Super-Soft X-ray Sources (SSS) are a small class of X-ray sources characterised by a blackbody-like spectrum of effective temperature 30-100 eV (several 10^5 K) and luminosities above 10^36 erg/s. Owing to their softness, galactic SSS are more difficult to observe and interpret because of high galactic extinction and uncertain distances, respectively. While a small number of permanent SSS are known since the 80s, novae have been predicted to pass through a phase of SSS emission that has indeed been observed with, e.g., ROSAT, BeppoSAX, or ASCA.
Attempts of spectral modeling of nova SSS spectra ranged from blackbody fits to most refined local thermodynamic equilibrium (LTE) and non-LTE atmosphere modeling, but the low resolution of CCD spectra allows no unique constraint of spectral parameters of complex models. The X-ray grating spectrometers on board XMM-Newton and Chandra allow much more detailed analysis of SSS spectra and, as always in nature, the truth is much more complicated than believed. I will first present historic observations and attempts of interpretation, and then show the grating spectra with the details. A large variety in grating spectra of canonical SSS spectra and those of novae emerged, and I will show approaches how to find trends and to explain some commonalities.
Spectral modeling is currently not possible, but I will present and discuss some approachesAdd to my calendar