We present new measurements of the rotational profile of 56 nearby stars of spectral types A-F obtained by line profile analysis. Together with earlier work, we now know of 33 stars in which Sun-like differential rotation was identified by line profile analysis. We find evidence of two populations of differential rotators, one group of rapidly rotating A stars at the granulation boundary with strong horizontal shear, and another group of mid- to late-F type stars with moderate rates of rotation and less shear. There is a gap between A and F stars, in which the stars appear to exhibit very little shear. Apparently, the physical conditions of differential rotation change at early-F spectral types.

On 16 April 2011 the IAU's Office of Astronomy for Development (OAD) was launched jointly by the President of the IAU and the South African Minister of Science and Technology, at the South African Astronomical Observatory in Cape Town. This OAD was set up to realise the IAU's strategic plan which aims to use astronomy as a tool for development. Communicating astronomy with the public is one of the OAD's focus areas.

It is remarkable that the long gamma-ray bursts, as objects connected with the supernovae - i.e. with the end-stages of massive stars, trace the star formation rate. This connection is discussed in this contribution. The presentation is in essence a recapitulation of the article by Mészáros et al. (2006).

Convection is simulated numerically based on two-dimensional Boussinesq equations for a fluid layer with a specially chosen stratification such that the convective instability is much stronger in a thin subsurface sublayer than in the remaining part of the layer. The developing convective flow has a small-scale component superposed onto a basic large-scale roll flow.

We discuss the effect of binary interactions on the tracers of star formation rate (including L1500, L2800, LHα, L[OII] and LFIR) at different metallicities (0.0001–0.03).

In Han & Han (2012), we have preliminarily built BayeSED and applied it to a sample of hyperluminous infrared galaxies. The physically reasonable results obtained from Bayesian model comparison and parameter estimation show that BayeSED could be a useful tool for understanding the nature of complex systems, such as dust obscured starburst-AGN composite galaxies, from decoding their complex SEDs. In this contribution, we present a more rigorous test of BayeSED by making a mock catalog from model SEDs with the value of all parameters to be known in advance.

The α-effect is central to magnetic field generation in αΩ dynamo theory (Parker, 1955), however, it lacked observational and experimental supports over a long term (Sokoloff, 2007). Mirror asymmetries of magnetic field (magnetic helicity) were not observed until the recent 20 years (Seehafer, 1990; Pevtsov et al., 1995, Bao & Zhang, 1998). Later, the advancement in local helioseismology has made possible the measurements of solar subsurface velocity field and the vorticity (or kinetic helicity) as well (Zhao & Kosovichev, 2003). Apparently, frozen flow with the magnetic field in the fluid of high magnetic Reynold number is a necessary condition for the α-effect in the framework of Parker's dynamo model.

We present SINFONI observations of IRAS 19115-2124, dubbed the Bird, an intriguing triple galaxy encounter. NIR line strengths and line ratios are used to study the sequence of events in this complex system. The most massive and obscured component shows LINER-like activity, while the least massive irregular component is the source of 3/4 of the current total SF. This most recent compact starburst lies 3 kpc away from the dynamically dominant components. Cool and warm gas inflows and outflows are detected at the locations of the progenitor nuclei.

Photometric redshifts, i.e. redshifts derived by comparing an observed spectral-energy distribution (SED) to a range of empirical or theoretical SED templates, are commonly used in studies of the high-redshift Universe. Often, the next step is to use these redshifts as fixed input parameters for SED fitting to derive physical properties for each galaxy. However, this two-step approach ignores degeneracies between redshift and, e.g., stellar mass. Here I present first results using an improved approach that integrates both methods. I find that mass determinations are, on average, three times more uncertain than they seem from the common two-step approach. If not accounted for, these underestimated uncertainties can impact our ability of making meaningful comparisons between observations and simulations of galaxy evolution.

The meeting “Galaxy Evolution through Secular Processes,” hosted as Special Session 3 at the XVIIIth General Assembly of the IAU in Beijing, brought together a broad community of astronomers actively working on topics related to the evolution of galaxies. This evolution is currently thought to have two phases: (1) a formative chaotic phase, where baryonic matter collected into dark halo “seeds” with the occurrence of frequent mergers; and (2) a slower secular evolutionary phase where internal perturbations such as bars and spirals interacted (and likely still interact) with a galaxy's stars and gas clouds to redistribute material and slowly change the morphology, such as growing bulges or pseudobulges from disk material.

It is very difficult to start from scratch a new Astrophysics program in a country with very little or no researchers in the field. In 2007, we began to set-up an Astrophysics program by TWINNING the Université de Ouagadougou with the Université de Montréal in Canada, the Université de Provence in France and the University of Cape Town in South Africa. Already, courses are given at the undergraduate and Master levels and a teaching Observatory has been built. A 1m research telescope was also moved from the La Silla Observatory in Chile to Burkina Faso and the infrastructure is being built at the moment on mount Djaogari in the north-eastern part of the country. In the meantime, 6 students are doing their PhD in Astrophysics overseas (Canada, France and South Africa) and will become the core of the research group at the Université de Ouagadougou. An engineer is also doing his PhD in Astronomical Instrumentation to help with the maintenance of the equipment on the Research Telescope.

