Library of dust cross-sections of spheroidal particles

This library provides cross-section efficiencies of spheroidal (prolate) dust particles computed using the code of Voshchinnikov N. (2004). The following quantities are included as functions of wavelength, volume-equivalent radius Rv, and magnetic-field orientation Oma: - extinction efficiency Qext - linear polarisation efficiency Qpol - circular polarisation efficiency Qcpol - scattering efficiency Qsca The dust cross-section is given by: C = pi * Rv^2 * Q (cm^2) ----------------------------------------------------------------------Parameter ranges---------------------------------------------------------------------- wel: Wavelength between 0.908 mic and 1 cm, sampled in 283 bins. Rv: Volume-equivalent particle radius, starting at 6 nm and increasing by 5% from one bin to the next, up to the material-dependent maximum radius given below. Vvac: Porosity (in percent). - Amorphous carbon and silicate grains: Vvac in {0, 5, 10, 20, 30, 40, 50} (%) - Dark dust (DD): Vvac in {5, 10, 20} (%) a/b: Axial ratio of prolate spheroids, with five cases: a/b in {1.5, 2.0, 2.5, 3.0, 4.0} Align: Grain alignment: - pdg : perfectly aligned - randu : randomly oriented (no alignment) Omega: Magnetic-field orientation between 0 and 90 degrees, sampled in steps of 3 degrees. ----------------------------------------------------------------------Materials---------------------------------------------------------------------- The following grain materials are included: - Amorphous carbon (aC), Rv < 0.76 mic - Silicate (Si), Rv < 0.355 mic - Micrometre-sized dust agglomerates (DD, "dark dust"), Rv < 100 mic Optical constants are provided in the corresponding files and are basedon the dust model of Siebenmorgen R. (2023, A&A 670, A115). ----------------------------------------------------------------------File naming convention---------------------------------------------------------------------- File names follow the format: d.Q<cc>V<xx>align_ab<y.y> where: <cc> : material identifier (aC, Si, DD) <xx> : porosity in percent align : alignment flag (pdg or randu followed by magnetic field angle Omega in deg) <y.y> : axial ratio a/b ----------------------------------------------------------------------Examples---------------------------------------------------------------------- d.QSiV30randu_ab2.0 30% porosity, randomly oriented silicate grains with a/b = 2.0 d.QaCV05pdg60_ab3.0 5% porosity, perfectly aligned amorphous carbon grains with Omega = 60 deg and a/b = 3.0 d.QDDV10pdg33_ab2.5 10% porosity, perfectly aligned dark dust grains with Omega = 33 deg and a/b = 2.5 ----------------------------------------------------------------------Number of files---------------------------------------------------------------------- The parameter grid is sparsely sampled. The total number of files is: - 896 files for amorphous carbon grains - 896 files for silicate grains - 372 files for dark dust grains ----------------------------------------------------------------------Reference---------------------------------------------------------------------- Siebenmorgen R., Bagnulo S., Fanciullo L., Vannieuwenhuyse T., Guillet V. 2026, LIPS~III: Observational constraints on the structure of grains, A&A submitted Code repository at: https://doi.org/10.5281/zenodo.19190239 ----------------------------------------------------------------------Contact:---------------------------------------------------------------------- For questions or issues, please contact:[e-mail]