An Improved Estimate of the Mass of Dust in Cassiopeia A

Recent observations of sub-millimeter continuum emission toward supernova remnants (SNR) have raised the question of whether such emission is caused by dust within the SNR and thus produced by the supernova itself or along the line-of-sight. The importance of the present work is to establish evidence for the production of large amounts of dust in supernovae. The best tests can be made for young supernovae in our galaxy. Cassiopeia A is the best candidate for a measurement.Comment: 7 pages, 3 figures, accepted by A&A for publicatio

The Impact of Thermal Insulation of a Detached House in the Village of Karolínka on Running Expenses of this Property

Diplomová práce se zabývá posouzením vlivu zateplení rodinného domu na výdaje spojené s provozem této nemovitosti. V první části je popsána výstavba rodinných domů od historie až po současnost, dále legislativa spojená se zateplováním budov. Práce se také zabývá energetickou náročností budov, vývojem cen energií, druhy tepelných izolací a možnostmi zateplování rodinných domů. Důkladně je rozebrán zateplovací systém ETICS. Druhá část je věnovaná konkrétnímu rodinnému domu v obci Karolinka na zhodnocení ekonomické návratnosti investice. Zateplení je provedeno v sedmi variantách. Práce obsahuje tepelně technické posouzení původního stavu rodinného domu a poté tepelné posouzení jednotlivých variant po provedení zateplení na jeho ekonomickou návratnost. V závěru práce je zhodnocení jednotlivých variant zateplení a vypočtena prostá doba návratnosti investice.This thesis evaluates the influence of thermal insulation of a detached house on the expenses associated with the operation of the property. The first part describes the construction of houses from history to the present day, as well as legislation associated with the thermal insulation of buildings. The work also deals with the energy performance of buildings, energy price developments, types of thermal isolation and insulation of Houses. Thoroughly analyzes ETICS insulation systém. The second part is devoted to a particular detached house in the village Karolinka to evaluate the economic return on investment. Thermal insulation is solved in seven variants. The work includes thermal technical assessment of the condition of the original house and then heat the assessment of the options for the thermal insulation on its economic return. In conclusion, the assessment of individual variants insulation is calculated as a simple payback period.

The Relationship between Class I and Class II Methanol Masers

The Australia Telescope National Facility Mopra millimetre telescope has been used to search for 95.1-GHz class I methanol masers towards sixty-two 6.6-GHz class II methanol masers. A total of twenty-six 95.1-GHz masers were detected, eighteen of these being new discoveries. Combining the results of this search with observations reported in the literature, a near complete sample of sixty-six 6.6-GHz class II methanol masers has been searched in the 95.1-GHz transition, with detections towards 38 per cent (twenty-five detections ; not all of the sources studied in this paper qualify for the complete sample, and some of the sources in the sample were not observed in the present observations). There is no evidence of an anti-correlation between either the velocity range, or peak flux density of the class I and II transitions, contrary to suggestions from previous studies. The majority of class I methanol maser sources have a velocity range that partially overlaps with the class II maser transitions. The presence of a class I methanol maser associated with a class II maser source is not correlated with the presence (or absence) of main-line OH or water masers. Investigations of the properties of the infrared emission associated with the maser sources shows no significant difference between those class II methanol masers with an associated class I maser and those without. This may be consistent with the hypothesis that the objects responsible for driving class I methanol masers are generally not those that produce main-line OH, water or class II methanol masers.Comment: 21 pages, 6 figures, accepted for publication in MNRA

A Giant Outburst at Millimeter Wavelengths in the Orion Nebula

BIMA observations of the Orion nebula discovered a giant flare from a young star previously undetected at millimeter wavelengths. The star briefly became the brightest compact object in the nebula at 86 GHz. Its flux density increased by more than a factor of 5 on a timescale of hours, to a peak of 160 mJy. This is one of the most luminous stellar radio flares ever observed. Remarkably, the Chandra X-ray observatory was in the midst of a deep integration of the Orion nebula at the time of the BIMA discovery; the source's X-ray flux increased by a factor of 10 approximately 2 days before the radio detection. Follow-up radio observations with the VLA and BIMA showed that the source decayed on a timescale of days, then flared again several times over the next 70 days, although never as brightly as during the discovery. Circular polarization was detected at 15, 22, and 43 GHz, indicating that the emission mechanism was cyclotron. VLBA observations 9 days after the initial flare yield a brightness temperature Tb > 5 x 10^7 K at 15 GHz. Infrared spectroscopy indicates the source is a K5V star with faint Br gamma emission, suggesting that it is a weak-line T Tauri object. Zeeman splitting measurements in the infrared spectrum find B ~ 2.6 +/- 1.0 kG. The flare is an extreme example of magnetic activity associated with a young stellar object. These data suggest that short observations obtained with ALMA will uncover hundreds of flaring young stellar objects in the Orion region.Comment: 29 pages, 7 figures, accepted for publication in Ap

