| 1. |
- Jones, D. L., et al.
(författare)
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High dynamic range VLBI observations of NGC 6251
- 1986
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Ingår i: Astrophysical Journal. - Philadelphia, United States : Institute of Physics Publishing, Inc. - 0004-637X .- 1538-4357. ; 305:2, s. 684-697
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Tidskriftsartikel (refereegranskat)
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| 2. |
- Marcaide, J. M., et al.
(författare)
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The quasars 1038+528 A and B
- 1985
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 142:1, s. 71-84
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Tidskriftsartikel (refereegranskat)abstract
- The results of VLBI observations of the quasars 1038 + 528 A and B at 2.8, 3.6, 13, and 18 cm at various times between November 1979 and March 1981 are reported. The observations and data calibration are described, as are the mapping and astrometric techniques applied in the study. Both quasars are found to have 'core-jet' morphologies. The core of the A quasar dominates its morphology at centrimetric wavelengths with the brightness temperature of its 400 pc long jet being about 1/100 that of the core. By contrast, the 'jet' in the B quasar is very short (about 70 pc); the tail of this jet has the steepest spectral index found to date in extragalactic compact sources, indicating that high electron losses are responsible for the shortness of the jet. No evidence for appreciable morphological change in the B quasar was found over the time span of the study, whereas a new feature may be emerging from the A quasar core at superluminal speed.
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| 3. |
- Matveenko, L.I., et al.
(författare)
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Decimeter-wavelength structure in the quasar 3C 345
- 1986
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Ingår i: Pis'ma v Astronomicheskii Zhurnal. - Moscow : Izdatel'stvo Nauka. - 0320-0108. ; 12:1, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- The nuclear structure of the quasar 3C 345 has been surveyed at wavelength = 18 and 49 cm with two different VLBI networks. From the nucleus issues a jet, bending as it advances outward. Individual structure components are identified; their radio continuum and that of the nucleus indicate an optically thick source, the break in the spectrum shifting toward lower frequencies with increasing distance from the nucleus.
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| 4. |
- Mundy, Lee G., et al.
(författare)
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High-resolution images of the Orion molecular ridge in the CS J = 2-1 transition
- 1988
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 325:1, s. 382-388
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Tidskriftsartikel (refereegranskat)abstract
- The authors have constructed 7arcsec.5 resolution images of the CS J = 2-1 emission from a 3arcmin.5 section of the Orion molecular ridge using a maximum entropy algorithm to combine Owens Valley Millimeter-Wave Interferometer and Onsala Space Observatory 20 m data. The resulting images include all of the flux and have positional accuracy of 1arcsec-2arcsec on the small-scale features. The observed section of the ridge includes four condensations. The condensations have dimensions from 0.03 to 0.11 pc and virial massses from 30 to 80 M_sun;. Approximately 70% of the total mass within the 3arcmin region is contained in these condensations.
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| 5. |
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| 6. |
- Mundy, Lee G., et al.
(författare)
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Protostellar Condensations within the Orion Ridge
- 1986
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Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 304:2, s. L51-L55
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Tidskriftsartikel (refereegranskat)abstract
- Aperture synthesis observations of the CS J = 2 to 1 line and 95 GHz continuum emission from a 2 arcmin x 3 arcmin region around IRc2 in the OMC-1 molecular cloud have been obtained at 7.5 arcsec resolution with the Owens Valley Radio Observatory millimeter interferometer. These observations reveal four distinct condensations with the OMC-1 molecular ridge. The condensations lie along the edge of the bright central part of the H II region, M 42, suggesting that they may have been formed as a result of shock compression driven by the H II region. Their masses and densities, M about 50 solar masses and n about 10 to the 6th - 10 to the 7th/cu cm, suggest that the condensations will undergo further massive star formation on a short time scale (about 20,000 yr).
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| 7. |
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| 8. |
- Tang, G., et al.
(författare)
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Radio source structure from geodetic VLBI observations : evolution of the quasar 3C 345 at 8 GHz
- 1989
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 216:1-2, s. 31-38
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Tidskriftsartikel (refereegranskat)abstract
- Eight VLBI maps of 3C 345 were obtained at 8.3 GHz between 1980 and 1986. During this period, the two jet components C4 and C5 were shown to emerge from the core in succession and to move superluminally toward the west with angular velocities of 0.17 + or - 0.5 and 0.11 + or - 0.02 mas/yr, respectively. An emission detected between D and C5 after 1985.46 suggests that a new component emerged from the core, moving at an angular velocity of 0.2 mas/yr. The C3 component retained a velocity of about 0.44 mas/yr, and its proper motion was found to accelerate in the y-direction and decelerate in the x-direction.
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| 9. |
- Tang, Guoquiang, et al.
(författare)
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Radio source structure from geodetic VLBI observations : 8 GHz multi-epoch maps of the quasar 4C 39.25
- 1987
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Ingår i: Astronomy and Astrophysics. - Les Ulis : EDP Sciences. - 0004-6361 .- 1432-0746. ; 185:1-2, s. 87-93
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Tidskriftsartikel (refereegranskat)abstract
- Techniques for estimating and/or eliminating the effects of structure variations in the extragalactic radio sources used as fiducial points in 8.3-GHz geodetic VLBI observations are described and demonstrated. Particular attention is given to the data base statistics, the calibration of visibility data, the production of hybrid maps with AIPS, and the implementation of these steps in a software package. A set of X-band maps of 4C 39.25, obtained with the receivers of the Mark III dual-frequency VLBI network at six epochs during 1980-1985, is presented. Such maps are shown to be of value (1) for maintaining submarcsec accuracy in the extragalactic reference frame and (2) for qualitative astronomical monitoring of the sources. In 4C 39.25, for example, apparent superluminal motions, complex internal kinematics, and a double western component are observed.
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| 10. |
- Waara, Sylvia, 1958-, et al.
(författare)
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Somatic hybridization between anther-derived dihaploid clones of potato (Solanum tuberosum L.) and the identification of hybrid plants by isozyme analysis
- 1989
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Ingår i: Theoretical and Applied Genetics. - Heidelberg : Springer Berlin/Heidelberg. - 0040-5752 .- 1432-2242. ; 77:1, s. 49-56
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Tidskriftsartikel (refereegranskat)abstract
- Green mesophyll protoplasts of the dihaploid potato line 198∶2 (Solanum tuberosum L.) were fused with herbicide-bleached mesophyll protoplasts of the dihaploid potato line 67∶9 using a polyethylene glycol protocol. Heterokaryons were identified under a fluorescence microscope using the dual fluorescence of carboxyfluorescein-stained, herbicide-bleached protoplasts and the autofluorescence of green mesophyll protoplasts. About 20% of the protoplasts survived the fusion treatment, and the fusion frequency was 3%-4%. Unfused and fused protoplasts were mass cultured for 6 weeks after which vigorously growing calli were selected and transferred to shoot regeneration medium. Somatic hybrids were identified by a combination of five isozyme markers, and the ploidy level was determined by flow cytometry. Out of 15 calli that regenerated shoots, 6 plants derived from 2 different calli were identified as hexaploid somatic hybrids, while one morphologically deviant plant from a third callus was identified as a mixoploid that had lost some enzyme markers after 4 months of culturing.
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