This session is meant to fit RGS data from Jupiter using Gaussians and subsequently the charge exchange model (cx). We suggest the papers on this page for more information.
The files jupiter.res and jupiter.spo below contain an RGS spectrum of Jupiter. Load the spectrum into SPEX and try to fit the spectrum using Gaussians for the lines.
Hint: From GBR et al. A&A, 463, 761 (http://adsabs.harvard.edu/abs/2007A%26A...463..761B): the spectrum is best fitted with a model made up of a collisional ionisation equilibrium component (to represent Jupiters disk emission) with kT = 0.41 keV, a bremsstrahlung component (to represent an unresolved blend of CX lines) with kT = 0.2 keV and 12 emission lines (see below).
The Jupiter spectrum is expected to contain charge exchange lines and perhaps also low-temperature CIE or NEI plasma. Since CX models were not available at the time of the paper, try to fit the spectrum using a mix of these models. Can you get an acceptable fit?
Hint: Since this is a solar-system object, the normalisations of the model are expected to be very small. You can use a distance of 5.5 AU. One of the parameters required by CX is the H density, i.e. the density of Jupiters atmosphere where charge exchange takes place. Note: Cravens et al. 2003: O precipitation takes place at a density level of 2 x 1012 cm-3 = 2 x 1018 m-3.
If you have a best fit, simulate what your best fit spectrum would look like with ATHENA X-IFU. How much exposure time do you need to improve your result with respect to the RGS data?
Hint: The SPEX command 'simulate' can be used to generate a spectrum based on a spectral model. You will need a spo and res file containing the instrument properties of Athena XIFU. See below:
Note: The spo file contains a dummy spectrum. A spectral simulation will replace this spectrum in the computer memory.