I briefly draw comparisons between the fields of damped Lyα and metal-poor stellar abundances. In particular, I examine their complementary age-metallicity relations and comparisons between the damped Lyα and dwarf galaxy abundance patterns. Regarding the latter, I describe a series of problems concerning associating high z damped Lyα systems with present-day dwarfs.

Over the last half-century quantitative stellar spectroscopy has made great progress. However, most stellar abundance analyses today still employ rather simplified models, which can introduce severe systematic errors swamping the observational errors. Some of these uncertainties for late-type stars are briefly reviewed here: atomic and molecular data, stellar parameters, model atmospheres and spectral line formation.

Here we describe some of our latest results from measuring detailed abundances in Local Group dwarf galaxies with the VLT. Combining spectroscopic abundances with Color-Magnitude diagrams allows the effective measurement of detailed chemical evolution with time in these galaxies. Although there are not yet significant numbers of individual stars observed in local group dwarf galaxies, the uniformity of the abundance patterns of the majority of stars in galaxies with very different star formation histories must hint at general properties of all star formation in these small systems.

Investigations have been performed to understand the age of dwarf irregular galaxies from the point of view of their presently low chemical abundances and the enhanced star-formation rate. While for a few objects, like e.g. I Zw 18, their assumed relative youth can be verified by models taking a double-starburst behavior into account, those dlrrs with old underlying stellar populations have passed the regime of observed N/O-0 values within almost 2 Gyrs after their formation even with gas loss by means of supernova-driven galactic winds. Therefore alternative processes like gas infall must be invoked.

Stars more massive than ~ 20–25 M⊙ form a black hole at the end of their evolution. Stars with non-rotating black holes are likely to collapse ”quietly” ejecting a small amount of heavy elements (Faint supernovae). In contrast, stars with rotating black holes are likely to give rise to very energetic supernovae (Hypernovae). Nucleosynthesis in Hypernovae is characterized by larger abundance ratios (Zn,Co,V,Ti)/Fe and smaller (Mn,Cr)/Fe than normal supernovae, which can explain the observed trend of these ratios in extremely metal-poor stars. Nucleosynthesis in Faint supernovae is characterized by a large amount of fall-back. We show that the abundance pattern of the recently discovered most Fe-poor star, HE0107-5240, and other extremely metal-poor carbon-rich stars are in good accord with those of black-hole-forming supernovae, but not pair-instability supernovae. This suggests that black-hole-forming supernovae made important contributions to the early Galactic (and cosmic) chemical evolution as the First (Pop III) Supernovae.

Damped Lyman-alpha absorbers in quasar spectra provide a unique tool to directly measure the abundances of elements in galaxies at red-shifts 0 < z < 5, and hence probe the chemical evolution of galaxies over > 90% of the age of the Universe. Since cosmic chemical evolution models predict the global metallicity of galaxies to increase with time, it is of great interest to determine whether DLAs actually show such a trend. We discuss statistical analysis of existing DLA Zn data to examine the metallicity-redshift relation, and a comparison of the observed data with models of cosmic chemical evolution. We also describe efforts to expand the DLA abundance sample at z < 1.5, where the current data are particularly sparse. Finally, we discuss emission-line imaging studies of the absorber galaxies and compare constraints on their star formation rates with models based on the global star formation history.

The C II* technique for measuring star formation rates (SFRs) in damped Lya systems (DLAs) is described. We measure cooling rates of the gas from the strength of C II* 1335.7 absorption lines, and infer heating rates by assuming the gas is heated by the grain photoelectric mechanism. Since the heating rates depend on the intensity of FUV radiation, we deduce the SFRs per unit area, which are comparable to the value in the Milky Way disk. From DLA statistics we obtain the SFRs per unit comoving volume at z=[1.6,4.5], which are similar to the rates in Lyman Break Galaxies. Implications such as the presence of a two-phase medium, metal production, and feedback processes are described. The model is tested and found to be consistent with observations.

The IAU Joint Discussion 16 (JD16) was held in conjunction with the XXVth General Assembly in July, 2003. Papers related to the maintenance of the International Celestial Reference System were presented in the one-day session, and these were followed by discussion that pointed out the need for standard nomenclature. This issue was addressed by the formation of a Division 1 Working Group on the subject. JD16 also pointed out the requirement for a dynamical expression for precession which was addressed by the creation of a Division 1 Working Group on Precession and the Ecliptic. It also showed that although plans are being implemented to provide reference frames for the future, there is a need for improved coordination of astrometric observations. Finally it should be noted that the discussion pointed out the concern for the future organization of IAU Division 1.

