1,497 research outputs found
Optical detection and spectroscopic confirmation of supernova remnant G213.0-0.6 (now re-designated as G213.3-0.4)
During a detailed search for optical counterparts of known Galactic supernova
remnants (SNRs) using the Anglo Australian Observatory/United Kingdom Schmidt
Telescope (AAO/UKST) HAlpha survey of the southern Galactic plane we have found
characteristic optical HAlpha filaments and associated emission in the area of
SNR G213.0-0.6. Although this remnant was previously detected in the radio as a
non-thermal source, we also confirm emission at 4850 MHz in the Parkes-MIT-NRAO
(PMN) survey and at 1400 MHz in the NRAO/VLA Sky Survey (NVSS). There is an
excellent match in morphological structure between the optical (HAlpha) and
radio emission. We subsequently obtained optical spectroscopy of selected
HAlpha filaments using the South African Astronomical Observatory 1.9-m
telescope which confirmed shock excitation typical of supernova remnants. Our
discovery of HAlpha emission and the positional match with several radio
frequency maps led us to reassign G213.0-0.6 as G213.3-0.4 as these
co-ordinates more accurately reflect the actual centre of the SNR shell and
hence the most probable place of the original supernova explosion. Support for
this new SNR ID comes from the fact that the X-ray source 1RXS J065049.7-003220
is situated in the centre of this new remnant and could be connected with the
supernova explosion.Comment: 9 pages, 8 figures, Accepted for publishing in MNRA
G315.1+2.7: a new Galactic SNR from the AAO/UKST HAlpha survey
New narrow-band HAlpha imaging and subsequent optical spectra confirm
G315.1+2.7, a previously identified candidate supernova remnant (SNR), as a
bona-fide Galactic SNR. Present observations are based on independent discovery
of filamentary optical emission nebulosity on images of the AAO/UKST HAlpha
survey of the southern Galactic plane which were found to co-incide with
existing multi-frequency radio detections. Separate medium and high dispersion
spectra were taken across two locations of this 11 arcmin N-S aligned optical
filament. The resulting spectral signatures were found to strongly confirm the
SNR identification based on standard emission line ratio discriminators which
characterise emission from shock heated gas. The average observed ratios of
[SII]/HAlpha=1.13, [NII]/HAlpha=1.43 and [SII] 6717/6731=1.46, together with
the simultaneous detection of [OII] at 3727A, [OIII] 5007A and [OI] 6300A, all
point to an SNR origin of the observed optical emission. Careful scrutiny of
the low-resolution but high sensitivity SHASSA HAlpha survey also revealed a
low-level but distinct optical emission arc. This arc precisely correlates with
the large, 2.5 degree, north-south angular extent of the proposed new SNR also
seen as a fractured structure in the extant radio data. G315.1+2.7 was detected
previously at 2400 and 4800 MHz and at 408 and 1420 MHz. We also identified
associated radio emission at 843 MHz from the now publicly available SUMSS
survey. On the basis of optical imaging and spectra and radio observations at
five frequencies, we identify G315.1+2.7 as a new Galactic SNR. The large
projected angular extent of the new remnant, together with the distance
estimate of ~1.7 kpc and diameter of ~80pc, make G315.1+2.7 one of the largest
remnants known.Comment: 10 pages, 10 figures. Accepted for MNRA
The first optical light from the supernova remnant G182.4+4.3 located in the Galactic anti-centre region
We report the discovery of optical filamentary and diffuse emission from
G182.4+4.3 using 1.5-m Russian-Turkish telescope. We present the optical CCD
images obtained with Halpha filter revealing the presence of mainly filamentary
structure at the northwest, filamentary and diffuse structure at the centre,
south and north regions of the remnant. The bright optical filaments located in
northwest and south regions are well correlated with the prominent radio shell
of the remnant strongly suggesting their association. From the flux-calibrated
CCD imaging, the average [SII]/Halpha ratio is found to be ~0.9 and ~1.1 for
south and northwest regions, which clearly indicates that the emission
originates from the shock heated gas. We also present the results of X-ray data
obtained from XMM-Newton that show diffuse emission with a very low luminosity
of ~7.3x10^31 erg s^-1 at a distance of 3 kpc in 0.3-10 keV energy band.
