Statistical Analysis of Spicule Inclinations and chromosphere thickness variations

Document Type : Research Article

Authors

1 Ph.D. Student, Department of Physics, Payame Noor University (PNU), Tehran, Iran

2 Associate Professor, Department of Physics, Payame Noor University (PNU), Tehran, Iran

Abstract

Spicules are intermittently rising above the surface of the Sun eruptions; EUV jets are now also reported immediately above surface layers. The orientation of spicules is a valuable parameter in the absence of direct magnetic field measurements with a sufficient spatial resolution in the chromospheric region because it is presumably determined by the confined flow of plasma, which should occur along the magnetic field lines, especially where the solar magnetic field pressure dominates the gas pressure. Of course, all these measurements suffer from the overlapping effect of spicules seen along each line of sight, the effect of which will be more critical when we look near the solar limb. In the case of macrospicules as well imaged by AIA of the SDO mission using the 304 filter recording the emissions of the HeII, resonance line, an additional effect arises due to the optical thickness of the line, especially on disk and also above the limb in the inner chromospheric shell.
The primary purpose of this paper is to determine automatically and objectively the apparent tilt angle of spicules, using the best available highly processed observations, from the Solar Optical Telescope (SOT) limb imaging experiment by using an H CaII line, onboard Hinode mission. Furthermore, the Hough transform is applied to the resulting images for making a statistical analysis of spicule orientations in different regions around the solar limb, from the pole to the equator. A technique for the automatic detection off-limb spicules was implemented, and statistical measurements were conducted to determine the tilt angle for spicules at different heliocentric angles.
We apply and develop a method with the following steps: (1) To increase the visibility of spicules, a radial logarithmic scale is applied; (2) To enhance linear features, while the Madmax operator is used. We investigated in more detail the apparent inclination of spicules and found the statistically average values for different locations around the solar limb for tilt angle. The results show a large difference of spicule apparent tilt angles in (i) the solar pole regions, (ii) the equatorial regions, (iii) the active regions, and (iv) the coronal hole regions. Analytically, during the minimum solar magnetically activity, from the equator to the poles, the inclination angles of the spicules are getting smaller and their lengths increase. As a result, the chromosphere thickness in this case is thicker than that of the solar maximum activities. When the spicules in the polar coronal holes are significantly inclined, the chromosphere and even transition regions thickness is thinner. Numerically, spicules are visible in a radial direction in the polar regions with a tilt angle <200. The tilt angle is even reduced to 10 degrees inside the coronal hole with open magnetic field lines and at the lower latitude, the tilt angle reaches values over 50 degrees. Usually, around an active region, they show a wide range of apparent angle variations from -60 to +60 degrees, which is in close resemblance to the rosettes that are made of dark mottles and fibrils in projection on the solar disk. However, large-scale activities with short life-time do not play a significant role in the thickness of the chromosphere, and they are removed for long term measurements by averaging. Therefore, this study considers the most statistical population of spicules in the minimum (and maximum) solar activity in the polar regions, and in lower latitude, to be considered as their inclination angles. While at the maximum laps of solar cycle, the opposite result will be expected, and fully confirmed, and give us a topological reason for the chromospheric prolateness at minimum activities.

