ﻻ يوجد ملخص باللغة العربية
We measure the physical properties of a local multi-component absorption-line system at V_sol ~ 200 km/s toward the quasar PKS0312-770 behind the Magellanic Bridge (MB) using Hubble Space Telescope STIS spectroscopy in conjunction with photoionization modeling. At an impact parameter of ~ 10 kpc from the Small Magellanic Cloud (SMC), this sightline provides a unique opportunity to probe the chemical properties and ionization structure in a nearby absorption line system with a column density of logN(HI) ~ 20.2, at the transition between Damped Lyman Alpha (DLA) and sub-DLA systems. We find that metallicity of -1.0 < logZ < -0.5 and ionization parameter of -6 < logU < -5 for three low-ionization components and logU ~ -2.6 for one high-ionization component. One component at V_sol = 207 km/s shows an alpha-element abundance log(Si/H) ~ -5.0, making it ~ 0.2 dex more metal rich than both SMC H II regions and stars within the MB and the SMC. The N/Si ratio in this component is log(N/Si) = -0.3+/-0.1, making it comparable to other N-poor dwarf galaxies and ~ 0.2 dex lower than H II regions in the SMC. Another component at V_sol = 236 km/s shows a similar Si/H ratio but has log(N/Si) = -1.0+/-0.2, indicating a nitrogen deficiency comparable to that seen in the most N-poor DLA systems. These differences imply different chemical enrichment histories between components along the same sightline. Our results suggest that, if these absorbers are representative some fraction of DLA systems, then 1) DLA systems along single sight-lines do not necessarily represent the global properties of the absorbing cloud, and b) the chemical composition within a given DLA cloud may be inhomogeneous.
We present the first direct evidence for cold gas in a high redshift DLA galaxy. We measured several multiplets of weak neutral carbon (CI) transitions in order to perform a curve of growth analysis. A delta chi-squared test constrains the best fit D
We present a detailed analysis of Magellanic Bridge Cepheid sample constructed using the OGLE Collection of Variable Stars. Our updated Bridge sample contains 10 classical and 13 anomalous Cepheids. We calculate their individual distances using optic
We analyze two years (mid-2010 to mid-2012) of OGLE-IV data covering ~65 deg^2 of the Magellanic Bridge (the area between the Magellanic Clouds) and find 130 transient events including 126 supernovae (SNe), two foreground dwarf novae and another two
We present new ~1 resolution data of the dense molecular gas in the central 50-100 pc of four nearby Seyfert galaxies. PdBI observations of HCN and, in 2 of the 4 sources, simultaneously HCO+ allow us to carefully constrain the dynamical state of the
We present Integral Field Spectroscopy (IFS) of NGC 595, one of the most luminous HII regions in M33. This type of observations allows studying the variation of the principal emission-line ratios across the surface of the nebula. At each position of