19 research outputs found
Molecular environment and thermal X-ray spectroscopy of the semicircular young composite supernova remnant 3C 396
We have investigated the molecular environment of the semicircular composite
supernova remnant (SNR) 3C396 and performed a Chandra spatially resolved
thermal X-ray spectroscopic study of this young SNR. With our CO millimeter
observations, we find that the molecular clouds (MCs) at V(LSR)~84km/s can
better explain the multiwavelength properties of the remnant than the
V(LSR)=67-72km/s MCs that are suggested by Lee et al. (2009). At around 84km/s,
the western boundary of the SNR is perfectly confined by the western molecular
wall. The CO emission fades out from west to east, indicating that the eastern
region is of low gas density. In particular, an intruding finger/pillar-like
MC, which may be shocked at the tip, can well explain the X-ray and radio
enhancement in the southwest and some infrared filaments there. The SNR-MC
interaction is also favored by the relatively elevated 12CO J=2-1/J=1-0 line
ratios in the southwestern "pillar tip" and the molecular patch on the
northwestern boundary. The redshifted 12CO (J=1-0 and J=2-1) wings (86-90km/s)
of an eastern 81km/s molecular patch may be the kinematic evidence for shock-MC
interaction. We suggest that the 69km/s MCs are in the foreground based on HI
self-absorption while the 84km/s MCs at a distance of 6.2 kpc (the tangent
point) are in physical contact with SNR 3C396. The X-ray spectral analysis
suggests an SNR age of ~3kyr. The metal enrichment of the X-ray emitting gas in
the north and south implies a 13-15Msun B1-B2 progenitor star.Comment: 17 amulateapj pages, including 11 figures and 3 tables. Accepted to
ApJ. Version 2: minor correction
Discovery of molecular shells associated with supernova remnants. (II) Kesteven 75
The young composite supernova remnant (SNR) Kesteven 75, with a pulsar wind
nebula at its center, has an unusual morphology with a bright southern
half-shell structure in multiwavelengths. The distance to Kes 75 has long been
uncertain. Aiming to address these issues, we have made millimeter
spectroscopic observations of the molecular gas toward the remnant. The
V_{LSR}~83--96 km/s molecular clouds (MCs) are found to overlap a large
north-western region of the remnant and are suggested to be located in front of
the SNR along the line of sight. Also in the remnant area, the V_{LSR}= 45--58
km/s MC shows a blue-shifted broadening in the 12CO (J=1-0) line profile and a
perturbed position-velocity structure near the edge of the remnant, with the
intensity centroid sitting in the northern area of the remnant. In particular,
a cavity surrounded by a molecular shell is unveiled in the intensity map in
the broadened blue wing (45--51 km/s), and the southern molecular shell follows
the bright partial SNR shell seen in X-rays, mid-infrared, and radio continuum.
These observational features provide effective evidences for the association of
Kes 75 with the adjacent 54 km/s MC. This association leads to a determination
of the kinematic distance at ~10.6 kpc to the remnant, which agrees with a
location at the far side of the Sagittarius arm. The morphological coincidence
of the shell seen in multiwavelengths is consistent with a scenario in which
the SNR shock hits a pre-existing dense shell. This dense molecular shell is
suggested to likely represent the debris of the cooled, clumpy shell of the
progenitor's wind bubble proximately behind the 54 km/s cloud. The discovery of
the association with MC provides a possible explanation for the gamma-ray
excess of the remnant.Comment: 12 emulateapj pages (including 13 figures and 3 tables), some typos
are corrected. Accepted by Ap
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
Bacterial Inactivation of Wound Infection in a Human Skin Model by Liquid-Phase Discharge Plasma
Background: We investigate disinfection of a reconstructed human skin model contaminated with biofilm-formative Staphylococcus aureus employing plasma discharge in liquid. Principal Findings: We observed statistically significant 3.83-log10 (p,0.001) and 1.59-log10 (p,0.05) decreases in colony forming units of adherent S. aureus bacteria and 24 h S. aureus biofilm culture with plasma treatment. Plasma treatment was associated with minimal changes in histological morphology and tissue viability determined by means of MTT assay. Spectral analysis of the plasma discharge indicated the presence of highly reactive atomic oxygen radicals (777 nm and 844 nm) and OH bands in the UV region. The contribution of these and other plasma-generated agents and physical conditions to the reduction in bacterial load are discussed. Conclusions: These findings demonstrate the potential of liquid plasma treatment as a potential adjunct therapy for chronic wounds