Evidence of a mis-aligned secondary bar in the Large Magellanic Cloud

Evidence of a mis-aligned secondary bar, within the primary bar of the Large Magellanic Cloud (LMC) is presented. The density distribution and the de-reddened mean magnitudes ($I_0$) of the red clump stars in the bar obtained from the OGLE II data are used for this study. The bar region which predominantly showed wavy pattern in the line of sight in \citet{a03} was located. These points in the X-Z plane delineate an S-shaped pattern, clearly indicating a mis-aligned bar. This feature is statistically significant and does not depend on the considered value of $I_0$ for the LMC center. The rest of the bar region were not found to show the warp or the wavy pattern. The secondary bar is found to be considerably elongated in the Z-direction, with an inclination of 66$^o$.5 $\pm$ 0$^o$.9, whereas the undisturbed part of the primary bar is found to have an inclination of 15$^o$.1 $\pm$ 2$^o$.7, such that the eastern sides are closer to us with respect to the western sides of both the bars. The PA$_{maj}$ of the secondary bar is found to be 108$^o$.4 $\pm$ 7$^o$.3. The streaming motions found in the H I velocity map close to the LMC center could be caused by the secondary bar. The recent star formation and the gas distribution in LMC could be driven by the mis-aligned secondary bar.Comment: 10 pages, to appear in ApJ Letter

A New Kinematic Distance Estimator to the LMC

The distance to the Large Magellanic Cloud (LMC) can be directly determined by measuring three of its properties, its radial-velocity field, its mean proper motion, and the position angle \phi_ph of its photometric line of nodes. Statistical errors of 2% are feasible based on proper motions obtained with any of several proposed astrometry satellites, the first possibility being the Full-Sky Astrometric Mapping Explorer (FAME). The largest source of systematic error is likely to be in the determination of \phi_ph. I suggest two independent methods to measure \phi_ph, one based on counts of clump giants and the other on photometry of clump giants. I briefly discuss a variety of methods to test for other sources of systematic errors.Comment: submitted to ApJ, 13 page

Влияние времени нанесения на свойства и структуру триполифосфатных покрытий, полученных в условиях интенсивной промывки

Приведены результаты исследований по изучению влияния времени нанесения и интенсивной промывки водой на свойства и структуру химически осажденных на сталь триполифосфатных (ТПФ) покрытий. Построены графические зависимости характеристик физических и химических свойств покрытий с матричной структурой, промытых водой, от времени нанесения. Установлено, что с увеличением времени нанесения в интервале 1 – 10 минут удельная масса матрицы (феррум (III) типолифосфат) и количество гелиеподобного слоя ТПФ Na увеличиваются, дефектность матрицы и количество наполнителя, содержащегося в матрице в виде кристаллов ТПФ Na, уменьшается. Это сопровождается, в целом, увеличением удельной массы, снижением пористости и способствует повышению защитной способности и коррозионной стойкости покрытия в условиях атмосферной коррозии.Наведено результати досліджень з вивчення впливу часу нанесення й інтенсивного промивання водою на властивості та структуру хімічно нанесених на сталь триполіфосфатних (ТПФ) покриттів. Побудовано графічні залежності характеристик фізичних і хімічних властивостей покриттів з матричною будовою, промитих водою, від часу нанесення. Встановлено, що зі збільшенням часу нанесення в інтервалі 1 – 10 хвилин питома маса матриці (ферум (III) триполіфосфат) і кількість гелієподібного шару ТПФ Na збільшуються, дефектність матриці й кількість наповнювача, що міститься в матриці у вигляді кристалів ТПФ Na, зменшується. Це супроводжується, в цілому, збільшенням питомої маси, зниженням пористості й сприяє підвищенню захисної здатності та корозійної стійкості покриття в умовах атмосферної корозії.The studies results of the impact of the application time and intensive water washing on structure аnd properties of tripolyphosphate coatings chemically deposited on steel are given. The graphical dependencies of physical characteristics and chemical properties of coats with matrix structure, washed with water from the application time are built. It is found the specific gravity of the matrix (ferrum (III) tripolyphosphate) and the number of gel-like layer TPР Na increase also matrix defectiveness and filler amount that are contained in the matrix as TPP Na crystals, decreases when ap- plication time increases in the 1-10 minutes interval. This is followed by overall increasing of the specific gravity, porosity decreasing and facilitates increasing of the protective ability and corrosion resistance of the coating under atmospheric corrosion

A large local rotational speed for the Galaxy found from proper-motions: Implications for the mass of the Milky-Way

Predictions from a Galactic Structure and Kinematic model are compared to the absolute proper-motions of about 30,000 randomly selected stars with $9 < B_{\rm J} \le 19$ derived from the Southern Proper-Motion Program (SPM) toward the South Galactic Pole. The absolute nature of the SPM proper-motions allow us to measure not only the relative motion of the Sun with respect to the local disk, but also, and most importantly, the overall state of rotation of the local disk with respect to galaxies. The SPM data are best fit by models having a solar peculiar motion of +5 km~s$^{-1}$ in the V-component (pointing in the direction of Galactic rotation), a large LSR speed of 270 km~s$^{-1}$, and a disk velocity ellipsoid that points towards the Galactic center. We stress, however, that these results rest crucially on the assumptions of both axisymmetry and equilibrium dynamics. The absolute proper-motions in the U-component indicate a solar peculiar motion of $11.0 \pm 1.5$ km~s$^{-1}$, with no need for a local expansion or contraction term. The implications of the large LSR speed are discussed in terms of gravitational mass of the Galaxy inferred from the most recent and accurate determination for the proper-motion of the LMC. We find that our derived value for the LSR is consistent both with the mass of the Galaxy inferred from the motion of the Clouds ($3 - 4 \times 10^{12} M_\odot$ to $\sim 50$ kpc), as well as the timing argument, based on the binary motion of M31 and the Milky Way, and Leo I and the Milky Way ($\ge 1.2 \times 10^{12} M_\odot$ to $\sim 200$ kpc).Comment: 7 pages (AAS Latex macro v4.0), 2 B&W postscript figures, accepted for publication on ApJ, Letters sectio