The Joint Discussion on Atomic Data For X-ray Astronomy addressed all aspects of X-ray astronomy: (I) New Observations, (II) Atomic Theory, (III) Laboratory Measurements (IV) Numerical Simulations, and (V) Databases. There were 22 invited presentations and approximately 40 contributed papers. Following papers are brief summaries of the proceedings. A detailed description of the aims and contents of JD17 are given at: www.astronomy.ohio-state.edu/~pradhan/Iau/iau.html. The SOC consisted of: N. Brickhouse (USA), H. Hasan (USA), J. Houck (USA), A. Fabian (UK), J. Kaastra (Netherlands), F. Keenan (UK), S. Kahn (USA), T. Kallman (USA), H. Netzer (Israel), A.K. Pradhan (USA, Chair), P.L. Smith (USA), K. Yamashita (Japan).

Highlights of interesting astrophysical discoveries are reviewed in the context of high resolution X-ray spectroscopy made possible with Chandra and XMM-Newton, and its relevance to atomic physics calculations and measurements is discussed. These spectra have shown that the overlap between astrophysics and atomic physics is stronger than ever, as discoveries of new X-ray lines and edge structure is matching the need for increasingly detailed theoretical calculations and experimental measurements of atomic data.

“Solar X-ray Spectrometer (SOXS)” mission on-board GSAT-2 Indian spacecraft was launched on 08 May 2003 by GSLV-D2 and deployed in geostationery orbit to study the X-ray emission from solar flares with high spectral and temporal resolution. The SOXS consists of two independent payloads viz. SOXS Low Energy Detector (SLD) payload, and SOXS High Energy Detector (SHD) payload. The SLD consists of two solid state detectors Si PIN and CZT, which cover the energy range from 4-60 keV, while the SHD has NaI(Tl)/CsI(Na) sandwiched phoswich detector that covers energy range from 20 keV to 10 MeV. We present very briefly the science objectives and instrumentation of SLD payload. After the successful In-orbit Tests (IOT), the first light was fed into SLD payload on 08 June 2003 when the solar flare was already in progress. We briefly present the first results from the SLD payload.

Ongoing activities under an international collaboration of atomic physicists and astrophysicists under the Iron Project and the RmaX Project, with applications to X-ray astronomy, are briefly described.

Absorption L-lines of iron ions are observed, in spectra of Seyfert 1 galaxies by the new generation of X-ray satellites: Chandra and XMM-Newton. Lines associated to Fe 23+ to Fe16+ have been already observed in emission, in the solar corona and in laboratory. Whereas, those corresponding to Fe 15+ to Fe6+ have not been observed as emission lines, the upper level of the transition decaying preferentially by autoionization. Many atomic data are available for the first ion set. For the second set, some data have been recently published for n=2 to n’=3 transitions. We have recalculated them using another theoretical approach and have extended them to n’=4.

In order to upgrade the diagnostic capability associated with Fe Kα spectra, we have calculated detailed atomic models that include the effects of inner-shell photoionization, autoionization, collisional excitation at relatively high particle number densities, and photoexcitation in plasmas with high X-ray and/or UV energy densities. I discuss some of the potential uses of these models in the context of compact X-ray sources.

A multi-faceted, multi-institutional laboratory astrophysics program is carried out at the Livermore electron beam ion trap facility, which is a mature spectroscopic source with unsurpassed controls and capabilities, and an unparalleled assortment of spectroscopic equipment, including a full complement of grating and crystal spectrometers and a 6x6 micro-calorimeter array. Recent results range from the calibration of x-ray diagnostics, including the Fe XVII and Fe XXV emission lines, extensive lists of L-shell ions, the first laboratory simulation and fit of a cometary x-ray emission spectrum, and the discovery of new spectral diagnostics for measuring magnetic field strengths.

Recent experimental work on the photorecombination and the photoionization of astrophysically relevant atomic ions employing the merged-beams technique at heavy-ion storage-rings and synchrotron-light sources, respectively, is summarized. The resulting absolute photoionization cross sections and recombination rate coefficients benchmark corresponding theoretical calculations and are needed for the accurate determination of ionization equilibria in astrophysical plasmas.

The 900 ks Chandra spectrum of NGC 3783 was analyzed in various ways to study the properties of the absorbing gas. The main findings are: 1) On a time scale of 20-120 days, the source exhibits two very different spectral shapes with different softness ratios. The absorbing gas is not responding to these continuum variations. 2) Detailed photoionization modeling based on 10 silicon and sulphur lines near 5-7Å produces a satisfactory fit of the entire 3-25 A spectrum of the source. The only discrepancy is in the central wavelength of the iron UTA feature. 3) A combination of three ionized absorbers, each split into two kinematic components, can explain the strengths of almost all the absorption lines and bound-free edges. The three components span a large range of ionization and have a total column of about 4×1022 cm-2. Moreover, all three components are thermally stable and seem to have the same gas pressure.