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Detection of hidden structures on all scales in amorphous materials and complex physical systems: basic notions and applications to networks, lattice systems, and glasses
Recent decades have seen the discovery of numerous complex materials. At the
root of the complexity underlying many of these materials lies a large number
of possible contending atomic- and larger-scale configurations and the
intricate correlations between their constituents. For a detailed
understanding, there is a need for tools that enable the detection of pertinent
structures on all spatial and temporal scales. Towards this end, we suggest a
new method by invoking ideas from network analysis and information theory. Our
method efficiently identifies basic unit cells and topological defects in
systems with low disorder and may analyze general amorphous structures to
identify candidate natural structures where a clear definition of order is
lacking. This general unbiased detection of physical structure does not require
a guess as to which of the system properties should be deemed as important and
may constitute a natural point of departure for further analysis. The method
applies to both static and dynamic systems.Comment: (23 pages, 9 figures
One year of monitoring of the Type IIb supernova SN 2011dh
Optical photometry and low resolution spectroscopy of the type IIb
supernova SN 2011dh in M51 are presented, covering the first year after the
explosion. The light curve and spectral evolution are discussed. The early
phase light curve evolution of SN 2011dh is very similar to SN 1993J and SN
2008ax. In the late phase, however, SN 2011dh declines faster than SN 1993J.
The late phase decline in the -band is steeper than in the and
bands, indicating the possibility of dust formation. With a peak -band
absolute magnitude of mag, SN 2011dh is a marginally
faint type IIb event. The reddening corrected colour curves of SN 2011dh are
found to be redder than other well studied type IIb supernovae. The bolometric
light curve indicates 0.09 M of Ni is synthesized during
the explosion. The HeI lines were detected in the spectra during the rise to
maximum. The nebular spectra of SN 2011dh show a box shaped emission in the red
wing of the [OI] 6300-6363 \AA\ feature, that is attributed to H
emission from a shock excited circumstellar material. The analysis of nebular
spectra indicates that M of oxygen was ejected during the
explosion. Further, the [CaII]/[OI] line ratio in the nebular phase is
0.7, indicating a progenitor with a main sequence mass of 10-15 M.Comment: Accepted for publication in MNRA
Supernova SN 2012dn: A spectroscopic clone of SN 2006gz
We present optical and UV analysis of the luminous type Ia supernova SN
2012dn covering the period 11 to +109 days with respect to the band
maximum, that occurred on JD 2456132.89 0.19, with an apparent magnitude
of = 14.38 0.02. The absolute magnitudes at maximum in
and bands are and
, respectively. SN 2012dn is marginally
luminous compared to normal type Ia supernovae. The peak bolometric luminosity
of erg s suggests that
M of Ni was synthesized in the explosion. The
decline rate mag is lower than
that of normal type Ia supernovae, and similar to the luminous SN 1991T.
However, the photometric and spectroscopic behaviour of SN 2012dn is different
from that of SN 1991T. Early phase light curves in and bands are very
broad. The band peak has a plateau-like appearance similar to the
super-Chandra SN 2009dc. Pre-maximum spectra show clear evidence of C\,{\sc ii}
6580 \AA\, line, indicating the presence of unburned materials. The velocity
evolution of C\,{\ sc ii} line is peculiar. Except for the very early phase
(13 d), the C\,{\sc ii} line velocity is lower than the velocity
estimated using the Si\,{\sc ii} line. During the pre-maximum and close to
maximum phase, to reproduce observed shape of the spectra, the synthetic
spectrum code {\sc syn++} needs significantly higher blackbody temperature than
those required for normal type Ia events. The photospheric velocity evolution
and other spectral properties are similar to those of the carbon-rich SN
2006gz.Comment: Accepted for publication in MNRAS, 19 pages, 20 figure
Eprints@NML: Digital Repository of National Metallurgical Laboratory (CSIR),India
The National Metallurgical Laboratory (NML) of India established its EPrints repository in September 2009, providing its researchers with an easy solution for Open Access. This has allowed their researchers to promote their research and to draw an attention among their counterparts over the globe. By the end of this first year of operation, interest in their work has increased phenomenally and their repository has achieved a ten-fold increase in traffic, with over 80,000 document downloads per month and a cumulative total of 5 million hits
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