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  • 1
    Electronic Resource
    Electronic Resource
    Observations of Sgr A at 160 MHz with 1.9 arc min resolution (1974)
    [s.l.] : Nature Publishing Group
    Nature 248 (1974), S. 33-34 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Here we extend the high resolution observations of Sgr A down to 160 MHz. This is about the lowest frequency at which observations are possible because the exponential fall-off in flux makes the source undetectable below ^120 MHz. The 160 MHz observations were made with the radio-heliograph at ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/248033a0
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  • 2
    Electronic Resource
    Electronic Resource
    Europa and the Decametric Radiation from Jupiter (1968)
    [s.l.] : Nature Publishing Group
    Nature 220 (1968), S. 1218-1222 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1 shows the Europa effect for all frequencies of emission between 7 and 40 MHz. Careful examination shows two large irregular patches of emission at the same LCM intercepts as the lo-controlled early source, between80 and 180. The patches are approximately centred at about 100 and 280 along ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2201218a0
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  • 3
    Electronic Resource
    Electronic Resource
    Radio Emission from the Sun and Stars (1985)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Astronomy and Astrophysics 23 (1985), S. 169-224 
    Details
    ISSN: 0066-4146
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.aa.23.090185.001125
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  • 4
    Electronic Resource
    Electronic Resource
    The gyro-synchrotron radiation from moving type IV sources in the solar corona (1973)
    Springer
    Solar physics 32 (1973), S. 491-503 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Calculations of the gyro-synchrotron emission are made for conditions which might be expected in moving type IV sources in the solar corona. Two simple models for an evolving source are treated: a uniform cube and an inhomogeneous sphere. The results suggest that most moving sources have the following features: (1) A rather strong magnetic field, ≈ 10 G, is carried out within the source. This is required to achieve the high degree of circular polarization often observed. (2) Synchrotron self-absorption causes the source to be optically thick at frequencies less than about 100 MHz, thus restricting the bandwidth of the radiation. The self-absorption decreases as the source moves outward and expands. The turnover frequency, which separates the optically thick and thin spectral regimes, moves rapidly to lower frequencies, accompanied by a change from low to high circular polarization. In the case of an inhomogeneous source, the source appears to be larger at the lower frequencies. (3) Razin-Tsytovich suppression cannot be an important factor in determining the characteristics of most sources.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00154962
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  • 5
    Electronic Resource
    Electronic Resource
    Radio and EUV observations of a coronal hole (1977)
    Springer
    Solar physics 52 (1977), S. 349-367 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present observations of a coronal hole made with the EUV spectroheliometer of the Harvard College aboard Skylab and with ‘high resolution’ (2–4′) radio telescopes at Culgoora and Fleurs Australia and Bonn, West Germany. We attempt to derive the density and temperature distributions in the transition region and inner corona from the combined observations. No one ‘standard’ model can explain both sets of observations; characteristically, models based on EUV data yield higher radio brightnesses than are observed, while models based on radio data yield lower EUV line intensities than are observed. The discrepancy is essentially that the electron density inferred from the EUV data is about three times that inferred from the radio data. After examining several possible modifications of the standard models we suggest that the discrepancy would disappear if the abundances of the heavier elements were increased by about a factor of 10. Such increases could result from differential diffusion in the large temperature gradient of the transition region. We conclude therefore that models which incorporate thermal diffusion, as well as mass outflow and departures from ionization equilibrium, offer the greatest hope of reconciling the EUV and radio observations of coronal holes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00149652
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  • 6
    Electronic Resource
    Electronic Resource
    White light and radio studies of the coronal transient of 14–15 September 1973 (1976)
    Springer
    Solar physics 49 (1976), S. 369-394 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Observations of a coronal transient event were obtained in white light by the Skylab coronagraph and at metric wavelengths by the radioheliograph and spectrograph at Culgoora and the spectrograph-interferometer at Boulder. The continuum radio burst was found to originate above the outward-moving white light loop - a region of compressed material headed by a bow wave. The computed density in the region of radio emission, based on either gyro-synchrotron or harmonic plasma radiation mechanisms, was approximately 10 times the ambient coronal density; this is compatible with the density deduced from the white light observations. The magnetic energy density derived from the radio observations was greater than 10 times the thermal energy density, marginally larger than the kinetic energy density in the fastest moving portion of the transient, and considerably larger in most other regions. The ambient medium, the white light front, the compression region, the loop, and the slower, massive flow of material behind are each examined. It is found that the plasma was magnetically controlled throughout, and that magnetic forces provided the principal mechanism for acceleration of the transient material from the Sun.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00162459
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  • 7
    Electronic Resource
    Electronic Resource
    First millimetric detections of AE Aquarii (1994)
    Springer
    Space science reviews 68 (1994), S. 291-292 
    Details
    ISSN: 1572-9672
    Keywords: accretion, accretion disks ; binaries ; novae, cataclysmic variables ; radio continuum: stars ; stars: individual (AE Aquarii)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We report the first millimetric detections of the magnetic cataclysmic variable AE Aquarii, accompanied by contemporaneous microwave observations. These data show that the time-averaged spectrum is well fit by a power-law which extends to mm wavelengths. We suggest that the spectrum is consistent with that expected from a superposition of flare-like events.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00749154
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  • 8
    Electronic Resource
    Electronic Resource
    Observations of coronal disturbances from 1 to 9 R ⊙ (1974)
    Springer
    Solar physics 36 (1974), S. 203-217 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Hα, white-light and radio observations of a coronal disturbance on 1973 January 11 commencing at about 00h36m UT show that a piston-driven shock wave propagated outwards through the corona to heights of at least 9 R ⊙. Probably most of the expelled coronal gas originated in a coronal enhancement in the lower corona. Our estimate of the kinetic energy and the mass of the expelled gas is compatible with observations of piston-driven shock waves near the Earth. Shock-wave parameters are evaluated and a model of the disturbance outlined.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00151561
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  • 9
    Electronic Resource
    Electronic Resource
    Coronal magnetic fields (1978)
    Springer
    Solar physics 57 (1978), S. 279-295 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The observational evidence on the strength of the coronal magnetic field above active regions is reviewed. Recent advances in observations and plasma theory are used to determine which data are the more reliable and to revise some earlier estimates of field strength. The results from the different techniques are found to be in general agreement, and the relation 279-01, 1.02 ≲ R/R ⊙ ≲ 10 is consistent with all the data to within a factor of about 3.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00160102
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  • 10
    Electronic Resource
    Electronic Resource
    The onset of flares at the meter wavelengths (1976)
    Springer
    Solar physics 47 (1976), S. 285-292 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The onset of most flares at the meter wavelengths consists of type III bursts and their variants. These bursts usually occur during the explosive phase of flare events and in close association with similar impulsive bursts at other wavelengths. Pre-burst brightenings, corresponding to the preexplosive-phase heating observed at microwave and shorter wavelengths, have so far not been reported from observations with the Culgoora meterwave heliograph. At the same time, if substantial pre-heating occurred in the coronal source regions of meterwave radiation, then, on theoretical grounds, significant, but not spectacular, pre-burst brightenings would be expected at short meter wavelengths. A search for such pre-burst brightenings will become possible when the Culgoora heliograph begins to operate in a new mode which will allow all incoming data (rather than selected segments, as at present) to be kept for further analysis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00152266
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