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Determination of arsenic in gold by flow injection inductively coupled plasma mass spectrometry with matrix removal by reductive precipitation
XMM-Newton observations of the supernova remnant IC443: I. soft X-ray emission from shocked interstellar medium
The shocked interstellar medium around IC443 produces strong X-ray emission
in the soft energy band (E<1.5 keV). We present an analysis of such emission as
observed with the EPIC MOS cameras on board the XMM-Newotn observatory, with
the purpose to find clear signatures of the interactions with the interstellar
medium (ISM) in the X-ray band, which may complement results obtained in other
wavelenghts. We found that the giant molecular cloud mapped in CO emission is
located in the foreground and gives an evident signature in the absorption of
X-rays. This cloud may have a torus shape and the part of torus interacting
with the IC443 shock gives rise to 2MASS-K emission in the southeast. The
measured density of emitting X-ray shocked plasma increases toward the
northeastern limb, where the remnant is interacting with an atomic cloud. We
found an excellent correlation between emission in the 0.3-0.5 keV band and
bright optical/radio filament on large spatial scales. The partial shell
structure seen in this band therefore traces the encounter with the atomic
cloud.Comment: 10 pages, 10 figures, accepted for publication in ApJ (20 September
2006, v649). For hi-res figures, see
http://www.astropa.unipa.it/Library/OAPA_preprints/ic443ele1.ps.g
Is the Cygnus Loop two supernova remnants?
The Cygnus Loop is classified as a middle-aged supernova remnant (SNR)
located below the Galactic equator (l=74, b=-8.6) and 770 pc away from us. Its
large size and little confusion with Galactic emission makes it an ideal test
ground for evolutionary and structural theories of SNRs. New radio continuum
mapping of the Cygnus Loop at 2695 MHz with the Effelsberg 100-m telescope
provides indications that the Cygnus Loop consists of two separate SNRs.
Combining this result with data from the literature we argue that a secondary
SNR exists in the south with a recently detected neutron star close to its
center. Two interacting SNRs seem to be the best explanation to account for the
Cygnus Loop observations at all wavelengths.Comment: 4 pages, 2 figures, Astron. Astrophys., accepte
A Survey of Hydroxyl Toward Supernova Remnants: Evidence for Extended 1720 MHz Maser Emission
We present the results of GBT observations of all four ground-state hydroxyl
(OH) transitions toward 15 supernova remnants (SNRs) which show OH(1720 MHz)
maser emission. This species of maser is well established as an excellent
tracer of an ongoing interaction between the SNR and dense molecular material.
For the majority of these objects we detect significantly higher flux densities
with a single dish than has been reported with interferometric observations. We
infer that spatially extended, low level maser emission is a common phenomenon
that traces the large-scale interaction in maser-emitting SNRs. Additionally we
use a collisional pumping model to fit the physical conditions under which OH
is excited behind the SNR shock front. We find the observed OH gas associated
with the SNR interaction having columns less than approximately 10^17 per
square cm, temperatures of 20 to 125 K, and densities 10^5 per cubic cm.Comment: 24 pages, 23 figures, Accepted to ApJ, March 26, 2008; v2 - added
Figure 6, minor clarifications to text in Sections 3 and
XMM-Newton observations of the supernova remnant IC 443: II. evidence of stellar ejecta in the inner regions
We investigate the spatial distribution of the physical and chemical
properties of the hot X-ray emitting plasma of the supernova remnant IC 443, in
order to get important constraints on its ionization stage, on the progenitor
supernova explosion, on the age of the remnant, and its physical association
with a close pulsar wind nebula.
The hard X-ray thermal emission (1.4-5.0 keV) of IC 443 displays a
centrally-peaked morphology, its brightness peaks being associated with hot
(kT>1 keV) X-ray emitting plasma. A ring-shaped structure, characterized by
high values of equivalent widths and median photon energy, encloses the PWN.
Its hard X-ray emission is spectrally characterized by a collisional ionization
equilibrium model, and strong emission lines of Mg, Si, and S, requiring
oversolar metal abundances. Dynamically, the location of the ejecta ring
suggests an SNR age of ~4,000 yr.
The presence of overionized plasma in the inner regions of IC 443, addressed
in previous works, is much less evident in our observations.Comment: 9 pages, 7 figures, accepted for publication in A&A. For hi-res
figures, see
http://www.astropa.unipa.it/Library/OAPA_preprints/aa20079123.pd
Radio spectral properties and the magnetic field of the SNR S147
(Abridged) S147 is a large faint shell-type supernova remnant (SNR). Its
remarkable spectral break at cm-wavelengths is an important physical property
to characterize the SNR evolution. However, the spectral break is based on
radio observations with limited precision. We made new radio continuum and
polarization observations of S147 at 11cm and at 6cm with the Effelsberg 100-m
telescope and the Urumqi 25-m telescope, respectively. These new data were
combined with published lower frequency data from the Effelsberg 100-m
telescope and very high frequency data from WMAP to investigate the spectral
turnover and polarization properties of S147. S147 consists of numerous
filaments embedded in diffuse emission. We found that the integrated flux
densities of S147 are 34.8+/-4.0 Jy at 11cm and 15.4+/-3.0Jy at 6cm. These new
measurements confirm the known spectral turnover at ~1.5GHz, which can be
entirely attributed to the diffuse emission component. The spectral index above
the turnover is -1.35+/-0.20. The filamentary emission component has a constant
spectral index over the entire wavelength range up to 40.7GHz of -0.35+/-0.15.
