Limb Spicules from the Ground and from Space

Creators: Pasachoff, Jay M.; Jacobson, William A.; Sterling, Alphonse C.

Abstract

We amassed statistics for quiet-sun chromosphere spicules at the limb using ground-based observations from the Swedish 1-m Solar Telescope on La Palma and simultaneously from NASA's Transition Region and Coronal Explorer (TRACE) spacecraft. The observations were obtained in July 2006. With the 0.2 arcsecond resolution obtained after maximizing the ground-based resolution with the Multi-Object Multi-Frame Blind Deconvolution (MOMFBD) program, we obtained specific statistics for sizes and motions of over two dozen individual spicules, based on movies compiled at 50-second cadence for the series of five wavelengths observed in a very narrow band at Hα, on-band and at ± 0.035 nm and ± 0.070 nm (10 s at each wavelength) using the SOUP filter, and had simultaneous observations in the 160 nm EUV continuum from TRACE. The MOMFBD restoration also automatically aligned the images, facilitating the making of Dopplergrams at each off-band pair. We studied 40 Hα spicules, and 14 EUV spicules that overlapped Hα spicules; we found that their dynamical and morphological properties fit into the framework of several previous studies. From a preliminary comparison with spicule theories, our observations are consistent with a reconnection mechanism for spicule generation, and with UV spicules being a sheath region surrounding the Hα spicules.

Additional Information

© US Government 2009. Received: 4 November 2008. Accepted: 31 July 2009. Published online: 3 October 2009. We thank Mats Löfdahl of the Royal Swedish Academy of Sciences for his work on Multi-Object Multi-Frame Blind Deconvolution of the Swedish 1-m Solar Telescope data and Michiel van Noort there for helpful assistance. We thank Evan Tingle (Keck Northeast Astronomy Consortium Summer Fellow from Wesleyan University, sponsored by a Research Experiences for Undergraduates grant from the National Science Foundation) for his collaboration with data reduction. We are grateful to C. Alex Young (NASA's Goddard Space Flight Center) and Daniel B. Seaton (formerly Williams College, then University of New Hampshire, and now Royal Observatory of Belgium) for consultation on alignment of images.We thank former Williams College students Anne Jaskot and Megan Bruck for their participation while obtaining the data at the Swedish 1-m Solar Telescope and Jennifer Yee (KNAC Summer Fellow from Swarthmore College) for work on earlier SST spicule data. Bruck also worked on arranging MOMFBD. We appreciate the earlier undergraduate thesis work at Williams College on SST and TRACE data of Kamen Kozarev (now at Boston University) and Owen Westbrook (now at M.I.T.). We thank Bart De Pontieu (Lockheed Martin Solar and Astrophysics Laboratory) for assistance during the first of the three SST data runs, and Rolf Kever and the Telescope Operators for their help also on site. We thank Leon Golub, Edward DeLuca, and Jonathan Cirtain (Harvard-Smithsonian Center for Astrophysics) for consultations on the TRACE data reduction. We thank Steven P. Souza of Williams College's Astronomy Department for computing assistance and advice. J.M.P. thanks Michael Brown and the Division of Geological and Planetary Sciences of the California Institute of Technology for sabbatical hospitality during the preparation of this paper. Our work was funded in part by NASA grants NNG04GF99G and NNG04GK44G from the Solar Terrestrial Program and grant NNM07AA01G from NASA's Marshall Space Flight Center. A.C.S. was supported by funding from NASA's Office of Space Science through the Living with a Star, the Solar Physics Supporting Research and Technology, and the Sun – Earth Connection Guest Investigator Programs.

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