A few years before the Hinode space telescope was launched, an investigation based on the Hanle effect in atomic and molecular lines indicated that the bulk of the quiet solar photosphere is significantly magnetized, due to the ubiquitous presence of an unresolved magnetic field with an average strength 〈B〉, ≈ 130 G. It was pointed out also that this “hidden” field must be much stronger in the intergranular regions of solar surface convection than in the granular regions, and it was suggested that this unresolved magnetic field could perhaps provide the clue for understanding how the outer solar atmosphere is energized. In fact, the ensuing magnetic energy density is so significant that the energy flux estimated using the typical value of 1 km/s for the convective velocity (thinking in rising magnetic loops) or the Alfvén speed (thinking in Alfvén waves generated by magnetic reconnection) turns out to be substantially larger than that required to balance the chromospheric energy losses. Here we present a brief review of the research that led to such conclusions, with emphasis on a new three-dimensional radiative transfer investigation aimed at determining the magnetization of the quiet Sun photosphere from the Hanle effect in the Sr I 4607 Å line and the Zeeman effect in Fe I lines.

Almost all meteorites (about 99% by number) are samples from a few hundreds of asteroids that are leftover from planetesimals and protoplanets formed within several million years after the birth of the Solar System. These meteorites record detailed evolutionary history of dust to planets, including condensation, accretion, aqueous alteration, thermal metamorphism, partial and total melting.

The work here represents the summary of observations made with the Hartebeesthoek Radio Astronomy Observatory (HartRAO) 26 m telescope of the water vapour (H2O) Masers in the Orion KL source region for a period of 8 months during the flare of 2011. The observation setup, calibration method together with the resulting maser time series are discussed.

We solve the set of hydrodynamic equations for accretion disks in the spherical coordinates (rθφ) to obtain the explicit structure along the θ direction. The results display thinner, quasi-Keplerian disks for Shakura-Sunyaev Disks (SSDs) and thicker, sub-Keplerian disks for Advection Dominated Accretion Flows (ADAFs) and slim disks, which are consistent with previous popular analytical models, while an inflow region and an outflow region always exist, which supports the results of some recent numerical simulation works. Our results indicate that the outflows should be common in various accretion disks and stronger in slim disks and ADAFs.

The multiple-planet systems discovered by the Kepler mission show an excess of planet pairs with period ratios just wide of exact commensurability for first-order resonances like 2:1 and 3:2. In principle, these planet pairs could be in resonance if their orbital eccentricities are sufficiently small, because the width of first-order resonances diverges in the limit of vanishingly small eccentricity. We consider a widely-held scenario in which pairs of planets were captured into first-order resonances by migration due to planet-disk interactions, and subsequently became detached from the resonances, due to tidal dissipation in the planets. In the context of this scenario, we find a constraint on the ratio of the planet's tidal dissipation function and Love number that implies that some of the Kepler planets are likely solid. However, tides are not strong enough to move many of the planet pairs to the observed separations, suggesting that additional processes are at play.

We present K-band Integral Field Spectroscopy of six high mass young stellar objects (IRAS~18151–1208, AFGL~2136, S106~IRS4, V645 Cyg, IRAS~19065+0526, and G082.5682+ 00.4040) obtained using the adaptive optics assisted NIFS instrument mounted on the Gemini North telescope. The targets are chosen from the Red MSX Source survey led by University of Leeds. The data show the spectral features of Brγ, H2, and gas phase CO emissions and absorptions with a spectral resolution of R ≈ 5500, which allow a three-dimensional spectro-astrometric analysis of the line emissions. We discuss the results of the ionized jets and winds, and rotating CO torus.

We present new and independent estimates of the distances to the Magellanic Clouds (MCs) using near-infrared (NIR) and optical–NIR period–Wesenheit (PW) relations. The slopes of the PW relations are, within the dispersion, linear over the entire period range and independent of metal content. The absolute zero points were fixed using Galactic Cepheids with distances based on the infrared surface-brightness method. The true distance modulus we found for the Large Magellanic Cloud—(m − M)0 = 18.48 ± 0.01 ± 0.10 mag—and the Small Magellanic Cloud—(m − M)0 = 18.94 ± 0.01 ± 0.10 mag—agree quite well with similar distance determinations based on robust distance indicators. We also briefly discuss the evolutionary and pulsation properties of MC Cepheids.

