40,470 research outputs found
How to Make the Dream Come True: The Astronomers' Data Manifesto
Astronomy is one of the most data-intensive of the sciences. Data technology
is accelerating the quality and effectiveness of its research, and the rate of
astronomical discovery is higher than ever. As a result, many view astronomy as
being in a 'Golden Age', and projects such as the Virtual Observatory are
amongst the most ambitious data projects in any field of science. But these
powerful tools will be impotent unless the data on which they operate are of
matching quality. Astronomy, like other fields of science, therefore needs to
establish and agree on a set of guiding principles for the management of
astronomical data. To focus this process, we are constructing a 'data
manifesto', which proposes guidelines to maximise the rate and
cost-effectiveness of scientific discovery.Comment: Submitted to Data Science Journal Presented at CODATA, Beijing,
October 200
Bulk and Edge excitations in a quantum Hall ferromagnet
In this article, we shall focus on the collective dynamics of the fermions in
a quantum Hall droplet. Specifically, we propose to look at the
quantum Hall ferromagnet. In this system, the electron spins are ordered in the
ground state due to the exchange part of the Coulomb interaction and the Pauli
exclusion principle. The low energy excitations are ferromagnetic magnons. To
provide a means for describing these magnons, we shall discuss a method of
introducing collective coordinates in the Hilbert space of many-fermion
systems. These collective coordinates are bosonic in nature. They map a part of
the fermionic Hilbert space into a bosonic Hilbert space. Using this technique,
we shall interpret the magnons as bosonic collective ex citations in the
Hilbert space of the many-electron Hall system. By considering a Hall droplet
of finite extent, we shall also obtain the effective Lagrangian governing the
spin collective excitations at the edge of the sample.Comment: Plain TeX 18 Pages Proceedings for the Y2K conference on strongly c
orrelated fermionic systems, Calcutta, Indi
X-ray and radio prompt emission from a hypernova SN 2002ap
Here we report on combined X-ray and radio observations of SN 2002ap with
XMM-Newton ToO observation and GMRT observations aided with VLA published
results. In deriving the X-ray flux of SN 2002ap we account for the
contribution of a nearby source, found to be present in the pre-SN explosion
images obtained with Chandra observatory. We also derive upper limits on mass
loss rate from X-ray and radio data. We suggest that the prompt X-ray emission
is non-thermal in nature and its is due to the repeated compton boosting of
optical photons. We also compare SN's early radiospheric properties with two
other SNe at the same epoch.Comment: 4 pages, 5 figures. Uses espcrc2.sty. To appear in proceedings of
symposium on X-ray astronomy "The Restless High-Energy Universe", May 2003,
Amsterdam, The Netherlands, eds. E.P.J. van den Heuvel, J.J.M. in 't Zand,
and R.A.M.J. Wijer
Comets in Australian Aboriginal Astronomy
We present 25 accounts of comets from 40 Australian Aboriginal communities,
citing both supernatural perceptions of comets and historical accounts of
bright comets. Historical and ethnographic descriptions include the Great
Comets of 1843, 1861, 1901, 1910, and 1927. We describe the perceptions of
comets in Aboriginal societies and show that they are typically associated with
fear, death, omens, malevolent spirits, and evil magic, consistent with many
cultures around the world. We also provide a list of words for comets in 16
different Aboriginal languages.Comment: Accepted in the "Journal for Astronomical History & Heritage", 17
Pages, 6 Figures, 1 Tabl
"Bridging the Gap" through Australian Cultural Astronomy
For more than 50,000 years, Indigenous Australians have incorporated
celestial events into their oral traditions and used the motions of celestial
bodies for navigation, time-keeping, food economics, and social structure. In
this paper, we explore the ways in which Aboriginal people made careful
observations of the sky, measurements of celestial bodies, and incorporated
astronomical events into complex oral traditions by searching for written
records of time-keeping using celestial bodies, the use of rising and setting
stars as indicators of special events, recorded observations of variable stars,
the solar cycle, and lunar phases (including ocean tides and eclipses) in oral
tradition, as well as astronomical measurements of the equinox, solstice, and
cardinal points.Comment: Proceedings of IAU Symposium 278, Oxford IX International Symposium
on Archaeoastronomy, International Society for Archaeoastronomy & Astronomy
in Culture (ISAAC), held in Lima, Peru, 5-9 January 2011. 9 pages, 4 images,
1 table (Accepted
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