A Study Of The White Heart‐Rot Of Locust, Caused By Trametes Robiniophila

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141421/1/ajb205691.pd

Molecfit: A general tool for telluric absorption correction II. Quantitative evaluation on ESO-VLT X-Shooter spectra

Context: Absorption by molecules in the Earth's atmosphere strongly affects ground-based astronomical observations. The resulting absorption line strength and shape depend on the highly variable physical state of the atmosphere, i.e. pressure, temperature, and mixing ratio of the different molecules involved. Usually, supplementary observations of so-called telluric standard stars (TSS) are needed to correct for this effect, which is expensive in terms of telescope time. We have developed the software package molecfit to provide synthetic transmission spectra based on parameters obtained by fitting narrow ranges of the observed spectra of scientific objects. These spectra are calculated by means of the radiative transfer code LBLRTM and an atmospheric model. In this way, the telluric absorption correction for suitable objects can be performed without any additional calibration observations of TSS. Aims: We evaluate the quality of the telluric absorption correction using molecfit with a set of archival ESO-VLT X-Shooter visible and near-infrared spectra. Methods: Thanks to the wavelength coverage from the U to the K band, X-Shooter is well suited to investigate the quality of the telluric absorption correction with respect to the observing conditions, the instrumental set-up, input parameters of the code, the signal-to-noise of the input spectrum, and the atmospheric profiles. These investigations are based on two figures of merit, I_off and I_res, that describe the systematic offsets and the remaining small-scale residuals of the corrections. We also compare the quality of the telluric absorption correction achieved with moelcfit to the classical method based on a telluric standard star. (Abridged)Comment: Acc. by A&A; Software available via ESO: http://www.eso.org/sci/software/pipelines/skytools

Improved orbital solution and masses for the very low-mass multiple system LHS 1070

We present a refined orbital solution for the components A, B, and C of the nearby late-M type multiple system LHS 1070. By combining astrometric datapoints from NACO/VLT, CIAO/SUBARU, and PUEO/CFHT, as well as a radial velocity measurement from the newly commissioned near infrared high-resolution spectrograph CRIRES/VLT, we achieve a very precise orbital solution for the B and C components and a first realistic constraint on the much longer orbit of the A-BC system. Both orbits appear to be co-planar. Masses for the B and C components calculated from the new orbital solution (M_(B+C) = 0.157 +/- 0.009 M_sun) are in excellent agreement with theoretical models, but do not match empirical mass-luminosity tracks. The preliminary orbit of the A-BC system reveals no mass excess for the A component, giving no indication for a previously proposed fourth (D) component in LHS 1070.Comment: published in A&A, 2008, 484, 429; added CFHT acknowledgemen

A New Ultra-dense Group of Obscured Emission-Line Galaxies

We present the discovery of an isolated compact group of galaxies that is extremely dense (median projected galaxy separation: 6.9 kpc), has a very low velocity dispersion ($\sigma_{\rm 2D}$ = 67 km s$^{-1}$), and where all observed members show emission lines and are morphologically disturbed. These properties, together with the lack of spirals and the presence of a prominent tidal tail make this group one of the most evolved compact groups.Comment: 15 pages,LaTeX, 2figures. A Postscript figure with spectra is available at ftp://astro.uibk.ac.at/pub/weinberger/ . Accepted for publication in ApJ Letter

Symmetry Detection in Large Scale City Scans

In this report we present a novel method for detecting partial symmetries in very large point clouds of 3D city scans. Unlike previous work, which was limited to data sets of a few hundred megabytes maximum, our method scales to very large scenes. We map the detection problem to a nearestneighbor search in a low-dimensional feature space, followed by a cascade of tests for geometric clustering of potential matches. Our algorithm robustly handles noisy real-world scanner data, obtaining a recognition performance comparable to state-of-the-art methods. In practice, it scales linearly with the scene size and achieves a high absolute throughput, processing half a terabyte of raw scanner data over night on a dual socket commodity PC

Candidate Tidal Dwarf Galaxies in the Compact Group CG J1720-67.8

This is the second part of a detailed study of the ultracompact group CG J1720-67.8: in the first part we have focused the attention on the three main galaxies of the group and we have identified a number of candidate tidal dwarf galaxies (TDGs). Here we concentrate on these candidate TDGs. Absolute photometry of these objects in BVRJHKs bands confirms their relatively blue colors, as we already expected from the inspection of optical and near-infrared color maps and from the presence of emission-lines in the optical spectra. The physical conditions in such candidate TDGs are investigated through the application of photoionization models, while the optical colors are compared with grids of spectrophotometric evolutionary synthesis models from the literature. Although from our data self-gravitation cannot be proved for these objects, their general properties are consistent with those of other TDG candidates. Additionally we present the photometry of a few ``knots'' detected in the immediate surroundings of CG J1720-67.8 and consider the possibility that these objects might belong to a dwarf population associated with the compact group.Comment: Accepted for publication in the Astrophysical Journa

V605 Aql: The Older Twin of Sakurai's Object

New optical spectra have been obtained with VLT/FORS2 of the final helium shell flash (FF) star, V605 Aql, which peaked in brightness in 1919. New models suggest that this star is experiencing a very late thermal pulse. The evolution to a cool luminous giant and then back to a compact hot star takes place in only a few years. V605 Aql, the central star of the Planetary Nebula (PN), A58, has evolved from T$_{eff}\sim$5000 K in 1921 to $\sim$95,000 K today. There are indications that the new FF star, Sakurai's Object (V4334 Sgr), which appeared in 1996, is evolving along a similar path. The abundances of Sakurai's Object today and V605 Aql 80 years ago mimic the hydrogen deficient R Coronae Borealis (RCB) stars with 98% He and 1% C. The new spectra show that V605 Aql has stellar abundances similar to those seen in Wolf-Rayet [WC] central stars of PNe with ~55% He, and ~40% C. The stellar spectrum of V605 Aql can be seen even though the star is not directly detected. Therefore, we may be seeing the spectrum in light scattered around the edge of a thick torus of dust seen edge-on. In the present state of evolution of V605 Aql, we may be seeing the not too distant future of Sakurai's Object.Comment: 12 pages, 1 figure, ApJ Letters in pres