The background is a video of a solar flare extreme ultraviolet emission from NASA SDO AIA highly processed by Prof. Miloslav Druckmüller (http://www.zam.fme.vutbr.cz/~druck/).
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What drives heating in atmospheres of stars like the Sun?
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How can we best characterize and understand stellar variability?
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What are the new technologies, instruments and observations to better understand questions 1 and 2.
Solar and Stellar Atmospheres
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The solar corona is the outer atmosphere of the Sun and is hotter than the suface of the Sun (the photosphere). To be more specific, the corona is over 1,000,000 Kelvin (over 1.8 million degrees fahrenheit), while the photosphere is around 6,000 K (10 thousand degrees fahrenheit). The solar corona is less dense than the solar photosphere and thus much dimmer (the photosphere is 1 million times brighter than the corona). So the unaided human eye (the human eye without the aid of external optics like telescopes or binoculars), just observes the bright solar disc in visible light (never stare at the Sun without eclipse glases or other special Sun viewing equipment!!). Only when the light from the solar disc is blocked out, can the corona be easily viewed by the naked eye in visible light. This happens during solar eclipses (see video from the August 21, 2017 solar eclipse to the left).
Solar and Stellar
Magnetic Cycles
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The high temperature of the corona leads to high energy light emission. Ultraviolet and X-rays to be exact. Theses emissions are direct probes to the physical conditions of the plasma that created them. In general the high temperature plasma is confined by the near-surface magnetic fields in the atmosphere and change orientation over many timescales (seconds, minutes, hours , days and years). Below is a video depicting the monthly and yearly variations measured by the YohKoh satellite mission's Soft X-ray Telescope.
