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Lindsayjohnson - One of the best experts on this subject based on the ideXlab platform.
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2020Co-Authors: LindsayjohnsonAbstract:3 Bedrooms Bedrooms With 3 Bathrooms Bathrooms Single w/UBR Coming Soon E. Murchison St. In 3779 E. Murchison St., Meridian, Idaho 83642
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The - 3869 Murchison Street, Meridian, Idaho 83642
2019Co-Authors: LindsayjohnsonAbstract:4 Bedrooms Bedrooms With 4 Bathrooms Bathrooms Two-Story For Sale Murchison Street In 3869 Murchison Street, Meridian, Idaho 83642
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The Hudson - 3869 E Murchison Street, Meridian, Idaho 83642
2019Co-Authors: LindsayjohnsonAbstract:4 Bedrooms With 3 Bathrooms Two-Story Coming Soon E Murchison Street In 3869 E Murchison Street, Meridian, Idaho 83642
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The Aspen - 3954 E Murchison Street, Meridian, Idaho 83642
2019Co-Authors: LindsayjohnsonAbstract:3 Bedrooms Bedrooms With 2.5 Bathrooms Bathrooms Single Level Coming Soon E Murchison Street In 3954 E Murchison Street, Meridian, Idaho 83642
Sherwood Chang - One of the best experts on this subject based on the ideXlab platform.
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Deuterium Enrichment of Amino and Hydroxy Acids Found in the Murchison Meteorite: Constraints on Parent Body Conditions
1997Co-Authors: Narcinda R. Lerner, Sherwood ChangAbstract:The alpha-amino and alpha-hydroxy acids found in the Murchison carbonaceous chondrite are deuterium enriched. These compounds are thought to have originated from common deuterium enriched carbonyl precursors, by way of a Strecker synthesis which took place in a solution of HCN, NH3, and carbonyl compounds during the period of aqueous alteration of the meteorite parent body. However, the hydroxy acids found on Murchison are less deuterium enriched than the amino acids. With the objective of determining if the discrepancy in deuterium enrichment between the amino acids and the hydroxy acids found on Murchison is consistent with their formation in a Strecker synthesis, we have measured the deuterium content of alpha-amino and alpha-hydroxy acids produced in solutions of deuterated carbonyl compounds, KCN and NH4Cl, and also in mixtures of such solutions and Allende dust at 263 K and 295 K. Retention of the isotopic signature of the starting carbonyl by both alpha amino acids and alpha hydroxy acids is more dependent upon temperature, concentration and pH than upon the presence of meteorite dust in the solution. The constraints these observations place on Murchison parent body conditions will be discussed.
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Products of the Strecker Synthesis as Indicators of Parent Body Conditions of the Murchison Meteorite
Origins of Life and Evolution of Biospheres, 1996Co-Authors: Narcinda R. Lerner, G. W. Cooper, Sherwood ChangAbstract:The Strecker synthesis, R2C=O + HCN + NH3 yields R2C(NH2)CN + H2O yields R2C(NH2)CO2H has been proposed as a source of amino acids in meteorites. The detection of carbonlyl compounds, the precursors of the amino acids in the Strecker synthesis, and a-hydroxy acids, important by-products of the Strecker synthesis, in the Murchison meteorite supports this conjecture. However, the following observations raise questions about the Strecker synthesis as the source of a-amino and a-hydroxy acids in Murchison: a) Imino acetic acids are also important by-products of the Strecker synthesis and have not been reported in Murchison. b) a-aminisobutyric acid (AIBA) is one of the most abundant amino acids in Murchison but the Strecker synthesis conducted at room temperature produced only small amounts of AIBA relative to other amino acids. c) If the a-amino and a-hydroxy acids observed in Murchison arose from a common precursor this ought to be reflected in their relative abundances, but the straight chain a-hydroxy acids appeared to be relatively abundant compared with the analogous a-amino acids. In order to address question a) we have examined a non-hydrolyzed aqueous extract of the Murchison meteorite. Imino di acetic acid, Imino propionic acetic acid and Imino butyric acetic acid (both isomers) have been identified in this fraction. The relative abundances of amino acids and imino acetic acids in this fraction are consistent with a Strecker synthesis at low temperature (263 K) as a origin of both the amino acids and the imino acetic acids found on Murchison. To deal with questions b) and c) we have carried out laboratory simulations of the Strecker synthesis. The starting concentrations for carbonlyl compounds used were based on estimates of what these concentrations might have been on the parent body. for the carbonyl compounds this estimate was determined by the amount of carbonyl compound found on Murchison plus the amounts of the corresponding amino acid and hydroxy acid found on Murchison and the rock to water ratio estimated by Clayton and Mayeda (1984). The cyanide concentration was that estimated by Peltzer et al. (1984). The ammonia concentration and pH were varied. We studied these mixtures at 298 K and 263 K. We found that high relative abundances of AIBA were produced at 263 K but not at 298 K. We only produced a-methyl a-amino hydroxy acids at 263 K with no initial ammonia. The abundances of a-amino acids, a-hydroxy acids and imino acids found on Murchison are consistent with a Strecker synthesis which took place at low temperature and with a low concentration of ammonia.
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a search for c60 in carbonaceous chondrites
Geochimica et Cosmochimica Acta, 1993Co-Authors: M S De Vries, K Reihs, H R Wendt, William G Golden, Heinrich E Hunziker, R Fleming, Etta Peterson, Sherwood ChangAbstract:Analysis of interior samples of the Murchison meteorite by two routes yielded an upper limit of 2 ppb for its C60 content, as compared to parts per million levels for individual polycyclic aromatic hydrocarbons (PAHs). Provided the samples contain an interstellar component, which is probable since Murchison hydrocarbons contain excess deuterium, this result argues against the ubiquitous presence of C60 in the interstellar medium. A possible explanation for the absence of C60 was found in experiments showing how PAHs replace fullerenes as stable end products when hydrogen is present during carbon condensation. As a secondary result we found high molecular weight PAHs in the Murchison and Allende meteorites. Coronene and its methyl derivatives are especially interesting since features in the coronene spectrum have been shown to match some of the unidentified interstellar infrared emission bands.
