Vienna Atomic Line Database T. A. Ryabchikova Institute 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 content VALD 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 parameters T, P, abundances Select line: 1) LTE depth 2) Opacity 3) ??? 50 million atomic lines (100 million diatomic molecular lines) 3 mirror sites 877 users 30 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 lines in 130 sec on HP PA 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: Pars → Process, jobXXX → parserequest → VALD extraction tools → /ftp to the client Web interface: formulate/submit request, edit personal configuration file

List of clients

# Name Requests: SL EA EE ES VALD Mirror Sites Nikolai Piskunov Tanya Ryabchikova Friedrich Kupka VALD Administrator Werner W. Weiss Rainer Kuschnig Chuck Cowley Saul J. Adelman John Landstreet Charles R. Proffitt Masahide Takada-Hidai Alcione Mora Fernandez Evelyne Alecian 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)