| 1. |
- Bartel, N., et al.
(författare)
-
The Compact Radio Source 2021+614 : Simultaneous 2.3 and 8.3 GHz Mark III VLBI Observations
- 1984
-
Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 279:1, s. 116-121
-
Tidskriftsartikel (refereegranskat)abstract
- Second-epoch VLBI observations of the flat-spectrum radio source 2021+614 made simultaneously at 2.3 and 8.3 GHz with the Mark III system are reported. The maps derived from these observations reveal a complex, frequency-dependent radio structure on the milliarcsecond scale. The object has four nearly collinear components oriented at a position angle of about 35 degrees and embedded in an extended region. Two of these are optically thin, one has a flat spectrum, and the other appears to be synchrotron self-absorbed in the frequency range 2.3-8.3 GHz. No significant structural variation is found at either frequency between epochs separated by about three years. The formal estimate of the transverse velocity between two components, one with a flat and the other with an inverted spectrum, is v/c = 0.7 + or - 2.3. Remarkable similarities between 2021+614 and the unusual source 0316+413 are discussed.
|
|
| 2. |
- Bååth, L.B. 1948-, et al.
(författare)
-
High Resolution Observations of the QSO 3C 345 at 1.3 centimeters
- 1981
-
Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 243, s. L123-L126
-
Tidskriftsartikel (refereegranskat)abstract
- High-resolution VLBI observations made at a frequency of 22.235 GHz of the quasar 3C 345 are discussed. Antennas located at the Crimean Astrophysical Observatory, USSR; Onsala, Sweden; Effelsberg, West Germany; and the Haystack Observatory, Massachusetts were employed at 4-min integration times to provide baselines ranging up to 5.5 x 10 to the 8th wavelengths. About 40% of the total flux density of 7.85 Jy, observed in November 1977, and 8.05 Jy, observed in October 1978, is found to originate in an unresolved component of the quasar core in a region less than 0.1 milliarcsec in diameter. The elongated jet-like component of the quasar is observed to contain several peaks of emission extending up to 6 milliarsec from the core which decreased in extent between the two observations.
|
|
| 3. |
- Cotton, W. D., et al.
(författare)
-
High Resolution Observations of the Steep Spectrum Source 2147+145
- 1984
-
Ingår i: Astrophysical Journal. - Philadelphia, PA : Institute of Physics Publishing (IOPP). - 0004-637X .- 1538-4357. ; 277, s. L41-L44
-
Tidskriftsartikel (refereegranskat)abstract
- The results of an eight station, 18-cm intercontinental very long baseline interferometry for which the synthesized beam obtained was 0.008 x 0.003 arcsec are presented for the steep spectrum compact radio source 2147+145. These observations reveal a structure similar to flat spectrum compact sources and, if the source radiates due to the synchrotron process, a very weak magnetic field. The source consists of a line of knots 0.022 arcsec long along position angle of 38 deg dominated on one side by a component of size 0.0032 arcsec measured along a position angle of 38 deg. It is suggested that 2147+145 and, perhaps, related steep spectrum objects are similar to flat spectrum, optically active sources except that the magnetic field is much weaker.
|
|
