Developing ALFA and NEAT for JWST data
Lead Research Organisation:
University College London
Department Name: Physics and Astronomy
Abstract
The two tools to be developed in order to be ready for the arrival of the first MIRI observations (e.g. of SN 1987A) are ALFA (Automated Line Fitting Algorithm) and NEAT (Nebular Empirical Analysis Tool). ALFA is a software tool designed to rapidly and automatically return the continuum and line fluxes, with associated uncertainties, from emission line spectra. The deeper and richer the spectra taken, the more significant its advantage over manual fitting. NEAT takes a list of emission line fluxes from ALFA and calculates the nebular electron temperature and density and elemental abundances from
their relative intensities. Uncertainties are propagated from the line flux measurements into the final results, using a Monte Carlo technique. Both codes run quickly and with minimal user input, though with several configurable parameters. These tools were originally developed to analyse optical spectra - we will extend their capabilities to the James Webb Space Telescope's infrared range.
their relative intensities. Uncertainties are propagated from the line flux measurements into the final results, using a Monte Carlo technique. Both codes run quickly and with minimal user input, though with several configurable parameters. These tools were originally developed to analyse optical spectra - we will extend their capabilities to the James Webb Space Telescope's infrared range.
Planned Impact
Developing the ALFA and NEAT tools to handle JWST spectra will potentially benefit a large number of astronomers worldwide who will use JWST spectra.
Organisations
Publications
Aleman I
(2019)
Characterization of the planetary nebula Tc 1 based on VLT X-shooter observations
in Monthly Notices of the Royal Astronomical Society
Barlow Michael J.
(2021)
The Ring Nebula as a laboratory for the interaction of molecules, PAHs and dust in strong UV radiation fields
in JWST Proposal. Cycle 1
Jones D
(2020)
The post-common-envelope binary central star of the planetary nebula PN G283.7-05.1 A possible post-red-giant-branch planetary nebula central star
in Astronomy & Astrophysics
Matsuura Mikako
(2021)
Planetary nebula NGC 6302 - a testbed for dust formation and processing in a dense torus irradiated by harsh UV radiation
in JWST Proposal. Cycle 1
| Description | JWST Cycle 1 time was awarded in 2020 to two proposals that utilise ALFA and NEAT. The JWST was launched on December 25th 2021 and the observations were carried out during July and August 2022. Early results utilising ALFA and NEAT for Program 1558 (The Ring Nebula as a laboratory for the interaction of molecules, PAHs and dust in strong UV radiation fields) were reported by Dr Roger Wesson at the `First Science Results from JWST Conference', held at STScI, Baltimore, USA from December 12-15 2022. A youtube recording of Dr Wesson's talk is available at the URL given below (from 3h 20m 30s onwards) |
| Exploitation Route | ALFA and NEAT are publicly available |
| Sectors | Education |
| URL | https://www.youtube.com/watch?v=RWDYWNerHcc&t=11863s |
| Title | rwesson/NEAT: v2.3 |
| Description | Empirical analysis of ionised nebulae, with uncertainty propagation |
| Type Of Technology | Software |
| Year Produced | 2020 |
| Open Source License? | Yes |
| Impact | NEAT is a program for calculating chemical abundances in photoionised nebulae. It can propagate uncertainties and compensate for measurement biases affecting weak lines. The code includes the necessary atomic data files |
| URL | https://zenodo.org/record/4327165 |