We present a study of the VLBA polarimetry of GHz-Peaked Spectrum (GPS) quasar OQ172. GPS quasar OQ172 is one of the source with the extremely highest rest-frame rotation measure (RM > 20,000 rad/m2). By analyzed our of VLBA polarimetry observation, we found the Rotation Measure on C & X band would be well fitted by linear relationship of the square of λ2. Combined other evidences of physical environment in the core of OQ172, we suggest that this source might be a young AGN.

We investigate the curvature radiation from relativistic particles streaming along magnetic field lines and co-rotating with a pulsar. The co-rotation affects the trajectories of the particles and hence the emission properties, especially the polarization. For three density models in the form of core, cone and patches, we calculate the polarized emission at a given height and also the integrated emission for the whole open field line region, and try to explain the generation of circular polarization.

Very Long Baseline Interferometry (VLBI) observations can provide the positions of compact radio sources with an accuracy of order 50 micro-arcseconds. This is sufficient to measure the trigonometric parallax and proper motions of any object within 500 pc of the Sun to better than a few percent. Because they are magnetically active, young stars are often associated with compact radio emission detectable using VLBI techniques. Here we show how VLBI observations have already constrained the distance to the most often studied nearby regions of star formation (Taurus, Ophiuchus, Orion, etc.) and have started to provide information about their internal structure and kinematics. We will then briefly describe a large project, the ‘Gould's Belt Distances Survey,’ which has been designed to provide a detailed view of star formation in the solar neighborhood using VLBI observations.

Site-testing measurements by the Australian group has already shown that Dome C on the Antarctic plateau is one of the best ground-based astronomical sites. Furthermore, Dome A, the Antarctic Kunlun Station, as the highest point on Antarctic inland plateau, where a Chinese Antarctic scientific expedition team first reached in 2005, is widely predicted to be an even better astronomical site by the international astronomical community. Preliminary site-testing carried out by the Center for Antarctic Astronomy (CAS) also confirms Dome A as a potential astronomical site. Multi-aperture scintillation sensors (MASS) can measure the seeing and isoplantic angle, the turbulence profile, etc., which are very important site-testing parameters that we urgently need. The MASS site testing at Dome A is presented here, and includes the method of processing data and the hardware for the extreme conditions of Dome A, Antarctica.

We have examined solar polar fields during the solar cycles 21–23 using both ground and space based synoptic magnetograms. It has been shown that the unsigned polar fields in the latitude range (78°–90°) show a steady decline starting ~1995–1996 till the maximum of cycle 23. We also find that the long term changes in the unsigned polar fields at higher latitudes are well correlated with changes in the surface meridional flow speed that have been reported for the cycle 23.

We studied the color distribution of satellite galaxies in three groups of galaxies and found that nearly a half of galaxies show statistically significant radial color gradients, which are indicative of changing stellar ages and metallicities. We found that the disk-dominated satellite galaxies with positive color and age gradients (i.e., evolving in outside-in fashion) are residing, predominantly, in the inner, dense group regions, within the characteristic radius R200, while those galaxies, residing in the outer group in-fall region, show typically zero or negative gradients.

We have performed a search for faint companions around the nearest massive galaxies. We see a clear signature of clustering of faint objects, both in projected separation and in velocity offset. The inferred satellite luminosity functions confirm that the abundance of faint satellites seen in the Local Group is typical of other nearby systems.

About 0.2 solar mass is absorbed by the millisecond pulsar (MSP) at the binary accretion phase, while the polar magnetic field of MSP is diluted to a magnitude of order 108.5 Gauss, which is proportionally related to the mass accretion rate. It is found that the minimum magnetic field of MSP can be as low as 107 Gauss if the accretion rate of the binary system reaches its the minimum value of 1015 g/s. This bottom field has nothing to do with the MSP initial field. Some questions on MPSs are proposed and answered.

Many planets have been detected in close binary stars with separation only ~20 AU. These discoveries challenge the current theory of planet formation because binary stars with such an close separation are thought to have strong perturbations and thus inhibit planet formation around them. To address this issue, another scenario had been suggested: the binary separation was wider enough for binary formation in early stages, but it shrank to the present one after a transient triple star phase (stellar scattering phase). Here, we investigate how could planet survive or be ejected under this scenario. We find that (1) the odds of planetary survival are significantly reduced if scatterings between planets and/or planetesimals are included (2) circumbinary planets/planetesimals could be readily formed during such a transient phase.