A Comparison of the Red and Green Coronal Line Intensities at the 29 March 2006 and the 1 August 2008 Total Solar Eclipses: Considerations of the Temperature of the Solar Corona

Voulgaris, A.; Athanasiadis, Theodoros; Seiradakis, J. H.; Pasachoff, Jay M.

doi:10.1007/s11207-010-9575-7

Cited by 15 publications

(7 citation statements)

References 18 publications

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“…the same amount of shift as the H α line (as shown hereafter), thus indicate chromospheric origin like the Balmer emission lines. Indeed, these lines have been seen during solar total eclipses (Voulgaris et al 2010), supporting their chromospheric origin. Also, the 5 876 Å line appears in emission in very strong solar flares (Johns-Krull et al 1997 and references therein).…”

Section: Optical Spectroscopic Observationsmentioning

confidence: 54%

Early optical follow-up of the nearby active star DG CVn during its 2014 superflare

Caballero-Garcia

Šimon

Jelínek

et al. 2015

Mon. Not. R. Astron. Soc.

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DG CVn is a binary system in which one of the components is an M type dwarf ultra fast rotator, only three of which are known in the solar neighborhood. Observations of DG CVn by the Swift satellite and several ground-based observatories during its super-flare event on 2 014 allowed us to perform a complete hard X-ray -optical follow-up of a super-flare from the red-dwarf star. The observations support the fact that the super-flare can be explained by the presence of (a) large active region(s) on the surface of the star. Such activity is similar to the most extreme solar flaring events. This points towards a plausible extrapolation between the behaviour from the most active red-dwarf stars and the processes occurring in the Sun.

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Section: Optical Spectroscopic Observationsmentioning

confidence: 54%

Early optical follow-up of the nearby active star DG CVn during its 2014 superflare

Caballero-Garcia

Šimon

Jelínek

et al. 2015

Mon. Not. R. Astron. Soc.

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“…We have also estimated the temperature using the line ratio technique. Recently, Voulgaris et al (2010) have reported the relative intensity ratios of the red and green lines to be 0.577 and 2.161 during the solar eclipses in 2006 and 2008, respectively. However, during this observation we have measured this ratio to be between 0.45 to 1, which indicates that the relative intensity of the red line has decreased, at least in this observed coronal structure.…”

Section: Discussionmentioning

confidence: 99%

“…We note that the solar corona has a multitemperature coronal structure, as intensity ratios vary in different structures and with solar radii. The conclusion drawn by Voulgaris et al (2010) is based on limited data for a few coronal structures. One must have observations for longer periods and over a large portion of the solar corona to conclude that the temperature varies with activity on shorter time scales.…”

Section: Discussionmentioning

confidence: 99%

Spectroscopic Observation of Oscillations in the Corona During the Total Solar Eclipse of 22 July 2009

et al. 2011

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We performed high resolution spectroscopy of the solar corona during the total solar eclipse of 22 July 2009 in two emission lines: the green line at 5303 Å due to Fe XIV and the red line at 6374 Å due to Fe X, simultaneously from Anji (latitude 30°28.1 N; longitude 119°35.4 E; elevation 890 m), China. A two-mirror coelostat with 100 cm focal length lens produced a 9.2 mm image of the Sun. The spectrograph using 140 cm focal length lens in Littrow mode and a grating with 600 lines per millimeter blazed at 2 µm provided a dispersion of 30 mÅ and 43 mÅ per pixel in the fourth order around the green line and third order around the red line, respectively. Two Peltier cooled 1k × 1k CCD cameras, with a pixel size of 13 µm square and 14-bit readout at 10 MHz operated in frame transfer mode, were used to obtain the time sequence spectra in two emission lines simultaneously. The duration of totality was 341 s, but we could get spectra for 270 s after a trial exposure at an interval of 5 s. We report here on the detection of intensity, velocity, and line width oscillations with periodicity in the range of 25 -50 s. These oscillations can be interpreted in terms of the presence of fast magnetoacoustic waves or torsional Alfvén waves. The intensity ratios of green to red emission lines indicate the temperature of the corona to be 1.65 MK in the equatorial region and 1.40 MK in the polar region, relatively higher than the expected temperature during the low activity period. The width variation of the emission lines in different coronal structures suggests different physical conditions in different structures.

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“…Its data were recorded with a second RED Epic camera, to continue the studies of coronal temperature from the [Fe x]/ [Fe xiv] ratio, as previously reported by our group (Voulgaris et al 2010(Voulgaris et al , 2012. The RED Epic camera has a high dynamic range of 13.5 stops, up to 120 fps at 5k resolution with an effective 13.8 megapixel 14 bit CMOS sensor.…”

Section: Mt Carbinementioning

confidence: 98%

“…Equipment included a sophisticated spectrograph (constructed by A.V.) for the temperature measurements (Voulgaris et al 2010(Voulgaris et al , 2012. A satellite site was 20 km north along the coast.…”

Section: Coastal Observationsmentioning

confidence: 99%

Structure and Dynamics of the 2012 November 13/14 Eclipse White-Light Corona

Pasachoff

Rusin

Санига

et al. 2015

ApJ

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Continuing our series of observations of coronal motion and dynamics over the solar-activity cycle, we observed from sites in Queensland, Australia, during the 2012 November 13 (UT)/14 (local time) total solar eclipse. The corona took the low-ellipticity shape typical of solar maximum (flattening index ε = 0.01), a change from the composite coronal images we observed and analyzed in this journal and elsewhere for the 2006 and 2008-2010 eclipses. After crossing the northeast Australian coast, the path of totality was over the ocean, so further totality was seen only by shipborne observers. Our results include velocities of a coronal mass ejection (CME; during the 36 minutes of passage from the Queensland coast to a ship north of New Zealand, we measured 413 km s−1 ) and we analyze its dynamics. We discuss the shapes and positions of several types of coronal features seen on our higherresolution composite Queensland coronal images, including many helmet streamers, very faint bright and dark loops at the bases of helmet streamers, voids, and radially oriented thin streamers. We compare our eclipse observations with models of the magnetic field, confirming the validity of the predictions, and relate the eclipse phenomenology seen with the near-simultaneous images from NASA's Solar Dynamics Observatory (SDO/AIA), NASA's Extreme Ultraviolet Imager on Solar Terrestrial Relations Observatory, ESA/Royal Observatory of Belgium's Sun Watcher with Active Pixels and Image Processing (SWAP) on PROBA2, and Naval Research Laboratory's Large Angle and Spectrometric Coronagraph Experiment on ESA's Solar and Heliospheric Observatory. For example, the southeastern CME is related to the solar flare whose origin we trace with a SWAP series of images.

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A Comparison of the Red and Green Coronal Line Intensities at the 29 March 2006 and the 1 August 2008 Total Solar Eclipses: Considerations of the Temperature of the Solar Corona

Cited by 15 publications

References 18 publications

Early optical follow-up of the nearby active star DG CVn during its 2014 superflare

Early optical follow-up of the nearby active star DG CVn during its 2014 superflare

Spectroscopic Observation of Oscillations in the Corona During the Total Solar Eclipse of 22 July 2009

Structure and Dynamics of the 2012 November 13/14 Eclipse White-Light Corona

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