1,766 research outputs found

    On the nature of the progenitors of three type II-P supernovae: 2004et, 2006my and 2006ov

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    The pre-explosion observations of the type II-P supernovae 2006my, 2006ov and 2004et, are re-analysed. In the cases of supernovae 2006my and 2006ov we argue that the published candidate progenitors are not coincident with their respective supernova sites in pre-explosion Hubble Space Telescope observations. We therefore derive upper luminosity and mass limits for the unseen progenitors of both these supernovae, assuming they are red supergiants: 2006my (log L/Lsun = 4.51; mass < 13Msun) and 2006ov (log L/Lsun = 4.29; mass < 10Msun). In the case of supernova 2004et we show that the yellow-supergiant progenitor candidate, originally identified in Canada France Hawaii Telescope images, is still visible ~3 years post-explosion in observations from the William Herschel Telescope. High-resolution Hubble Space Telescope and Gemini (North) adaptive optics late-time imagery reveal that this source is not a single yellow supergiant star, but rather is resolved into at least three distinct sources. We report the discovery of the unresolved progenitor as an excess of flux in pre-explosion Isaac Newton Telescope i'-band imaging. Accounting for the late-time contribution of the supernova using published optical spectra, we calculate the progenitor photometry as the difference between the pre- and post-explosion, ground-based observations. We find the progenitor was most likely a late K to late M-type supergiant of 8 +5/-1 Msun. In all cases we conclude that future, high-resolution observations of the supernova sites will be required to confirm these results.Comment: 43 pages (pre-print format), 12 figures, 10 tables. Significant revision following referee's comments. Accepted for publication in MNRA

    Ageing at home? Meeting housing, health and social needs

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    Purpose – The purpose of this paper is to consolidate the range of issues relevant to owner occupiers who age in place and to offer an initial overview of how effective partnerships can respond to and meet the changing needs of housing, health and social care of our ageing population. Design/methodology/approach – Issues affecting older people’s changing needs are considered holistically and considered in terms of how partnerships can be enhanced to develop improved services in the future. Findings – Most owners wish to stay in their own homes for as long as possible and it can be cost-effective to do so; however, we need to look at new and innovative ways of developing and providing front-line services to enhance health and safety in the home, but also quality of life and wellbeing such as combating loneliness and isolation. However, although there are examples of evidence-based good practice, service provision is variable and there is a risk that many older home owners may miss out on services for which they may are eligible. With this in mind, it may be helpful to develop a new framework where one key practitioner holds responsibility to consolidate and coordinate the range of local services available as a package that offers a range of housing, health and social care services. Originality/value – There are currently many policy and practice gaps in older owner occupier's housing conditions and suitability to meet their changing needs. This paper has a particular starting point in housing, and how other personal or technological services can help support independence for as long as possible and adapt to the owner-occupier's changing health and social care needs as they age in place. The authors emphasise the importance of sharing evidence-based good practice partnerships

    Herschel observations of EXtra-Ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey Toward Orion KL II. Chemical Implications

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    We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH3_{3}CN, C2_{2}H3_{3}CN, C2_{2}H5_{5}CN, and NH2_{2}CHO systematically trace hotter gas than the oxygen bearing organics CH3_{3}OH, C2_{2}H5_{5}OH, CH3_{3}OCH3_{3}, and CH3_{3}OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (Tkin_{\rm kin}∼\sim300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales ≳\gtrsim 105^{5} years, with several species being under predicted by less than 3σ\sigma. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules which also contain oxygen (i.e. SO, SO2_{2}, and OCS) tend to probe the hottest gas toward Orion KL indicating the formation pathways for these species are most efficient at high temperatures.Comment: 31 pages, 6 figures, 1 Table, accepted to the Astrophysical Journa

    A combined IRAM and Herschel/HIFI study of cyano(di)acetylene in Orion KL: tentative detection of DC3N

