1,701 research outputs found
Doppler Tomography of Dwarf Nova IY UMa during Quiescence
Quiescent Doppler tomography of the newly discovered deeply-eclipsing SU UMa
system IY UMa reveals properties of the region where the accretion stream from
the donor impacts the edge of the disc. A very strong bright spot is produced
and the Keplerian disc emission in the impact region is disrupted or obscured.
The differing properties of Halpha, Hbeta and He I emission will allow physical
parameters of the converging flow region to be studied.Comment: 6 pages, 5 figures. To appear in Proceedings of Astro-Tomography
Workshop, Brussels, July 2000, Eds. H. Boffin, D. Steeghs, Springer-Verlag
Lecture Notes in Physic
Heliocentric Escape and Lunar Impact from Near Rectilinear Halo Orbits
Spacecraft departing from the Gateway in a Near Rectilinear Halo Orbit (NRHO) experience gravitational forces from the Moon, the Earth, and the Sun, all of which can be simultaneously significant. These complex dynamics influence the post-separation risk of recontact with the Gateway and the eventual destinations of the departing spacecraft. The current investigation examines the flow of objects leaving NRHOs in the Bicircular Restricted Four-Body Problem, and results are applied to heliocentric escape and lunar impact trajectories in a higher-fidelity ephemeris model. Separation maneuver magnitude, direction, and location are correlated with risk of recontact with the Gateway and successful departure to various destinations
PIRATE: A Remotely-Operable Telescope Facility for Research and Education
We introduce PIRATE, a new remotely-operable telescope facility for use in
research and education, constructed from 'off-the-shelf' hardware, operated by
The Open University. We focus on the PIRATE Mark 1 operational phase where
PIRATE was equipped with a widely- used 0.35m Schmidt-Cassegrain system (now
replaced with a 0.425m corrected Dall Kirkham astrograph). Situated at the
Observatori Astronomic de Mallorca, PIRATE is currently used to follow up
potential transiting extrasolar planet candidates produced by the SuperWASP
North experiment, as well as to hunt for novae in M31 and other nearby
galaxies. It is operated by a mixture of commercially available software and
proprietary software developed at the Open University. We discuss problems
associated with performing precision time series photometry when using a German
Equatorial Mount, investigating the overall performance of such 'off-the-shelf'
solutions in both research and teaching applications. We conclude that PIRATE
is a cost-effective research facility, and also provides exciting prospects for
undergraduate astronomy. PIRATE has broken new ground in offering practical
astronomy education to distance-learning students in their own homes.Comment: Accepted for publication in PASP. 14 pages, 11 figure
Establishment of leucaena in Australia
Leucaena (Leucaena leucocephala ssp. glabrata) is a highly productive tropical perennial legume used primarily in extensive beef grazing systems across northern Australia. Its productivity provides substantial benefits to grazing businesses and economically significant areas of leucaena have been established in Queensland, with much smaller areas in both the Northern Territory and Western Australia. Specific environmental conditions (particularly soil type) and management practices are required to obtain reliable establishment and high productivity from leucaena-grass grazing systems. Significant research, development and extension have been undertaken in northern Australia, particularly in central Queensland, resulting in management packages which ensure establishment reliability and long-term productivity. However expansion into new areas can be constrained by regionally-specific establishment issues. Adaptation of known establishment and management practices together with research and development are required for leucaena-grass grazing systems in new regions
The detection of the donor star in IY UMa
We present the results of a search for the donor star in the high inclination
SU UMa type cataclysmic variable IY UMa. We detect absorption features in the
near infrared consistent with an M type dwarf donor star. Using the skew
mapping technique to exploit the velocity information provided by the 8183-8194
Angstrom Na I absorption doublet, we locate the absorption at the expected
donor velocity of IY UMa.Comment: 5 pages, 4 figures, accepted for publication in MNRA
Current Problems in Securities Regulation
This comment analyzes four areas of central significance to adequate protection for the investor: (1) qualifications of those in the securities industry who deal with the public; (2) dissemination of corporate publicity; (3) dissemination of investment advice; and (4) selling practices in the securities industry. The findings and recommendations of the Special Study are given special attention insofar as they bear upon the problems covered. In certain areas, however, recent developments in court and Commission decisions have brought about changes equally as significant as the findings and recommendations of the Special Study. Thus each section covers the background and recent developments in the designated area, as well as the Special Study itself
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Raman spectroscopy of biologically relevant amino acids under martian condtions
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Raman spectroscopy of amino acids and other biomarkers on Mars
In the search for life elsewhere in the Solar System, our nearest planetary neighbour, Mars, offers great potential for finding past or present life. Whether life is extant or not, signs of biological activity can be inferred through the detection of specific biomarkers, such as amino acids.
Raman spectroscopy is an extremely effective method of detecting biomarkers. It is non-destructive and is used to identify different molecular species through observations of the Raman shift created by the bonds within the molecule.
Amino acids that are part of a biological system could provide potential evidence of life on Mars. It is thought that amino acids could survive in the sub-surface of Mars, making them a high-priority biomarker candidate. Terrestrial life utilises homochiral amino acids, and if detected on Mars it would provide an important piece of evidence for the case for life on Mars.
In this work, a number of biologically essential amino acids that are utilised in terrestrial organisms will be studied using Raman spectroscopy. We aim to characterise the Raman signature for these molecules in detail in order to aid interpretation of results from future Mars landers, and presented here are initial results from the preliminary investigations.
Further work will extend to other high-priority biomarkers that may be found at the surface/sub-surface of Mars
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