Solar system X-rays from charge exchange processes

摘要: Summary of the spectral results obtained with Chandrafor all comets (denoted by A–H) which were observed from2000 to 2006: a ) 0.3–1.0 keV pulse height distributions, b )theecliptic latitudes and c phases in solar cycle observedcomets,and d )thededuced informationaboutthesolarwindheavyion content. Fig.3a,c,d adapted from Bodewits et al. (2007). rienced spectacular outburst, increased its dust andgasoutflowandopticalbrightnessbyalmostamilliontimeswithin hours,from under17 magto 3 mag, makingit farthe optically brightest comet observable Chandra sinceits launch. At time, 17P/Holmes was located at asufficiently high heliographic latitude (19 ◦ be exposedto polar wind minimum. It thus expectedthat this would exhibit considerably different X-rayproperties, fact observed: be-came first where did not detect any sig-nificant X-ray emission (Christian 2010). Themost likely explanation for dramatic faintness isthat so diluted ionization lowthat only very little flux generated charge ex-change energies above∼300eV. An instrumental effect,i.e., loss sensitivity, can definitively ruled out, be-cause two months later, another comet, 8P/Tuttle, wasobservedwith Chandra,andthiscomet,at lowlatitude (3