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Dodero, M. A.; Antonucci, E.; Giordano, S.; Martin, R.

doi:10.1023/a:1005007429583

Cited by 59 publications

(40 citation statements)

References 6 publications

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“…The relative contribution of these components strongly depends on outflow velocity through the progressive depletion, with increasing wind speed, of the radiative component, known as the Doppler dimming effect. Therefore, the intensity ratio of the O  lines is a sensitive measure of the Doppler dimming, affecting them for outflow speeds from about 50 km s −1 to 400 km s −1 , as proved by many authors (Noci et al 1987;Dodero et al 1998;Li et al 1998;Cranmer et al 1999a). Note that for outflow velocities greater than about 100 km s −1 the line ratio is ≥0.5.…”

Section: Outflow Velocitymentioning

confidence: 75%

“…According to Noci et al (1987) and Dodero et al (1998), these results might suggest that the outflow plasma velocity cannot exceed ∼50 km s −1 up to about 3 R in both streamers and adjacent regions. Above 3 R , the outflow velocity remains below 50 km s −1 in all the observed in-streamer regions at any heliocentric distance, except inside the streamer observed on Nov. 3 and 5, 1997, where an outflow of about 100 km s −1 can be inferred, with most of the acceleration occurring between 3.6 and 4.1 R .…”

Section: Outflow Velocitymentioning

confidence: 89%

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Streamers and adjacent regions observed by UVCS/SOHO: A comparison between different phases of solar activity

Ventura

Spadaro

Cimino

et al. 2005

A&A

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Abstract. UVCS/SOHO observations of the O  resonance doublet and H  Lyα line intensities and profiles, together with measurements of the visible linearly polarized radiance, have been performed during two MEDOC campaigns in 1997 and 2000, i.e. near solar minimum and approaching the solar maximum phase, respectively. During both observational runs midlatitude coronal regions in the West limb of the Sun have been scanned over a range of heliocentric distance from 1.39 to 4.1 R , to study the plasma properties of streamers and adjacent regions, such as ion kinetic temperature, electron density and outflow velocity, paying particular attention to comparing plasma conditions deduced for different ions in coronal structures observed on different days and during different phases of solar activity. Besides confirming some previous findings on significant differences between open and closed field-line structures at solar minimum, our results provide some evidence for differences in kinetic temperature among mid-latitude solar minimum streamers observed on different days from about 2 R outwards, as well as in their dynamical conditions at heliocentric distances greater than 3.6 R . For observations carried out in 2000, conversely, the mid-latitude coronal streamers and their surroundings are about 3 times, and more than one order of magnitude brighter, respectively, than their solar minimum counterparts and exhibit very similar kinetic and dynamical conditions. The kinetic temperatures in adjacent regions are higher than in streamers (by about a factor of 2) only within 2 R , while at greater heights such differences vanish, making it difficult to discriminate between open and closed structures. This is opposite to the behaviour detected at solar minimum, when adjacent regions appear to be characterized by kinetic temperatures progressively higher and higher than in streamers with increasing height, from 2 R outwards. Therefore, a clear characterization of open and closed configurations near the solar maximum might be quite difficult, probably due both to the intrisically more complex magnetic configuration of the corona in this phase of the solar activity and the line-of-sight contamination effects that in a highly structured solar corona may strongly mix background and foreground plasma with different properties. The transition from the solar minimum to maximum also seems characterized by a global increase in the electron density inside streamers of about a factor of 4 at 1.7 R and then it progressively decreases with height.

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Section: Outflow Velocitymentioning

confidence: 75%

Section: Outflow Velocitymentioning

confidence: 89%

Streamers and adjacent regions observed by UVCS/SOHO: A comparison between different phases of solar activity

Ventura

Spadaro

Cimino

et al. 2005

A&A

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“…Previous literature clearly pointed to the incompatibility of the isotropic solution with the observational data beyond 2 R Kohl et al 1998;Li et al 1998;Dodero et al 1998;Wilhelm et al 1998;Antonucci et al 2000;Cranmer et al 1999). In these papers the issue of the degree of anisotropy has been addressed in the light of coronal heating models based on ion-cyclotron resonance scattering, which in principle can explain an extremely large anisotropy of the oxygen ion velocity distribution (e.g.…”

Section: Discussionmentioning

confidence: 99%

“…Spectroscopic observations of the polar coronal holes performed with the Ultraviolet Coronagraph Spectrometer (UVCS) on board the Solar and Heliospheric Observatory (SOHO) have revealed preferential heating of the O +5 ions across the magnetic field in the regions where the fast wind is accelerated Kohl et al 1998;Li et al 1998;Dodero et al 1998;Wilhelm et al 1998;Cranmer et al 1999). This phenomenon is likely to be ascribed to ion-cyclotron resonance scattering by high frequency Alfvén waves Cranmer et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Oxygen temperature anisotropy and solar wind heating above coronal holes out to 5R$_\odot$

Telloni¹,

Antonucci²,

Dodero

2007

A&A

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“…We kept the O VI λ1032/λ1037 intensity ratio equal to 3.2 (as in exposure 1) for the narrow component since it represents static material along the line of sight with a strong radiative component. On the other hand, the intensity ratio for the broader Gaussian was assumed to be 1.75 due to the fact that the radiative component of the oxygen lines is washed out at the high post-shock velocities of the plasma, while the pumping of the O VI 1037Å line from the C II 1037.0Å and 1036.4Å lines keeps this ratio lower than 2 (Li et al 1998;Dodero et al 1998). In Table 2 we summarize the parameters used for the above model.…”

Section: Application Of An Ion Heating Modelmentioning

confidence: 99%

UVCS/SOHO observations of a CME-driven shock: Consequences on ion heating mechanisms behind a coronal shock

Mancuso

Raymond

Kohl

et al. 2002

A&A

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Abstract.We report the observation of a 1100 km s −1 CME-driven shock with the UltraViolet Coronagraph Spectrometer (UVCS) telescope operating on board SOHO on March 3, 2000. The shock speed was derived from the type II radio burst drift rate and from UVCS observations that can yield the density profile just before the passage of the shock. A CME projected speed of 920 km s −1 was deduced from the Large Angle Spectrometric Coronagraph (LASCO) white light images, indicating that the CME leading edge was lagging behind at about 20% of the shock speed. The spectral profiles of both the O VI and Lyα lines were Doppler dimmed and broadened at the passage of the shock by the emission from shocked material along the line of sight. The observed line broadening for both protons and oxygen ions was modeled by adopting a mechanism in which the heating is due to the nondeflection of the ions at the shock ramp in a quasi-perpendicular shock wave. This specific ion heating model was able to reproduce the observed spectroscopic properties of the shocked plasma.

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Untitled

Cited by 59 publications

References 6 publications

Streamers and adjacent regions observed by UVCS/SOHO: A comparison between different phases of solar activity

Streamers and adjacent regions observed by UVCS/SOHO: A comparison between different phases of solar activity

Oxygen temperature anisotropy and solar wind heating above coronal holes out to 5R$_\odot$

UVCS/SOHO observations of a CME-driven shock: Consequences on ion heating mechanisms behind a coronal shock

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