Credit: Jorge Sanz-Forcada and ESA
Spikes
Young stars are active, full of energy. One good example is AB Dor, a fast rotating star almost reaching maturity. It's a favorite X-ray target since X-rays probe stellar activity at the highest energies. The image above is an X-ray spectrum obtained by the Reflection Grating Spectrometer (RGS) instrument on the XMM-Newton observatory. The RGS spectrum reveals numerous emission lines produced by highly ionized elements like O VIII, Ne X, C VI, and other elements which have lost nearly all their electrons. The line strengths allow astronomers to infer the chemical abundances in the X-ray emitting gas, and they find an unusual thing: abundances depend on how easily ionized the element is. This so called "First ionization Potential" effect is also seen in the sun, and is believed to signify the importance of magnetic fields in producing the extremely hot, X-ray emitting gas.
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Last modified Tuesday, 27-Feb-2024 10:09:56 EST
