Discovery of Extensive Optical Emission Associated with the X-ray Bright, Radio Faint Galactic SNR G156.2+5.7

We present wide-field Halpha images of the Galactic supernova remnant G156.2+5.7 which reveal the presence of considerable faint Halpha line emission coincident with the remnant's X-ray emission. The outermost Halpha emission consists largely of long and thin (unresolved), smoothly curved filaments of Balmer-dominated emission presumably associated with the remnant's forward shock front. Patches of brighter Halpha emission along the western, south-central, and northeastern regions appear to be radiative shocked ISM filaments like those commonly seen in supernova remnants, with relatively strong [O I] 6300,6364 and [S II] 6716,6731 line emissions. Comparison of the observed Halpha emission with the ROSAT PSPC X-ray image of G156.2+5.7 shows that the thin Balmer-dominated filaments lie along the outermost edge of the remnant's detected X-ray emission. Brighter radiative emission features are not coincident with the remnant's brightest X-ray or radio regions. Areas of sharply weaker X-ray flux seen in the ROSAT image of G156.2+5.7 appear spatially coincident with dense interstellar clouds visible on optical and IRAS 60 and 100 micron emission images, as well as maps of increased optical extinction. This suggests significant X-ray absorption in these regions due to foreground interstellar dust, especially along the western and southern limbs. The close projected proximity and alignment of the remnant's brighter, radiative filaments with several of these interstellar clouds and dust lanes hint at a possible physically interaction between the G156.2+5.7 remnant and these interstellar clouds and may indicate a smaller distance to the remnant than previously estimated.Comment: To appear in Monthly Notices of the Royal Astronomical Societ

Physics of SNeIa and Cosmology

We give an overview of the current understanding of Type Ia supernovae relevant for their use as cosmological distance indicators. We present the physical basis to understand their homogeneity of the observed light curves and spectra and the observed correlations. This provides a robust method to determine the Hubble constant, 67 +- 8 (2 sigma) km/Mpc/sec, independently from primary distance indicators. We discuss the uncertainties and tests which include SNe Ia based distance determinations prior to delta-Ceph. measurements for the host galaxies. Based on detailed models, we study the small variations from homogeneities and their observable consequences. In combination with future data, this underlines the suitability and promises the refinements needed to determine accurate relative distances within 2 to 3 % and to use SNe Ia for high precision cosmology.Comment: to be published in "Stellar Candles", eds. Gieren et al. Lecture Notes in Physics (http://link.springer.de/series/lnpp

Near-Infrared Spectroscopy of the Cassiopeia A and Kepler Supernova Remnants

Near-infrared spectra (0.95 - 2.4 micron) of the Cassiopeia A and Kepler supernova remnants (SNRs) are presented. Low-dispersion (R = 700) spectra were obtained for five bright fast-moving ejecta knots (FMKs) at two locations on the main shell and for three bright circumstellar knots (QSFs) near the southwest rim of Cas A. The main shell FMKs in Cas A exhibit a sparse near-infrared spectrum dominated by [S II] 1.03 micron emission with a handful of other, fainter emission lines. Among these are two high-ionization silicon lines, [Si VI] 1.96 micron and [Si X] 1.43 micron, which have been detected in AGNs and novae but never before in a supernova remnant. The near-infrared spectra of circumstellar QSFs in Cas A show a much richer spectrum, with strong He I 1.083 micron emission and over a dozen bright [Fe II] lines. Observed [Fe II] line ratios indicate electron densities of 5 - 9 * 10^4 cm^-3 in the QSFs. The Cas A QSF data are quite similar to the observed spectrum of a bright circumstellar knot along the northwest rim of the Kepler SNR, which also shows strong He I and [Fe II] emission with a measured electron density of 2.5 - 3 * 10^4 cm^-3. Finally, we present J- and K-band images of Cas A. The K-band image shows faint diffuse emission which has no optical or mid-infrared counterpart but is morphologically similar to radio continuum maps and may be infrared synchrotron radiation

