11 research outputs found
Multiplet Effects in the Quasiparticle Band Structure of the Anderson Model
In this paper, we examine the mean field electronic structure of the
Anderson lattice model in a slave boson approximation, which should
be useful in understanding the physics of correlated metals with more than one
f electron per site such as uranium-based heavy fermion superconductors. We
find that the multiplet structure of the ion acts to quench the crystal
field splitting in the quasiparticle electronic structure. This is consistent
with experimental observations in such metals as .Comment: 9 pages, revtex, 3 uuencoded postscript figures attached at en
Calculation of Effective Coulomb Interaction for , , and
In this paper, the Slater integrals for a screened Coulomb interaction of the
the Yukawa form are calculated and by fitting the Thomas-Fermi wavevector, good
agreement is obtained with experiment for the multiplet spectra of
and ions. Moreover, a predicted multiplet spectrum for the heavy
fermion superconductor is shown with a calculated Coulomb U of 1.6 eV.
These effective Coulomb interactions, which are quite simple to calculate,
should be useful inputs to further many-body calculations in correlated
electron metals.Comment: 8 pages, revtex, 3 uuencoded postscript figure
Chasing rainbows and ocean glints: Inner working angle constraints for the Habitable Worlds Observatory
NASA is engaged in planning for a Habitable Worlds Observatory (HabWorlds), a coronagraphic space mission to detect rocky planets in habitable zones and establish their habitability. Surface liquid water is central to the definition of planetary habitability. Photometric and polarimetric phase curves of starlight reflected by an exoplanet can reveal ocean glint, rainbows, and other phenomena caused by scattering by clouds or atmospheric gas. Direct imaging missions are optimized for planets near quadrature, but HabWorlds’ coronagraph may obscure the phase angles where such optical features are strongest. The range of accessible phase angles for a given exoplanet will depend on the planet’s orbital inclination and/or the coronagraph’s inner working angle (IWA). We use a recently created catalog relevant to HabWorlds of 164 stars to estimate the number of exo-Earths that could be searched for ocean glint, rainbows, and polarization effects due to Rayleigh scattering. We find that the polarimetric Rayleigh scattering peak is accessible in most of the exo-Earth planetary systems. The rainbow due to water clouds at phase angles of ∼20◦ − 60◦ would be accessible with HabWorlds for a planet with an Earth equivalent instellation in ∼46 systems, while the ocean glint signature at phase angles of ∼130◦ − 170◦ would be accessible in ∼16 systems, assuming an IWA = 62 mas (3λ/D). Improving the IWA = 41 mas (2λ/D) increases accessibility to rainbows and glints by factors of approximately 2 and 3, respectively. By observing these scattering features, HabWorlds could detect a surface ocean and water cycle, key indicators of habitability.Atmospheric Remote SensingAstrodynamics & Space Mission