We briefly review ground-based (sub)millimeter dust continuum observations of the prestellar core mass function (CMF) and its connection to the stellar initial mass function (IMF). We also summarize the first results obtained on this topic from the Herschel Gould Belt survey, one of the largest key projects with the Herschel Space Observatory. Our early findings with Herschel confirm the existence of a close relationship between the CMF and the IMF. Furthermore, they suggest a scenario according to which the formation of prestellar cores occurs in two main steps: 1) complex networks of long, thin filaments form first, probably as a result of interstellar MHD turbulence; 2) the densest filaments then fragment and develop prestellar cores via gravitational instability.

The Extragalactic Background Light (EBL) at UV, optical and NIR wavelengths consists of the integrated light of all unresolved galaxies along the line of sight plus any contributions by intergalactic matter including hypothetical decaying relic particles. The measurement of the EBL has turned out to be a tedious problem. This is because of the foreground components of the night sky brightness, much larger than the EBL itself: the Zodiacal Light (ZL), Integrated Starlight (ISL), Diffuse Galactic Light (DGL) and, for ground-based observations, the Airglow (AGL) and the tropospheric scattered light. We have been developing a method for the EBL measurement which utilises the screening effect of a dark nebula on the EBL. A differential measurement in the direction of a high-latitude dark nebula and its surrounding area provides a signal that is due to two components only, i.e. the EBL and the diffusely scattered ISL from the cloud. We present a progress report of this method where we are now utilising intermediate resolution spectroscopy with ESO's VLT telescope. We detect and remove the scattered ISL component by using its characteristic Fraunhofer line spectral signature. In contrast to the ISL, in the EBL spectrum all spectral lines are washed out. We present a high quality spectrum representing the difference between an opaque position within our target cloud and several clear OFF positions around the cloud. We derive a preliminary EBL value at 400 nm and an upper limit to the EBL at 520 nm. These values are in the same range as the EBL lower limits derived from galaxy counts.

Unit: We will use in this paper the abbreviation 1 cgs = 10−9erg s−1cm−2sr−1Å−1

Galileo radio-occultation measurements show that all four of the Galilean satellites possess ionospheres. Peak ionospheric densities for the icy satellites are several thousand electrons per cubic centimeter, and the distributions are not spherically symmetric. Io’s ionosphere is much denser and remarkably similar to that measured by Voyager.

Our Galactic Center hosts over 10% of the known massive stars in the Galaxy. The majority of these stars are located in three particularly massive clusters that formed within the past 5 Myr. While these clusters are extraordinary, their formation repesents about half of the total inferred star-formation rate in the Galactic Center. There is mounting evidence that the clusters are just present-day examples of the hundreds of such similar clusters that must have been created in the past, and whose stars now comprise the bulk of all stars seen in the region. I discuss the massive stellar content in the Galactic Center and present a new analysis that suggests that effects of continuous star-formation in the Galactic Center can be seen in the observed luminosity functions newly-obtained HST-nicmos and Gemini-ao data.

The MACHO Collaboration’s search for baryonic dark matter via its gravitational microlensing signature has generated a massive database of time ordered photometry of millions of stars in the LMC and the bulge of the Milky Way. The search’s experimental design and capabilities are reviewed and the dark matter results are briefly noted. Preliminary analysis of the ~ 39,000 variable stars discovered in the LMC database is presented and examples of periodic variables are shown. A class of a periodically variable Be star is described which is the closest background to microlensing which has been found. Plans for future work on variable stars using the MACHO data are described.

The time is ripe for planning an array with a collecting area of 1 km2 (14 times larger than Arecibo and 75 times larger than the VLA). In view of its major astronomical target I have dubbed this concept ‘The Hydrogen Array’, although 1μJy continuum sources will also be reliably detected. I present some initial thoughts about the issues involved.

