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Kuiper, T. B. H.

Publications and source records attributed to Kuiper, T. B. H..

82 records · Page 5
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NASA NTRS1975

Radio observations of IC 434

Continuum radio emission and hydrogen recombination-line emission were measured at 2.37 GHz with the 64-m antenna at Goldstone, California. The radio emission has the same general distribution as the optical nebula. The radial velocity of the nebula agrees with that of the adjacent dust cloud L 1630. The electron temperature is estimated to be approximately 7000 K. The excitation of the nebula is compared with current estimates of the ionizing flux from the exciting star, sigma Orionis.

Kuiper, T. B. H.↗
NASA NTRS1975

Radio recombination line observations of the C II region NGC 2023

The reflection nebula NGC 2023 has been observed at four frequencies in a study of its carbon recombination line emission. The observations show the recombination line region to be about 2 pc in diameter, with an average electron density of about 0.2 per cu cm and electron temperature of about 20 K. The electron density increases exponentially near the B1.5 star HD 37903, the illuminating star of NGC 2023. The most reasonable interpretation of the observational results is that the carbon emission lines arise in a cold C II region surrounding HD 37903. The coexistence of the C II region with a region of enhanced CO emission suggests that the CO in NGC 2023 may be excited by electron collisions.

Knapp, G. R.↗
NASA NTRS1975

CO observations of the expanding envelope of IRC plus 10216

High-sensitivity emission profiles were observed for the transition of C12O16 and C13O16 towards IRC + or - 10216. It appears that the spherically symmetric uniform mass-outflow model proposed by Morris is necessary to describe the line profiles. The outflow appears to be slightly accelerated, having a velocity of 15 km/sec at the edges of the CO cloud, compared with 12 km/sec for the more centrally confined molecules.

Kuiper, T. B. H.↗
NASA NTRS1974

Coronal density structures in regions of type III activity

The density of the corona over the active regions generating the type III exciters are examined, taking into account radio data together with daily white light coronal observations obtained with a K-coronameter. The intensity profiles and the synoptic maps derived from the K-corona data make it possible to distinguish between dense structures and low intensity regions. A deconvolution technique developed by Leblanc et al. (1970) is applied to calculate the electron density of these structures. For the low intensity regions van de Hulst's (1950) method has been used to compute the electron density of models.

Leblanc, Y.↗
NASA NTRS1973

Detailed comparison of type III radio bursts with H alpha activity. II

Isolated type III radio bursts activity was observed at Clark Lake Radio Observatory in March and the first part of April 1971 to occur in discrete regions of the corona above certain active regions. When these regions were examined under high resolution in H alpha all the type III events appeared to have associated activity in H alpha. The potential coronal magnetic field in these regions appeared to be either open or diverging, whereas the field over a rather active region which did not have radio burst activity was closed in a magnetic arcade. The latter feature has been associated with streamers. Streamers have also been associated with dark filaments. The occurrence of a stable dark filament in an active region appeared to have an inhibiting effect on type III activity. It is suggested that a streamer field configuration is not favorable to the escape of isolated type III exciters.

Kuiper, T. B. H.↗
NASA NTRS1973

The log-periodic array at the Clark Lake Radio Observatory

A log-periodic array, 3 km in length, is operating at Clark Lake Radio Observatory. It makes one-dimensional sweeps of the solar brightness distribution in the frequency range 20 to 65 MHz once per sec. The phasing of the array and the receiving system are described, as well as how the dynamic spectra are analyzed for the positions of solar radio sources. Simultaneous measurements at many frequencies enable the observer to remove the effects of ionospheric refraction and to obtain fundamental positions to an accuracy of about one arc min at decametric wavelengths. Fundamental positions are given for Cassiopeia A.

Erickson, W. C.↗
NASA NTRS1973

Detailed correlation of type III radio bursts with H alpha activity. I - Active region of 22 May 1970.

Comparison of observations of type III impulsive radio bursts made at the Clark Lake Radio Observatory with high-spatial-resolution cinematographic observations taken at the Big Bear Solar Observatory. Use of the log-periodic radio interferometer makes it possible to localize the radio emission uniquely. This study concentrates on the particularly active region close to the limb on May 22, 1970. Sixteen of the 17 groups were associated with some H alpha activity, 11 of them with the start of such activity.

Kuiper, T. B. H.↗
NASA NTRS1973

On the density of the corona in regions of type 3 activity

The east-west positions of 190 type 3 bursts were measured between 30 and 65 MHz with the log-periodic array at Clark Lake. A method is described to find the intrinsic variation of position with frequency of type 3 bursts based on the comparison of the positions of the bursts measured at any two arbitrary frequencies. It is found that the variation of position frequency agrees with the behaviour expected from coronal density models. This suggests that the measured positions were not seriously affected by scattering in the corona. Knowing the functional form of the variation of position with frequency for type 3 bursts, it is shown that the observed burst positions can be corrected for the effects of ionospheric refraction.

Kuiper, T. B. H.↗