About
A public database of T-matrix cross sections for non-spherical dust and condensate grains.
The database
What it contains and what it is for.
This database collects the extinction, absorption and scattering cross sections of cosmic dust and atmospheric condensates, computed with the T-matrix formalism for particles of different shapes, from single spheres to compact, elongated and porous aggregates. Each curve gives σ(λ) for one species, one shape and one particle size, over 1–25 µm.
The data are meant for the interpretation of observations of exoplanetary atmospheres and of the interstellar medium, where the shape and the internal structure of the grains can change the extinction significantly with respect to homogeneous spheres.
All cross sections are computed with NP_TMcode; the method and the data are described in the papers listed in Cite, together with the indication of which one to cite for what.
You can browse the species and look at the structure of each aggregate, plot and compare curves, and download single files or whole selections.
Acknowledgments
A summary of the acknowledgments of the papers listed in Cite; the full text is in each paper.
This work was supported by the Italian Ministry of University and Research (MUR) through the PRIN project Exo-CASH (PRIN 2022, no. 2022J7ZFRA), and by the Italian Research Center on High Performance Computing, Big Data and Quantum Computing (ICSC), funded by the European Union – NextGenerationEU and the National Recovery and Resilience Plan (NRRP), Mission 4 Component 2, within the activities of Spoke 3 “Astrophysics and Cosmos Observations”.
NP_TMcode is the parallel implementation of the T-matrix formalism developed and maintained at the INAF – Astronomical Observatory of Cagliari as a contribution to the activities of ICSC Spoke 3, on the basis of the codes originally written by F. Borghese, P. Denti and R. Saija. It is registered in the Astrophysics Source Code Library (ascl.net/2510.003).
The models were calculated on the computing cluster of the Osservatorio Astronomico di Cagliari, funded by the National Operational Program (PON) of the Italian Ministry of University and Research “Research and Innovation 2014–2020” (Notice D.D. 424 of 02/28/2018, Action II.1, project proposal PIR01_00010). Part of the work was completed at the CINECA GPU Hackathon 2024, part of the Open Hackathons program, with the support of OpenACC-Standard.org.
A. Petralia and G. Aresu acknowledge support from the INAF project 1.05.23.04.02 – MINI-GRANTS (2023) of RSN2 “Modelling of exoplanetary atmospheres in different physical conditions”. M. A. Iatì and F. Saija acknowledge the project “Space It Up” funded by ASI and MUR (Contract n. 2024-5-E.0, CUP I53D24000060005).
Releases
Every version of the database, newest first. Cite the version you used.
People
The database is the result of the work of the co-authors of the papers listed in Cite.
Licence
How you may use the data.
The cross sections are released under the CC BY 4.0 licence: you are free to share and adapt them, also for commercial purposes, as long as you give appropriate credit. Credit means citing the paper(s) indicated in Cite.
The refractive indices used as input come from published sources, indicated on the page of each species, and remain subject to the terms of those sources.
Privacy
What the site records.
To understand how the data are used, the site counts page views, downloads and searches. No cookies are used for this, IP addresses and browser details are never stored (a visit is only an anonymous code that changes every day), and browsers that send "Do Not Track" are not counted. Detailed records are deleted after 90 days and only daily totals are kept.
If you have an account, your own download history (what, when and from which release) is kept in your account page, visible only to you, until you clear it.
Contact
Questions, problems or requests for new species.
The database is maintained by Giambattista Aresu.