Until now, just a few extrasolar planets (30 out of 860) have been found through the direct imaging method. This number should greatly improve when the next generation of High Contrast Instruments like Gemini Planet Imager (GPI) at Gemini South Telescope or SPHERE at VLT will became operative at the end of this year. In particular, the Integral Field Spectrograph (IFS), one of the SPHERE subsystems, should allow a first characterization of the spectral type of the found extrasolar planets. Here we present the results of the last performance tests that we have done on the IFS instrument at the Institut de Planetologie et d'Astrophysique de Grenoble (IPAG) in condition as similar as possible to the ones that we will find at the telescope. We have found that we should be able to reach contrast down to 5 × 10−7 and make astrometry at sub-mas level with the instrument in the actual conditions. A number of critical issues have been identified. The resolution of these problems could allow to further improve the performance of the instrument.

We have been undertaking a comprehensive survey for pulsars and fast radio transients in the dwarf spheroidal satellite galaxies of the Milky Way using the Green Bank Radio Telescope operating at a central frequency of 350 MHz. Our search pipeline allows the detection of periodical signals and single dispersed pulses and it is optimized to search for millisecond radio pulsars. Here we present preliminary results of the searches we have conducted in the Ursa Minoris, Draco and Leo I dwarf spheroidal satellite galaxies. Our searches have revealed no periodic signals but a few unconfirmed millisecond single pulses at various dispersion measures, possibly related to neutron stars. Detecting neutron stars in these systems can potentially help to test the existence of haloes of dark matter surrounding these systems as predicted by Dehnen & King (2006).

We present a calibration of the metallicity and physical parameters (temperature, luminosity, gravity, mass, radius) for RR Lyrae stars using the ugrizsdss photometric system. Our work is based on calculations of synthetic horizontal branches (HBs), fully taking into account evolutionary effects for a wide range in metallicities and HB morphologies. We provide analytical fits that are able to provide all quantities mentioned with very high (internal) precision, based solely on mean sdss magnitudes and colors.

The motivation for our research was to study the correlation between the chirality of filaments and the handedness (S- or Z-shape) of sigmoids. It was assumed that sigmoids would mostly coincide with filaments and that the S-shaped sigmoids would correlate well with filaments of sinistral chirality, which we found that to be at best a very weak relation. Since we had a full solar cycle of filament metadata at hand it was easy to verify the supposedly known hemispheric preference of filament chirality. We discovered that the hemispheric chirality rule was confirmed for the epoch where a thorough manual study had been performed, but that at other phases of the solar cycle the rule seems to disappear and sometimes even reverse.

It is often claimed that there is not only one, but two different types of solar dynamos: the one that is responsible for the appearance of sunspots and the 11-yr cycle, frequently referred to as the “global dynamo”, and a statistically time-invariant dynamo, generally referred to as the “local dynamo”, which is supposed to be responsible for the ubiquitous magnetic structuring observed at small scales. Here we examine the relative contributions of these two qualitatively different dynamos to the small-scale magnetic flux, with the following conclusion: The local dynamo does not play a significant role at any of the spatially resolved scales, nearly all the small-scale flux, including the flux revealed by Hinode, is supplied by the global dynamo. This conclusion is reached by careful determination of the Sun's noise-corrected basal magnetic flux density while making use of a flux cancellation function determined from Hinode data. The only allowed range where there may be substantial or even dominating contributions from a local dynamo seems to be the scales below about 10 km, as suggested by observations of the Hanle depolarization effect in atomic spectral lines. To determine the fraction of the Hanle depolarization that may be due to the action of a local dynamo, a synoptic program is being initiated at IRSOL (Istituto Ricerche Solari Locarno).

Magnetic field decay in neutron stars has been a long debated subject, since the early realization that radio pulsars were likely spinning neutron stars endowed with a 1E12 G magnetic dipole. This problem has however eluded all attempts of solution so far, mostly due to the scarcity of observational indications. Here I discuss the observational evidence for decay of the dipole magnetic field in magnetar candidates (Soft Gamma Repeaters and Anomalous X-ray Pulsars) and present a quantitative study of its main properties. I show that the decaying dipole does not have enough energy to power the persistent X-ray emission of magnetars. The latter must thus directly reveal the decay of an additional, stronger field component, presumably hidden in the interior of these neutron stars. Using existing models it is possible to characterize the salient properties of this internal field component and their implications for magnetar astrophysics. Finally, I sketch preliminary considerations on evolutionary links between magnetars and other classes of neutron stars with strong dipole field that do not show magnetar-like activity.

