Upcoming release of CHIANTI 10.1: element abundances

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Peter Young

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May 11, 2023, 12:23:48 PM5/11/23

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Hi everyone,

The CHIANTI team is preparing the next major release of the database, which will be labeled 10.1. We're hoping to distribute it in 2 or 3 weeks time along with the paper describing the update.

This message is to highlight some changes to the element abundance files that may affect code that you have written if you have hard-coded the name of an abundance file.

With CHIANTI 10, the default abundance file is sun_photospheric_2015_scott.abund. This will be changed to sun_photospheric_2021_asplund.abund, which contains the abundances from the Asplund et al. (2021) paper.

All abundance files are stored in the dbase/abundance directory and there are 13 files currently in this directory with a mixture of "coronal" and "photospheric" files. Our plan for CHIANTI 10.1 is to move all of these files to the sub-directory "archive", except for the asplund_2021 and scott_2015 files.

We will add a new file called "sun_coronal_2021_chianti.abund", which takes the asplund_2021 file and increases the abundances of elements with FIPs below 10 eV by 0.5 dex (a factor 3.16). This will be the new, recommended coronal abundance file.

If you use one of the existing coronal abundance files (e.g., feldman_1992 or schmelz_2012) we recommend that you switch to using the new file. These older files were generated by applying corrections to photospheric abundance files that are now out-of-date, hence the CHIANTI team feels that it is preferable to use a representative coronal abundance file that is generated directly from the most recent photospheric abundance file.

To emphasize: the feldman_1992 and schmelz_2012 files will be moved to the archive sub-directory as they are now considered out-of-date in relation to the new photospheric abundances. If you want to continue using them, then you should modify the path to dbase/abundance/archive.