Coronal dynamics and spectra

Fig. 1. Flash spectrum from the total solar eclipse on 1th of August 2008. Observations are near Novosibirsk, Russia (Voulgaris et al., 2010).

A team from Williams College (Williamstown, Massachusetts) headed by Professor Jay Pasachoff will observe with a variety of spatial and spectral imagers from Longyearbyen. They will be extending their studies of the dynamics of coronal plumes and streamers as well as of coronal mass ejections and erupting prominences; three of the eruptions were visible simultaneously, for example, during the 2013 total solar eclipse that they observed from Gabon.

Besides Pasachoff, the team includes Robert Lucas from Australia; Vojtech Rusin from Slovakia; Ron Dantowitz from Brookline, Massachusetts, U.S.; Michael Kentrianakis from New York City, U.S.; Michael Zeiler from Santa Fe, New Mexico, U.S.; Allison Carter, a Williams College undergraduate student '16; and John Seiradakis and Aristeidis Voulgaris from the Aristotle University of Thessaloniki, Greece. Zeiler is a premier eclipse mapper, with website http://eclipse-maps.com. Their work is supported in large part by a grant from the Committee for Research and Exploration of the National Geographic Society. Arrangements for the core research group and for an accompanying tourist group are made by Mark Sood of aclassictour.com. Naomi Pasachoff, U.S., and Helen Robinson, Australia, will also participate.

Their work on coronal dynamics will be carried out with a variety of telescopes and cameras equipped with CCD and CMOS imagers, with full calibrations and control of some of the instruments with Xavier Jubier's Solar Eclipse Maestro software. Pasachoff and his team have obtained spatial observations that have been combined into composites showing a large dynamic range, working both with Wendy Carlos of New York for overall coronal structure and Miloslav Druckmüller and Hana Druckmülerová for high-contrast structure. They use their composite images together with observations of the solar disk in the extreme ultraviolet from NASA's Solar Dynamics Observatory/Atmospheric Imaging Assembly and from ESA's PROBA2/Sun-Watcher-With-Active-Pixels(SWAP) on the solar disk and extreme lower corona; and also with observations of the outer corona from ESA/NASA/NRL's Solar Dynamics Observatory/Large-Angle-Spectroscopic-Coronagraph (LASCO)'s C2 for moderate outer corona and C3 for extreme outer corona. Only by combining eclipse images with the spacecraft images can one get a complete picture of the solar atmosphere, so such complete pictures are available only on the days of total solar eclipses.

The Pasachoff team will also be comparing the eclipse composites with predictions of the coronal streamers and plumes made by Zoran Mikic in California and Y.-M. Yang in Washington, DC, based on photospheric magnetic-field observations from ground-based observatories, such as the Wilcox Solar Observatory of Stanford University, and Stanford's Helioseismic Magnetic Imager on NASA's Solar Dynamics Observatory (superseding an earlier instrument on the Solar and Heliospheric Observatory).

The expedition will continue an unbroken sequence of overall eclipse images and their publication in The Astrophysical Journal or in Solar Physics since the 2005 eclipse in mid-Pacific, including the 2006 eclipse on Kastellorizo, Greece; the 2008 eclipse from Akademgorodok, Siberia, Russia; the 2009 eclipse from Tianhuangping, China; the 2010 eclipse from Easter Island; and the 2012 eclipse from Queensland, Australia, with data from the 2013 eclipse from Gabon being prepared for publication.

Both Dantowitz and Voulgaris will bring their spectrographs to study the flash and coronal spectra during totality, including ingress and egress. Both had been at the 2012 eclipse, with Dantowitz's giving data in clear skies; only Voulgaris's had been at the 2013 eclipse. Papers for Solar Physics from both eclipses are now in preparation. The spectra since the 2006 total eclipse in Greece have shown how the overall coronal temperature has increased with the peak of the solar-activity cycle (most easily seen as the sunspot cycle), measured from the changing ratio of the strength of the thirteen-times-ionized iron line (Fe XIV) to the nine-times-ionized iron line (Fe X), that is, the so-called coronal-green-line to the coronal-red-line ratio.

The team will also measure terrestrial-atmospheric parameters as they vary during the entire eclipse period of about 3 hours, data that will be analyzed in collaboration with Prof. Marcos Peñaloza-Murillo of Universidad de los Andes in Venezuela. The change in temperature from eclipse onset in the cold conditions in Svalbard should make an interesting contrast with temperature changes measured in Easter Island, Australia, and elsewhere during eclipses.

Jay Pasachoff
eclipse@williams.edu

Jay Pasachoff is Field Memorial Professor of Astronomy at Williams College, a visiting scientist at Caltech, and Chair of the International Astronomical Union's Working Group on Eclipses. He will be on his 61st solar eclipse expedition in Svalbard.

References:

Websites

On behalf of the Working Group on Eclipses of the International Astronomical Union: http://www.eclipses.info with connections to maps, information on how and why to observe eclipses, etc.

Past Pasachoff expeditions, with images: http://totalsolareclipse.org

Books (see also http://www.solarcorona.com)

Golub, Leon, and Jay M. Pasachoff 2010, The Solar Corona, 2nd ed., Cambridge University Press.

Pasachoff, Jay M., and Alex Filippenko 2014, The Cosmos: Astronomy in the New Millennium, 4th edition, Cambridge University Press.

Pasachoff, Jay M., 2014, First Guide to Astronomy, 2nd ed., The Peterson First Guide Series, Houghton Mifflin Harcourt Co.

