We map the stellar distribution on Hess diagram in the Anti-Center roughly in the boxes 130<l<230, −30<b<−10 and 10<b<30. There are ‘extra components’ associated with the anti-center structures of figure 1 of Newberg et al. (2002). The turnoff point of the structure in the North sky is at 16m.5 and the turnoff point in the South is at 17m.5. In our work, these structures can be found in all of the longitude in our box that can't be explained by standard thin or thick disk models. The distance of the North structure is about 2 kpc (we call it the North near structure) and the galactic height is about 0.7 kpc, the distance of the South structure is about 4 – 6 kpc (we call it the South middle structure). The Vgsr distribution of stars selected along the North near structure has a kinematic distribution similar to that of thick disk stars. But the metallicities of these stars are quite similar to the metallicity distribution of thin disk stars. We try to explain these structures with wave structure of the Galactic plane.

UVMag is a medium-size space telescope equipped with a high-resolution spectropolarimetrer working in the UV and visible domains. It will be proposed to ESA for a future M mission. It will allow scientists to study all types of stars as well as e.g. exoplanets and the interstellar medium. It will be particularly useful for massive stars, since their spectral energy distribution peaks in the UV. UVMag will allow us to study massive stars and their circumstellar environment (in particular the stellar wind) spectroscopically in great details. Moreover, with UVMag's polarimetric capabilities we will be able, for the first time, to measure the magnetic field of massive stars simultaneously at the stellar surface and in the wind lines, i.e. to completely map their magnetosphere.

We obtained the chemical abundances of more than 20 Barium (Ba) stars by analysing high resolution echelle spectra. They show obvious overabundances of neutron capture process elements, such as Y, Zr, Ba, La and Eu. Their abundance pattern can be explained by binary accretion through stellar wind, where the Ba stars have accreted the ejecta from the companion stars which were in AGB stages at that time and now evolve as white dwarfs.

Although barotropic matter does not constitute a realistic model for magnetic stars on short timescales, it would be interesting to confirm a recent conjecture that states that magnetized stars with a barotropic equation of state would be dynamically unstable (Reisenegger 2009). In this work we construct a set of barotropic equilibria, which can eventually be tested using a stability criterion. A general description of the ideal MHD equations governing these equilibria is summarized, allowing for both poloidal and toroidal magnetic field components. A new finite-difference numerical code is developed in order to solve the so-called Grad-Shafranov equation describing the equilibrium of these configurations, and some properties of the equilibria obtained are briefly discussed.

Multiwavelength identification of AGN is crucial not only to obtain a more complete census, but also to learn about the physical state of the nuclear activity (obscuration, efficiency, etc.). A panchromatic strategy plays an especially important role when the host galaxies are star-forming. Selecting far-Infrared galaxies at 0.3<z<1, and using AGN tracers in the X-ray, optical spectra, mid-infrared, and radio regimes, we found a twice higher AGN fraction than previous studies, thanks to the combined AGN identification methods and in particular the recent Mass-Excitation (MEx) diagnostic diagram. We furthermore find an intriguing relation between AGN X-ray absorption and the specific star formation rate (sSFR) of the host galaxies, indicating a physical link between X-ray absorption and either the gas fraction or the gas geometry in the hosts. These findings have implications for our current understanding of both the AGN unification model and the nature of the black hole-galaxy connection.

The origin of the Galactic center diffuse X-ray emission (GCDX) is still under intense investigation. We have found a clear excess in a longitudinal GCDX profile over a stellar number density profile in the nuclear bulge region, suggesting a significant contribution of diffuse, interstellar hot plasma to the GCDX. We have estimated that contributions of an old stellar population to the GCDX are ∼50% and ∼20% in the nuclear stellar disk and nuclear star cluster, respectively. Our near-infrared polarimetric observations show that the GCDX region is permeated by a large scale, toroidal magnetic field. Together with observed magnetic field strengths in nearly energy equipartition, the interstellar hot plasma could be confined by the toroidal magnetic field.

We present results of observations of 22 664 stars in the Kepler field of view acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) in the years 2011 – 2012, and provide a database of the atmospheric parameters derived from those data.