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    We present a study of cyanoacetylene (HC3N) and cyanodiacetylene (HC5N) in Orion KL, through observations from two line surveys performed with the IRAM 30m telescope and the HIFI instrument on board the Herschel telescope. The frequency ranges covered are 80-280 GHz and 480-1906 GHz. We model the observed lines of HC3N, HC5N, their isotopologues (including DC3N), and vibrational modes, using a non-LTE radiative transfer code. To investigate the chemical origin of HC3N and DC3N in Orion KL, we use a time-dependent chemical model. We detect 40 lines of the ground state of HC3N and 68 lines of its 13C isotopologues. We also detect 297 lines of six vibrational modes of this molecule (nu_7, 2nu_7, 3nu_7, nu_6, nu_5, and nu_6+nu_7) and 35 rotational lines of the ground state of HC5N. We report the first tentative detection of DC3N in a giant molecular cloud with a DC3N/HC3N abundance ratio of 0.015. We provide column densities and isotopic and molecular abundances. We also perform a 2x2" map around Orion IRc2 and we present maps of HC3N lines and maps of lines of the HC3N vibrational modes nu_6 and nu_7. In addition, a comparison of our results for HC3N with those in other clouds allows us to derive correlations between the column density, the FWHM, the mass, and the luminosity of the clouds. The high column densities of HC3N obtained in the hot core, make this molecule an excellent tracer of hot and dense gas. In addition, the large frequency range covered reveals the need to consider a temperature and density gradient in the hot core in order to obtain better line fits. The high D/H ratio (comparable to that obtained in cold clouds) that we derive suggests a deuterium enrichment. Our chemical models indicate that the possible deuterated HC3N present in Orion KL is formed during the gas-phase. This fact provides new hints concerning the processes leading to deuteration.Comment: 50 pages, 33 figures, 13 tables. Accepted for publication in A&

    A Direct Measurement of the Total Gas Column Density in Orion KL

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    The large number of high-J lines of C^(18)O available via the Herschel Space Observatory provide an unprecedented ability to model the total CO column density in hot cores. Using the emission from all the observed lines (up to J = 15-14), we sum the column densities in each individual level to obtain the total column after correcting for the population in the unobserved states. With additional knowledge of source size, V_(LSR), and line width, and both local thermodynamic equilibrium (LTE) and non-LTE modeling, we have determined the total C^(18)O column densities in the Extended Ridge, Outflow/Plateau, Compact Ridge, and Hot Core components of Orion KL to be 1.4 × 10^(16) cm^(–2), 3.5 × 10^(16) cm^(–2), 2.2 × 10^(16) cm^(–2), and 6.2 × 10^(16) cm^(–2), respectively. We also find that the C^(18)O/C^(17)O abundance ratio varies from 1.7 in the Outflow/Plateau, 2.3 in the Extended Ridge, 3.0 in the Hot Core, and to 4.1 in the Compact Ridge. This is in agreement with models in which regions with higher ultraviolet radiation fields selectively dissociate C^(17)O, although care must be taken when interpreting these numbers due to the size of the uncertainties in the C^(18)O/C^(17)O abundance ratio

    Ground- and Space-based Detection of the Thermal Emission Spectrum of the Transiting Hot Jupiter KELT-2Ab

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    We describe the detection of water vapor in the atmosphere of the transiting hot Jupiter KELT-2Ab by treating the star-planet system as a spectroscopic binary with high-resolution, ground-based spectroscopy. We resolve the signal of the planet's motion with deep combined flux observations of the star and the planet. In total, six epochs of Keck NIRSPEC LL-band observations were obtained, and the full data set was subjected to a cross correlation analysis with a grid of self-consistent atmospheric models. We measure a radial projection of the Keplerian velocity, KPK_P, of 148 ±\pm 7 km s−1^{-1}, consistent with transit measurements, and detect water vapor at 3.8σ\sigma. We combine NIRSPEC LL-band data with SpitzerSpitzer IRAC secondary eclipse data to further probe the metallicity and carbon-to-oxygen ratio of KELT-2Ab's atmosphere. While the NIRSPEC analysis provides few extra constraints on the SpitzerSpitzer data, it does provide roughly the same constraints on metallicity and carbon-to-oxygen ratio. This bodes well for future investigations of the atmospheres of non-transiting hot Jupiters.Comment: accepted to A

    CSO and CARMA Observations of L1157. I. A Deep Search for Hydroxylamine (NH2_2OH)

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    A deep search for the potential glycine precursor hydroxylamine (NH2_2OH) using the Caltech Submillimeter Observatory (CSO) at λ=1.3\lambda = 1.3 mm and the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at λ=3\lambda = 3 mm is presented toward the molecular outflow L1157, targeting the B1 and B2 shocked regions. We report non-detections of NH2_2OH in both sources. We a perform non-LTE analysis of CH3_3OH observed in our CSO spectra to derive kinetic temperatures and densities in the shocked regions. Using these parameters, we derive upper limit column densities of NH2_2OH of ≤1.4×1013\leq1.4 \times 10^{13}~cm−2^{-2} and ≤1.5×1013\leq1.5 \times 10^{13}~cm−2^{-2} toward the B1 and B2 shocks, respectively, and upper limit relative abundances of NNH2OH/NH2≤1.4×10−8N_{NH_2OH}/N_{H_2} \leq1.4 \times 10^{-8} and ≤1.5×10−8\leq1.5 \times 10^{-8}, respectively.Comment: Accepted in the Astrophysical Journa
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