The Square Kilometre Array (SKA) Epoch of Reionisation and Cosmic Dawn (EoR/CD) experiments aim to explore the growth of structure and production of ionising radiation in the first billion years of the Universe. Here I describe the experiments planned for the future low-frequency components of the Observatory, and work underway to define, design and execute these programs.

Extremely strong magnetic fields of the order of 1015G are required to explain the properties of magnetars, the most magnetic neutron stars. Such a strong magnetic field is expected to play an important role for the dynamics of core-collapse supernovae, and in the presence of rapid rotation may power superluminous supernovae and hypernovae associated to long gamma-ray bursts. The origin of these strong magnetic fields remains, however, obscure and most likely requires an amplification over many orders of magnitude in the protoneutron star. One of the most promising agents is the magnetorotational instability (MRI), which can in principle amplify exponentially fast a weak initial magnetic field to a dynamically relevant strength. We describe our current understanding of the MRI in protoneutron stars and show recent results on its dependence on physical conditions specific to protoneutron stars such as neutrino radiation, strong buoyancy effects and large magnetic Prandtl number.

High energy photon radiations of gamma-ray bursts (GRBs) and active galactic nuclei (AGNs) are dominated by their jet radiations. It was suggested that relativistic jets powered by different mass-scale black holes may share the same physical laws. A tight relation among the peak luminosity, the peak photon energy in the νfν spectrum, and the initial Lorentz factor is found for GRBs. With samples of GeV-TeV BL Lacs, FSRQs, and NLS1 galaxies, we show that these sources do not follow this relation. This may be attributed to the jet geometry and continuous/episodic jet as well as radiation physics for different kinds of sources.

The characterization of short-period detached low-mass binaries, by the determination of their physical and orbital parameters, reveal the most precise basic parameters of low-mass stars. Particularly, when photometric and spectroscopic data of eclipsing binaries (EBs) are combined. Recently, 16 new low-mass EBs were discovered by the WFCAM Transit Survey (WTS), however, only three of them were fully characterized. Therefore, new spectroscopic data were already acquired with the objective to characterize five new detached low-mass EBs discovered in the WTS, with short periods between 0.59 and 1.72 days. A preliminary analysis of the radial velocity and light curves was performed, where we have derived orbital separations of 2.88 to 6.69 R⊙, and considering both components, we have found stellar radii ranging from 0.40 to 0.80 R⊙, and masses between 0.24 and 0.71 M⊙. In addition to the determination of the orbital parameters of these systems, the relation between mass, radius and orbital period of these objects can be investigated in order to study the mass-radius relationship and the radius anomaly in the low main-sequence.

Some magnetic early B-type stars display Hα emission originating in their Centrifugal Magnetospheres (CMs). To determine the rotational and magnetic properties necessary for the onset of emission, we analyzed a large spectropolarimetric dataset for a sample of 51 B5-B0 magnetic stars. New rotational periods were found for 15 stars. We determined physical parameters, dipolar magnetic field strengths, magnetospheric parameters, and magnetic braking timescales. Hα-bright stars are more rapidly rotating, more strongly magnetized, and younger than the overall population. We use the high sensitivity of magnetic braking to the mass-loss rate to test the predictions of Vink et al. (2001) and Krtička (2014) by comparing ages t to maximum spindown ages tS, max. For stars with M* < 10 M⊙ this comparison favours the Krtička recipe. For the most massive stars, both prescriptions yield t ≪ tS, max, a discrepancy which is difficult to explain via incorrect mass-loss rates alone.

The chromosphere is a complex region that acts as an intermediary between the magnetic flux emergence in the photosphere and the magnetic features seen in the corona. Large eruptions in the chromosphere of flares and filaments are often accompanied by ejections of coronal mass off the sun. Several studies have observed fast-moving progressive trains of compact bright points (called Sequential Chromospheric Brightenings or SCBs) streaming away from chromospheric flares that also produce a coronal mass ejection (CME). In this work, we review studies of SCBs and search for commonalties between them. We place these findings into a larger context with contemporary chromospheric and coronal observations. SCBs are fleeting indicators of the solar atmospheric environment as it existed before their associated eruption. Since they appear at the very outset of a flare eruption, SCBs are good early indication of a CME measured in the chromosphere.

