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ViennaAtomic
LineDatabase
T. A. RyabchikovaInstitute of Astronomy RAS
• Little history 1991 – ...• VALD content• VALD extraction tools• VALD mirrors• VALD clients• VALD statistics• VALD collaboration• VALD future
Little History
• VALD started in 1991 in Vienna
• Over the last 8 years 12 people were involved in VALD development resulting in 5 PhDs and 11 Masters
• Initial goal – Opacity calculations for stars with peculiar abundances. We ended up creating a database that would be useful for spectral synthesis and opacities
• The VALD-1 (1994) included Kurucz line lists from 1993 and some simple extraction tools
VALD contentVALD is a collection of about 1 million of classified spectral
lines with the reliable atomic parameters for accurate abundance
analysis of stellar atmospheres and more than 40 million lines
for opacity calculations.
For each line VALD contains:
1. Wavelength, transition probability log(gf)
2. Energy, quantum number J, Lande factor of the lower
and upper levels
3. Radiative, Stark and Van der Waals damping constants
4. Term designation, error in log(gf)
5. Reference for log(gf)
VALD content• Today VALD contains 137 line lists for spectroscopy• Original lists are compressed and stored separately • Total storage requirement is 12 Gbytes• The data is stored in a compressed format• Compression ratio in average is 1:2.5 for binary files• One can start decompression within 1000 records from
any specified wavelength• All original lists are saved and extraction is performed
according to ranking system• For each list rank is assigned to each data item
according to its quality• Final selection is merged according to the ranks• The default ranking is assigned by VALD group of
experts• VALD client can keep a separate personal configuration
VALD
User request
Line Database
Physical parametersT, P, abundances
Select line:1) LTE depth 2) Opacity3) ???
50 million atomic lines(100 million diatomicmolecular lines)
3 mirror sites877 users30 requests/day
How do we select the H2 lines?
VALD extraction tools
• Extraction is performed by a pipeline of programs – flexibility
• Two tools can initiate a pipeline: SHOWLINE and PRESELECT
• Next stage in the pipeline selects lines according to certain criteria (e.g. known damping constants)
• The most important tool is SELECT. It has two modes: synthesis and opacity. In the synthesis mode it solves the RT in the center of each spectral line and extracts only significant ones. In the opacity mode it selects the lines that produce significant opacity
• Performance: SELECT analyses 39500 lines in 130 sec on HP PA 8600 440 MHz workstation
VALD mirrors● 3 mirror sites. Automatic synchronization of line lists, list of
clients, statistics, personal configuration
VALD Mirror Sites 1.Uppsala Astronomical Observatory
2.NASA Goddard Space Flight Center (presently at STScI, internally)
3.AIP, Potsdam
VALD mirrors
● Synchronization is initiated by Vienna● Mirror sites pack all the information that changed
since the last synch and send it to Vienna● In Vienna newer files3 are copied and the latest
version is sent back to the mirror sites● The exchange is kompressed, encrypted and
uuencoded● No software (source code or executable) is
synchronized
VALD data retrieval
• VALD-EMS is run by cron once every 20 minutes:Parsemail → Process, jobXXX → parserequest →
VALD extraction tools → email/ftp to the client
• Web interface: formulate/submit request, edit personal configuration file
List of clients
---------------------------------------------------------------------------------------------------------- # Name Requests: SL EA EE ES
-----------------------------------------------------------------------------------------------------------------------------
1 VALD Mirror Sites 210 23 19 69 99
2 Nikolai Piskunov 433 20 37 202 174
3 Tanya Ryabchikova 1122 13 0 11 1098
4 Friedrich Kupka 0 0 0 0 0
5 VALD Administrator 2 1 1 0 0
6 Werner W. Weiss 2 2 0 0 0
7 Rainer Kuschnig 0 0 0 0 0
8 Chuck Cowley 48 0 14 34 0
9 Saul J. Adelman 702 2 0 700 0
10 John Landstreet 72 0 1 1 7 0
...........
293 Charles R. Proffitt 962 0 259 703 0
............
304 Masahide Takada-Hidai 136 98 30 8 0
............
350 Alcione Mora Fernandez 17237 2 16329 1 905
............
629 Evelyne Alecian 20701 1 0 0 20700
............
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Statistics
Statistics
VALD collaboration
• R. Kurucz
• D.R.E.A.M. - Data Base on Rare-Earths at Mons University (Belgium)
• BELDATA – Data Base on Stark widths in Belgrade
• Institute of Spectroscopy, RAS
• University of Amsterdam (calculations for Fe-peak elements)
• University of Wisconsin, Madison (experimental transition probabilities)
VALD future
• Molecular line lists• Molecular opacities• Molecular equilibrium• Telluric spectrum• Interface with VO (STScI)
