Resumen
We analyze the flux of long-period comets (orbital periods P > 10^3 yr) and ``new'' comets (semimajor axes a > 10^4 AU) in the region interior to Jupiter's orbit with the aim of evaluating the population of the Oort cloud. New comets are those considered to come from the Oort cloud to the inner planetary region by the first time. Dynamical studies show that the powerful gravitational fields of Jupiter and Saturn prevent most Oort cloud comets from reaching the inner planetary region, so only a small fraction reach the inner planetary region, coming from distant regions (semimajor axes a > 3.5×10^4) that we shall call the outer Oort cloud. These comets are subject to stellar perturbations and the tidal force of the galactic disk that can decrease their perihelion distances from distances greater than Neptune's to less than a few AU after a revolution (e.g. Fernández 2005, ASSL, 328; Rickman et al. 2008, CeMDA, 102, 111). Preliminary estimates give an influx rate of about 1 new comet every 4 years within Earth's orbit with an absolute total magnitude brighter than 9 (that roughly corresponds to a radius greater than about 1 km). We find that the distribution of perihelion distances of the new comets coming from the outer Oort cloud is more or less constant within Jupiter's region, but that it tends to increase for comets with smaller semimajor axes believed to have more than one passage. The estimated mass of the outer Oort cloud is found to be a function of the degree of thermalization of the Oort cloud population. A primordial -old- population will be by now thermalized, a larger mass of the order of 2 Earth's mass, is required to keep the observed flux of new comets. A fresher, near-ecliptic Oort cloud population from the Scattered Disk (Fernández et al. 2004, Icarus, 172, 372) would provide the observed comet flux more efficiently with only about 10^{-2} Earth's mass.