Golub, Leon, and Jay M. Pasachoff, 2014, Nearest Star: The Surprising Science of Our Sun, 2nd ed., Cambridge University Press.

Review Articles

Pasachoff, Jay M., 2009, "Solar Eclipses as an Astrophysical Laboratory," Nature, June 11, 459, 789-795, DOI 10.1038/nature07987.

Pasachoff, Jay M., 2009, "Scientific Observations at Total Solar Eclipses," Research in Astronomy and Astrophysics 9, 613-634.

http://www.raa-journal.org/raa/index.php/raa/article/view/182.

Pasachoff, Jay M., 2010, "Resource Letter SP-1 on Solar Physics," American Journal of Physics, 78, September, 890-901.

Articles about Coronal Dynamics

Pasachoff, Jay M., Vojtech Rusin, Miloslav Druckmüller, Hana Druckmüllerová, Marcel Bělík, Metod Saniga, Milan Minarovjech, Eva Marková, Bryce A. Babcock, Steven P. Souza, and Jesse S. Levitt, 2008, "Polar Plume Brightening During the 29 March 2006 Total Eclipse," Astrophysical Journal 682, 638-643.

Pasachoff, Jay M., Vojtech Rusin, Miloslav Druckmüller, Peter Aniol, Metod Saniga, Milan Minarovjech, 2009, "The 2008 August 1 Eclipse Solar-Minimum Corona Unraveled," Astrophys. J. 702, 1297-1308. http://arxiv.org/pdf/0907.1643v1:http://stacks.iop.org/0004-637X/702/1297

Voulgaris, Aristeidis, Tilemachos M. Athanasiadis, John H. Seiradakis, and Jay M. Pasachoff, 2010, "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," Solar Physics 264, #1, 45-55. DOI 10.1007/s11207-010-9575-7 http://arxiv.org/pdf/0911.0325

Pasachoff, Jay M.,Vojtech Rušin, Metod Saniga, Hana Druckmüllerová, and Bryce A. Babcock, 2011, "Structure and Dynamics of the 22 July 2009 Eclipse White-Light Corona," Astrophys. J. 742, 29-42.

Pasachoff, Jay M., Vojtech Rušin, Hana Druckmüllerová, Metod Saniga, Muzhou Lu, Craig Malamut, Daniel B. Seaton, Leon Golub, Alex J. Engell, Steele W. Hill, and Robert Lucas, 2011, "Structure and Dynamics of the 11 July 2010 Eclipse White-Light Corona," Astrophys. J., 734, 114-123. http://stacks.iop.org/0004-637X/734/114

Pasachoff, J. M., V. Rušin, M. Saniga, B. A. Babcock, M. Lu, A. B. Davis, R. Dantowitz, P. Gaintatzis, A. Voulgaris, D. B. Seaton, and K. Shiota, 2014/2015, "Structure and Dynamics of the 13/14 November 2012 White-Light Corona," Astrophysical Journal, in press. http://arxiv.org/abs/1412.1155

Articles about Spectral Studies

Voulgaris, Aristeidis, Tilemachos M. Athanasiadis, John H. Seiradakis, and Jay M. Pasachoff, 2010, "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," Solar Physics 264, #1, 45-55. DOI 10.1007/s11207-010-9575-7 http://arxiv.org/pdf/0911.0325

Voulgaris, Aris, Paul Gaintatzis, John H. Seiradakis, Jay M. Pasachoff, and Thanasis E. Economou, 2012, "Spectroscopic Coronal Observations during the Total Solar Eclipse of 11 July 2010," Solar Physics 278 (1), 187-202; DOI: 10.1007/s11207-012-9929-4. http://arxiv.org/abs/1202.1535

Articles about Terrestrial Atmospheric Studies

Peñaloza-Murillo, Marcos A., and Jay M. Pasachoff, 2013, "Air-cooling mathematical analysis as inferred from the air temperature observation during the 1st total occultation of the Sun of the 21st century in June 21, 2001, at Lusaka, Zambia," Journal of Atmospheric and Solar-Terrestrial Physics, accepted for publication.

Articles about Art and Eclipses

Pasachoff, J. M., and R. J. M. Olson, 2014, "Art of the Eclipse," Nature 506, cover and pp. 314-5. http://www.nature.com/nature/journal/v508/n7496/full/508314a.html

Olson, Roberta J. M., and Jay M. Pasachoff, 2007, "St. Benedict Sees the Light: Asam's Solar Eclipses as a Metaphor," Religion and the Arts 11, 299-329. (www.brill.nl/rart). Also http://apod.nasa.gov/apod/ap080128.html

Olson, Roberta J. M., and Jay M. Pasachoff, 2009, "Blinded by the Light: Solar Eclipses in Art—Science, Symbolism, and Spectacle," Sixth meeting on the Inspiration of Astronomical Phenomena, Venice; in The Inspiration of Astronomical Phenomena VI, ed. by Enrico Maria Corsini (San Francisco: Astronomical Society of the Pacific, 2011), 205-215.

Pasachoff, J. M., and R. J. M. Olson, 2014, "The 1918 Eclipse Mural Series by Howard Russell Butler for the American Museum of Natural History and the Hayden Planetarium
," Proceedings of the Eighth meeting on the Inspiration of Astronomical Phenomena, INSAP8 (insap.org), New York, 2013, ed. Brian Abbott (San Francisco: Astronomical Society of the Pacific), submitted.

Text by Jay Pasachoff, 2015.