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Contact: F.X.Timmes
my one page vitae,
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research statement, and
teaching statement.
$ \def\Mzams{M_{\rm ZAMS}} \def\Msun\ensuremath{{\rm M}_\odot} \def\Lsun\ensuremath{{\rm L}_\odot} \def\Zsun\ensuremath{{\rm Z}_\odot} \def\Lnu\ensuremath{L_\nu} \def\Lgamma\ensuremath{L_\gamma} $ An Expanded Set of Los Alamos OPLIB Tables in MESA: Type-1 Rosseland-mean Opacities and Solar Models (2024)

In this article we present a set of 1194 Type-1 Rosseland-mean opacity tables for four different metallicity mixtures. These new Los Alamos OPLIB atomic radiative opacity tables are an order of magnitude larger in number than any previous opacity table release, and span regimes where previous opacity tables have not existed. For example, the new set of opacity tables expands the metallicity range to $Z$=10$^{-6}$ to $Z$=0.2 which allows improved accuracy of opacities at low and high metallicity, increases the table density in the metallicity range $Z$=10$^{-4}$ to $Z$=0.1 to enhance the accuracy of opacities drawn from interpolations across neighboring metallicities, and adds entries for hydrogen mass fractions between $X$=0 and $X$=0.1 including $X$=$10^{-2}, 10^{-3}, 10^{-4}, 10^{-5}, 10^{-6}$ that can improve stellar models of hydrogen deficient stars. We implement these new OPLIB radiative opacity tables in MESA, and find that calibrated solar models agree broadly with previously published helioseismic and solar neutrino results. We find differences between using the new 1194 OPLIB opacity tables and the 126 OPAL opacity tables range from $\approx$20-80% across individual chemical mixtures, up to $\approx$8% and $\approx$15% at the bottom and top of the solar convection zone respectively, and $\approx$7% in the solar core. We also find differences between standard solar models using different opacity table sources that are on par with altering the initial abundance mixture. We conclude that this new, open-access set of OPLIB opacity tables does not solve the solar modeling problem, and suggest the investigation of physical mechanisms other than the atomic radiative opacity.


Figure 1: Location of each Type-1 opacity table in the X-Z plane (left panel) and the log T-log R plane (right panel). Orange circles mark the location of the 126 OPAL Type-1 tables (Rogers & Iglesias 1992). Blue circles mark the location of the new 1194 Type-1 opacity tables.


Figure 2: Opacities and partial derivatives with respect to temperature and density for a X = 0.7, Z = 0.02 Grevesse & Sauval (1998) abundances generated from OPLIB radiative opacities and MESA's kap module. Left column: These quantities as a function of T for different ρ (colorbar). Dashed black lines show scaling relations for H- and Kramers opacities. Black dots mark the locations where a pure H composition is 1/2 ionized. Colored regions show thermal ionization stages of key elements for nondegenerate material. Right column: These quantities as contours in the ρ-T plane. Regions where different opacity sources dominate are labeled, as are the log R = -8 and log R = 1.5 table limits of the OPLIB radiative opacities. Both columns: Black curves show the profile of a standard solar model (see Section 3). Red circles on the solar profile mark the inner and outer boundaries of the convective region and are connected with a dashed blue curve.


Figure 3: Opacity as a function of T for three values of log(ρ) (black labels) and five compositions with Grevesse & Sauval (1998) abundances (colored curves), generated from OPLIB radiative opacities and MESA's kap module. Dashed black lines show scaling relations for H- and Kramers opacities. Black circles mark the half-ionization points for the pure atomic H composition (dark blue curves, Equation 6) and the pure atomic He composition (dark orange curves, Equation 8). Colored regions show thermal ionization stages of key elements for nondegenerate material.