The Nature of the Molecular Environment within 5 pc of the Galactic Center

We present a detailed study of molecular gas in the central 10pc of the Galaxy through spectral line observations of four rotation inversion transitions of NH3 made with the VLA. Updated line widths and NH3(1,1) opacities are presented, and temperatures, column densities, and masses are derived. We examine the impact of Sgr A East on molecular material at the Galactic center and find that there is no evidence that the expansion of this shell has moved a significant amount of the 50 km/s GMC. The western streamer, however, shows strong indications that it is composed of material swept-up by the expansion of Sgr A East. Using the mass and kinematics of the western streamer, we calculate an energy of E=(2-9)x10^{51} ergs for the progenitor explosion and conclude that Sgr A East was most likely produced by a single supernova. The temperature structure of molecular gas in the central ~20pc is also analyzed in detail. We find that molecular gas has a ``two-temperature'' structure similar to that measured by Huttemeister et al. (2003a) on larger scales. The largest observed line ratios, however, cannot be understood in terms of a two-temperature model, and most likely result from absorption of NH3(3,3) emission by cool surface layers of clouds. By comparing the observed NH3 (6,6)-to-(3,3) line ratios, we disentangle three distinct molecular features within a projected distance of 2pc from Sgr A*. Gas associated with the highest line ratios shows kinematic signatures of both rotation and expansion. The southern streamer shows no significant velocity gradients and does not appear to be directly associated with either the circumnuclear disk or the nucleus. The paper concludes with a discussion of the line-of-sight arrangement of the main features in the central 10pc.Comment: 51 pages, 16 figures, accepted for publication in ApJ. Due to size limitations, some of the images have been cut from this version. A complete, color PS or PDF version can be downloaded from http://www.astro.columbia.edu/~herrnstein/NH3/paper

Spectral energy distribution modelling of Southern candidate massive protostars using the Bayesian inference method

Concatenating data from the millimetre regime to the infrared, we have performed spectral energy distribution modelling for 227 of the 405 millimetre continuum sources of Hill et al. (2005) which are thought to contain young massive stars in the earliest stages of their formation. Three main parameters are extracted from the fits: temperature, mass and luminosity. The method employed was Bayesian inference, which allows a statistically probable range of suitable values for each parameter to be drawn for each individual protostellar candidate. This is the first application of this method to massive star formation. The cumulative distribution plots of the SED modelled parameters in this work indicate that collectively, the sources without methanol maser and/or radio continuum associations (MM-only cores) display similar characteristics to those of high mass star formation regions. Attributing significance to the marginal distinctions between the MM-only cores and the high-mass star formation sample we draw hypotheses regarding the nature of the MM-only cores, including the possibility that the population itself is comprised of different types of source, and discuss their role in the formation scenarios of massive star formation. In addition, we discuss the usefulness and limitations of SED modelling and its application to the field. From this work, it is clear that within the valid parameter ranges, SEDs utilising current far-infrared data can not be used to determine the evolution of massive protostars or massive young stellar objects.Comment: 16 pages, 3 figures, 5 tables : accepted by MNRA

Detection of new sources of methanol emission at 107 and 108 GHz with the Mopra telescope

A southern hemisphere survey of methanol emission sources in two millimeter wave transitions has been carried out using the ATNF Mopra millimetre telescope. Sixteen emission sources have been detected in the 3(1)-4(0)A+ transition of methanol at 107 GHz, including six new sources exhibiting class II methanol maser emission features. Combining these results with the similar northern hemisphere survey, a total of eleven 107-GHz methanol masers have been detected. A survey of the methanol emission in the 0(0)-1(-1)E transition at 108 GHz resulted in the detection of 16 sources; one of them showing maser characteristics. This is the first methanol maser detected at 108 GHz, presumably of class II. The results of LVG statistical equilibrium calculations confirm the classification of these new sources as a class II methanol masers.Comment: 11 pages, 6 figures, accepted for publication in MNRAS, mn.sty include

A search for 85.5- and 86.6-GHz methanol maser emission

We have used the Australia Telescope National Facility Mopra 22m millimetre telescope to search for emission from the 85.5-GHz and 86.6-GHz transitions of methanol. The search was targeted towards 22 star formation regions which exhibit maser emission in the 107.0-GHz methanol transition, as well as in the 6.6-GHz transition characteristic of class II methanol maser sources. A total of 22 regions were searched at 85.5 GHz resulting in 5 detections, of which 1 appears to be a newly discovered maser. For the 86.6-GHz transition observations were made of 18 regions which yielded 2 detections, but no new maser sources. This search demonstrates that emission from the 85.5- and 86.6-GHz transitions is rare. Detection of maser emission from either of these transitions therefore indicates the presence of special conditions, different from those in the majority of methanol maser sources. We have observed temporal variability in the 86.6-GHz emission towards 345.010+1.792, which along with the very narrow line width, confirms that the emission is a maser in this source. We have combined our current observations with published data for the 6.6-, 12.1-, 85.5-, 86.6-, 107.0-, 108.8- and 156.6-GHz transitions for comparison with the maser model of Sobolev & Deguchi (1994). This has allowed us to estimate the likely ranges of dust temperature, gas density, and methanol column density, both for typical methanol maser sources and for those sources which also show 107.0-GHz emission.Comment: 11 pages, accepted for publication in MNRAS, Latex, mn2e.cl