Researchers resolve 20-12 months-old paradox in photo voltaic physics

In 1998, the journal Character released a seminal letter concluding that a mysterious signal, which experienced been identified although examining the polarization of daylight, indicates that the photo voltaic chromosphere (an vital layer of the photo voltaic environment) is practically unmagnetised, in sharp contradiction with widespread knowledge. This paradox motivated laboratory experiments and theoretical investigations, which as a substitute of providing a option, raised new troubles, and even led some experts to dilemma the quantum theory of make any difference-radiation conversation.

Now, scientists at the Istituto Ricerche Solari (IRSOL) in Locarno-Monti (affiliated to USI Università della Svizzera italiana), and the Instituto de Astrofísica de Canarias (IAC) in Tenerife, have observed the remedy to this intriguing paradox, opening up a new window for discovering the elusive magnetic fields of the photo voltaic chromosphere in the existing new era of substantial-aperture photo voltaic telescopes. Their conclusions are published in Actual physical Review Letters.

Twenty-five decades in the past, an enigmatic signal was identified when examining the polarization of daylight with a new instrument, the Zurich Imaging Polarimeter (ZIMPOL), designed at ETH Zurich and afterwards mounted at IRSOL. This mysterious linear polarization sign, manufactured by scattering processes, seems at the wavelength of a neutral sodium line (the so-identified as D1 line), the place, according to quantum mechanics, no these scattering polarization should really be existing. This signal was consequently thoroughly unpredicted, and its interpretation instantly opened an intensive scientific debate. The mystery even further improved two decades later, when the journal Nature posted an rationalization implying that the layer of the solar atmosphere known as the chromosphere is totally unmagnetised, in clear contradiction with proven outcomes researchers believed that (outside the house sunspots) this location is permeated by magnetic fields in the gauss vary. The new findings opened a serious paradox that has challenged solar physicists for quite a few years, and even led some scientists to problem the accessible quantum idea of make a difference-radiation interaction.

Now, in an report published by Bodily Review Letters, Ernest Alsina Ballester (IRSOL, IAC), Luca Belluzzi (IRSOL), and Javier Trujillo Bueno (IAC) display the answer to this intriguing paradox. The results ended up obtained by carrying out the most superior theoretical modeling of the photo voltaic D1 line polarization ever tried, involving a few years of operate carried out by means of a shut cooperation amongst the Istituto Ricerche Solari (IRSOL) in Locarno-Monti (affiliated to USI Università della Svizzera italiana) and the POLMAG team of the Instituto de Astrofísica de Canarias (IAC) in Tenerife.

The researchers reveal: “This consequence has incredibly vital outcomes. Scattering polarization alerts, like the one particular observed in the D1 line of sodium, are incredibly attention-grabbing since they encode distinctive data on the elusive magnetic fields existing in the solar chromosphere. This crucial interface layer of the photo voltaic ambiance, positioned amongst the fundamental cooler photosphere and the overlying million-diploma corona, is at the main of a number of enduring troubles in solar physics, which include the understanding and prediction of the eruptive phenomena that might strongly influence our know-how-dependent modern society. The magnetic discipline is regarded to be the key driver of the magnificent dynamical action of the solar chromosphere, but our empirical know-how of its depth and geometry is continue to mainly unsatisfactory. The option of the lengthy-standing paradox of photo voltaic D1 line polarization proves the validity of the existing quantum theory of spectral line polarization, and opens up a new window to take a look at the magnetism of the solar environment in the current new period of significant-aperture solar telescopes.”

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Università della Svizzera italiana