And the CoMP instrument is uniquely designed to measure these quantities and hence the magnetic fields,” says Dr.Ramping up solar power to replace fossil fuels is considered critical to cutting greenhouse gases in California. “Once we measure the wave properties and the density of the corona, then by using the mathematical formula (derived from MHD theory), we can compute the magnetic fields in the corona. From the theoretical calculation, it can be shown that the properties of the transverse MHD wave are directly related to the strength of magnetic fields and the density of the corona. There are different types of MHD waves, and one of these is the transverse MHD wave. The waves that propagate through a magnetic plasma are called magnetohydrodynamic (MHD) waves. Waves can be longitudinal waves (for example, sound waves) or transverse waves (for example, ripples on a lake surface). By measuring certain wave properties and doing a reverse calculation, some of the properties of the medium through which they have travelled may be, in principle, obtained. The properties of waves depend on the medium in which they travel. This will help understand the spectacular solar eruptions and predictions of space weather and many more things. India’s first solar mission, Aditya-L1 satellite will aim to measure the solar coronal magnetic fields regularly. He adds that while ground-based measurements pose challenges,
We plan to regularly measure coronal magnetic fields using our sophisticated techniques to understand the physical processes of the highly dynamic corona,” says Dr. “the measurement of global coronal magnetic fields was missing in the past since the coronal magnetic fields are very weak. It is very important to measure the corneal magnetic fields regularly since the solar corona is highly dynamic and varies within seconds to a minute time scale. It is located at Mauna Loa Solar Observatory, near the summit of that volcano on the big island of Hawaii. CoMP is an instrument operated by High Altitude Observatory, of the U.S. The team used the improved measurements of the Coronal Multi-channel Polarimeter (CoMP) and advanced data analysis to measure the coronal magnetic field. “In the past, these techniques were occasionally used in small regions of the corona, or some coronal loops due to limitations of our instruments/and proper data analysis techniques,” explains Dr.
This method requires the measurement of the properties of magnetohydrodynamic (MHD) waves and the density of the corona simultaneously. The team used a technique known as coronal seismology or magnetoseismology to measure the coronal magnetic field which has been known for a few decades. “Magnetic reconnection is a process where oppositely polarity magnetic field lines connect and some of the magnetic energy is converted to heat energy and also kinetic energy which leads to the generation of heating, solar flares, solar jets, etc,” says Tanmoy Samanta, a postdoctoral research fellow working at George Mason University, and Johns Hopkins University Applied Physics Laboratory of the U.S. These are driven by magnetic reconnections happening in the Sun’s corona. The other set of questions pertain to the mechanisms of eruptions of the Sun, such as solar flares and coronal mass ejections. Hence the present work will help understand and verify these theories better. Popular attempts to explain this puzzle invoke the magnetic field of the corona. What causes the atmosphere of the Sun (corona) to heat up again, though the surface (photosphere) is cooler than the interior? That is the question which has baffled solar physicists. It is at a temperature of one million degrees or more. However, its corona or outer atmosphere, which stretches up to several million kilometres beyond its surface, is much, much hotter than the surface. Though the core of the Sun is at a temperature of about 15 million degrees, its outer layer, the photosphere is a mere 5700 degrees hot. There are two main puzzles about the Sun which this advancement will help address. This research has been published in the journal The group has measured the global magnetic field of the Sun’s corona, or outer atmosphere, for the very first time. A significant advancement has been made by an international team of solar physicists led by those from Peking University, China, and National Center for Atmospheric Research of the United States.
Yet, it has many associated puzzles that are unexplained.
The Sun is our closest star and we have been studying it for a long time.
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