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Variations of the emission lines in the spectrum of the yellow symbiotic star AG Dra have been studied for over 14 years (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011), using more than 500 spectra obtained on the 1.5-metre telescope at Tartu Observatory, Estonia. The time interval covered includes the major (cool) outburst of AG Dra that started in 2006. Main findings can be summarized as follows: (i) cool and hot outbursts of AG Dra can be distinguished from the variations of optical emission lines; (ii) the Raman scattered emission line of O vi at λ 6825 almost disappeared during the cool outburst; (iii) lower excitation emission lines did not change significantly during the cool outburst, but they vary in hot outbursts and also follow orbital motion; (iv) similarity of variations in AG Dra to those in the prototypical symbiotic star Z And allows to suggest that a "combination nova" model proposed for the latter object might also be responsible for the outburst behaviour of AG Dra.

Abstract. We have combined recent radial velocity measurements of Fekel et al. (2000) with previously studied older ones, to test for the continued presence of the second period, found by Gális et al. (1999), which could be due to pulsations of the cool component of the AG Dra binary system. Fekel's data, even taken by themselves, also marginally suggest the presence of variations near the previously found second period. The period is in any case clearly seen, when all radial velocity measurements are combined.

AG Dra is a well known bright symbiotic binary with a white dwarf and a pulsating red giant. The long-term photometry monitoring and a new behaviour of the system are presented. The detailed period analysis of photometry as well as spectroscopy was carried out. In the system of AG Dra, two periods of variability are detected. The longer one around 550 days is related to the orbital motion, and the shorter one around 355 days is interpreted as pulsations of the red giant in our older paper. In addition the active stages change distinctively, but the outbursts are repeated with the periods from 359 to 375 days.

We report on the results of INTEGRAL observations of the neutron star low mass X-ray binary SAX J1810.8-2609 during its latest active phase in August 2007. The current outburst is the first one since 1998 and the derived luminosity is 1.1 − 2.6 × 10 36 erg s −1 in the 20-100 keV energy range. This low outburst luminosity and the long-term time-average accretion rate of ∼ 5 × 10 −12 M ⊙ yr −1 suggest that SAX J1810.8-2609 is a faint soft X-ray transient. During the flux increase, spectra are consistent with a thermal Comptonization model with a temperature plasma of kT e ∼ 23-30 keV and an optical depth of τ ∼ 1.2-1.5, independent from luminosity of the system. This is a typical low hard spectral state for which the X-ray emission is attributed to the upscattering of soft seed photons by a hot, optically thin electron plasma. During the decay, spectra have a different shape, the high energy tail being compatible with a single power law. This confirm similar behavior observed by BeppoSAX during the previous outburst, with absence of visible cutoff in the hard X-ray spectrum. INTEGRAL/JEM-X instrument observed four X-ray bursts in Fall 2007. The first one has the highest peak flux (≈ 3.5 Crab in 3-25 keV) giving an upper limit to the distance of the source of about 5.7 kpc, for a L Edd ≈ 3.8 × 10 38 erg s −1 . The observed recurrence time of ∼1.2 days and the ratio of the total energy 1 INTEGRAL is an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: