Alissa Mezzacappa

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The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the(More)
In large stars that have exhausted their nuclear fuel, the stellar core collapses to a hot and dense protoneutron star that cools by the radiation of neutrinos and antineutrinos of all flavors. Depending on its final mass, this may become either a neutron star or a black hole. Black hole formation may be triggered by mass accretion or a change in the(More)
We explore the implications of the QCD phase transition during the postbounce evolution of core-collapse supernovae. Using the MIT bag model for the description of quark matter, we model phase transitions that occur during the early postbounce evolution. This stage of the evolution can be simulated with general relativistic three-flavor Boltzmann neutrino(More)
With exact three-flavor Boltzmann neutrino transport, we simulate the stellar core collapse, bounce, and postbounce evolution of a 13M star in spherical symmetry, the Newtonian limit, without invoking convection. In the absence of convection, prior spherically symmetric models, which implemented approximations to Boltzmann transport, failed to produce(More)
Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and (18)O/(16)O in water and (13)C/(12)C,(More)
Massive progenitor stars end their life in an explosion event with kinetic energies of the order 1051 erg. Behind the explosion ejecta, the low density and high entropy region formed immediately after the explosion is subject to neutrino heating. The neutrinos emitted from the remnant at the center, a protoneutron star (PNS), continually heat the material(More)
Early black hole formation in a core-collapse supernova will abruptly truncate the neutrino fluxes. The sharp cutoff can be used to make model-independent time-of-flight neutrino mass tests. Assuming a neutrino luminosity of 1052 erg s per flavor at cutoff and a distance of 10 kpc, Super-Kamiokande can detect an electron neutrino mass as small as 1.8 eV,(More)
The most important weak nuclear interaction to the dynamics of stellar core collapse is electron capture, primarily on nuclei with masses larger than 60. In prior simulations of core collapse, electron capture on these nuclei has been treated in a highly parametrized fashion, if not ignored. With realistic treatment of electron capture on heavy nuclei come(More)
We investigate neutrino-driven convection in core collapse supernovae and its ramifications for the explosion mechanism. We begin with an “optimistic” 15 M⊙ precollapse model, which is representative of the class of stars with compact iron cores. This model is evolved through core collapse and bounce in one dimension using multigroup(More)