SIMBAD references

A new analysis of velocity distribution, optical photometry, and X-ray surface brightness from ROSAT Position Sensitive Proportional Counter data of the galaxy cluster A2319 is presented. The temperature profile recently derived from ASCA data by Markevitch is taken into account. A method to check the hydrostatic model in the presence of a temperature gradient is proposed. Consistency of the hydrostatic isothermal model and the explanation of the ``β-discrepancy'' are discussed. Galaxy and gas density profiles of the main component A2319A are derived, allowing for the effect of the secondary component A2319B. The inadequacy of a polytropic model, which would produce a binding mass decrease with respect to the isothermal β-model, is discussed. A simple interpolation of the temperature profile provides instead an increase of the binding mass and a lower baryon fraction, thus mitigating the ``baryon catastrophe.'' Assuming as typical the value f_b~0.2, a comparison with the most recent estimate of Ω^nucl_b implies for the cosmological parameter Ω₀≲0.4.