A warped m=2 water maser disc in V778 Cyg?

The silicate carbon star V778 Cyg is a source of 22 GHz water maser emission which was recently resolved by MERLIN. Observations revealed an elongated S-like structure along which the velocities of the maser features show a linear dependence on the impact parameter. This is consistent with a doubly-warped m=2 disc observed edge-on. Water masers and silicate dust emission (detected by IRAS and ISO) have a common origin in O-rich material and are likely to be co-located in the disc. We propose a detailed self-consistent model of a masing gas-dust disc around a companion to the carbon star in a binary system, which allows us to estimate the companion mass of 1.7 +- 0.1 M_sun, the disc radius of 40 +-3 AU and the distance between companions of about 80 AU. Using a dust-gas coupling model for water masing, we calculate the maser power self-consistently, accounting for both the gas and the dust energy balances. Comparing the simulation results with the observational data, we deduce the main physical parameters of the masing disc, such as the gas and dust temperatures and their densities. We also present an analysis of the stability of the disc.Comment: 7 pages, 5 figures. This paper is accepted for publication in MNRA

Herschel PACS and SPIRE observations of blazar PKS 1510-089: a case for two blazar zones

We present the results of observations of blazar PKS 1510-089 with the Herschel Space Observatory PACS and SPIRE instruments, together with multiwavelength data from Fermi/LAT, Swift, SMARTS and SMA. The source was found in a quiet state, and its far-infrared spectrum is consistent with a power-law with a spectral index of alpha ~ 0.7. Our Herschel observations were preceded by two 'orphan' gamma-ray flares. The near-infrared data reveal the high-energy cut-off in the main synchrotron component, which cannot be associated with the main gamma-ray component in a one-zone leptonic model. This is because in such a model the luminosity ratio of the External-Compton and synchrotron components is tightly related to the frequency ratio of these components, and in this particular case an unrealistically high energy density of the external radiation would be implied. Therefore, we consider a well-constrained two-zone blazar model to interpret the entire dataset. In this framework, the observed infrared emission is associated with the synchrotron component produced in the hot-dust region at the supra-pc scale, while the gamma-ray emission is associated with the External-Compton component produced in the broad-line region at the sub-pc scale. In addition, the optical/UV emission is associated with the accretion disk thermal emission, with the accretion disk corona likely contributing to the X-ray emission.Comment: 13 pages, 8 figures, 7 tables; accepted for publication in the Astrophysical Journa

Mid-Infrared Imaging and Modelling of the Dust Shell around Post-AGB star HD 187885 (IRAS 19500-1709)

We present 10 and 20 micron images of IRAS 19500-1709 taken with the mid-infrared camera, OSCIR, mounted on the Gemini North Telescope. We use a 2-D dust radiation transport code to fit the spectral energy distribution from UV to sub-mm wavelengths and to simulate the images.Comment: 4 pages, 5 figures. To appear in "Asymmetric Planetary Nebulae III", eds. M.Meixner, J.Kastner, N.Soker & B.Balick. 2004, ASP Conference Serie

Distribution of the DAZ gene transcripts in human testis.

Involvement of variety of genes, especially located on Y chromosome, is critical for the regulation of spermatogenesis. In particular, fertility candidate genes such as deleted in azoospermia (DAZ) are believed to have important function in sperm production, since DAZ is frequently deleted in azoospermic and severy oligozoospermic men. The role of the DAZ gene is supported by its exclusive expression in the testis and by its deletion in about 10% of azoospermic and severely oligozoospermic patients. The distribution of DAZ transcripts in seminiferous epithelium of human testis is reported in the present study. The use of Adobe Photoshop and Scion Image softwares allowed for semi-quantitative analysis of in situ RT-PCR (ISRT-PCR) results. The intensity of ISRT-PCR product's fluorescence was different within individual seminiferous tubules. It was clearly shown by using the pseudocolour scale and transforming the intensity of the fluorescence into levels of greyscale images. The more intense fluorescence characterised single spermatogonia and those organized in small groups inside separate tubules. The most intense accumulation of DAZ mRNA was observed in spermatogonia

Infrared OH absorption lines in 1612 MHz OH maser sources

ISO mid-infrared absorption data helps to distinguish between radiative and collisional pumping mechanisms in 1612 MHz OH masers in various environments. Archive data of OH absorption at 34.6 and 53.3m shows different behavior and different pumping rates for different types of maser sources. © 2008 International Astronomical Union.Acknowledgments This work was partly supported by the Chinese National Science Foundation under Grant No. 10433030 and 10503011

The Herschel Planetary Nebula Survey (HerPlaNS) - a comprehensive dusty photoionization model of NGC6781

We perform a comprehensive analysis of the planetary nebula (PN) NGC6781 to investigate the physical conditions of each of its ionized, atomic, and molecular gas and dust components and the object's evolution, based on panchromatic observational data ranging from UV to radio. Empirical nebular elemental abundances, compared with theoretical predictions via nucleosynthesis models of asymptotic giant branch (AGB) stars, indicate that the progenitor is a solar-metallicity, 2.25-3.0 Msun initial-mass star. We derive the best-fit distance of 0.46 kpc by fitting the stellar luminosity (as a function of the distance and effective temperature of the central star) with the adopted post-AGB evolutionary tracks. Our excitation energy diagram analysis indicate high excitation temperatures in the photodissociation region (PDR) beyond the ionized part of the nebula, suggesting extra heating by shock interactions between the slow AGB wind and the fast PN wind. Through iterative fitting using the Cloudy code with empirically-derived constraints, we find the best-fit dusty photoionization model of the object that would inclusively reproduce all of the adopted panchromatic observational data. The estimated total gas mass (0.41 Msun) corresponds to the mass ejected during the last AGB thermal pulse event predicted for a 2.5 Msun initial-mass star. A significant fraction of the total mass (about 70 percent) is found to exist in the PDR, demonstrating the critical importance of the PDR in PNe that are generally recognized as the hallmark of ionized/H+ regions.Comment: 34 pages, 13 Figures and 16 Tables, accepted for publication in the Astrophysical Journal Supplement Serie