This business meeting was held from 16:00 to 17:30. Toshio Fukushima and George Kaplan were welcomed as the next president and vice-president, respectively. The following, in no particular order, are the summary reports from the various offices. The full versions will be made available on the Commission 4 website at <http://iau-comm4.jpl.nasa.gov/>.

Division III gathers astronomers engaged in the study of a comprehensive range of phenomena in the solar system and its bodies, from the major planets via comets to meteorites and interplanetary dust.

We examine the fate of ionizing radiation from massive stars on global scales. First, we compare the observed Hα luminosities of LMC Hii regions with those predicted by the latest generation of stellar atmosphere models. Our results imply that classical Hii regions are on average radiation-bounded, rather than density-bounded, as we found a decade ago. This is likely to necessitate an additional ionizing source for the diffuse, warm ionized medium (WIM) in galaxies. Secondly, we present new results from the SINGG Hα galaxy survey, showing that starburst galaxies have a lower fraction of WIM emission than normal star-forming galaxies. The most intriguing and consequential possible cause for this effect is the escape of ionizing radiation from starbursts. We show that the observations are also consistent with our predictions for the escape of ionizing radiation. Nevertheless, other observations do not necessarily support this scenario and other possible explanations must be considered.

The Business Meeting opened with a recall of the memory of a member of the Organizing Committee, Willem Wamsteker. N. Kaifu, past president of the Working Group, was thanked for his outstanding service.

On Tuesday 22 August 2006 approximately 40 people attended the Commission 41 History of Astronomy Business Meeting at the IAU XXVI General Assembly in Prague. Commission president Alex Gurshtein opened the meeting, welcoming the commission members and calling for a moment of silence for those members who passed away in the last triennium. David DeVorkin was appointed recording secretary for the meeting, with Steven Dick as the scruitineer of the ballot. A moment of silence was then observed in the memory of members departed over the last triennium, including: Jerzy Dobrzycki (Poland), Robert Duncan (Australia), Mohammad Edalati (Iran), Philip Morrison (USA), John Perdix (Australia), Neil Porter (Ireland), Gibson Reaves (USA), Brian Robinson (Australia), and Raymond E. White (USA).

We discuss the nature of the Galactic center lobe (GCL), a degree-tall, loop-like structure apparently erupting from the central few hundred parsecs of our Galaxy. Although its coincidence with the Galactic center has inspired diverse models for its origin, the observational evidence connecting this structure to the GC region has been thin. We describe a multiwavelength observing campaign with the VLA, GBT, Spitzer, and other telescopes that finds compelling evidence that the structure is likely formed by a mass outflow from the central tens of parsecs of our Galaxy. The size and mass of the putative outflow is consistent with that expected from the observed supernova rate and gas pressure in the GC region. If the GCL is a mass outflow, its relative proximity offers a unique opportunity for studying these structures in unprecedented detail.

We review the role of rotation in massive close binary systems. Rotation has been advocated as an essential ingredient in massive single star models. However, rotation clearly is most important in massive binaries where one star accretes matter from a close companion, as the resulting spin-up drives the accretor towards critical rotation. Here, we explore our understanding of this process, and its observable consequences. When accounting for these consequences, the question remains whether rotational effects in massive single stars are still needed to explain the observations.

Commission 5 has been very active during the IAU XXVI General Assembly in Prague: the Commission, its Working Groups and its Task Force held business meetings. In addition, Commission 5 sponsored two Special Sessions: Special Session 3 on The Virtual Observatory in Action: New Science, New Technology, and Next Generation Facilities which was held for three days 17–22 August, and Special Session 6 on Astronomical Data Management, which was held on 22 August. Commission 5 also participated in the organisation of Joint Discussion 16 on Nomenclature, Precession and New Models in Fundamental Astronomy, which was held 22-23 August. The General Assembly and Commission 5 web sites provides links to detailed information about all these meetings.

We present a parameter study of WR-type mass loss, based on the PoWR hydrodynamic model atmospheres. These new models imply that optically thick WR-type winds are generally formed close to the Eddington limit. This is demonstrated for the case of hydrogen rich WNL stars, which turn out to be extremely massive, luminous stars with progenitor masses above ≈ 80 M⊙. We investigate the dependence of WR-type mass loss on various stellar parameters, including the metallicity Z. The results depend strongly on the L/M ratio, the stellar temperature T*, and the assumed wind clumping. For high L/M ratios, strong WR-type winds can be maintained down to very low Z. Even for primordial massive stars we predict considerable mass loss if their surfaces are self-enriched by primary elements.

The members of the Resolutions Committee 2003-2006 were Christopher J. Corbally (chair, USA), Jocely S. Bell Burnell (UK), Matthew Colless (Australia) Georges Meylan (Switzerland), Silvia Torres-Peimbert (Mexico), Rachel L. Webster (Australia), and Robert Williams (USA).