Judd D Bowman - One of the best experts on this subject based on the ideXlab platform.
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the challenges of low frequency radio polarimetry lessons from the Murchison widefield array
Publications of the Astronomical Society of Australia, 2017Co-Authors: E Lenc, Craig S Anderson, N Barry, Judd D Bowman, Iver H Cairns, J S Farnes, B M Gaensler, G Heald, M Johnstonhollitt, David L KaplanAbstract:We present techniques developed to calibrate and correct Murchison Widefield Array low-frequency (72–300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous ( u , v )-coverage and sensitivity to degree-scale structure that the Murchison Widefield Array provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the Murchison Widefield Array, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.
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Science with the Murchison Widefield Array
Publications of the Astronomical Society of Australia, 2013Co-Authors: Judd D Bowman, Iver H Cairns, David L Kaplan, Gianni Bernardi, Tara Murphy, Divya Oberoi, Lister Staveley-smith, W. Arcus, David G. Barnes, Frank H. BriggsAbstract:Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
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the Murchison widefield array the square kilometre array precursor at low radio frequencies
Publications of the Astronomical Society of Australia, 2013Co-Authors: S J Tingay, T. Booler, Judd D Bowman, Daniel A. Mitchell, Stephen M. Ord, R Goeke, D Emrich, M F Morales, B Crosse, R B WaythAbstract:The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
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science with the Murchison widefield array
arXiv: Instrumentation and Methods for Astrophysics, 2012Co-Authors: Judd D Bowman, Iver H Cairns, David L Kaplan, Gianni Bernardi, Tara Murphy, Divya Oberoi, W. Arcus, David G. Barnes, L Staveleysmith, F BriggsAbstract:Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21 cm emission from the epoch of reionisation in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
Brian Crosse - One of the best experts on this subject based on the ideXlab platform.
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The Phase II Murchison Widefield Array: Design overview
Publications of the Astronomical Society of Australia, 2018Co-Authors: Randall B. Wayth, Melanie Johnston-hollitt, Steven Tingay, Cathryn M. Trott, David Emrich, B. Mckinley, Bryan Gaensler, Adam P. Beardsley, T. Booler, Brian CrosseAbstract:We describe the motivation and design details of the ‘Phase II’ upgrade of the Murchison Widefield Array radio telescope. The expansion doubles to 256 the number of antenna tiles deployed in the array. The new antenna tiles enhance the capabilities of the Murchison Widefield Array in several key science areas. Seventy-two of the new tiles are deployed in a regular configuration near the existing array core. These new tiles enhance the surface brightness sensitivity of the array and will improve the ability of the Murchison Widefield Array to estimate the slope of the Epoch of Reionisation power spectrum by a factor of ∼3.5. The remaining 56 tiles are deployed on long baselines, doubling the maximum baseline of the array and improving the array u, v coverage. The improved imaging capabilities will provide an order of magnitude improvement in the noise floor of Murchison Widefield Array continuum images. The upgrade retains all of the features that have underpinned the Murchison Widefield Array’s success (large field of view, snapshot image quality, and pointing agility) and boosts the scientific potential with enhanced imaging capabilities and by enabling new calibration strategies.
David L Kaplan - One of the best experts on this subject based on the ideXlab platform.
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the challenges of low frequency radio polarimetry lessons from the Murchison widefield array
Publications of the Astronomical Society of Australia, 2017Co-Authors: E Lenc, Craig S Anderson, N Barry, Judd D Bowman, Iver H Cairns, J S Farnes, B M Gaensler, G Heald, M Johnstonhollitt, David L KaplanAbstract:We present techniques developed to calibrate and correct Murchison Widefield Array low-frequency (72–300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous ( u , v )-coverage and sensitivity to degree-scale structure that the Murchison Widefield Array provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the Murchison Widefield Array, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.
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Science with the Murchison Widefield Array
Publications of the Astronomical Society of Australia, 2013Co-Authors: Judd D Bowman, Iver H Cairns, David L Kaplan, Gianni Bernardi, Tara Murphy, Divya Oberoi, Lister Staveley-smith, W. Arcus, David G. Barnes, Frank H. BriggsAbstract:Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the southern hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21-cm emission from the EoR in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
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science with the Murchison widefield array
arXiv: Instrumentation and Methods for Astrophysics, 2012Co-Authors: Judd D Bowman, Iver H Cairns, David L Kaplan, Gianni Bernardi, Tara Murphy, Divya Oberoi, W. Arcus, David G. Barnes, L Staveleysmith, F BriggsAbstract:Significant new opportunities for astrophysics and cosmology have been identified at low radio frequencies. The Murchison Widefield Array is the first telescope in the Southern Hemisphere designed specifically to explore the low-frequency astronomical sky between 80 and 300 MHz with arcminute angular resolution and high survey efficiency. The telescope will enable new advances along four key science themes, including searching for redshifted 21 cm emission from the epoch of reionisation in the early Universe; Galactic and extragalactic all-sky southern hemisphere surveys; time-domain astrophysics; and solar, heliospheric, and ionospheric science and space weather. The Murchison Widefield Array is located in Western Australia at the site of the planned Square Kilometre Array (SKA) low-band telescope and is the only low-frequency SKA precursor facility. In this paper, we review the performance properties of the Murchison Widefield Array and describe its primary scientific objectives.
