An experiment to measure the photodesorption of physisorbed gases from a cold fused quartz substrate by near UV photons is described. The observed yield (mol photon–1) is as large as 10–5, a higher yield is likely in the vacuum UV. Included is a discussion of the photodesorption process and some applications to the interstellar medium. The observed yield is enough to maintain molecular abundances in moderate density interstellar clouds in equilibrium.

When, in consequence of a close approach, a comet of the Jupiter group changes its osculating semimajor axis from a > 1 to a < 1 (á = 1 for Jupiter's orbit), or vice versa, then the normal case is that of an abrupt change from one side of Jupiter's orbit to the other one. Under special conditions, however, temporary capture into satellite or ‘Trojan’ status is possible. P/Slaughter-Burnham, the first known comet in temporary 1:1 resonance with Jupiter, sheds some light on the requirements for Trojan captures. In consideration of the recent finding that the Trojan ‘cloud’ around L4 contains probably as many as 700 Trojans brighter than magnitude 20.9, it is suggested that at least some comets of the Jupiter group may have originated among these accumulations around L4 and L5.

The subject of this paper is an attempt to predict what can be seen in the vicinity of Saturn through a UV photometer on board the Mariner-Jupiter-Saturn mission. We will restrict ourselves to the study of atomic hydrogen and OH and to H2O which can be the parent molecule and will consider only the particles ejected from the rings and from Titan.

Polarization observations show the existence of a well-defined group of young pulsars with highly linearly polarized mean pulse profiles. Many of these pulsars have interpulses. I suggest that both the main pulse and the interpulse in these pulsars are part of a very wide conal beam emitted along field lines emanating from a single magnetic pole. Such wide beams may be responsible for all interpulse emission.

Clumpy galaxies are prominent in the early Universe. We present morphological and photometric properties of a wide range of galaxy types and their star-forming clumps in the Hubble Ultra Deep Field. Sizes, scale lengths, and scale heights suggest that galaxies grow by a factor of 2 from z = 4 to the present, and that thick disks are present in the early Universe. The largest clumps of star formation are 107–109M⊙ in different galaxies, much more massive than large star-forming complexes in local galaxies. Dissolved clumps may account for both the exponential disks and the early thick disks of spirals and proto-spiral galaxies.

Main-sequence massive stars possess convective cores that likely harbor strong dynamo action. To assess the role of core convection in building magnetic fields within these stars, we employ the 3-D anelastic spherical harmonic (ASH) code to model turbulent dynamics within a 10 M⊙ main-sequence (MS) B-type star rotating at 4 Ω⊙. We find that strong (900 kG) magnetic fields arise within the turbulence of the core and penetrate into the stably stratified radiative zone. These fields exhibit complex, time-dependent behavior including reversals in magnetic polarity and shifts between which hemisphere dominates the total magnetic energy.

The James Webb Space Telescope (JWST) is the scientific successor to the Hubble and Spitzer missions. Its wavelength range (1 - 28μm) and sensitivity (1 nJy - 1 μJy) complement the submillimeter facilities of the coming decade, Herschel and ALMA. The JWST development is on schedule for a June 2013 launch to L2 on an Ariane 5.

Magnetic fields have been observed on all scales in our Galaxy, from AU to kpc. With pulsar dispersion measures and rotation measures, we can directly measure the magnetic fields in a very large region of the Galactic disk. The results show that the large-scale magnetic fields are aligned with the spiral arms but reverse their directions many times from the innermost arm (Norma) to the outer arm (Perseus). The Zeeman splitting measurements of masers in HII regions or star-formation regions not only show the structured fields inside clouds, but also have a clear pattern in the global Galactic distribution of all measured clouds which indicates the possible connection of the large-scale and small-scale magnetic fields.

40 years have passed since the first molecular detection outside our Galaxy. Since then, our knowledge on the distribution, kinematics and composition of the molecular material in the extragalactic ISM has built up significantly based not only on the carbon monoxide observations but also in the more than 50 molecular species detected. In particular, line surveys have been proven to be excellent tools to study the chemical composition in the nuclei of galaxies. Such studies have been favored by the increasing instantaneous bandwidth of current mm and sub-mm facilities. Here I will summarize the highlights of extragalactic molecular spectroscopy, mostly focusing in the results from molecular line surveys published in the last few years as well as the aims of still ongoing projects.

Valuable model-independent information about the chemical composition of WR stars can be obtained by using lines of different ions arising at transitions between highly excited energy levels. We determine the abundances of He, H, C, N, O using theoretical line intensities obtained by solving statistical equilibrium equations for level populations for different subtype WR envelope conditions.

