The CHIANTI database

The CHIANTI atomic database provides a critically evaluated set of up-to-date atomic data for calculating spectra from astrophysical plasmas. For full details, user guides and references see the CHIANTI Homepage.

The CHIANTI package is written in IDL and is distributed as part of the SolarSoft library.

VOTADA

The VOTADA proposal, that was selected in the 2006 AstroGrid Tool Call, aims at providing accurate basic atomic data (and derived products), together with tools for astrophysical applications, within Astrogrid. The broad objective here is to make CHIANTI available to a wide range of astronomers and to allow retrieval of CHIANTI information without the need to use IDL. This objective was achieved by importing CHIANTI information into a relational database, that can be queried from the Astrogrid VODesktop.

VOTADA is principally aimed at the interpretation of optically-thin emission from plasmas collisionally excited and in equilibrium, however it also provides basic ion atomic data that are useful for other modelling purposes. VOTADA-CHIANTI includes a subset of the atomic data present in CHIANTI, and some derived products.

The database and examples queries to it are described below. The current version of the database was obtained from CHIANTI Version 5.2. For any questions please contact Giulio Del Zanna (gdz -at- mssl.ucl.ac.uk) or Silvia Dalla (sdalla -at- uclan.ac.uk).

Database Access

Chianti data can be accessed via VODesktop.

• Follow this link for help in downloading and running up VODesktop.
• Start a VOExplorer session, double click on Example Lists, then click on Solar services.
• On the list that appears on the rhs, click on Chianti Data Set. Now, under Actions, click on Build ADQL. This will take you to the Query Builder.
• Once the Query Builder appears, you can type in your query as a string. You can select the table to query on from the drop-down box next to Table. After typing in your query, click on Validate Edit: this will check that the syntax of your query is correct and will report any errors in the Diagnostics box.
• To submit the query click on Execute.

• See below for example CHIANTI queries and how to run them.

The catalogue database

At present the database of CHIANTI information available via Astrogrid consists of two tables: SpectralLines and LineEmissivities. SpectralLines describes the spectral lines part of CHIANTI. Line Emissivities gives the values of the emissivity calculated on a grid of temperatures and densities.

The table SpectralLines contains all the information for each spectral line present in the CHIANTI database. Most importantly, observed and theoretical wavelengths, transition probability, weighted oscillator strength, full spectroscopic notation together with observed and theoretical energies of initial and final levels. Please reference these data as CHIANTI version 5.2 (Landi et al. 2006) and acknowledge usage of Astrogrid to retrieve the information from the VOTADA database. Also, the references found in the CHIANTI files should be cited, whenever appropriate.

In optically-thin plasmas, spectral line intensities are proportional to the 'fractional line emissivity', which is the product of the Einstein A-value and the fractional population of the upper level of the emitting ion. The table LineEmissivities contains the values of the spectral line emissivities calculated for a grid of electron temperatures and densities. The emissivities in the table have been calculated adopting standard options and do not include photo-excitation. Please read the information in the original CHIANTI files for limits of applicability and references to original publications.

The spectral line intensities are also proportional to the ion and element abundances. The ion abundances are currently calculated assuming ionization equilibrium.

Below is a description of columns of SpectralLines

Name	Description	Units
LINE_NUMBER	identifier of the line in the database
CHEMICAL_ELEMENT	atomic Z number of the element
IONISATION_STAGE	ionisation stage
ION_TYPE	Type of ion ('d' for dielectronic or 'n')
TITLE	Short description of the line
FINAL_LEVEL_INDEX	index of the lower energy level
INITIAL_LEVEL_INDEX	index of the upper energy level
TRANSITION_TYPE	Type of transition
WAVELENGTH_METERS	Observed vacuum wavelength (0 for 2-photon trans.; Theoretical wavel. if not available)	m
THEORETICAL_WAVELENGTH	Theoretical wavelength (0 for two-photon trans.; -1 if not available)	m
WEIGHTED_OSCILLATOR_STRENGTH	gf value (weighted oscill. strength, 0 if trans. is not electric-dipole allowed)
EINSTEIN_A	A-value (transition probability)	{s-1}
FINAL_LEVEL_CONFIGURATION	Configuration of lower level
FINAL_LEVEL_SPIN	Spin 2S+1 of lower level
FINAL_LEVEL_L	Angular momentum L of lower level
FINAL_LEVEL_J	Total angular momentum J of lower level
FINAL_LEVEL_ENERGY	Observed energy of lower level	cm{-1}
FINAL_LEVEL_THEORETICAL_ENERGY	Theoretical energy of lower level (-1 if not available)
INITIAL_LEVEL_CONFIGURATION	Configuration of upper level
INITIAL_LEVEL_SPIN	Spin 2S+1 of upper level
INITIAL_LEVEL_L	Angular momentum L of upper level
INITIAL_LEVEL_J	Total angular momentum J of upper level
INITIAL_LEVEL_ENERGY	Observed energy of upper level (-1 if not available)	cm{-1}
INITIAL_LEVEL_THEORETICAL_ENERGY	Theoretical energy of upper level (-1 if not available)
COMMENT	References to papers, comments

Example queries

Once the Query Builder appears, you can type in your query as a string. For example this query:

    Select * From SpectralLines as t1 where t1.WAVELENGTH_METERS > 1.8E-8 and t1.WAVELENGTH_METERS < 2.0E-8

returns all lines in the database with wavelength in the required range.

To submit the query click on Execute.

To view the results launch Topcat. Then click on the result file and from the Result menu of Task Runner choose Attempt to send table to Topcat.

Note: In the screenshot above, the result file returned from the query is Stored in Cache. This works fine for small result files, however if your query returns a large result, the Store in cache option may result in an error. In this case, you need to save the result of the query in your VOSpace.

To store the query result in VOSpace, under Outputs, click on this icon: and point to the file in your VO Workspace where you want to save the file. You can overwrite an existing file or type in the name of a new one.

The database of CHIANTI spectral data available via AstroGrid allows retrieval of lines and emissivity information in a single query:

    Select * From SpectralLines as a, LineEmissivities as b where a.WAVELENGTH_METERS > 1.8E-8
    and a.WAVELENGTH_METERS < 2.0E-8 and a.LINE_NUMBER=b.LINE_NUMBER AND b.LOG_DENSITY=10.0 
    and b.LOG_TEMPERATURE=5.0

Here emissivities for lines in the given wavelength range are retrieved for the specified values of the log of the density (cm{-3}) and log of temperature (Kelvin).

The Figure below shows the result VOTable containing spectral line and emissivity information.