HIGH-SENSITIVITY HARD X-RAY OBSERVATIONS OF SOLAR AND STELLAR FLARES WITH FOXSI AND NUSTAR

THE PROPOSED RESEARCH PLANS TO HARNESS THE EXCEPTIONAL CAPABILITIES OF HARD X-RAY INSTRUMENTS USING FOCUSING OPTICS FOXSI AND NUSTAR TO EXTEND OUR UNDERSTANDING OF SOLAR AND STELLAR PHENOMENA. FOXSI IS THE FIRST SOLAR-DEDICATED INSTRUMENT TO USE A DIRECTIMAGING TECHNIQUE FOR OBSERVING THE SUN IN HARD X-RAYS AND HAS BEEN SUCCESSFULLY TESTED ON TWO SOUNDING ROCKET FLIGHTS TO DATE. RESEARCH ACTIVITIES FOR FOXSI WILL INCLUDE ANALYSIS OF FOXSI FLIGHT DATA ALONG WITH DETECTOR WORK TO SUPPORT THE THIRD FOXSI FLIGHT. DURING THE SECOND FOXSI FLIGHT TWO MICROFLARES WERE OBSERVED; IMAGING AND SPECTRAL ANALYSIS WILL BE USED TO EXAMINE THE SPATIAL STRUCTURE AND DYNAMICS OF THESE SMALL-SCALE EVENTS WHICH WILL ADD TO OUR UNDERSTANDING OF HOW THESE EVENTS CONTRIBUTE TO THE HEATING OF THE CORONA. ADDITIONALLY UPGRADES TO THE DETECTOR CALIBRATION PLAN AND SIMULATIONS OF THE DETECTOR RESPONSE WILL ENHANCE THE ANALYSIS CAPABILITIES FOR FOXSI-3. NUSTAR A NASA SMALL EXPLORER LAUNCHED IN 2012 ALSO USES FOCUSING OPTICS FOR HARD X-RAYS BUT WAS DESIGNED TO PRIMARILY OBSERVE ASTROPHYSICAL SOURCES. THE PROPOSED RESEARCH WILL UTILIZE NUSTAR S CAPABILITIES TO STUDY FLARES ON MAGNETICALLY ACTIVE STARS FOCUSING SPECIFICALLY ON YOUNG STELLAR OBJECTS (YSOS). BY STUDYING THE SPECTRA OF FLARING YSOS FROM THE RHO OPHIUCHI STAR-FORMING REGION INSIGHT CAN BE GAINED INTO WHETHER IONIZING RADIATION FROM FLARES CAN SUFFICIENTLY PENETRATE THE CIRCUMSTELLAR DISK WHICH COULD HAVE IMPLICATIONS FOR PLANET FORMATION. THE DESCRIBED RESEARCH ACTIVITIES ARE LARGELY RELEVANT TO THE GOALS OF THE HELIOPHYSICS RESEARCH PROGRAM IN THAT THEY WILL ENHANCE OUR UNDERSTANDING OF THE PHYSICAL PROCESSES TAKING PLACE ON THE SUN. ANALYSIS OF NUSTAR OBSERVATIONS WILL ADDITIONALLY SUPPORT THE GOALS OF THE ASTROPHYSICS RESEARCH PROGRAM BY EXPLORING THE ORIGIN AND EVOLUTION OF STARS.