The linear polarization of comets depends upon the cometary dust physical properties, as well as upon the phase angle and the wavelength. The observed similarities and discrepancies provide drastic constraints on the physical properties of the dust. A series of measurements of light scattering properties on clouds of particles and of the aggregates they form under microgravity conditions should allow the interpretation of the observations in terms of physical properties of the dust.

Computations of AGB stellar evolution which include the effects of mass loss are still relatively rare. However, in order to relate numbers of Mira variables, OH/IR stars and carbon stars to associated stellar populations, it is necessary to understand evolutionary timescales on the AGB.

The dominant factors controlling very late AGB evolution are shell flashes and mass loss, and some quantitative estimate of the latter is needed for stellar evolution calculations. The favoured mechanism for the production of the large mass loss rates observed in late AGB stars such as OH/IR stars and dust-enshrouded carbon stars, which have mass loss rates up to a few times 10−5 M⊙ yr−1 (see van der Veen and Rugers 1989 for a compilation), is a dual process involving the lévitation of matter above the photosphere by large-amplitude radial pulsation followed by the formation of grains on which radiation pressure acts to drive the circumstellar material away from the star (Castor 1981; Holzer and MacGregor 1985; Hearn 1990). The studies by Wood (1979) and Bowen (1988) show that, by themselves, neither pulsation nor radiation pressure acting on grains can produce the very large mass loss rates from AGB stars.

The notion that December 21, 2012 will bring physical catastrophes, a transformation of consciousness, or even a New Age is an unanticipated and unintentional consequence of early speculation by credentialed academic experts. It has grown as a result of its subsequent interpretation through the lens of speculative, counterculture metaphysics by individuals with both academic and non-academic backgrounds. This article provides a historical review of the most significant contributions to the emergence of the 2012 phenomenon.

Stars with masses of $\gtsim 20$$M_{odot}$ have short Kelvin times that enable them to reach the main sequence while still accreting from their natal clouds. The resulting nuclear burning produces a huge luminosity and a correspondingly large radiation pressure force on dust grains in the accreting gas. This effect may limit the upper mass of stars that can form by accretion. Indeed, simulations and analytic calculations to date have been unable to resolve the mystery of how stars of 50 $M_{odot}$ and up form. We present two new ideas to solve the radiation pressure problem. First, we use three-dimensional radiation hydrodynamic adaptive mesh refinement simulations to study the collapse of massive cores. We find that in three dimensions a configuration in which radiation holds up an infalling envelope is Rayleigh-Taylor unstable, leading radiation driven bubbles to collapse and accretion to continue. We also present Monte Carlo radiative transfer calculations showing that the cavities created by protostellar winds provides a valve that allow radiation to escape the accreting envelope, further reducing the ability of radiation pressure to inhibit accretion.

Coronal mass ejections (CMEs) are large scale structures of plasma (~1016g) and magnetic field expelled from the solar corona to the interplanetary medium. During their travel in the inner heliosphere, these “interplanetary CMEs” (ICMEs), suffer acceleration due to the interaction with the ambient solar wind. Based on hydrodynamic theory, we have developed an analytical model for the ICME transport which reproduce well the observed deceleration of fast ICMEs. In this work we present the results of the model and its application to the CME observed on May 13, 2005 and the associated interplanetary type II burst.

Before discussing the results of the radio observations of the Magellanic Clouds in detail, it is worth while to briefly review some of our current ideas about radio emission from “normal” galaxies which would be the classification given to the Clouds by radio astronomers. A “normal” galaxy has no striking visual peculiarity and has a much lower ratio of radio to light flux than the “radio” galaxy.