Keywords

Main Subjects

References

Athay, G., 1986, Physics of the Sun, ed. Sturrock, P. A., Vol. II: The solar atmosphere.
Auchere, F., Boulade, S., Koutchmy, S., Smartt, R. N., Delaboudiniere, J. P., Georgakilas, A., Gurman, J. B. and Artzner, G. E., 1998, The prolate solar chromosphere. A & A, 336L, 57.
Bazin, C. and Koutchmy, S., 2013, Helium shells and faint emission lines from slitless flash spectra. Journal of Advanced Research, 4(3), 307–313.
Beckers, J.M., 1968, Solar spicules. Solar Phys., 3, 367-433.
De Pontieu, B., Erdelyi, R. and James, S.P. (2004). Solar chromospheric spicules from the leakage of photospheric oscillations and flows, Nature, 430, 536-539.
De Pontieu, B ., Mcintosh, S.W., Carlsson, M., Hansteen, V. H., Tatrbell, T. D., Schrijver, C. J., Title, A. M., Shine, R. A., Tsuneta, S., Katsukawa, Y., Ichimoto, K,. Suematsu, Y., Shimizu, T. and Nagata, S., 2007, Chromospheric Alfvénic Waves Strong Enough to Power the Solar Wind, Science, 318, 1574-1577
Filippov, B., 2008, private communication.
Filippov, B. and Koutchmy, S., 2000, On the Origin of the Prolate Solar Chromosphere, Solar Phys., 196, 311- 320.
Filippov, B., Koutchmy, S. and Vilinga, J., 2007, On the dynamic nature of the prolate solar chromosphere: jet formation, A&A, 464, 1119- 1125.
Filippov, B., Koutchmy, S. and Tavabi, E., 2013, Formation of a White-Light Jet Within a Quadrupolar Magnetic Configuration, Solar Phys., 286, 143-156.
Goodarzi, H., Koutchmy, S. and Ajabshirzadeh, A., 2015, Improved SOT (Hinode mission) high resolution solar imaging observations, Astrophysics and Space Science, 358, 13.
Heristchi, D. and Mouradian, Z., 1992, On the Inclination and the Axial Velocity of Spicules. Solar Phys., 142, 21-34.
Johannesson, A. and Zirin, H., 1996, The Pole-Equator Variation of Solar Chromospheric Height, The Astrophysical Journal, 471, 510-520.
Koutchmy, O. and Koutchmy, S., 1989, High Spatial Resolution Solar Observations, Proc. of the 10th Sacramento Peak Summer Workshop, 217.
Koutchmy, S. and Loucif, M. L., 1991, Mechanisms of Chromospheric and Coronal Heating, ed. P. Ulmschneider, E. R. Priest, & R. Rosner (Berlin:Springer-Verlag), 152-158.
Koutchmy, S., Hara, H., Shibata, K., Suematsu, Y. and Reardon, K., 1998, Observational Plasma Astrophysics: Five Years of Yohkoh and Beyond, 87- 94.
Kosugi, T., Matsuzaki, K., Sakao, T., Shimizu, T., Sone, Y., Tachikawa, S., Hashimoto, T., Minesugi, K., Ohnishi, A., Yamada, T., Tsuneta, S., Hara, H., Ichimoto, K., Suematsu, Y., Shimojo, M., Watanabe, T., Shimada, S., Davis, J. M., Hill, L. D., Owens, J. K., Title, A. M., Culhane, J. L., Harra, L. K., Doschek, G. A. and Golub, L., 2007, The Hinode (Solar-B) Mission: An Overview, Solar Phys., 273, 3-17.
Lorrain, P. and Koutchmy, S., 1998, Chromospheric heating by electric currents induced by fluctuating magnetic elements. Solar Phys., 178, 39-42.
Moore, R. L., Sterling, A.C. and Falconer, D.A., 2015, Magnetic untwisting in solar jets that go into the outer corona in polar coronal holes. The Astrophysical Journal.
Mosher, J. M. and Pope, T. P., 1977, A statistical study of spicule inclinations. Solar Phys., 53, 375-384.
Mouradian, Z., 1965, Contribution a l’etude du Bord Solaire et de la Structure chromospherique. Annales d'Astrophysique, 28, 805.    
