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SOLAR MEAN MAGNETIC FIELD

27th June, 2023

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Context

  • According to the Department of Science and Technology, scientists now are one step closer to identifying the source of the Solar Mean Magnetic Field (SMMF).

Solar Mean Magnetic Field

  • The Sun has a complicated magnetic field structure; many features of the Sun and proxies for the solar activity are related to the evolution of the Sun’s magnetic field.
  • The solar mean magnetic field (SMMF) is a non-zero measurement of the imbalance of opposite polarities of magnetic flux observed on the full visible disc of the Sun.

Definition

The Solar Mean Magnetic Field (SMMF) is the mean value of the line-of-sight (LOS) component of the solar vector magnetic field averaged over the visible hemisphere of the Sun.

The SMMF is also sometimes referred to as the general magnetic field or the mean magnetic field of the Sun.

The Sun and Magnetism

  • The Sun's magnetic field is generated by electrical currents acting as a magnetic dynamo inside the Sun. These electrical currents are generated by the flow of hot, ionized gases in the Sun's convection zone.
  • The Sun's magnetic dynamo has a 22-year cycle. During the first half of the cycle, the Sun's magnetic north pole is in the northern hemisphere while the magnetic south pole is in the southern hemisphere.
  • Right around the peak of the sunspot cycle (solar maximum), the magnetic poles flip or exchange places so that the magnetic north is now located in the southern hemisphere. This flip occurs about every 11 years at solar maximum.
  • The 22-year magnetic cycle greatly influences the most prominent manifestation of the dynamo, sunspots and active regions, which migrate towards the solar equator from high latitudes over the course of the solar 11-year "sunspot cycle".
  • Sunspots and Active Regions are manifestations of the magnetic field generated in the Sun's interior poking through the visible region of the atmosphere.
  • Active regions are responsible for the production of intense and violent energy burst, called flares, and events where very large amounts of hot gas, trapped by the magnetic field of the active region, are released from the Sun's atmosphere and into space, called coronal mass ejections (CMEs).

READ:

SOLAR FLARE: https://www.iasgyan.in/daily-current-affairs/solar-flares

STRUCTURE OF THE SUN: https://www.iasgyan.in/blogs/structure-of-the-sun

GEOMAGNETIC STORM: https://www.iasgyan.in/daily-current-affairs/geomagnetic-storm

SOLAR CYCLE: https://www.iasgyan.in/blogs/solar-cycle

ANATOMY OF THE SUN: https://www.iasgyan.in/daily-current-affairs/anatomy-of-the-sun

PRACTICE QUESTION

Q. Consider the following statements:

1.The Solar Mean Magnetic Field (SMMF) is the mean value of the line-of-sight (LOS) component of the solar vector magnetic field averaged over the visible hemisphere of the Sun.

2.The solar dynamo is a physical process that generates the Sun's magnetic field.

3.The magnetic field at an average place on the Sun is around 1 Gauss, about ten times as strong as the average field on the surface of Earth.

Which of the above statements is/are correct?

(a) 1 and 2 only

(b) 2 and 3 only

(c) 1 and 3 only

(d) All of the above.

Correct Answer: (a) 1 and 2 only

Explanation:

The Sun has a very large and very complex magnetic field. The magnetic field at an average place on the Sun is around 1 Gauss, about twice as strong as the average field on the surface of Earth (around 0.5 Gauss).2

https://dst.gov.in/novel-observations-solar-mean-magnetic-field-smmf-establish-closer-connection-interplanetary#:~:text=These%20electrical%20currents%20are%20generated,visible%20hemisphere%20of%20the%20Sun