We present the results of a study to optimize the principal component analysis (PCA) algorithm for planet detection, a new algorithm complementing ADI and LOCI for increasing the contrast achievable next to a bright star. We apply PCA to our Fomalhaut VLT NACO Apodizing Phase Plate NB4.05 data.

We discuss the roles of protostellar outflow feedback in cluster formation using observational data of nearby cluster-forming regions like rho Oph, NGC1333, and Serpens. The observations suggest that observed protostellar outflow feedback appears to be sufficient both to maintain supersonic turbulence and to dynamically support the parent cluster-forming clumps. However, it is not enough to destroy the parent clumps by the current outflow activity. This implies that star formation process may not be too short and probably last at least for several local dynamical times.

We present an analysis of the lensed Lyman Break Galaxy (LBG), the 8 o'clock arc, at redshift 2.735. We reduced Near-IR IFU data from SINFONI on VLT covering λ= 2900 Å to 6500 Å in the rest-frame. From this we recovered the Hβ map and the spatially-resolved Hβ profile which are shown in the right plot in Fig. 1. We can see that Hβ shows different profiles at different spatial pixels and it is composed of multiple components. To study the de-lensed morphology of the galaxy we make use of existing B & H band imaging from the HST. Based on this we constructed a rigorous lens model for the system using the Bayesian grid based lens modeling technique presented by Vegetti & Koopmans (2009, MNRAS, 392, 945). In order to obtain a robust lens model, we first considered the high resolution B band HST image (rest-frame UV, left plot in Fig. 1) and then used this modeling to reconstruct the Hβ line map of the galaxy. We then present the de-lensed Hβ line map, velocity and velocity dispersion maps of this LBG galaxy.

The Kepler mission has found many planetary systems, among them more than 80 systems host three planet candidates which reveal a configuration of near 4:2:1 mean motion resonance. In this paper, we focus on the configuration formation of resonant systems. As shown from our model and N-body simulations, we find that 3:2 mean motion resonance always forms at the early stage of star evolution and planets undergo high rate of migration, while 2:1 mean motion resonance happens at the late stage of the star formation, more often.

Numerical simulations of hot accretion flows have shown that the mass accretion rate decreases with decreasing radius. Two models have been proposed to explain this result. In the adiabatic inflow-outflow solution (ADIOS), it is thought to be due to the loss of gas in outflows. In the convection-dominated accretion flow (CDAF) model, it is explained as because that the gas is locked in convective eddies. In this paper we use hydrodynamical (HD) and magnetohydrodynamical (MHD) simulations to investigate which one is physical. We calculate and compare various properties of inflow (gas with an inward velocity) and outflow (gas with an outward velocity). Systematic and significant differences are found. For example, for HD flows, the temperature of outflow is higher than inflow; while for MHD flows, the specific angular momentum of outflow is much higher than inflow. We have also analyzed the convective stability of MHD accretion flow and found that they are stable. These results suggest that systematic inward and outward motion must exist, i.e., the ADIOS model is favored. The different properties of inflow and outflow also suggest that the mechanisms of producing outflow in HD and MHD flows are buoyancy associated with the convection and the centrifugal force associated with the angular momentum transport mediated by the magnetic field, respectively. The latter mechanism is similar to the Blandford & Payne mechanism but no large-scale open magnetic field is required here. Possible observational applications are briefly discussed.

A comparison between the observed periodic flaring of methanol maser sources in the star forming region G9.62+0.20E and the continuum emission from parts of a background HII region is made. Using a colliding wind binary (CWB) model preliminary calculations show that the CWB model results fit the maser light curves very well.

The astrophysical drivers for far-infrared spectroscopy of the Galactic interstellar medium using a 15m class telescope on Dome A are compelling. For the diffuse, atomic phase, the most important lines in the far-IR spectrum are OI at 63μm and CII at 158μm. These are the dominant cooling lines of the cool, neutral medium, and they show rich spectral structure in Herschel observations at low latitudes. But theory predicts that they should both be highly sub-thermal in excitation, so that the level populations are not in equilibrium with the kinetic temperature of the gas. A large single dish telescope or an interferometer may be able to study the absorption and emission to determine the optical depth and column density of atoms and the physical conditions in the emission regions. Comparison of Herschel CII spectra with 21-cm absorption spectra indicates that a significant fraction of the 158μm flux may be coming from the atomic rather than the molecular phase.