Bayesian foreground analysis with CMB data

The quality of CMB observations has improved dramatically in the last few years, and will continue to do so in the coming decade. Over a wide range of angular scales, the uncertainty due to instrumental noise is now small compared to the cosmic variance. One may claim with some justification that we have entered the era of precision CMB cosmology. However, some caution is still warranted: The errors due to residual foreground contamination in the CMB power spectrum and cosmological parameters remain largely unquantified, and the effect of these errors on important cosmological parameters such as the optical depth τ and spectral index n_s is not obvious. A major goal for current CMB analysis efforts must therefore be to develop methods that allow us to propagate such uncertainties from the raw data through to the final products. Here we review a recently proposed method that may be a first step towards that goal.     

Equilibrium Structures of Rotationally and Tidally Distorted Polytropic Models of Stars

We propose suitable modifications in the concept of Roche equipotentials to account for the effect of mass distribution inside a star. The Kippenhahn and Thomas (1970) approach is used to incorporate the effects of rotational and tidal forces in the equations of stellar structure. The proposed method is applied to compute structures of certain rotationally and tidally distorted polytropic models.     

Automated Detection of EUV Prominences

We present methods to detect automatically off-limb prominences in the extreme ultraviolet (EUV), using synoptic images taken by the extreme-ultraviolet imaging telescope (EIT) on board SOHO. The 304 Å line is essential for the detection of EUV prominences, but the optimal detection is achieved through a combined image processing of the four synoptic EIT images. In addition, the difference between consecutive 304 Å images serves to identify erupted prominences. Representation maps of the quiescent EUV prominences for a given Carrington rotation are generated and used for further analysis of the detected structures. Longitudinal profiles of long-lived prominences are investigated for three examples at different latitudes, in conjunction with on-disk intensity profiles in the EUV. The observations coincide with theoretically predicted apparent longitudinal profiles, which can be distinguished from the profile of a prominence rising before eruption. The developed algorithms may be relevant to study the 3D geometry of features seen in the EUV and may facilitate the analysis of data from the future STEREO mission.     

Detection of Methanol Maser Flares Near 19.9 and 20.9 GHz toward the Massive Source of Active Star Formation G358.931-0.030

Astronomy Letters - We have investigated the methanol CH3OH lines at frequencies of 19.967 GHz [21-30 E(vt = 0) transition] and 20.971 GHz [101-112 E+(vt = 1) transition] toward the massive region...     

The Gyldén‐type problem revisited: More refined analytical solutions

We resume and consistently extend our previous researches concerning the Gyldén‐type problem (a two‐body problem with time‐dependent equivalent gravitational parameter). To approach most of the concrete astronomical situations to be modelled in this way, we consider a periodic small perturbation. For the nonresonant case, we present a second‐order analytical solution. For the resonant case, we adopt the most realistic astronomical situation: only one dominant term of the Hamiltonian. In this case we point out a fundamental model of resonance, common to every resonant situation, and, moreover, identical to the first fundamental model of resonance . Considering the simplest model of periodic change of the equivalent gravitational parameter, we .nd that all possible resonances are con.ned to the first fundamental model. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A concept for a superconducting tunnelling junction based spectrograph

We describe a multi-order spectrograph concept suitable for 8-m class telescopes, using the intrinsic spectral resolution of superconducting tunnelling junction detectors to sort the spectral orders. The spectrograph works at low orders, 1–5 or 1–6, and provides spectral coverage with a resolving power of   R ≃ 8000  from the atmospheric cut-off at 320 nm to the long-wavelength end of the infrared H or K band at 1800 nm or 2400 nm. We calculate that the spectrograph would provide substantial throughput and wavelength coverage, together with high time resolution and sufficient dynamic range. The concept uses currently available technology, or technologies with short development horizons, restricting the spatial sampling to two linear arrays; however, an upgrade path to provide more spatial sampling is identified. All of the other challenging aspects of the concept – the cryogenics, thermal baffling and magnetic field biasing – are identified as being feasible.