( Mostly) Atomic and (Some ) Molecular Data for Analytic Stellar Spectroscopy

1. (Mostly) Atomic and (Some ) Molecular Data for AnalyticStellar Spectroscopy Charles R. Cowley: U. Michigan Saul J. Adelman: The Citadel Donald J. Bord: UM Dearborn Lots of help from many others!!

2. Outline of Talk • Ionization Energies for neutrals and first • four ions. 2. Atomic Data Bases 3. Partition functions 4. Opacity: photoionization cross sections; TopBase

3. Part 1: Ionization Energies Visit our website: http://astro.lsa.umich.edu/users/cowley/ionen.htm Or, a number of others for more general info: http://www.hbcpnetbase.com/hbcp/ http://physics.nist.gov/PhysRefData/ http://plasma-gate.weizmann.ac.il/DBfAPP.html http://urania.astro.spbu.ru/staff/afk/- AtDatCentre/DtBases/db.html

5. Part 2: Atomic Data For Atomic Data, conveniently arranged for spectral synthesis, two primary sources: http://cfaku5.harvard.edu http://www.astro.univie.ac.at/~vald/ There may be other instances in the history of science where so many have owed so much to so few, but I don’t know of them. Both of these sites are under continuous revision.

6. Generally speaking: Either of these sources will provide the basis for an encouraging synthesis of atomic features in most stars. Details are another matter. Even within small wavelength intervals, of 5 to 10 A, there are generally a few features for which one cannot find an appropriate atomic line, even by modifying the oscillator strength by an order of magnitude or more. This is typical in a region with molecular features, when using VALD, which has not (as of May 2002) yet included molecules. But it is also common in other regions, and very probably due to incompleteness of atomic data: Either the lines are not in the data bases, or the oscillator strengths are egregiously in error.

7. Here is a rather shocking plot comparing VALD and Kurucz-site log(gf)’s for Fe I

8. Standard deviation: 0.86 Standard error: 0.05

9. The big differences are all for “second-generation lines,” lines not in the Multiplet Tables. So they are not lines typically studied. However, they are all from classifies levels, and would appear in any spectrum synthesis.

10. Generally speaking, one might prefer VALD for elements heavier than the iron peak. Changes in the Kurucz data beyond what is on the CDRoms (and therefore in VALD) are mostly for the important spectra of Fe I and Fe II. This was the situation when I browsed the Kurucz site at the end of March 2002, and it it subject to change.

11. 10.06.02

12. We have choices other than just RLK or VALD. Check the NIST site, and hunt around among the links. An E-book is nearing completion, which will contain much useful information on the first two spectra of elements from H to Es. There will be wavelengths for some 11,000 lines, but gf’s for only about 2500 lines. A NIST project that is just beginning will have much more extensive data, including gf’s and hfs. Of course, any improvements by NIST should be incorporated in VALD and Kurucz data bases!

13. The Main Problem is PERSON Power Snooping on the internet can bring up a wealth of relevant information. Here are just a few examples of places from which one can get useful data: Be advised that sometimes, one must get a reference, and then pull up the journal electronically. Here is an incomplete example of what one can find.

18. Part 3: Partition functions Focus on two aspects of partition functions: 1. Completeness of low levels. 2. Treatment of levels above those known experimentally -------------------------------------------------- Various algorithms are in use to give the partition function u(T). Undoubtedly some are better than others. All must be based on data that is sufficiently complete. Partition functions are important, algorithms less so.

19. Recent examples: Added levels from Cowan code, or laboratory work. REE III (1994) Ho II, W, Os (2002) Mostly the changes are small—a few per cent, except in cases where ranks were D, E, or missing altogether. For Ho II, nearly 50%: worth making!

20. Following a little-known study by Van’t Veer-Menneret (CR, 253, 380, 1961), we assert that the contribution to the partition function from levels above those typically known, ARE NOT IMPORTANT for the cal- culation of line strengths. It is easy to see this in a simple case. We consider the situation where the dominant ion is the first— virtually all atoms are first ionized. But, we are to compute a line arising from the first (neutral) spectrum.

22. We assert that in general, the partition function for the atom or ion (i) is unimportant for the line strength if the element is predominantly (i+1)-th fold ionized. It is easy to see from the previous slide that this must be approximately the case, but the assertion covers a lot of parameter space, and should be checked for special cases.

23. Part 4: Photoionization cross sections “Opacity of opacity, saith the Preacher, opacity of opacity; all is opacity.” Ecclesiastes – From a recently translated Agnostic gospel. Continuum  Red level interacts with continuum First ionization limit  These lines are in Kurucz tables.

24. Solid line: TopBase Dotted: Hydrogenic Cooper minimum

25. PEC: 4s-4p (H and K) PEC

26. It is straightforward to smooth these TopBase cross sections without changing the net absorption. This has been done by a number of people, and systematically by Prieto (2002). The next step, already being carried out, is to parameterize the smoothed fits for use in opacity routines, such as si1op, al1op, fe1op, etc. used in the Atlas codes. These routines give what I call the “K-factor”: Ca I 4s4d 1D

27. Dotted: Hydrogenic

28. Doted: Hydrogenic

30. Epilog: Molecular Spectra, et al. Best overall site: cfaku5.harvard.edu. New TiO, H2O RadEn Database: www.chem.msu.su/eng/raden/ HITRAN: cfs-www.harvard.edu/HITRAN/ NIST: webbook.nist.gov/chemistry/form-ser.html Atomic and Molecular Data and software: ccp7.dur.ac.uk DREAM (REE): www.umh.ac.be/~astro/dream.shtml

31. Thank you Thank you Thank you The End