The chemical composition of WR stars strongly differs from the mean cosmic composition. In the case of WN stars nuclear processed CNO products of H-burning are revealed in the envelopes and He-burning products in the WC envelopes.

The abundance of oxygen in WC stars differs from the predictions of recent evolutionary calculations which account for the new 12C(α,γ) 16O reaction rate.

Yellow hypergiant, HD 217476, (HR 8752) is known to have extensive circumstellar envelope. Its unusual spectrum makes it enigmatic object. On the H-R diagram this hypergiant lies among the most luminous stars known in six Local Group galaxies (Humphreys et al., 1984). We have observed it with the same equipment during last fifteen years at the Dominion Astrophysical Observatory. Our present results arg based upon several hundreds of high dispersion spectra (6 and 10 Å/mm).

Effective temperatures of 30 turnoff stars with $-3.2 {<}$[Fe/H]${<}{-}1.5$ have been derived from the profiles of Balmer lines in high S/N, VLT/UVES spectra. While the systematic error of $T_{\rm eff}$ may be of the order of 100K, the differential values of $T_{\rm eff}$ are determined with a one-sigma precision of ${\sim}25$K. These precise $T_{\rm eff}$ values are used in a study of the slope and dispersion of the Li abundance as a function of [Fe/H]. A small, but significant cosmic dispersion in $A$(Li) appears to be present exemplified by the two very metal-poor stars G64-12 and G64-37.

An analytical formula for the time transformation TDB–TDT valid over a few thousand years around J2000 has been computed with an accuracy at the 1 ns level. The coefficients for a formula accurate at the 100 ns level are provided here. The numerical and analytical procedures to compute this transformation are discussed. We note that these procedures cannot comply with recommendation 5 of the 1976 IAU meeting. Furthermore, these procedures yield different units for the corresponding TDB time scales. We also note that this transformation is independent of the two PPN parameters γ and β and of the 3 most commonly used coordinate systems (isotropic, standard-Schwarzschild, Painlevé) at least at the 1 ns level.

Markarian survey (or the First Byurakan Survey, FBS) was the first systematic survey for active galaxies and was a new method for search for such objects. Until now, it is the largest objective prism survey of the sky (17,000 deg2). It was carried out in 1965–1980 by B. E. Markarian and his colleagues and resulted in discovery of 1517 UV-excess (Markarian) galaxies. They contain many active galaxies, as well as powerful gamma-, X-ray, IR and radio sources (Mrk 180, 231, 421, 501, etc.), BCDGs (Mrk 116) and interacting/merging systems (Mrk 266, 273, etc.). They led to the classification of Seyfert galaxies into Sy1 and Sy2 and the definition of Starbursts (SB). Several catalogs of Markarian galaxies have been published (Mazzarella & Balzano 1986; Markarian et al. 1989; Bicay et al. 1995; Petrosian et al. 2007) and they are accessible in all corresponding databases. Markarian survey also served as a basis for search for UVX stellar objects (including QSOs and Seyferts), late-type stars and optical identification of IR sources. At present the survey is digitized and DFBS database is available. I will review the main characteristics of the Markarian survey, its comparison with other similar surveys and the importance of Markarian galaxies in modern astrophysics.

The axial component of Earth rotation, which is conventionally expressed by Universal Time (UT1), contains small physical signals with diurnal and subdiurnal periods. This part of the spectrum is dominated by the tidal effects which are regular and predictable. The largest components express the influence of the gravitationally forced ocean tides with diurnal and semidiurnal periods and amplitudes up to 0.02 milliseconds (ms) in UT1 corresponding to an angular displacement of 0.30 milliarcseconds (mas); see Table 8.3 of the IERS Conventions (IERS, 2003). There are also smaller subdiurnal components (amplitudes up to 0.03 mas), designated as “spin libration” by Chao et al. (1991), due to direct influence of the tidal gravitation on those features of the Earth's density distribution which are expressed by the non-zonal terms of the geopotential. These components are not included in the models recommended by the IERS Conventions, in contrast to the corresponding effect in polar motion (ibid., Table 5.1).

