Discovery of Two New Class II Methanol Maser Transitions in G345.01+1.79

We have used the Swedish ESO Submillimetre Telescope (SEST) to search for new class II methanol maser transitions towards the southern source G345.01+1.79. Over a period of 5 days we observed 11 known or predicted class II methanol maser transitions. Emission with the narrow line width and characteristic velocity of class II methanol masers (in this source) was detected in 8 of these transitions, two of which have not previously been reported as masers. The new class II methanol maser transitions are the 13(-3)-12(-4)E transition at 104.1 GHz and the 5(1)-4(2)E transition at 216.9 GHz. Both of these are from transition series for which there are no previous known class II methanol maser transitions. This takes the total number of known class II methanol maser series to 10, and the total number of transitions (or transition groups) to 18. The observed 104.1 GHz maser suggests the presence of two or more regions of masing gas with similar line of sight velocities, but quite different physical conditions. Although these newly discovered transitions are likely to be relatively rare, where they are observed combined studies using the Australia Telescope Compact Array and the Atacama Large Millimeter Array offer the prospect to be able to undertake multi-transition methanol maser studies with unprecedented detail.Comment: 8 pages, 3 figures, accepted for publication in ApJ Letter

Electrically charged pulsars

n the present work we investigate one possible variation on the usual electrically neutral pulsars: the inclusion of electric charge. We study the effect of electric charge in pulsars assuming that the charge distribution is proportional to the energy density. All calculations were performed for zero temperature and fixed entropy equations of state

The TTF finite-energy spectral features in photoemission of TTF-TCNQ: The Hubbard-chain description

A dynamical theory which accounts for all microscopic one-electron processes is used to study the spectral function of the 1D Hubbard model for the whole $(k, \omega)$-plane, beyond previous studies which focused on the weight distribution in the vicinity of the singular branch lines only. While our predictions agree with those of the latter studies concerning the tetracyanoquinodimethane (TCNQ) related singular features in photoemission of the organic compound tetrathiafulvalene-tetracyanoquinodimethane (TTF-TCNQ) metallic phase, the generalized theory also leads to quantitative agreement concerning the tetrathiafulvalene (TTF) related finite-energy spectral features, which are found to correspond to a value of the on-site repulsion $U$ larger than for TCNQ. Our study reveals the microscopic mechanisms behind the unusual spectral features of TTF-TCNQ and provides a good overall description of those features for the whole $(k, \omega)$-plane.Comment: To appear in Journal of Physics: Condensed Matte

The B-ring's surface mass density from hidden density waves: Less than meets the eye?

Saturn's B ring is the most opaque ring in our solar system, but many of its fundamental parameters, including its total mass, are not well constrained. Spiral density waves generated by mean-motion resonances with Saturn's moons provide some of the best constraints on the rings' mass density, but detecting and quantifying such waves in the B ring has been challenging because of this ring's high opacity and abundant fine-scale structure. Using a wavelet-based analyses of 17 occultations of the star gamma Crucis observed by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft, we are able to examine five density waves in the B ring. Two of these waves are generated by the Janus 2:1 and Mimas 5:2 Inner Lindblad Resonances at 96,427 km and 101,311 km from Saturn's center, respectively. Both of these waves can be detected in individual occultation profiles, but the multi-profile wavelet analysis reveals unexpected variations in the pattern speed of the Janus 2:1 wave that might arise from the periodic changes in Janus' orbit. The other three wave signatures are associated with the Janus 3:2, Enceladus 3:1 and Pandora 3:2 Inner Lindblad Resonances at 115,959 km, 115,207 km and 108,546 km. These waves are not visible in individual profiles, but structures with the correct pattern speeds can be detected in appropriately phase-corrected average wavelets. Estimates of the ring's surface mass density derived from these five waves fall between 40 and 140 g/cm^2, even though the ring's optical depth in these regions ranges from 1.5 to almost 5. This suggests that the total mass of the B ring is most likely between one-third and two-thirds the mass of Saturn's moon Mimas.Comment: 40 Pages, 21 Figures, Accepted for publication in Icarus, a few typos fixe