Observations of Split-Band Harmonic Type II Bursts with the Culgoora Radioheliograph at 80 and 160 MHz

(Solar Phys.) When the Culgoora radioheliograph started operating at both 80 MHz (the initial frequency) and 160 MHz (from May 1972) it became possible for the first time to make simultaneous observations of the fundamental and second harmonic sources in type II bursts. Three such bursts, each having harmonically related split-bands, have been observed so far. The new 80 and 160 MHz heliograph observations are illustrated in Figure 1. Since all three events had split-band structure the results are presented separately for the lower- (l) and upper- (u) frequency components and differences between the source positions in the two components will be highlighted. For the burst of 1973 May 19, which was observed at large zenith angles, calculated corrections for ionospheric refraction – approximately 1′ to 2′ for the 80 MHz sources – have been applied; the remaining two events are presented as observed since the refraction effects are thought to be small.

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On Split-Band Structure in Type II Radio Bursts from the Sun

Symposium - International Astronomical Union ◽

10.1017/s0074180900234542 ◽

1974 ◽

Vol 57 ◽

pp. 389-393 ◽

Cited By ~ 9

Author(s):

S. F. Smerd ◽

K. V. Sheridan ◽

R. T. Stewart

Keyword(s):

Band Structure ◽

The Sun ◽

Radio Bursts ◽

Type Ii ◽

Band Splitting ◽

Measured Amount ◽

Type Ii Radio Bursts ◽

Type Ii Bursts ◽

Split Band

(Astrophys. Letters). The measured amount of band-splitting, Δf, in the spectra of nine harmonic type II bursts is illustrated in Figure 1. Here, as in previous, smaller samples (Roberts, 1959; Maxwell and Thompson, 1962; Weiss, 1965) Δf is found to increase with frequency, f.

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Observations of Split-Band Harmonic Type II Bursts with the Culgoora Radioheliograph at 80 and 160 MHz

Coronal Disturbances ◽

10.1007/978-94-010-2257-6_39 ◽

1974 ◽

pp. 345-348

Author(s):

G. J. Nelson ◽

K. V. Sheridan

Keyword(s):

Type Ii ◽

Type Ii Bursts ◽

Split Band

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Unusual Absorption of a Solar Type II Burst by ‘Shadow’ Type III Bursts

Symposium - International Astronomical Union ◽

10.1017/s0074180900234311 ◽

1974 ◽

Vol 57 ◽

pp. 245-248

Author(s):

K. Kai

Keyword(s):

Band Structure ◽

Absorption Feature ◽

Spectral Features ◽

Type Ii ◽

Type Iii ◽

Solar Type ◽

Split Band

(Proc. Astron. Soc. Australia). The Hα-flare on 1968 August 23d23h45m was followed by a short-lived type II burst. The radio spectrograph record obtained at Culgoora is shown in Figure 1. The type II burst was of split-band structure with unusual spectral features in each component of the split band. The most remarkable one is an absorption feature between 23h52m02s and 23h52m10s: suppression of the bright type II emission along an ‘inverted U’ (between 120 and 85 MHz).

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Unusual Absorption of a Solar Type II Burst by ‘Shadow’ Type III Bursts

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000013655 ◽

1973 ◽

Vol 2 (4) ◽

pp. 219-222 ◽

Cited By ~ 10

Author(s):

K. Kai

Keyword(s):

Band Structure ◽

Dynamic Spectrum ◽

Absorption Feature ◽

Spectral Features ◽

Type Ii ◽

Type Iii ◽

Lower Band ◽

Solar Type ◽

Absorption Features ◽

Split Band

A Hα flare (12°N., 49°W.) on 1968 August 23d23h45m was followed by a short-lived type II burst whose dynamic spectrum, as recorded with the Culgoora radio-spectrograph, is shown in Figure 1. The type II burst had split-band structure; the upper band drifted from 130 MHz to 80 MHz, the lower band from 100 MHz to below 80 MHz (at the time the 25-74 MHz band of the spectrograph was less sensitive than the 74-220 MHz). Unusual spectral features can be seen in each split band. The most remarkable one is an absorption feature between 23h52m02s and 23h52m 10s – the depression in the bright type II emission along an ‘inverted U’ (between 120 and 85 MHz). Several other similar, though less marked, absorption features can be found between 23h51m45s and 23h52m30s.

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On Split-Band Structure in Type II Radio Bursts from the Sun

Coronal Disturbances ◽

10.1007/978-94-010-2257-6_47 ◽

1974 ◽

pp. 389-393 ◽

Cited By ~ 40

Author(s):

S. F. Smerd ◽

K. V. Sheridan ◽

R. T. Stewart

Keyword(s):

Band Structure ◽

The Sun ◽

Radio Bursts ◽

Type Ii ◽

Type Ii Radio Bursts ◽

Split Band

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Relative Positions of Fundamental and Second Harmonic Type III Bursts

Publications of the Astronomical Society of Australia ◽

10.1017/s1323358000013059 ◽

1972 ◽

Vol 2 (2) ◽

pp. 100-101 ◽

Cited By ~ 33

Author(s):

R. T. Stewart

Keyword(s):

Plasma Level ◽

Second Harmonic ◽

Type Ii ◽

Type Iii ◽

Scattering Effects ◽

Type Ii Bursts

Observations of the relative positions of fundamental and second harmonic bursts can be used to study refraction and scattering effects in the corona. Smerd, Wild and Sheridan have pointed out that the observed positions of type II bursts can be interpreted as favouring the backward emission of the second harmonic in a smooth corona. In this case the harmonic is seen after reflection from near the fundamental plasma level. Several other examples of type II and type III bursts have been reported which show this effect. We wish to present further evidence from a recent study of a large number of type III bursts observed with the 80 MHz heliograph and 158 MHz interferometer.

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Ionized AGN outflows are less powerful than assumed: A multi-wavelength census of outflows in type II AGN

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320002975 ◽

2019 ◽

Vol 15 (S356) ◽

pp. 225-225

Author(s):

Dalya Baron

Keyword(s):

Optical Emission ◽

Infrared Emission ◽

Type Ii ◽

Ionized Gas ◽

Kinetic Coupling ◽

Mass Outflow ◽

Multi Wavelength ◽

Novel Method ◽

First Time ◽

Ionization Parameter

AbstractIn this talk I will show that multi-wavelength observations can provide novel constraints on the properties of ionized gas outflows in AGN. I will present evidence that the infrared emission in active galaxies includes a contribution from dust which is mixed with the outflow and is heated by the AGN. We detect this infrared component in thousands of AGN for the first time, and use it to constrain the outflow location. By combining this with optical emission lines, we constrain the mass outflow rates and energetics in a sample of 234 type II AGN, the largest such sample to date. The key ingredient of our new outflow measurements is a novel method to estimate the electron density using the ionization parameter and location of the flow. The inferred electron densities, ∼104.5 cm−3, are two orders of magnitude larger than found in most other cases of ionized outflows. We argue that the discrepancy is due to the fact that the commonly-used [SII]-based method underestimates the true density by a large factor. As a result, the inferred mass outflow rates and kinetic coupling efficiencies are 1–2 orders of magnitude lower than previous estimates, and 3–4 orders of magnitude lower than the typical requirement in hydrodynamic cosmological simulations. These results have significant implications for the relative importance of ionized outflows feedback in this population.

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