SIMBAD references

We present an analysis of recent X-ray observations of the symbiotic star AG Peg. The X-ray emission of AG Peg as observed with Swift in 2015 shows considerable variability on time-scale of days as variability on shorter time-scales might be present as well. Analysis of the X-ray spectra obtained in 2013 and 2015 confirms that AG Peg is an X-ray source of class β of the X-ray sources amongst the symbiotic stars. The X-ray emission of AG Peg as observed with ROSAT (1993 June) might well originate from colliding stellar winds (CSWs) in binary system. On the other hand, the characteristics of the X-ray emission of AG Peg in 2013 and 2015 (Swift ) are hard to accommodate in the framework of the CSW picture. Analysis of the light curves in 2015 shows that the power spectrum of the X-ray variability in AG Peg resembles that of the flicker noise (or flickering) being typical for accretion processes in astronomical objects. This is a sign that CSWs did not play a key role for the X-ray emission from AG Peg in 2013-2015 and a different mechanism (probably accretion) is also getting into play.