I review the major science outcomes to date of the Galactic Census of High- and Medium-mass Protostars (CHaMP), and also report the latest observational results on this unbiased, uniform sample of massive, cluster-forming molecular clumps, based on new mm-wave and IR data. These clouds represent the vast, subthermally-excited population of clumps predicted by Narayanan et al. (2008) to dominate the molecular mass of disk galaxies. Besides confirming their existence, we have presented evidence that these massive clumps probably spend a large fraction (90–95%) of their long lives (possibly up to 100 Myr) in a mostly quiescent, low star formation rate (SFR) state. This is likely ended when a density or internal pressure threshold is crossed, after which vigorous, massive cluster formation consumes the densest gas with a high SFR, dispersing the embedding envelope. New results presented in two other posters at this Symposium include (1) the first analysis of HCN emission from the dense gas (Schap et al.2015), and (2) the first deep photometry of clusters in this sample based on NIR AAT & CTIO data, and on MIR Warm Spitzer IRAC data (Dallilar et al.2015).

The fast stellar winds can blow bubbles in the circumstellar material ejected from previous phases of stellar evolution. These are found at different scales, from planetary nebulae (PNe) around stars evolving to the white dwarf stage, to Wolf-Rayet (WR) bubbles and up to large-scale bubbles around massive star clusters. In all cases, the fast stellar wind is shock-heated and a hot bubble is produced. Processes of mass evaporation and mixing of nebular material and heat conduction occurring at the mixing layer between the hot bubble and the optical nebula are key to determine the thermal structure of these bubbles and their evolution. In this contribution we review our current understanding of the X-ray observations of hot bubbles in PNe and present the first spatially-resolved study of a mixing layer in a PN.

Japanese group is promoting infrared space astrometry missions, JASMINE project series, in international collaboration with Gaia DPAC team. In this paper, the outline of Nano-JASMINE and Small-JASMINE missions is shown.

We present simulator of alerts for the Large Synoptic Survey Telescope (LSST) developed by Belgrade group. This simulator will be used in testing the functionality of external event brokers/Complex Event Processing (CEP) engines. It is based on current LSST Simulation framework and allows for different classes of objects to be ‘alerted’. A Web service based on our simulator is prototyped and can be accessed by developers of brokers/CEP engines.

While several scenarios have been proposed to explain supra-arcade downflows (SADs) observed descending through turbulent hot regions, none of them have systematically addressed the consideration of thermal conduction. The SADs are known to be voided cavities. Our model assumes that SADs are triggered by bursty localized reconnection events that produce non-linear waves generating the voided cavity. These subdense cavities are sustained in time because they are hotter than their surrounding medium. Due to the low density and large temperature values of the plasma we expect the thermal conduction to be an important process. Our main aim here is to study if it is possible to generate SADs in the framework of our model considering thermal conduction. We carry on 2D MHD simulations including anisotropic thermal conduction, and find that if the magnetic lines envelope the cavities, they can be isolated from the hot environment and be identified as SADs.

An introduction is given to the use of prototype-based models in supervised machine learning. The main concept of the framework is to represent previously observed data in terms of so-called prototypes, which reflect typical properties of the data. Together with a suitable, discriminative distance or dissimilarity measure, prototypes can be used for the classification of complex, possibly high-dimensional data. We illustrate the framework in terms of the popular Learning Vector Quantization (LVQ). Most frequently, standard Euclidean distance is employed as a distance measure. We discuss how LVQ can be equipped with more general dissimilarites. Moreover, we introduce relevance learning as a tool for the data-driven optimization of parameterized distances.

The behavior of Active Regions (ARs) is directly related to the occurrence of some remarkable phenomena in the Sun such as solar flares or coronal mass ejections (CME). In this sense, changes in the magnetic field of the region can be used to uncover other relevant features like the evolution of the ARs magnetic structure and the plasma flow related to it. In this work we describe the evolution of the magnetic structure of the active region AR NOAA12443 observed from 2015/10/30 to 2015/11/10, which may be associated with several X-ray flares of classes C and M. The analysis is based on observations of the solar surface and atmosphere provided by HMI and AIA instruments on board of the SDO spacecraft. In order to investigate the magnetic energy buildup and release of the ARs, we shall employ potential and linear force free extrapolations based on the solar surface magnetic field distribution and the photospheric velocity fields.

