### The Solar Corona Heating Problem
The Sun’s surface, the photosphere, has a temperature of approximately , while the corona, the outermost layer of the solar atmosphere, reaches temperatures of over . 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?
- The waves must propagate into regions of decreasing plasma density to become unstable and dissipate.Cevap
- BOpposing magnetic field lines must be forced together, break, and reconnect.
- CThe waves must remain stable and maintain a constant frequency as they cross regions of high plasma density.
- DThe magnetic field lines must be twisted and sheared by the continuous motion of nanoflares.