| 1. |
- Marcaide, J. M., et al.
(författare)
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Discovery of shell-like radio-structure in SN1993J
- 1995
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Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 373:6509, s. 44-45
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Tidskriftsartikel (refereegranskat)abstract
- SUPERNOVA explosions are poorly understood, partly because of difficulties in modelling them theoretically(1), and partly because there have been no supernovae observed in our Galaxy since the invention of the telescope. But the recent discovery(2) of supernova SN1993J in the nearby galaxy M81 offers an opportunity to investigate the evolution of the remnant, and its interaction with the surrounding interstellar medium, at high resolution. Here we present radio observations of SN1993J, made using very-long-baseline interferometry, which show the development of a shell structure. This 8-month-old radio shell is the youngest ever discovered in a supernova. The data suggest that the supernova explosion and the expanding shell of the remnant have nearly spherical symmetry, with small deviations where some parts of the shell are brighter than others. If these deviations arise because of variations in the density of the shell, this may reconcile earlier reports of symmetric radio emission(3) with the observed optical asymmetry(4,5), as the density variations could easily cause the latter. We infer that the radio emission is generated at the interface(6-9), where the surrounding gas is shocked by the ejecta.
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| 2. |
- Moore, R.L., et al.
(författare)
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Superluminal Acceleration in 3C345
- 1983
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Ingår i: Nature. - London, United Kingdom : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 306:5938, s. 44-46
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Tidskriftsartikel (refereegranskat)abstract
- The superluminal quasar 3C345 has a curved, one-sided jet-like radio structure1,2. Ejected material has been observed travelling at apparent speeds of 13–17c (ref. 3). We report here new observations at 22 GHz which show that the most recently ejected component4 is not moving radially away from the compact radio core, but along a trajectory which could be interpreted as either a curved path originating in the compact core, or a straight line, in which case the origin of ejection is not coincident with the compact radio core. The observations provide evidence of acceleration of this component. © 1983 Nature Publishing Group.
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| 3. |
- Wagner, W, et al.
(författare)
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Europe ambivalent on biotechnology
- 1997
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Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 387, s. 845-847
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Tidskriftsartikel (refereegranskat)abstract
- The Eurobarometer on Biotechnology (46.1) was conducted during October and November 1996. The survey conducted in each EU (European Union) country used a multi-stage random sampling procedure and provided a statistically representative sample of national residents aged 15 and over. The total sample within the EU was 16,246 respondents (about 1,000 per EU country). The survey questionnaire was designed by the authors as part of a larger study involving the comparative analysis of public perceptions, media coverage and public policy in relation to biotechnology from 1973 to the present.
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| 4. |
- Zensus, J. A., et al.
(författare)
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The inner radio jet of 3C273
- 1988
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Ingår i: Nature. - London : Nature Publishing Group. - 0028-0836 .- 1476-4687. ; 334:6181, s. 410-412
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Tidskriftsartikel (refereegranskat)abstract
- Radio maps of 3C273 obtained with very long baseline interferometry (VLBI) have been limited by low dynamic range and poor north-south resolution resulting from the low declination (2°) of this quasar1. Dramatic improvement can now be achieved using larger arrays and antennas in the Southern Hemisphere2,3. A new VLBI map, made at 5 GHz with angular resolution and dynamic range unsurpassed at this frequency for this source, shows a narrow jet extending to a projected distance lproj∼125 h-;1 parsecs from the core. Superluminal motion exists out to at least lproj≈46h-1 parsecs. Successive superluminal components emerge from the core and appear to move on a fixed curved path with similar speeds of about 1 milliarcseconds per year. © 1988 Nature Publishing Group.
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