We first introduce the primary target allocation requirements and restrictions for the parallel control multiple fiber system, which is used in the LAMOST spectroscopic survey. The fiber positioner anti-collision model is imported. Then several target allocation methods and features are discussed in detail, including a network flow algorithm, high priority for fiber unit holding less target number, target allocation algorithm for groups, target allocation method for add-ons and target reallocation. Their virtues and weaknesses are analyzed for various kinds of scientific research situations. Furthermore an optimization concept using the Simulate Anneal Arithmetic (SAA) is developed to improve the fiber utilizing efficiency.

Several supernovae exploding in a compact cluster of massive stars generate a galactic outflow with embedded shock waves. Based on numerical simulations for an expanding superbubble above the Galactic center we find that these individual waves generated by the repeated SN-explosions, interact with each other and finally coalesce into a single strong shock at a distance of 5 kpc above the Galactic plane at about 5 ċ 106 years after outbreak. The resulting shock with a Mach number M ≃ 10 propagates up to 100 kpc in less than 108 years. The time-dependent mass an energy loss out of the superbubble affects the further evolution of the outflow. In such long lasting shock waves energetic particles can be accelerated above the knee of 1015 eV already near the galactic plane by a first-order Fermi-mechanism. The additional pressure gradients from such cosmic rays lead to further accelerations of the galactic outflow since these ultra-relativistic particles suffer less from adiabatic losses than the thermal gas.

Blue supergiants (BSGs) to the right the main sequence band in the HR diagram can not be reproduced by standard stellar evolution calculations. We investigate whether a reduced convective core mass due to strong internal magnetic fields during the main sequence might be able to recover this population of stars. We perform calculations with a reduced mass of the hydrogen burning convective core of stars in the mass range 3–30 M⊙ in a parametric way, which indeed lead to BSGs. It is expected that these BSGs would still show large scale magnetic fields in the order of 10 G.

We have analyzed the magnetized equilibrium studies with strong toroidal magnetic fields and found that the negative toroidal current density inside the star is very important for the strong toroidal magnetic fields. The strong toroidal magnetic fields require the strong poloidal current, but the strong poloidal current results in the localized strong toroidal current density in the axisymmetric system. This localized toroidal current changes the magnetic field configuration and makes the size of the toroidal magnetic field region smaller. As a result, the toroidal magnetic field energy can not become large. We need to cancel out the localized toroidal current density in order to obtain the large toroidal fields solutions. We have found and showed that the negative toroidal current cancels out the localized toroidal current density and sustain the large toroidal magnetic field energy inside the star. We can explain the magnetized equilibrium studies with strong toroidal magnetic fields systematically using the negative current density. Physical meaning of the negative current is key to the magnetar interior magnetic fields.

We examined the complete short cadence sample of fundamental-mode Kepler RR Lyrae stars to further investigate the recently discovered dynamical effects such as period doubling and additional modes. Here we present the findings on four stars. V450 Lyr may be a non-classical double-mode RR Lyrae star pulsating in the fundamental mode and the second overtone. For the three remaining stars we observe the interaction of three different modes. Since the period ratios are close to resonant values, we observe quasi-repetitive patterns in the pulsation cycles in the stars. These findings support the mode-resonance explanations of the Blazhko effect.

There exist strong evidence supporting the co-evolution of central supermassive black holes and their host galaxies; however it is still under debate how such a relation comes about and whether it is relevant for all or only a subset of galaxies. A rich multi-wavelength dataset is available for the North Ecliptic Pole field, most notably surveyed by the AKARI infrared space telescope. We investigate the star-formation properties of the host galaxies of radio-AGN together with the radio feedback mechanism, potentially responsible for the eventual quenching of star formation. Using broadband SED modelling, the nuclear and host galaxy components of these sources are studied as a function of their radio luminosity. Here we present results concerning the AGN content of the radio sources in this field, while offering evidence supporting a “maintenance” type of feedback from powerful radio-jets.

