The Solar Wind

Manoharan, P. K.

doi:10.1007/3-540-36963-5_9

Cited by 6 publications

(4 citation statements)

References 56 publications

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“…A detailed account of the IPS observation using the ORT and data analysis procedure is given in Manoharan (2003). In brief, the Fourier transformation and spectrum computation from the recorded intensity scintillation measurements are performed to get the power spectrum of the intensity fluctuations to bring out the statistical properties of the intervening medium.…”

Section: Observations and Resultsmentioning

confidence: 99%

Occultation Observation to Probe the Turbulence Scale Size in the Plasma Tail of Comet Schwassmann-Wachmann 3-B

Roy

Manoharan

Chakraborty

2007

ApJ

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We present the occultation observation of compact radio source B0019Ϫ000 through the plasma tail of comet Schwassmann-Wachmann 3-B. The observation was made with the Ooty Radio Telescope at 326.5 MHz on 2006 May 26, when the plasma tail of the comet was in front of this source. The scintillation was found to be increased significantly for the target source compared to that of a control source. The intensity fluctuation power spectra show both steepening at high spatial scales and excess power at low spatial scales. This observation can be attributed to the turbulence in the comet plasma tail. A two-regime plasma turbulence can explain the timeevolution of the power spectrum during the occultation observation.

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Section: Observations and Resultsmentioning

confidence: 99%

Occultation Observation to Probe the Turbulence Scale Size in the Plasma Tail of Comet Schwassmann-Wachmann 3-B

Roy

Manoharan

Chakraborty

2007

ApJ

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“…It implies that whenever solar wind turbulence levels change, they will be reflected in IPS measurements as changes in m. It is worth mentioning here that IPS is sufficiently sensitive to changes in N that it has been used to probe density fluctuations in tenuous cometary ion tails ) and to study solar wind disappearance events wherein average densities at 1 AU drop to values <0.1 cm −3 (Janardhan et al 2005). On the other hand, IPS measurements have also been useful to study the propagation of largescale disturbances like CME (e.g., Manoharan 2006). The CME, while propagating in the IPM causes an increase in density and turbulence in its sheath region, which can be mapped by obtaining the enhancement in the g-index (g = S/ S) for each observation of all the radio sources obscured by the CME.…”

Section: Probing Density Fluctuations In Interplanetary Mediummentioning

confidence: 99%

Preparing for solar and heliospheric science with the SKAO: An Indian perspective

et al. 2023

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The Square Kilometre Array Observatory (SKAO) is perhaps the most ambitious radio telescope envisaged yet. It will enable unprecedented studies of the Sun, corona and heliosphere and help to answer many of the outstanding questions in these areas. Its ability to make a vast previously unexplored phase space accessible, also promises a large discovery potential. The Indian solar and heliospheric physics community has been preparing for this science opportunity. A significant part of this effort has been towards playing a leading role in pursuing science with SKAO precursor instruments. This paper briefly summarises the current status of the various aspects of work done as a part of this enterprise and our future goals.

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“…At Solar angles larger than 10 degrees, the SW velocity is roughly constant, and thus the density falls like distance squared because of the mass conservation principle. Although the density near the Sun is quite variable spatially, a rough bi-modality can be detected (Coles 1996): a high-velocity (600 to 800 km/s) and low-density mode (∼3 cm −3 ), called the fast wind, versus a low-velocity (<400 km/s, see Tokumaru et al 2010) and denser mode (∼5 to 10 cm −3 , see Manoharan 2003) called the slow wind. The 11-year Solar activity cycle is an important factor in the SW behaviour.…”

Section: Solar Wind Structurementioning

confidence: 99%

On the usefulness of existing solar wind models for pulsar timing corrections

Tiburzi

Verbiest

Shaifullah

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Dispersive delays due to the Solar wind introduce excess noise in high-precision pulsar timing experiments, and must be removed in order to achieve the accuracy needed to detect, e.g., low-frequency gravitational waves. In current pulsar timing experiments, this delay is usually removed by approximating the electron density distribution in the Solar wind either as spherically symmetric, or with a two-phase model that describes the contributions from both high-and low-speed phases of the Solar wind. However, no dataset has previously been available to test the performance and limitations of these models over extended timescales and with sufficient sensitivity. Here we present the results of such a test with an optimal dataset of observations of pulsar J0034−0534, taken with the German stations of LOFAR. We conclude that the spherical approximation performs systematically better than the two-phase model at almost all angular distances, with a residual root-mean-square (rms) given by the two-phase model being up to 28% larger than the result obtained with the spherical approximation. Nevertheless, the spherical approximation remains insufficiently accurate in modelling the Solar-wind delay (especially within 20 degrees of angular distance from the Sun), as it leaves timing residuals with rms values that reach the equivalent of 0.3 µs at 1400 MHz. This is because a spherical model ignores the large daily variations in electron density observed in the Solar wind. In the short term, broadband observations or simultaneous observations at low frequencies are the most promising way forward to correct for Solar-wind induced delay variations.

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The Solar Wind

Cited by 6 publications

References 56 publications

Occultation Observation to Probe the Turbulence Scale Size in the Plasma Tail of Comet Schwassmann-Wachmann 3-B

Occultation Observation to Probe the Turbulence Scale Size in the Plasma Tail of Comet Schwassmann-Wachmann 3-B

Preparing for solar and heliospheric science with the SKAO: An Indian perspective

On the usefulness of existing solar wind models for pulsar timing corrections

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