X-ray observations of the hot phase in Sgr~A*

We analyze 134 ks Chandra ACIS-I observations of the Galactic Centre (GC) performed in July 2011. The X-ray image with the field of view $17' \times 17'$ contains the hot plasma surrounding the Sgr~A*. The obtained surface brightness map allow us to fit Bondi hot accretion flow to the innermost hot plasma around the GC. We have fitted spectra from region up to $5"$ from Sgr~A* using a thermal bremsstrahlung model and four Gaussian profiles responsible for K$_{\alpha}$ emission lines of Fe, S, Ar, and Ca. The X-ray surface brightness profile up to $3"$ from Sgr~A* found in our data image, was successfully fitted with the dynamical model of Bondi spherical accretion. By modelling the surface brightness profile, we derived the temperature and number density profiles in the vicinity of the black hole. The best fitted model of spherical Bondi accretion shows that this type of flow works only up to $3"$ and implies outer plasma density and temperature to be: $n_{\rm e}^{\rm out}=18.3 \pm {0.1}$ cm$^{-3}$ and $T_{\rm e}^{\rm out}= 3.5 \pm {0.3}$ keV respectively. We show that the Bondi flow can reproduce observed surface brightness profile up to $3"$ from Sgr~A* in the Galactic Center. This result strongly suggests the position of stagnation radius in the complicated dynamics around GC. The Faraday rotation computed from our model towards the pulsar PSR J1745-2900 near the GC agrees with the observed one, recently reported.Comment: 10 pages, 7 figures, accepted for publication in A&

Germination in pea seeds : proteolytic enzyme activity and electron microscopy

This study was undertaken with two primary objectives in mind. The first objective was to isolate several pea seed hydrolases present during early seed germination. The second objective was to perform an ultrastructural investigation of protein mobilization in normally senescing and de-shooted cotyledons. It has been demonstrated biochemically that protein mobilization is delayed in de-shooted cotyledons (Guardiola and Sutcliffe 1971; Malek 1987). Peas were chosen for this study due to their large size, availability and the wealth of literature that was available as background. Despite the large amount of study, few pea seed enzymes have been purified to homogeneity. Isolation, characterization and localization of pea seed proteases will be necessary in order to piece together the puzzle of protein mobilization during germination