Abstract
The tables of sunspot and flocculi heliographic positions included in the catalogs published by the Ebro Observatory in the 1930s have recently been recovered and converted into digital format by using optical character recognition (OCR) technology. We here analyzed these data by computing the angular velocity of several sunspot and flocculi groups. A difference was found in the rotational velocity for sunspots and flocculi groups at high latitudes, and we also detected an asymmetry between the northern and southern hemispheres, which is especially marked for the flocculi groups. The results were then fitted with a differential-rotation law [\(\omega=a+b \sin^{2} B\)] to compare the data obtained with the results published by other authors. A dependence on the latitude that is consistent with former studies was found. Finally, we studied the possible relationship between the sunspot/flocculi group areas and their corresponding angular velocity. There are strong indications that the rotational velocity of a sunspot/flocculi group is reduced (in relation to the differential rotation law) when its maximum area is larger.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Adams, W.S., Lasby, J.B.: 1911, An Investigation of the Rotation Period of the Sun by spectroscopic methods 138, Carnegie Inst., Washington, 118. https://ia600301.us.archive.org/26/items/investigationofr00adamrich/investigationofr00adamrich.pdf .
Astronomer Royal: 1924, The Rotational Period of the Sun Derived from Measures of Solar Faculae. Mon. Not. Roy. Astron. Soc. 84, 431. ADS .
Carrington, R.C.: 1863, Observations of the Spots on the Sun from November 9, 1853 to March 24, 1861 made at Redhill, Williams and Norgate, London, Edinburgh. https://archive.org/details/observationsofsp00carr .
Casas, R., Vaquero, J.M.: 2015, The solar rotation in the period 1853–1870 from the sunspot catalogues of Carrington, Peters, and de la Rue. Solar Phys. 290, 2189. DOI . ADS .
Curto, J.J., Solé, J.G., Genescà, M., Blanca, M.J., Vaquero, J.M.: 2016, Historical Heliophysical Series of the Ebro Observatory. Solar Phys. DOI .
DeLury, R.E.: 1939, The law of the solar rotation. J. Roy. Astron. Soc. Can. 33, 345. ADS .
Dyson, F.W., Maunder, E.W.: 1913, The Position of the Sun’s Axis as determined from photographs of the Sun from 1874 1912, measured at the Royal Observatory, Greenwich. Mon. Not. Roy. Astron. Soc. 73, 673. DOI . ADS .
Faye, H.: 1865, Comptes rendus Acad. Sci. Paris 60, 89 and 138.
Fox, P.: 1921, The rotation period of the sun as determined from measures of plates taken with the Rumford spectroheliograph, Pub. Yerkes Observatory 3, University of Chicago Press, Chicago. ADS .
Gigolashivli, M.Sh., Japaridze, D.R., Mdzinarishvili, T.G., Chargeishvili, B.B.: 2005, N–S Asymmetry in the Solar Differential Rotation. Solar Phys. 227, 27. DOI . ADS .
Gupta, S.S., Sivaraman, K.R., Howard, R.F.: 1999, Measurement of Kodaikanal White-Light Images – III. Rotation Rates and Activity Cycle Variations. Solar Phys. 188, 225. DOI ADS .
Hale, G.E.: 1908, Preliminary note on the rotation of the Sun as determined from the motions of the hydrogen flocculi. In: Contributions from the Mount Wilson Observatory 25, Carnegie Institution of Washington, Washington, 1. ADS .
Hale, G.E., Fox, P.: 1908, The rotation period of the sun as determined from the motions of the calcium flocculi, Pub. No. 93. Carnegie Institution of Washington, Washington. ADS .
Hathaway, D.H., Wilson, R.M.: 1990, Solar rotation and the sunspot cycle. Astrophys. J. 357, 271. DOI ADS .
Javaraiah, J.: 2003, Long-Term Variations in the Solar Differential Rotation. Solar Phys. 212, 23. DOI . ADS .
Kempf, P.: 1916, Pub. Astrophys. Observ. Potsdam 71. ADS .
Maunder, E.W., Maunder, A.S.D.: 1905, Mon. Not. Roy. Astron. Soc. 65, 813. DOI . ADS .
Nesme-Ribes, E., Ferreira, E.N., Mein, P.: 1993, Astron. Astrophys. 274, 563. ADS .
Newton, H.W., Nunn, M.L.: 1951, The Sun’s rotation derived from sunspots 1934-1944 and additional results. Mon. Not. Roy. Astron. Soc. 111, 413. DOI . ADS .
Rodés, L.: 1929–1937, Heliofísica. Boletín mensual del Observatorio del Ebro. Publicaciones del Observatorio del Ebro 28. adsbit.harvard.edu/cgi-bin/iarticle_query?journal=BMOE.&volume=0028&type=SCREEN_THMB .
Snodgrass, H.B., Ulrich, R.K.: 1990, Rotation of Doppler features in the solar photosphere. Astrophys. J. 351, 309. DOI . ADS .
Ward, F.: 1966, Determination of the solar rotation rate from the motion of identifiable features. Astrophys. J. 145, 416. DOI . ADS .
Zappala, R.A., Zuccarello, F.: 1991, Angular velocities of sunspot-groups and solar photospheric rotation. Astron. Astrophys. 242, 480. ADS .
Acknowledgements
First of all, this work has been possible thanks to the recovery and digitalization of some sunspot/flocculi catalogs published at the beginning of the twentieth century by the Ebro Observatory. The authors would like to thank Jordi Vega and María José Blanca for their effort in digitalizing Ebro solar bulletins, and Alberto Gómez and Núria de Paula for their support. Ricard Casas acknowledges the financial support received from the Spanish Ministerio de Ciencia e Innovación (MICINN), project ESP2013-48274.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Disclosure of Potential Conflicts of Interest
The authors declare that they have no conflicts of interest.
Rights and permissions
About this article
Cite this article
de Paula, V., Curto, J.J. & Casas, R. The Solar Rotation in the 1930s from the Sunspot and Flocculi Catalogs of the Ebro Observatory. Sol Phys 291, 2269–2279 (2016). https://doi.org/10.1007/s11207-016-0974-2
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11207-016-0974-2