The height of the polar chromosphere in 2012—2023 according to observations on the Ernest Gurtovenko telescope
Heading:
| Osipov, SM, 1Pishkalo, MI 1Astronomical Observatory of Taras Shevchenko National University of Kyiv, Kyiv, Ukraine |
| Kinemat. fiz. nebesnyh tel (Online) 2024, 40(6):73-85 |
| https://doi.org/10.15407/kfnt2024.06.073 |
| Language: Ukrainian |
Abstract: According to the results of observations in the line fulfilled on the horizontal solar telescope of Ernest Gurtovenko, the height of the Sun’s polar chromosphere in 2012—2023 was determined as the difference in the positions of the maxima of the radial brightness gradients in the continuum and in the core of the line. It is found that the height of the polar chromosphere is lower near the maximum of solar cycle (~4500 km or ~6.3") and higher near the minimum of th cycle (~5000 km or ~6.9"). The height of the chromosphere at the southern pole in 2012—2013 and especially in 2016—2017 was higher than at the northern pole. This north-south asymmetry is probably related to differences in the dynamics and magnitude of the polar magnetic fields in Solar Cycle 24. It was shown that time changes in the height of the chromosphere are closely correlated with the number of sunspots, the intensity of the polar magnetic field, and the chromospheric indices of solar activity.The correlation coefficient between the average annual height of the chromosphere and the smoothed relative sunspot numbers is –0.64 in the northern hemisphere, and –0.75 in the southern hemisphere. The correlation coefficient between the average annual height of the chromosphere and the smoothed values of the polar magnetic field strength (according to data from the Wilcox Solar Observatory) is 0.86 for the northern hemisphere and 0.53 for the southern hemisphere (the latter value increases to 0.77 when the time shift of +1 year was used). The correlation coefficient between the average annual height of the chromosphere and the chromospheric index IK2 has a high value both at the northern (0.91) and southern (0.80) poles. |
| Keywords: chromosphere, limb, magnetic fields, spectral observations, Sun |
References:
1. Osipov S. (2014) The program of investigations of long term changes of Fraunhofer lines in solar spectra. Bull. Taras Shevchenko Kyiv Nat. Univ. Astron., 51(1), 34-36.
2. Pishkalo M. I., Leiko U. M. (2016) Dynamics of the circumpolar magnetic field of the Sun at a maximum of cycle 24. Kinemat. Phys. Celest. Bodies, 32, 78-85.
https://doi.org/10.3103/S0884591316020069
3. Auchre F., Boulade S., Koutchmy S., Smartt R. N., Delaboudinire J. P., Georga¬kilas A., Gurman J. B., Artzner G. E. (1998) The prolate solar chromosphere. Аstron. and Astrophys., 336, L57-L60.
4. Fracastoro M. G. (1948) Altezza e distribuzione della cromosfera solare. MmArc., 64, 33-47.
5. Hill H. A., Stebins R. T., Oleson J. R. (1975) The finite fourier transform definition of an edge on the solar disk. Astrophys. J., 200, 484.
https://doi.org/10.1086/153814
6. Janardhan P., Fujiki K., Ingale M., Bisoi S. K., Rout D. (2018) Solar cycle 24: an unusual polar field reversal. Аstron. and Astrophys., 618, A148.
https://doi.org/10.1051/0004-6361/201832981
7. Johannesson A., Zirin H. (1996) The pole-equator variation of solar chromospheric height. Astrophys. J., 471, 510.
https://doi.org/10.1086/177987
8. Lippincott S. L. (1957) Chromospheric spicules. Smithsonian Contribs Astrophys., 2(2), 15.
https://doi.org/10.5479/si.00810231.2-2.15
9. Lowder C., Qiu J., Leamon R. (2017) Coronal holes and open magnetic flux over cycles 23 and 24. Solar Phys., 292, id. 18.
https://doi.org/10.1007/s11207-016-1041-8
10. Parmenter B. C. (1966) Observations of solar chromospheric spicules. Publs Astron. Soc. Pacif., 78(462), 250.
https://doi.org/10.1086/128338
11. Petrie G. J. D. (2023) Polar photospheric magnetic field evolution and global flux transport. Solar Phys., 298(3), id. 43.
https://doi.org/10.1007/s11207-023-02134-5
12. Pishkalo M. I. (2019) On polar magnetic field reversal in solar cycles 21, 22, 23, and 24. Solar Phys., 294, id. 137.
https://doi.org/10.1007/s11207-019-1520-9
13. Rabin D., Moore R. L. (1980) Coronal holes, the height of the chromosphere, and the origin of spicules. Astrophys. J. 241(1). 394.
https://doi.org/10.1086/158352
14. Shetye J., Verwichte E., Stangalini M., Doyle J. G. (2021) The nature of high-frequency oscillations associated with short-lived spicule-type events. Astrophys. J. , 921, 30.
https://doi.org/10.3847/1538-4357/ac1a12
15. Svalgaard L., Kamide Y. (2013) Asymmetric solar polar field reversals. Astrophys. J., 763(1), id. 23.
https://doi.org/10.1088/0004-637X/763/1/23
16. Taffara L. (1946) L'attivitа del Sole nell' anno 1946. MmSAI., 18, 249.
https://doi.org/10.1108/eb031396
17. White O. R., Livingston W. (1981) Solar luminosity variation. III. Calcium K variation from solar minimum to maximum in cycle 21. Astrophys. J., 249, 798.
https://doi.org/10.1086/159338
18. Zirin H. (1996) The mystery of the chromosphere. Solar Phys., 169(2), 313.
https://doi.org/10.1007/BF00190608