Results 11 to 20 of about 1,877,814 (242)

The lost sunspot cycle: Reanalysis of sunspot statistics [PDF]

Astronomy & Astrophysics, 2003
We have recently suggested that one low sunspot cycle was possibly lost in 1790s (Usoskin et al. 2001, A&A, 370, L31). In this paper we present the results of a rigorous statistical analysis of all available sunspot observations around the suggested additional cycle minimum in 1792-1793.
I. G. Usoskin, K. Mursula, G. A. Kovaltsov   +2 more
openaire   +2 more sources

Bistability in the sunspot cycle [PDF]

Europhysics Letters
Abstract A direct dynamical test of the sunspot cycle is carried out to indicate that a stochastically forced nonlinear oscillator characterizes its dynamics. The sunspot series is then decomposed into its eigen time-delay coordinates.
Vashishtha, Sumit, Sreenivasan, Katepalli   +1 more
core   +6 more sources

An upper limit prediction of the peak sunspot number for solar cycle 24

Journal of Space Weather and Space Climate, 2011
In this paper we address the prediction of the maximum sunspot number in solar cycle 24. We correlate the integral sunspot activity related to the variability of the cycle decrease speed in the declining phase with the height of the next sunspot maximum.
Van der Linden R., Podladchikova T.
doaj   +2 more sources

Solar activity cycle 25: the first three years

Solar-Terrestrial Physics, 2023
We analyze features of current solar activity cycle 25 for the first three years of its development (2020–2022). Compared to cycle 24, the current cycle is shown to exceed the previous one in the number of sunspot groups (1.5 times), the number of flares
Yazev S. A., Isaeva E. S., Hos-Erdene B.   +2 more
doaj   +1 more source

Change of Sunspot Groups Observed from 2002 to 2011 at ButterStar Observatory [PDF]

Journal of Astronomy and Space Sciences, 2012
Since the development of surface magnetic features should reflect the evolution of the solar magnetic field in the deep interior of the Sun, it is crucial to study properties of sunspots and sunspot groups to understand the physical processes working ...
Sung-Jin Oh, Heon-Young Chang
doaj   +1 more source

Von Lindener's sunspot data: sunspot group number and individual sunspot number

, 2023
Hayakawa et al. (2023) derived sunspot group number and individual sunspot number from von Liindener's records. These data have been extracted from von Lindener's manuscript (Akc.1985/15) in the Library of Wrocław University and Bode (1819).
早川, 尚志, Hayakawa, Hisashi
core   +1 more source

Katsue Misawa's sunspot data: sunspot group number and individual sunspot number

, 2023
These files show Katsue Misawa's sunspot observations with her 3-inch rafractor telescope from 1921 to 1934.
早川, 尚志, Hayakawa, Hisashi
core   +1 more source

Properties of sunspots in cycle 23 [PDF]

Astronomy & Astrophysics, 2007
In this paper we investigate the dependence of umbral core brightness, as well as the mean umbral and penumbral brightness on the phase of the solar cycle and on the size of the sunspot. Albregtsen & Maltby (1978) reported an increase in umbral core brightness from the early to the late phase of solar cycle from the analysis of 13 sunspots which ...
Mathew, S., Martínez Pillet, V., Solanki, S., Krivova, N.   +3 more
openaire   +3 more sources

Katsue Misawa's sunspot drawngs: 1921 -- 1934

, 2023
These files show Katsue Misawa's sunspot observations with her 3-inch rafractor telescope from 1921 to 1934. Their original records are preserved in Misawa Memorial Archives.
Misawa, Katsue, 三澤, 勝衛
core   +1 more source

Frequency of Solar Spotless Days and Flare Index as Indices of Solar Cycle Activity [PDF]

Journal of Astronomy and Space Sciences, 2014
There was a research on the prolongation of solar cycle 23 by the solar cyclic variation of solar, interplanetary geomagnetic parameters by Oh & Kim (2013).
Suyeon Oh
doaj   +1 more source