This instrument has allowed us to make far more detailed observations and measurements of the Sun.Д¬ombined with good viewing conditions, advanced computer simulations, and the efforts of an international team of scientists from seven research institutions, we used the IBIS to finally confirm, for the first time, the existence of AlfvГ©n waves in solar magnetic flux tubes. One such instrument is the Interferometric Bidimensional Spectropolarimeter (IBIS) for imaging spectroscopy, installed at the Dunn Solar Telescope in the US state of New Mexico. ThereвЂ™s so much happening on the SunвЂ™s surface and in its atmosphere вЂ“ from phenomena many times larger than Earth to small changes below the resolution of our instrumentation вЂ“ that direct observational evidence of AlfvГ©n waves in the photosphere has not been achieved before.Д«ut recent advances in instrumentation have opened a new window through which we can examine solar physics. Observing AlfvГ©n wavesД«ut there remained the problem of actually observing these waves. These magnetic plasma waves are now called AlfvГ©n waves, and their part in explaining coronal heating led to AlfvГ©n being awarded the Nobel Prize in Physics in 1970.

Sunspots are darker patches on the SunвЂ™s surface. The heat travels along what are called solar magnetic flux tubes before bursting into the corona, producing its high temperature. He reasoned that within the SunвЂ™s magnetized plasma any bulk motions of electrically charged particles would disturb the magnetic field, creating waves that can carry huge amounts of energy along vast distances вЂ“ from the SunвЂ™s surface to its upper atmosphere. These fields are then dragged up from the SunвЂ™s interior by convection, and burble onto its visible surface in the form of dark sunspots, which are clusters of magnetic fields that can form a variety of magnetic structures in the solar atmosphere. The movement of this plasma in the convection zone вЂ“ the upper part of the solar interior вЂ“ produces huge electrical currents and strong magnetic fields. The Sun is composed almost entirely of plasma, which is highly ionized gas that carries an electrical charge. Scientists looked to the SunвЂ™s properties to explain this disparity. The extreme heat of the SunвЂ™s corona is one of the most vexing problems in astrophysics. EdlГ©n and GrotrianвЂ™s finding that the SunвЂ™s corona is so much hotter than the photosphere вЂ“ despite being further from the SunвЂ™s core, its ultimate source of energy вЂ“ has led to much head-scratching in the scientific community. Over many decades of study, the photosphereвЂ™s temperature has been consistently estimated at around 6,000вЊ. Estimating the photosphereвЂ™s heat has always been relatively straightforward: we just need to measure the light that reaches us from the Sun and compare it to spectrum models that predict the temperature of the lightвЂ™s source. This represents temperatures up to 1,000 times hotter than the photosphere beneath it, which is the surface of the Sun that we can see from Earth. The coronal heating problem has been established since the late 1930s, when the Swedish spectroscopist Bengt EdlГ©n and the German astrophysicist Walter Grotrian first observed phenomena in the SunвЂ™s corona that could only be present if its temperature was a few million degrees celsius. Our recent study has finally achieved this, validating AlfvГ©nвЂ™s 80-year-old theory and taking us a step closer to harnessing this high-energy phenomenon here on Earth. The theory had been tentatively accepted вЂ“ but we still needed proof, in the form of empirical observation, that these waves existed.

Sun corona hotter