The optical astrometry observations of latitude/universal time variations made with 48 instruments at 31 observatories are used to determine the Earth orientation parameters (EOP) since the beginning of the century. The Hipparcos Catalogue is used to bring more than four million individual observations, made in the interval 1899.7-1992.0, into the International Celestial Reference System. The Earth orientation parameters (polar motion, celestial pole offsets and, since 1956.0, also universal time UT1) are determined at 5-day intervals, with average uncertainties ranging from 8 mas (in the eighties) to about 40 mas (in the forties). Making use of very long series of ground-based observations, the solution also leads to the improvement of proper motions of about ten per cent of the observed Hipparcos stars, with precision of ±0.2 — 0.5 mas/yr. In addition, 474 auxiliary parameters, describing the rheological properties of the Earth and seasonal deviations of the observations at contributing observatories, are found. The new solution provides the EOP series suitable for further analyses, e.g., for studying long-periodic polar motion, length-of-day changes or precession/nutation.

In this paper, we discuss the Be stars which show recurrent shell structure and/or cyclic variations in the profiles of their emission lines with periods near 100d and, thus, are good candidates for interacting binaries undergoing mass-exchange. The periodic spectral variations observed in the Ble star HR 2142 are reviewed and brought up to date in the light of recent observations. HR 2142 is then compared with other periodic binary Be stars (AX Mon, 17 Lep, HD 218393, HD 173219, and φ Per) in order to point out the wide variance in observed spectra which interacting binaries can display.

Recent improvements of observational accuracy, stellar catalogues and efficiency of the procedures for searching for asteroid close encounters (Kuzmanoski and Knežević, 1993) gave rise to an increased interest in the problem of determination of asteroid masses (Bowell et al., 1995).

A defining property of massive stars is the dominant, dynamical role played by radiation throughout the stellar interior, atmosphere, and wind. Associated with this radiation hydrodynamics are several distinct kinds of instabilities that can lead to convection in both core and envelope, clumping in atmosphere and wind outflow, and perhaps even the dramatic mass loss outbursts associated with Luminous Blue Variable phases. Here I review these instabilities with emphasis on basic physical properties of radiative driving. I draw on two specific examples of dynamical instability, namely the strong instability associated with line-driving of a stellar wind outflow, and the global stellar instabilities associated with approaching or exceeding a modified Eddington limit. I conclude with a brief mention of recent ideas on the role of stellar rotation in the shaping of bipolar LBV outbursts.

We analyze coronagraph observations of a polar jet eruption observed by SECCHI/STEREO. The brightness distribution of the jet in white-light coronagraph images is compared with a kinetic particle model. In this first application, we consider only gravity as the dominant force on the jet particles along the magnetic field. The kinetic model explains well the observed brightness evolution. The initial particle velocity distribution is fitted by Maxwellian distributions and we find deviations of the high energy tail from the Maxwellian distributions. The jets total mass is between 3.2×1014 and 1.8×1015 g. The total kinetic energy of all the particles in the jet source region amounts from 2.1×1028 to 2.4×1029 ergs.

The newly established Inter-Union Commission on Solar-Terrestrial Physics (IUCSTP) has inquired of selected experts about actions useful in the period of the next solar maximum, which need an organization and coordination on international basis. These inquiries have shown that one of the problems, in which a broad international cooperation might lead to substantial improvement of scientific results, is the coordination of ground-base and space-vehicle observations of the Sun and its active phenomena.

Therefore, in order to help the IUCSTP in its preparatory work, the chairmen of IAU Commissions 10 (Solar Activity) and 44 (Observations from outside the Atmosphere) agreed to hold a joint meeting of these two Commissions during the IAU Assembly in Prague, on ‘Coordination of solar observations made at ground-base Observatories and with space vehicles’. It was anticipated that other IAU members interested in this problem, particularly members of Commissions 12 and 40, would also take part in the discussion.

We discuss measurements of disk mass from non-circular streaming motions of gas in the barred galaxies NGC 3095 and NGC 4123. in these galaxies with strong shocks and non-circular motions, the inner regions must be disk-dominated to reproduce the shocks. This requires dark matter halos of low central density and low concentration, compared to LCDM halo predictions. in addition, the baryonic collapse to a disk should have compressed the halo and increased the dark matter density, which sharpens the disagreement. One possible resolution is a substantial amount of angular momentum transfer from disk to halo, but this is not particularly attractive nor elegant.