We selected and studied 180 pairs with d V < 800 km s−1 and Dp < 60 kpc containing Markarian (MRK) galaxies to investigate the dependence of galaxies integral parameters, star-formation (SF) and active galactic nuclei (AGN) properties on kinematics of pairs, their structure and large-scale environments. Projected radial separation Dp and perturbation level P are better measures of interaction strength than dV. The latter correlates with the density of large-scale environment and with the morphologies of galaxies. Both galaxies in a pair are of the same nature, the only difference is that MRK galaxies are usually brighter than their neighbors. Specific star formation rates (SSFR) of galaxies in pairs with smaller Dp or d V is in average 0.5 dex higher than that of galaxies in pairs with larger Dp or d V. Closeness of a neighbor with the same and later morphological type increases the SSFR, while earlier-type neighbors do not increase SSFR. Major interactions/mergers trigger SF and AGN more effectively than minor ones. The fraction of AGNs is higher in more perturbed pairs and pairs with smaller Dp. AGNs typically are in stronger interacting systems than star-forming and passive galaxies. There are correlations of both SSFRs and spectral properties of nuclei between pair members.

There is statistical evidence for a dearth of short-period (Porb < 4h) black hole (BH) low mass X-ray binaries (LMXBs) in the Galaxy. At short periods accretion onto the central object (be it a BH) may become inefficient because the cooling timescale of the gas is greater than the accretion timescale (this is the well known ADAF model). The nature of the switch is important in terms of the outburst timescales of transient sources. The switch may be sharp or occur smoothly over time. I show that the dearth can be explained if the switch to inefficiency occurs sharply at some fraction of the Eddington luminosity of the BH (fLEdd).

We have calculated many Hall equilibrium states within the neutron star crust under various boundary conditions in order to investigate the influences of the boundary conditions clearly. We have found two important features of these solutions. First, the magnitude of the core magnetic fields affects the toroidal to total magnetic field energy ratio within the crust (Et/E). If the core magnetic fields are vanished, the crustal toroidal magnetic fields become weak and the typical energy ratio is only Et / E ~ 0.1%. If the core magnetic fields are strong, however, the crustal toroidal magnetic fields become strong and the typical ratio reaches Et / E ~ 15%. Second, the core toroidal magnetic fields and the twisted magnetosphere around the star make the size of the crustal toroidal magnetic field regions large. Therefore if the strong core magnetic fields have strong toroidal component, both strength and size of the crustal toroidal magnetic fields become large. These results show that the Hall MHD evolutions would be deeply affected by both inner and outer boundary conditions.

We present the overview of an observational program carring out on the 6-m telescope of Special Astrophysical Observatory from 2012. This program aims the searches of new Bp stars with surface magnetic field and the detailed study of known magnetic CP star from the stellar association Ori OB1. HD 34736 is the most interesting star that was found as magnetic within the program recently.

The relationship derived by Morgan et al. (2007) for type-c RR Lyrae variables (RRc) between values of [Fe/H] – φ31 – P has been revised and expanded. New relationships are based upon Fourier coefficients of 163 RRc variables in 19 Galactic globular clusters using the metallicity scales of Harris (2010), Zinn & West (1984) and Carretta et al. (2009). This larger database includes more low-metallicity clusters ([Fe/H] < −2.0), and the best fitting relations are found to depend upon values of log P rather than P. The new relations are applied to various populations of RRc including Milky Way field variables, LMC globular clusters variables, ω Cen RRc, and RRc in various OGLE III databases.

The Scandium abundances for 85 metal-poor stars are presented. Our result shows that NLTE corrections for Sc II lines are small (−0.04 to +0.06 dex). The abundance trends in stars of different populations are discussed.

Mira and semi-regular variable stars have been studied for centuries but continue to be enigmatic. One unsolved mystery is the presence of polarization from these stars. In particular, we present 40 years of polarization measurements for the prototype o Ceti and V CVn and find very different phenomena for each star. The polarization fraction and position angle for Mira is found to be small and highly variable. On the other hand, the polarization fraction for V CVn is large and variable, from 2–7%, and its position angle is approximately constant, suggesting a long-term asymmetric structure. We suggest a number of potential scenarios to explain these observations.