We have calculated a large set of detailed binary models and used them to test the observed stellar population ratios that compare the relative populations of blue supergiants, red supergiants and Wolf-Rayet stars at different metallicities. We have also used our models to estimate the relative rate of type Ib/c to type II supernovae. We find, with an interacting binary fraction of about two thirds, that we obtain better agreement between our models and observations than with single stars. We discuss the use of models in determining the nature of supernova progenitors and show the surprising result that many type Ib/c supernova progenitors are less luminous and less massive in our models than the observed population of Wolf-Rayet stars.

Throughout cosmic time, the feedback of massive star winds and supernova explosions has been instrumental in determining the phase structure of the interstellar medium, controlling important aspects of both the formation and evolution of galaxies, producing galactic winds and enriching the intergalactic medium with heavy elements. In this paper, I review progress made in our theoretical understanding of how these feedback processes have operated throughout cosmic time from the epoch of the first stars through to the present day.

The James Webb Space Telescope (JWST) is a large, infrared-optimized space telescope scheduled for launch in 2013. JWST will find the first stars and galaxies that formed in the early universe, connecting the Big Bang to our own Milky Way galaxy. JWST will peer through dusty clouds to see stars forming planetary systems, connecting the Milky Way to our own Solar System. JWST's instruments are designed to work primarily in the infrared range of 1 - 28 μm, with some capability in the visible range. JWST will have a large segmented mirror, ~6.5 m in diameter, and will be diffraction-limited at 2 μm (< 0.1 arcsec resolution). JWST will be placed in an L2 orbit about 1.5 million km from the Earth. The instruments will provide imaging, coronography, and multi-object and integral-field spectroscopy across the 1 - 28 μm wavelength range. The breakthrough capabilities of JWST will enable new studies of massive stars from the Milky Way to the early universe.

Long-duration gamma-ray bursts are the manifestations of massive stellar death. Due to the immense energy release they are detectable from most of the observable universe. In this way they allow us to study the deaths of single (or binary) massive stars possibly throughout the full timespan massive stars have existed in the Universe. GRBs provide a means to infer information about the environments and typical galaxies in which massive stars are formed. Two main obstacles remain to be crossed before the full potential of GRBs as probes of massive stars can be harvested: i) we need to build more complete and well understood samples in order not to be fooled by biases, and ii) we need to understand to which extent GRBs may be intrinsically biased in the sense that they are only formed by a limited subset of massive stars defined by most likely a restricted metallicity interval. I describe the status of an ongoing effort to build a more complete sample of long-duration GRBs with measured redshifts. Already now we can conclude that the environments of GRB progenitors are very diverse with metallicities ranging from solar to a hundredth solar and extinction ranging from none to AV > 5 mag. We have also identified a sightline with significant escape of Lyman continuum photons and another with a clear 2175 Å extinction bump.

After a brief discussion it was agreed that this membership is well distributed in terms of geography, gender, and fields of planetary work.

The most recent stellar models have shown that the faster a massive star spins, the more its nuclear yields, mass-loss rate and lifetime are different from the standard model. One thus needs to know the rotation rate of massive stars to trace their evolutionary tracks adequately. In Wolf-Rayet (WR) stars, the direct measurement of the rotational velocity is impossible, since their continuum emission is formed in the dense wind that hides the hydrostatic, stellar surface. Here, we present a technique to derive the rotation rates of WR stars from a periodic wind phenomenon, the corotating interaction regions (CIR). For five WR stars, a first estimate of the rotation rates has been deduced from the CIR periods.

Division XI connects astronomers using space techniques or particle detectors for an extremely large range of investigations, from in-situ studies of bodies in the solar system to orbiting observatories studying the Universe in wavelenghts ranging from radio waves to γ-rays, to underground detectors for cosmic neutrino radiation.

The potential advantages of the new generation of Extremely Large Telescopes arebriefly summarized. When used in combination with advanced adaptive opticsmodules which can substantially remove the effect of atmospheric turbulence atinfrared wavelengths, these telescopes will provide unique capabilities both interms of photon collecting power (→2-4 magnitude advantage) andangular resolution (4-5 times higher than with current 8-10m telescopes). Theinstruments under study for the TMT and E-ELT projects are presented andcompared. I discuss the impact of the ELTs on three major science topics:stellar populations in galaxies to the Virgo distance, chemical abundances ofthe brighter stars in nearby galaxies and high redshift SN and GRBs.

Very massive primordial stars (140 M⊙ < M < 260 M⊙) are supposed to end their lives as PISN. Such an event can be traced by a typical chemical signature in low metallicity stars, but at the present time, this signature is lacking in the extremely metal-poor stars we are able to observe. Does it mean that those very massive objects were not formed, contrarily to the primordial star formation scenarios ? Could it be possible that they avoided this tragic fate ?

We explore the effects of rotation, anisotropical mass loss and magnetic field on the core size of very massive Population III models. We find that magnetic fields provide the strong coupling that is lacking in standard evolution metal-free models and our 150 M⊙ Population III model avoids indeed the pair-instability explosion.

Most of the Commission's three 90-minute time slots at the General Assembly were devoted to a series of 20 and 50 minute presentations, informally termed “Time and Astronomy”. The first part of the meeting was dedicated to time and general relativity. The second part of the session was dedicated to pulsar timing.