Direct Radio Probing and Interpretation of the Sun's Plasma Density Profile

Cairns, Iver H.; Lobzin, V. V.; Warmuth, A.; Li, B.; Robinson, P. A.; Mann, G.

doi:10.1088/0004-637x/706/2/l265

Cited by 36 publications

(64 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Increases in C N 2 (R) and decreases in l i (R) would lead to more scattering. Work on both n e (R) and dn(R)/n e (R) may be useful [e.g., Efimov et al, 2008;Cairns et al, 2009]. It is quite possible that scattering observations and theory will provide useful constraints on these five quantities and therefore on the processes heating the solar corona and accelerating the solar wind.…”

Section: Discussion and Summarymentioning

confidence: 99%

Constraints on coronal turbulence models from source sizes of noise storms at 327 MHz

Subramanian

Cairns

2011

J. Geophys. Res.

View full text Add to dashboard Cite

[1] We seek to reconcile observations of small source sizes in the solar corona at 327 MHz with predictions of scattering models that incorporate refractive index effects, inner scale effects, and a spherically diverging wavefront. We use an empirical prescription for the turbulence amplitude C N 2 (R) based on very long baseline interferometry observations by Spangler et al. of compact radio sources against the solar wind for heliocentric distances R ≈ 10-50 R . We use the Coles and Harmon model for the inner scale l i (R), which is presumed to arise from cyclotron damping. In view of the prevalent uncertainty in the power law index that characterizes solar wind turbulence at various heliocentric distances, we retain this index as a free parameter. We find that the inclusion of spherical divergence effects suppresses the predicted source size substantially. We also find that inner scale effects significantly reduce the predicted source size. An important general finding for solar sources is that the calculations substantially underpredict the observed source size. Three possible, nonexclusive, interpretations of this general result are proposed. First and simplest, future observations with better angular resolution will detect much smaller sources. Consistent with this, previous observations of small sources in the corona at metric wavelengths are limited by the instrument resolution. Second, the spatially varying level of turbulence C N 2 (R) is much larger in the inner corona than predicted by straightforward extrapolation sunward of the empirical prescription, which was based on observations between 10 and 50 R . Either the functional form or the constant of proportionality could be different. Third, perhaps the inner scale is smaller than the model, leading to increased scattering. These results and interpretations are discussed and compared with earlier work.

show abstract

Section: Discussion and Summarymentioning

confidence: 99%

Constraints on coronal turbulence models from source sizes of noise storms at 327 MHz

Subramanian

Cairns

2011

J. Geophys. Res.

View full text Add to dashboard Cite

show abstract

“…Alternatively, assuming a constant velocity for the exciting electrons we can derive the density profile of the ambient plasma (e.g. Cairns et al, 2009). However, the electrons do not stream freely but produce Langmuir waves.…”

Section: Quasi-linear Theorymentioning

confidence: 99%

A review of solar type III radio bursts

Reid

Ratcliffe

2014

Res. Astron. Astrophys.

339

217

View full text Add to dashboard Cite

Solar type III radio bursts are an important diagnostic tool in the understanding of solar accelerated electron beams. They are a signature of propagating beams of nonthermal electrons in the solar atmosphere and the solar system. Consequently, they provide information on electron acceleration and transport, and the conditions of the background ambient plasma they travel through. We review the observational properties of type III bursts with an emphasis on recent results and how each property can help identify attributes of electron beams and the ambient background plasma. We also review some of the theoretical aspects of type III radio bursts and cover a number of numerical efforts that simulate electron beam transport through the solar corona and the heliosphere.

show abstract

“…Coronal type IIIs are one of the most important diagnostics of electron acceleration in flares and coronal conditions (Aschwanden 2002(Aschwanden , 2006. For example, coronal type IIIs have been used to extract the Sun's density profile, and solar-wind-like regions with n e ∝ (r − R ) −2 are found to be common below 2 R , where R is the solar radius (Cairns et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Imprints of coronal temperature disturbances on type III bursts

Cairns

Robinson

2010

A&A

Self Cite

View full text Add to dashboard Cite

The electron temperature T e and ion temperature T i in the corona vary with time and location, due to transient and persistent activity on the Sun. The effects of spatially localized disturbances in T e and T i on coronal type III radio bursts are simulated. The disturbances are superimposed on monotonically varying temperature backgrounds and arise from spatially confined solar activity, Qualitatively and quantitatively different imprints are found on the curve of the maximum flux versus frequency of type III bursts, because of the disturbances in T e and T i . The results indicate that nonthermal coronal type III bursts offer a new tool to probe and distinguish between spatially localized structures of T e and T i along the paths of type III beams. Furthermore, localized temperature disturbances may be responsible for some fine structures in type III bursts, e.g., striae in type IIIb bursts in the presence of multiple, localized temperature disturbances.

show abstract

Direct Radio Probing and Interpretation of the Sun's Plasma Density Profile

Cited by 36 publications

References 15 publications

Constraints on coronal turbulence models from source sizes of noise storms at 327 MHz

Constraints on coronal turbulence models from source sizes of noise storms at 327 MHz

A review of solar type III radio bursts

Imprints of coronal temperature disturbances on type III bursts

Contact Info

Product

Resources

About