The weak polarized emission of S147 is at the same level as the ambient diffuse
Galactic polarization. The rotation measure of the eastern filamentary shell is
about -70 rad/m2. The filamentary and diffuse emission components of S147 have
different physical properties, which make S147 outstanding among shell type
SNRs.The weak polarization of S147 at 11cm and at 6cm can be attributed to a
section of the S147 shell showing a tangential magnetic field direction.Comment: 11 pages, 17 figures, accepted for publication in Astronomy &
Astrophysics, the resolution of some figures have been reduced. For high
resolution version, see
ftp://ftp.mpifr-bonn.mpg.de/outgoing/p098wre/xiao-etal.pdf,revised following
the language edito
GBT Observations of IC 443: the Nature of OH(1720 MHz) Masers and OH Absorption
We present results of spectral line observations of the ground state
transitions of hydroxyl(OH) toward supernova remnant IC 443 carried out with
the Green Bank Telescope. At a spatial resolution of 7.2 arcminutes we detect
weak, extended OH(1720 MHz) maser emission with OH(1667/5,1612 MHz) absorption
along the southern extent of the remnant, where no bright compact maser sources
have been observed previously. These newly detected SNR-type masers are
coincident with known molecular clumps and a ridge of shocked molecular
hydrogen indicative of the SNR shock front interacting with the adjacent
molecular cloud. Simultaneous observation of all four ground-state transitions
of OH permits us to fit physical conditions of the shocked gas at the
interaction site. A simple two-component model for the line profiles yields the
physical parameters for detected regions of maser emission including excitation
temperature, OH column density and filling factor. Observed line profiles
suggest the shock is largely propagating toward the line-of-sight in the region
of these newly identified weak masers. The implications of shock geometry and
physical parameters in producing extended OH maser emission in SNRs are
explored. We also present VLA radio continuum observations at 330 MHz for
comparison with OH line observations of the remnant.Comment: 20 pages, 4 figures, 3 tables, submitted to Ap
Promising pre-clinical validation of targeted radionuclide therapy using a [131I] labelled iodoquinoxaline derivative for an effective melanoma treatment
Targeted internal radionuclide therapy (TRT) would be an effective alternative to current therapies for dissemi- nated melanoma treatment. At our institution, a class of iodobenzamides has been developed as potent melanoma- seeking agents. This review described the preclinical vali- dations of a quinoxaline derivative molecule (ICF01012) as tracer for TRT application. It was selected for its high, specific and long-lasting uptake in tumour with rapid clear- ance from non-target organs providing suitable dosimetry parameters for TRT. Extended in vivo study of metabolic profiles confirmed durable tumoural concentration of the unchanged molecule form. Moreover melanin specificity of ICF01012 was determined by binding assay with syn- thetic melanin and in vivo by SIMS imaging. Then, we showed in vivo that [131I] ICF01012 treatment drastically inhibited growth of B16F0, B16Bl6 and M4Beu tumours whereas [131I] NaI or unlabelled ICF01012 treatment was without significant effect. Histological analysis showed that residual tumour cells exhibit a significant loss of aggres- siveness after treatment. This anti-tumoural effect was associated with a lengthening of the treated-mice survival time and an inhibition of lung dissemination for B16Bl6 model. Results presented here support the concept of TRT using a [131I] labelled iodoquinoxaline derivative for an effective melanoma treatment.<br /
The Relation Between the Surface Brightness and the Diameter for Galactic Supernova Remnants
In this work, we have constructed a relation between the surface brightness
() and diameter (D) of Galactic C- and S-type supernova remnants
(SNRs). In order to calibrate the -D dependence, we have carefully
examined some intrinsic (e.g. explosion energy) and extrinsic (e.g. density of
the ambient medium) properties of the remnants and, taking into account also
the distance values given in the literature, we have adopted distances for some
of the SNRs which have relatively more reliable distance values. These
calibrator SNRs are all C- and S-type SNRs, i.e. F-type SNRs (and S-type SNR
Cas A which has an exceptionally high surface brightness) are excluded. The
Sigma-D relation has 2 slopes with a turning point at D=36.5 pc: (at 1
GHz)=8.4 D
WmHzster (for
WmHzster and D36.5 pc) and (at 1
GHz)=2.7 10 D
WmHzster (for
WmHzster and D36.5 pc). We discussed the theoretical
basis for the -D dependence and particularly the reasons for the change
in slope of the relation were stated. Added to this, we have shown the
dependence between the radio luminosity and the diameter which seems to have a
slope close to zero up to about D=36.5 pc. We have also adopted distance and
diameter values for all of the observed Galactic SNRs by examining all the
available distance values presented in the literature together with the
distances found from our -D relation.Comment: 45 pages, 2 figures, accepted for publication in Astronomical and
Astrophysical Transaction
SRAO CO Observation of 11 Supernova Remnants in l = 70 to 190 deg
We present the results of 12CO J = 1-0 line observations of eleven Galactic
supernova remnants (SNRs) obtained using the Seoul Radio Astronomy Observatory
(SRAO) 6-m radio telescope. The observation was made as a part of the SRAO CO
survey of SNRs between l = 70 and 190 deg, which is intended to identify SNRs
interacting with molecular clouds. The mapping areas for the individual SNRs
are determined to cover their full extent in the radio continuum. We used
halfbeam grid spacing (60") for 9 SNRs and full-beam grid spacing (120") for
the rest. We detected CO emission towards most of the remnants. In six SNRs,
molecular clouds showed a good spatial relation with their radio morphology,
although no direct evidence for the interaction was detected. Two SNRs are
particularly interesting: G85.4+0.7, where there is a filamentary molecular
cloud along the radio shell, and 3C434.1, where a large molecular cloud appears
to block the western half of the remnant. We briefly summarize the results
obtained for individual SNRs.Comment: Accepted for publication in Astrophysics & Space Science. 12 pages,
12 figures, and 3 table
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