with the provided choices.
The option specifying propagation into regions of decreasing plasma density is the correct match.
This confirms the correct option while identifying why the other choices represent incorrect claims or belong to Scientist 2's model.

Key Concept

Identifying core claims and hypotheses in conflicting scientific viewpoints
Estimated Time:1m 30s
Rate this question

Topics

Identifying Core Claims and Hypotheses

More questions from this topic