Pasachoff, J.M., William, A.J. and Sterling, A.C., 2009, Limb Spicules from the Ground and from Space. Solar Phys., 260, 59-82.
Roberts, W. O., 1945, A Preliminary Report on Chromospheric Spicules of Extremely Short Lifetime. ApJ, 101, 136.
Secchi, S. J., 1877, Le Soleil. Gauthier-Villars, 38.
Shimizu, T., Nagata, S., Tsuneta, S., Tarbell, T., Edwards, C., Shine, R., Hoffmann, C., Thomas, E., Sour, S., Rehse, R., Ito, O., Kashiwagi, Y., Tabata, M., Kodeki, K., Nagase, M., Matsuzaki, K., Kobayashi, K., Ichimoto, K. and Suematsu, Y., 2008, Image Stabilization System for Hinode (Solar-B) Solar Optical Telescope. Solar Phys., 249, 221-232.
Shapiro, L. and Stockman, G., 2001, Computer Vision, Prentice-Hall, Inc.
Sterling, A.C., 2000, Solar Spicules: A Review of Recent Models and Targets for Future Observations – (Invited Review), Solar Phys., 196, 79-111.
Suematsu, Y. and Takeuchi, A., 1991, Flare Physics in Solar Activity Maximum 22, Proceedings of the International SOLAR-A Science Meeting Held at Tokyo, Japan, 23-26 October 1990, Lecture Notes in Physics, 387, 259.
Suematsu, Y., Ichimoto, K., Katsukawa, Y., Shimizu, T., Okamoto, T., Tsuneta, S., Tarbell, T. and Shine, R. A., 2008, High Resolution Observations of Spicules with Hinode/SOT. Astronomical Society of the Pacific, 397, 27.
Sterling, A. C., Moore, R.L., Falconer, D.A. and Adams, M., 2015, Small-scale filament eruptions as the driver of X-ray jets in solar coronal holes. Nature, 523, 437-440.
Tavabi, E.,  Koutchmy, S. and Ajabshirzadeh, A., 2011a, A Statistical Analysis of the SOT-Hinode Observations of Solar Spicules and Their Wave-Like Behavior. New Astronomy, 16, 296-305.
Tavabi, E.,  Koutchmy, S. and Ajabshirzadeh, A., 2011b, Contribution to the Modeling of Solar Spicules. Advances in Space Research, 47, 2019-2029.
Tavabi, E.,  Koutchmy, S. and Ajabshirizadeh, A., 2013, Increasing the Fine Structure Visibility of the Hinode SOT Ca II H Filtergrams. Solar Phys., 283, 187-194.
Tavabi, E., Koutchmy, S. and Golub, L. (2015). Limb Event Brightenings and Fast Ejection Using IRIS Mission Observations. Solar Phys., 290, 2871-2877.
Tsuneta, S., Ichimoto, K., Katsukawa, Y., Nagata, S., Otsubo, M., Shimizu, T., Suematsu, Y., Nakagiri, M., Noguchi, M., Tarbell, T., Title, A., Shine, R., Rosenberg, W., Hoffmann, C., Jurcevich, B., Kushner, G., Levay, M., Lites, B., Elmore, D., Matsushita, T., Kawaguchi, N., Saito, H., Mikami, I., Hill, L. D., Owens, J. K. (2008). The Solar Optical Telescope for the Hinode Mission: An Overview. Solar Phys., 249, 167-196.
Van de Hulst, H. C. (1953). The Sun Edited by Gerard P. Kuiper. Chicago: The University of Chicago Press, 207.
Wilhelm, K., Abbo, L., Auchère, F., Barbey, N., Feng, L., Gabriel, A. H., Giordano, S., Imada, S., Llebaria, A., Matthaeus, W. H., Poletto, G., Raouafi, N. E., Suess, S. T., Teriaca, L., Wang, Y.M. (2011). Morphology, Dynamics and Plasma Parameters of Plumes and Inter-Plume Regions in Solar Coronal Holes. The Astronomy and Astrophysics Review, 19(1), 35.
Zhang, J.,White, S. M. & Kundu, M. R. (1998). The Height Structure of the Solar Atmosphere from the Extreme-Ultraviolet Perspective. The Astrophysical Journal, 504, L127- L130.
Journal of the Earth and Space Physics
Volume 48, Issue 3
online publication date: 6 December 2022
December 2022
Pages 657-671

Files

Share

How to cite

Statistics