Infrared spectra from the Spitzer Space Telescope trace the evolution of carbon-rich dust from the asymptotic giant branch (AGB) to young planetary nebulae (PNe). On the AGB, amorphous carbon dominates the dust, but SiC and MgS also appear. In more evolved systems with warmer central stars, the spectra reveal the unidentified 21 μm feature, features from aliphatic hydrocarbons, and spectra from polycyclic aromatic hydrocarbons (PAHs), often with shifted feature positions indicative of the presence of aliphatics. More evolved systems with hot central stars show more typical PAH spectra, along with fullerenes and/or an emission feature known as the big-11 feature at ~11 μm. This features arises from a combination of SiC and PAHs, and it is usually accompanied by a shoulder at 18 μm, which while unidentified might be from cool silicate grains. The strong emission from MgS and SiC in young PNe probably arises from coatings on carbonaceous grains.

A Danish computer, GIER, from 1961 played a vital role in the development of a new method for astrometric measurement. This method, photon counting astrometry, ultimately led to two satellites with a significant role in the modern revolution of astronomy. A GIER was installed at the Hamburg Observatory in 1964 where it was used to implement the entirely new method for the measurement of stellar positions by means of a meridian circle, at that time the fundamental instrument of astrometry. An expedition to Perth in Western Australia with the instrument and the computer was a success. This method was also implemented in space in the first ever astrometric satellite Hipparcos launched by ESA in 1989. The Hipparcos results published in 1997 revolutionized astrometry with an impact in all branches of astronomy from the solar system and stellar structure to cosmic distances and the dynamics of the Milky Way. In turn, the results paved the way for a successor, the one million times more powerful Gaia astrometry satellite launched by ESA in 2013. Preparations for a Gaia successor in twenty years are making progress.

Within the ‘earliest phases of star formation’ (EPoS) Herschel project, we observed the NH3 inversion lines of 6 very young high-mass star-forming regions at high spatial resolution (3-5″) with the JVLA. While the Herschel data provide details about the dust continuum, the ammonia data reveal the kinematics and temperatures. Here we present the exciting star-forming clump ISOSS23053 that shows multiple velocity components. We observe a prominent velocity step within the clump, which could be a sign of colliding or converging flows that triggers star formation. Furthermore, we used the JVLA in the C-array configuration to study this source in more detail and we present the first results from the new data. They support the idea of converging flows, as we observe two components in the NH3(1,1) and (2,2) line, whereas the higher excited NH3(3,3) line shows one component that links the two lower excited lines.

Here we report ongoing efforts for an untriggered search of rapid optical transients of various astrophysical and non-astrophysical origins on time scales down to fractions of a second with Mini-MegaTORTORA. Mini-MegaTORTORA is a novel 9-channel wide-field optical monitoring system in operation since 2014 at Special Astrophysical Observatory on Russian Caucasus.

Recent studies of WNh stars at the cores of young massive clusters have challenged the previously accepted upper stellar mass limit (~150 M⊙), suggesting some of these objects may have initial masses as high as 300 M⊙. We investigated the possible existence of observed stars above ~150 M⊙ by i) examining the nature and stellar properties of VFTS 682, a recently identified WNh5 very massive star, and ii) studying the uncertainties in the luminosity estimates of R136’s core stars due to crowding. Our spectroscopic analysis reveals that the most massive members of R136 and VFTS 682 are very similar and our K-band photometric study of R136’s core stars shows that the measurements seem to display higher uncertainties than previous studies suggested; moreover, for the most massive stars in the cluster, R136a1 and a2, we found previous magnitudes were underestimated by at least 0.4 mag. As such, luminosities and masses of these stars have to be significantly scaled down, which then also lowers the hitherto observed upper mass limit of stars.

The sky-averaged (global) 21-cm signal is a very promising probe of the Cosmic Dawn, when the first luminous sources were formed and started to shine in a substantially neutral intergalactic medium. I here report on the status and early result of the Large-Aperture Experiment to Detect the Dark Age that focuses on observations of the global 21-cm signal in the 16 ≲ z ≲ 30 range.

We carried out high resolution simulations of weakly-magnetized core-collapse supernovae in two-dimensional axisymmetry in order to see the influence of the magnetic field and rotation on the explosion. We found that the magnetic field amplified by magnetorotational instability (MRI) has a great positive impact on the explosion by enhancing the neutrino heating, provided that the progenitor has large angular momentum close to the highest value found in stellar evolution calculations. We also found that even for progenitors neither involving strong magnetic flux nor large angular momentum, the magnetic field is greatly amplified by the convection aand rotation, and this leads to the boost of the explosion again by enhancing the neutrino heating.