Hardening self-compacing mortar expsoed to gamma radiation

For the disposal of high level radioactive waste, cementitious barriers are considered worldwide and for various purposes. The Belgian supercontainer concept, for example, considers the use of cylindrical concrete containers: the radwaste is emplaced inside a hardened self-compacting concrete buffer, and for closure of the supercontainer the remaining gap is filled by casting a selfcompacting mortar. As a consequence, this cementitious layer is exposed to the radioactive waste and gamma radiation during hardening. In this research study, small self-compacting mortar samples are irradiated by gamma rays during hardening, and exposed to different doses (Gy) and different dose rates (Gy/h) at different hardening times at first exposure to investigate the cement-waste interactions that might occur during hardening of the cementitious barrier. The effect on the strength and the microstructure is investigated, by means of compressive strength tests, scanning electron microscopy, and nitrogen adsorption tests. It was found that the observed strength loss due to gamma irradiation increases with an increasing total received dose. Furthermore, the age at which irradiation starts, plays a role in the effect of the gamma irradiation. A link between the strength of the mortar samples and its porosity is found by means of the nitrogen adsorption tests. A higher received dose increases the porosity which leads to a decrease in compressive strength. BET-analysis shows that the specific surface of the pores also increase due to gamma irradiation. Finally, SEM-analysis revealed that gamma irradiation during hardening of cementitious samples affects the microstructure

Exploring the link between attribution biases and aggressive behavior among adolescents : are parents' attributions and management of peers contributing factors?

Advisors: Nina S. Mounts.Committee members: Julie Crouch; Greg Waas.The current thesis project investigated two parental influences on adolescents' hostile intent attributions and aggression - mothers' hostile intent attributions regarding adolescents' peers and management of peer relationships. Consistent with the small literature on parent-child concordance of hostile attributions, mothers' instrumental hostile intent attributions (IHIAs) were related in a positive fashion to adolescents' hostile attributions about peers in the same scenarios. Findings were the first among a sample of mothers and adolescents older than fifth grade. There was some evidence for an interactive effect of mothers' instrumental hostile attributions on higher levels of boys', but not girls', overt aggression. Mothers' peer-management behaviors were not related to adolescents' hostile attributions or aggression, and they did not mediate relations between mothers' hostile attributions and adolescents' aggression. There was some evidence to suggest that mothers' hostile attribution biases regarding relational peer conflict were related to lower levels of consulting about peers.M.A. (Master of Arts

GAUSS als Mensch

Erweiterte Fassung des am 28. April 1977 zur Eröffnung der Gauß-Ausstellung in Braunschweig gehaltenen Vortrage

Spectroscopic detection of Carbon Monoxide in the Young Supernova Remnant Cassiopeia A

We report the detection of carbon monoxide (CO) emission from the young supernova remnant Cassiopeia A (Cas A) at wavelengths corresponding to the fundamental vibrational mode at 4.65 micron. We obtained AKARI Infrared Camera spectra towards 4 positions which unambiguously reveal the broad characteristic CO ro-vibrational band profile. The observed positions include unshocked ejecta at the center, indicating that CO molecules form in the ejecta at an early phase. We extracted a dozen spectra across Cas A along the long 1 arcmin slits, and compared these to simple CO emission models in Local Thermodynamic Equilibrium to obtain first-order estimates of the excitation temperatures and CO masses involved. Our observations suggest that significant amounts of carbon may have been locked up in CO since the explosion 330 years ago. Surprisingly, CO has not been efficiently destroyed by reactions with ionized He or the energetic electrons created by the decay of the radiative nuclei. Our CO detection thus implies that less carbon is available to form carbonaceous dust in supernovae than is currently thought and that molecular gas could lock up a significant amount of heavy elements in supernova ejecta.Comment: ApJ Letter, 747, 6 and see http://www.ir.isas.jaxa.jp/AKARI/Outreach/results/PR2012_CasA/casa_e.htm