Furthermore, we find a surprisingly young age of ~4400 yr for this remnant with
such a large radius of ~22 pc.Comment: 9 pages, 6 figures and 1 table, Accepted for publication in MNRA
Newly confirmed and high quality candidate Galactic SNRs uncovered from the AAO/UKST HAlpha survey
We present a catalogue of 18 new Galactic supernova remnants (SNRs) uncovered
in the optical regime as filamentary emissions and extended nebulosities on
images of the Anglo Australian Observatory/United Kingdom Schmidt Telescope
(AAO/UKST) HAlpha survey of the southern Galactic plane. Our follow-up spectral
observations confirmed classical optical SNR emission lines for these 18
structures via detection of very strong [SII] at 6717 and 6731A relative to
HAlpha ([SII]/HAlpha> 0.5). Morphologically, 10 of these remnants have
coherent, extended arc or shell structures, while the remaining objects are
more irregular in form but clearly filamentary in nature, typical of optically
detected SNRs.
In 11 cases there was a clear if not complete match between the optical and
radio structures with H filamentary structures registered inside and along the
presumed radio borders. Additionally, ROSAT X-ray sources were detected inside
the optical/radio borders of 11 of these new remnants and 3 may have an
associated pulsar.
The multi-wavelength imaging data and spectroscopy together present strong
evidence to confirm identification of 18 new, mostly senile Galactic SNRs. This
includes G288.7-6.3, G315.1+2.7 and G332.5-5.6, identified only as possible
remnants from preliminary radio observations. We also confirm existence of
radio quiet but optically active supernova remnants.Comment: In original form 21 pages, 29 figures Accepted for MNRA
Living in the technopolis: Between reality and imagination
Perceived as one of the possible reflections of the contemporary society, the technopolis (or the 'techno-city') integrates the latest technology, various modernist and anti-modernist elements, as well as numerous 'utopian' features which should facilitate our lives and underline aspirations for the future. Consequently, our world, composed of overlapped digital and physical realms, flexible spaces and transformable webs, is balancing between utopia and anti-utopia, progress and decay, geography and non-geography. The stunning, but also horrifying images of the present create tension and confusion, while their fast-changing scales and modes additionally complicate the latest morphing and charting of the global world and its urban nodes. Obviously, the city, as always, depicts the technological background of the society, demonstrating its potentials, paradoxes and threats. However, the modern cities, whose spaces and buildings often represent the wonders of technology, are facing numerous problems. Placed between material and virtual reality, their landscapes are blended and distorted, but colored by similar imperatives and demands. Therefore, the purpose of this paper is to define and analyze the outcomes of the urban/architectural interventions which explicitly or implicitly used modern technologies, generating a stage for the 21st century technopolis.
IBPP Research Associates: Seattle, Washington, United States of America
The article is a November 30, 1999 interview of two Pakistani representatives by IBPP Research Associate Catherine Stupar at the World Trade Organization\u27s 3rd Ministerial Series, Seattle Round.
IBPP Commentary. The conflations of political rhetoric by privileged speakers with phenomenologies of the spoken for--viz., the wretched of the earth--are as timeless as they are intractable. Too often, the privileged come and go, while the wretched of the earth remain.
Author commentary is included in the article
Mesophilous Quercus frainetto Dominated Forests from Western Balkans
Hungarian oak (Quercus frainetto) has dominant or co-dominant role in many thermophilous deciduous forest communities in the Balkan Peninsula. However, recent field research in the north-western margin of its range has revealed that some stands have a pronounced mesophilous character, which was also supported by data from the literature. This paper aims to analyze this mesophilous community of Hungarian oak which is found in north-western Serbia, north-eastern Bosnia and Herzegovina (B&H) and eastern Croatia. Numerical analysis, which included classification and ordination of all 474 available relevés of Hungarian oak forests from the western and central Balkans, along with the 43 relevés of mesophilous forests of oak-hornbeam from B&H, have shown that 83 mesophilous Hungarian oak relevés are floristically and ecologically more similar to mesophilous forests of sessile oak-hornbeam (Erythronio-Carpinion) than to xero-thermophilous forests of Qeurcion confertae. The new association Carpino betuli-Quercetum frainetto ass. nova hoc loco was described, floristically and ecologically characterized and assigned to mesophilous oak-hornbeam forests of Erythronio-Carpinion. The study also discusses the syntaxonomical issues of Quercion confertae and its central association Quercetum frainetto-cerridis, considering the problem of the lack of good diagnostic species for both syntaxa, and introduces possible ways of dealing with these issues
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