Here we consider in detail the subdiurnal libration in UT1. We derive an analytical solution for the structural model of the Earth consisting of an elastic mantle and a liquid core which are not coupled to each other. The reference solution for the rigid Earth is computed by using the satellite-determined coefficients of geopotential and the recent developments of the tide generating potential (TGP). We arrived to the conclusion that the set of terms with amplitudes exceeding the truncation level of 0.005 mas consists of 11 semidiurnal harmonics due to the influence of the TGP term u22 on the equatorial flattening of the Earth expressed by the Stokes coefficients C22, S22. There is an excellent agreement between our estimates for the rigid Earth and the amplitudes derived by Wünsch (1991). The only important difference is the term with the tidal code ν2, which seems to be overlooked in the development of Wünsch. Our amplitudes computed for an elastic Earth with liquid core appear to be in reasonable agreement with those derived by Chao et al. (1991), but the latter model was not complete. The estimated effect is superimposed on the ocean tide influences having the same frequencies but 9 to 11 times larger amplitudes. Nevertheless, its maximum peak-to-peak size is about 0.105 mas, hence definitely above the current uncertainty of UT1 determinations. Comparison with the corresponding model of prograde diurnal polar motion associated with the Earth's triaxiality (IERS Conventions, Table 5.1) shows that: 1) the two effects are of similar size, 2) there is consistency between the underlying dynamical models, parameters employed, etc. In conclusion, we recommend adding the model developed here to the set of procedures provided by the IERS Conventions.

Rapidly rotating B-type stars with gaseous mass-loss disks in Keplerian rotation are common central objects in X-Ray binaries. These disks are physically well understood in the framework of the viscous decretion disk, and their typical parameters have been established for a large number of single Be stars in the recent years. According to the current observational evidence, the Be stars and disks found in BeXRBs are well within the boundaries known from single Be stars, i.e., they are normal Be stars. New results have also been obtained on the orbital disk truncation and other tidal effects of the companion objects on the disk.

In the Titan Haze Simulation (THS) experiment, Titan's atmospheric chemistry is simulated by plasma discharge in the stream of a supersonic expansion, i.e. at low Titan-like temperature (150 K). Here, we present complementary gas and solid phase analyses of four N2-CH4-based gas mixtures that demonstrate the unique capability of the THS to monitor the chemical growth evolution in order to better understand Titan's chemistry and the origin of aerosol formation.

GG Tau is a textbook example of a binary system. The circumstellar material around GG Tau is divided in several distinct regions: 1) small, low mass, circumstellar disks, detected in the near-IR and mm domain, 2) a well defined ring, of inner radius 180 AU, detected in the mm domain and in scattered near-IR light, 3) a more extended, colder disk detected in the 13CO(2–1) and 13CO(1–0) lines. Recent observations of the 12CO(2–1) clearly show this extended disk, but also reveal a fourth component of the circumstellar material: (relatively) diffuse and hot gas in the tidally unstable region. Estimate of the gas content suggest this material may be feeding the inner disks at about 10−6 M⊙/yr.

In this paper, we introduce two compact, large-throughput CMB polarimeter designs (POLAR1 and BICEP3). These pathfinder experiments will pave the way for a comprehensive multi-frequency South Pole B-mode survey that, when jointly analyzed with arcminute-scale polarization data, can conclusively answer the question whether there is an appreciable fraction (>1%) of the primordial perturbations in the form of tensor modes (gravitational waves).

Recent observations of zodiacal light have established a reliable and consistent picture of the spatial distribution of interplanetary dust in the ecliptic plane. The spatial density nr varies with heliocentric distance r according to a power law nr ∝ r−ν. From Helios observations an exponent v = 1.3 is derived for the distance interval from 0.08 A.U. to 1 A.U. (Link et al. 1976). Outside the earth's orbit the Pioneer 10 and 11 results suggest a higher exponent v = 1.5 for the distance interval from 1 A.U. to 3.3. A.U. (Hanner et al., 1976). Giese and Grün (1976) showed that the results from zodiacal light observations are compatible with the micrometeoroid fluxes derived from in situ measurements and lunar crater statistics. They found that micrometeoroids in the size range from 10 μm to 100 μm radii (corresponding roughly to 10−8g to 10−5g) contribute most to the zodiacal light brightness.

The orbital distribution of large interplanetary particles (10−6 g < m < 10−3g) is known from meteor observations. Sekanina and Southworth (1975) reported average orbital elements of these particles: ā ∼ 1.25 A.U., ē ∼ 0.4 and ī ∼ 20°. Orbital information on micrometeoroids (m < 10−8g) is obtained from in situ detectors on board the Pioneer 8 and 9 and Helios 1 spaceprobes and the HEOS-2 satellite. Characteristics of the different micrometeoroid experiments are given in Table 1. There is almost no time overlap in the data taking intervals of the experiments. Therefore one has to assume that there are no time variations of the meteoroid flux on the time scale of 1 to 10 years if one compares the results from the different experiments. This assumption may be violated for the smallest of the observed particles (m < 10−13g) due to strong electromagnetic interaction of these particles with the interplanetary magnetic field (Morfill and Grün 1979).