Supernova Remnants in the Magellanic Clouds. V. The Complex Interior Structure of the N206 SNR

The N206 supernova remnant (SNR) in the Large Magellanic Cloud (LMC) has long been considered a prototypical "mixed morphology" SNR. Recent observations, however, have added a new twist to this familiar plot: an elongated, radially-oriented radio feature seen in projection against the SNR face. Utilizing the high resolution and sensitivity available with the Hubble Space Telescope, Chandra, and XMM-Newton, we have obtained optical emission-line images and spatially resolved X-ray spectral maps for this intriguing SNR. Our findings present the SNR itself as a remnant in the mid to late stages of its evolution. X-ray emission associated with the radio "linear feature" strongly suggests it to be a pulsar-wind nebula (PWN). A small X-ray knot is discovered at the outer tip of this feature. The feature's elongated morphology and the surrounding wedge-shaped X-ray enhancement strongly suggest a bow-shock PWN structure.Comment: 41 pages including 7 figures, accepted for publication by the Astrophysical Journa

Supernova Remnants in the Magellanic Clouds. IV. X-Ray Emission from the Largest SNR in the LMC

We present the first X-ray detection of SNR 0450-70.9 the largest known supernova remnant (SNR) in the Large Magellanic Cloud. To study the physical conditions of this SNR, we have obtained XMM-Newton X-ray observations, optical images and high-dispersion spectra, and radio continuum maps. Optical images of SNR 0450-70.9 show a large, irregular elliptical shell with bright filaments along the eastern and western rims and within the shell interior. The interior filaments have higher [S II]/Halpha ratios and form an apparent inner shell morphology. The X-ray emission region is smaller than the full extent of the optical shell, with the brightest X-ray emission found within the small interior shell and on the western rim of the large shell. The expansion velocity of the small shell is ~220 km/s, while the large shell is ~120 km/s. The radio image shows central brightening and a fairly flat radio spectral index over the SNR. However, no point X-ray or radio source corresponding to a pulsar is detected and the X-ray emission is predominantly thermal. Therefore, these phenomena can be most reasonably explained in terms of the advanced age of the large SNR. Using hydrodynamic models combined with a nonequilibrium ionization model for thermal X-ray emission, we derived a lower limit on the SNR age of about 45,000 yr, well into the later stages of SNR evolution. Despite this, the temperature and density derived from spectral fits to the X-ray emission indicate that the remnant is still overpressured, and thus that the development is largely driven by hot gas in the SNR interior.Comment: Accepted for publication in The Astrophysical Journa

The LOFT Ground Segment

LOFT, the Large Observatory For X-ray Timing, was one of the ESA M3 mission candidates that completed their assessment phase at the end of 2013. LOFT is equipped with two instruments, the Large Area Detector (LAD) and the Wide Field Monitor (WFM). The LAD performs pointed observations of several targets per orbit (~90 minutes), providing roughly ~80 GB of proprietary data per day (the proprietary period will be 12 months). The WFM continuously monitors about 1/3 of the sky at a time and provides data for about ~100 sources a day, resulting in a total of ~20 GB of additional telemetry. The LOFT Burst alert System additionally identifies on-board bright impulsive events (e.g., Gamma-ray Bursts, GRBs) and broadcasts the corresponding position and trigger time to the ground using a dedicated system of ~15 VHF receivers. All WFM data are planned to be made public immediately. In this contribution we summarize the planned organization of the LOFT ground segment (GS), as established in the mission Yellow Book 1 . We describe the expected GS contributions from ESA and the LOFT consortium. A review is provided of the planned LOFT data products and the details of the data flow, archiving and distribution. Despite LOFT was not selected for launch within the M3 call, its long assessment phase (> 2 years) led to a very solid mission design and an efficient planning of its ground operations.Comment: Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91446

Does the Milky Way have a Maximal Disk?

The Milky Way is often considered to be the best example of a spiral for which the dark matter not only dominates the outer kinematics, but also plays a major dynamical role in the inner galaxy: the Galactic disk is therefore said to be ``sub-maximal.'' This conclusion is important to the understanding of the evolution of galaxies and the viability of particular dark matter models. The Galactic evidence rests on a number of structural and kinematic measurements, many of which have recently been revised. The new constraints indicate not only that the Galaxy is a more typical member of its class (Sb-Sc spirals) than previously thought, but also require a re-examination of the question of whether or not the Milky Way disk is maximal. By applying to the Milky Way the same definition of ``maximal disk'' that is applied to external galaxies, it is shown that the new observational constraints are consistent with a Galactic maximal disk of reasonable $M/L$. In particular, the local disk column can be substantially less than the oft-quoted required \Sigma_{\odot} \approx 100 \msolar pc^{-2} - as low as 40 \msolar pc^{-2} in the extreme case - and still be maximal, in the sense that the dark halo provides negligible rotation support in the inner Galaxy. This result has possible implications for any conclusion that rests on assumptions about the potentials of the Galactic disk or dark halo, and in particular for the interpretation of microlensing results along both LMC and bulge lines of sight.Comment: Accepted for publication in The Astrophysical Journal. 23 Latex-generated pages, one (new) table, three figures (two new). A few additions to the bibliography, an expanded discussion, and slight quantitative changes, none of which affect the conclusion