Height correction in the measurement of solar differential rotation determined by
 coronal bright points

Brajša, R.; Wöhl, H.; Vršnak, Bojan; Ruždjak, V.; Clette, F.; Hochedez, J.‐F.; Roša, Dragan

doi:10.1051/0004-6361:20034082

Cited by 50 publications

(58 citation statements)

References 36 publications

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“…We found that CBPs observed by SDO/AIA in the 19.3 nm channel are located at an average height of ≈6300 km above the solar photosphere. This is slightly lower than in previous studies : Simon & Noyes (1972) ≈11 000 km, Brajša et al (2004) 8000−12 000 km, and Hara (2009) ≈12 000 km. On the other hand, Karachik et al (2006) suggest the value of 80 000 km, which is the height at which the Fe xiv λ195 line forms (Zhang & et al 2000).…”

Section: Discussioncontrasting

confidence: 63%

“…For example, Brajša et al (2004) found a slightly higher value of the equatorial rotation A = 14.454 ± 0.027 • day −1 in the period from 1998−1999 which is closer to the solar activity maximum. Wöhl et al (2010) found even faster equatorial rotation A = 14.499 ± 0.006 • day −1 with CBP data covering most of cycle 23 around its activity maximum.…”

Section: Solar Rotation Profile and Rotation Velocity Residualsmentioning

confidence: 86%

“…Coronal bright points (CBPs) have also been used very frequently by using the data obtained by different satellites. For example, Brajša et al (2001Brajša et al ( , 2002bBrajša et al ( , 2004, Vršnak et al (2003), Wöhl et al (2010) used SOHO/EIT data, Hara (2009) analysed Yohkoh/SXT measurements, while Kariyappa (2008) used both Yohkoh and Hinode data. Recently, Sudar et al (2015) have used SDO/AIA measurements in the 19.3 nm channel.…”

Section: Introductionmentioning

confidence: 99%

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Meridional motions and Reynolds stress from SDO/AIA coronal bright points data

Sudar

Saar

Skokić

et al. 2016

A&A

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Context. It is possible to detect and track coronal bright points (CBPs) in Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA) images. A combination of high resolution and high cadence provides a wealth of data that can be used to determine velocity flows on the solar surface with very high accuracy. Aims. We derived a very accurate solar rotation profile and investigated meridional flows, torsional oscillations, and horizontal Reynolds stress based on ≈6 months of SDO/AIA data. Methods. We used a segmentation algorithm to detect CBPs in SDO/AIA images. We also used invariance of the solar rotation profile with central meridian distance (CMD) to determine the height of CBPs in the 19.3 nm channel. Results. The best fit solar rotation profile is given by ω(b) = (14.4060 ± 0.0051 + (−1.662 ± 0.050) sin 2 b + (−2.742 ± 0.081) sin 4 b) • day −1 . The height of CBPs in the SDO/AIA 19.3 nm channel was found to be ≈6500 km. Meridional motion is predominantly poleward for all latitudes, while solar velocity residuals show signs of torsional oscillations. Horizontal Reynolds stress was found to be smaller than in similar works, but still showed transfer of angular momentum towards the solar equator. Conclusions. Most of the results are consistent with Doppler measurements rather than tracer measurements. The fairly small calculated value of horizontal Reynolds stress might be due to the particular phase of the solar cycle. Accuracy of the calculated rotation profile indicates that it is possible to measure changes in the profile as the solar cycle evolves. Analysis of further SDO/AIA CBP data will also provide a better understanding of the temporal behaviour of the rotation velocity residuals, meridional motions, and Reynolds stress.

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Section: Discussioncontrasting

confidence: 63%

Section: Solar Rotation Profile and Rotation Velocity Residualsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Meridional motions and Reynolds stress from SDO/AIA coronal bright points data

Sudar

Saar

Skokić

et al. 2016

A&A

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“…As discussed in WT, the expected propagation height of the CW at this time is above 15 Mm. Low-lying coronal structures, such as coronal bright points, remained undisturbed by the wave (bright points heights range from 5 to 20 Mm (Brajša et al 2004;Tian et al 2007). The lateral speed of the dimming is shown in Table 2.…”

Section: Imaging Analysismentioning

confidence: 99%

A coronal wave and an asymmetric eruptive filament in SUMER, CDS, EIT, and TRACE co-observations

Madjarska¹,

Doyle²,

Shetye³

2015

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Context. The investigation covers the complex subject of coronal waves and the phenomena contributing to and/or causing their formation. Aims. The objectives of the present study is to provide a better physical understanding of the complex inter-relation and evolution of several solar coronal features comprising a double-peak flare, a coronal dimming caused by a Coronal Mass Ejection (CME), a CME-driven compression, and a fast-mode wave. For the first time, the evolution of an asymmetric eruptive filament is analysed in simultaneous Solar Ultraviolet Measurement of Emitted Radiation (SUMER) spectroscopic and Transition Region and Coronal Explorer (TRACE) and Extreme-ultraviolet Imaging Telescope (EIT) imaging data. Methods. We use imaging observations from EIT and TRACE in the 195 Å channel and spectroscopic observations from the Coronal Diagnostic Spectrometer (CDS) in a rastering and SUMER in a sit-and-stare observing mode. The SUMER spectra cover spectral lines with formation temperatures from logT (K) ∼ 4.0 to 6.1. Results. Although the event was already analysed in two previous studies, our analysis brings a wealth of new information on the dynamics and physical properties of the observed phenomena. We found that the dynamic event is related to a complex flare with two distinct impulsive peaks, one according to the Geostationary Operational Environmental Satellite (GOES) classification as C1.1 and the second -C1.9. The first energy release triggers a fast-mode wave and a CME with a clear CME driven compression ahead of it. This activity is related to, or possibly caused, by an asymmetric filament eruption. The filament is observed to rise with its leading edge moving at a speed of ∼300 km s −1 detected both in the SUMER and CDS data. The rest of the filament body moves at only ∼150 km s −1 while untwisting. No signature is found of the fast-mode wave in the SUMER data, suggesting that the plasma disturbed by the wave had temperatures above 600 000 K. The erupting filament material is found to emit only in spectral lines at transition region temperatures. Earlier identification of a coronal response detected in the Mg x 609.79 Å line is found to be caused by a blend from the O iv 609.83 Å line. Conclusions. We present a unique analysis of the complex phenomenon called 'EIT/Coronal Wave', confirming its bimodal nature. We suggest that the disintegration of the dimming/CME and the CME-driven compression are either caused by a CME-CME interaction taking place in the low solar atmosphere or by an impulsive CME cavity overexpansion in the low solar atmosphere.

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“…The main physical characteristics of SBCS were summarised by Brajša et al (2004Brajša et al ( , 2008, and references therein), whilst their good latitudinal coverage on the Sun was described by, e.g. Brajša et al (2005, and references therein).…”

Section: Introductionmentioning

confidence: 99%