Nearly Century-scale Variation of the Sun’s Radius

Hiremath, K. M.; Rozelot, J. P.; Sarp, Volkan; Kılçık, Ali; Pavan, D G; Gurumath, Shashanka R.

doi:10.3847/1538-4357/ab6d08

Cited by 5 publications

(5 citation statements)

References 47 publications

(46 reference statements)

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“…Presenting their data in either physical or digital form, such archives have been used to derive information about the evolution of plage regions (e.g. Antonucci et al 1977;Ermolli et al 2009b;Dorotovic et al 2010;Chatzistergos et al 2016Chatzistergos et al , 2019bBarata et al 2018;Tlatov & Tlatova 2019, and references therein), the solar radius variations (Meftah et al 2018;Hiremath et al 2020), network cell properties (e.g. Berrilli et al 1999;Ermolli et al 2003;Chatterjee et al 2017;Raju 2018), photometric properties of disc features over the solar cycle (e.g.…”

Section: Introductionmentioning

confidence: 99%

Analysis of full-disc Ca II K spectroheliograms

Chatzistergos

Ermolli

Krivova

et al. 2020

A&A

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Context. Studies of long-term solar activity and variability require knowledge of the past evolution of the solar surface magnetism. The archives of full-disc Ca II K observations that have been performed more or less regularly at various sites since 1892 can serve as an important source of such information. Aims. We derive the plage area evolution over the last 12 solar cycles by employing data from all Ca II K archives that are publicly available in digital form, including several as-yet-unexplored Ca II K archives. Methods. We analysed more than 290 000 full-disc Ca II K observations from 43 datasets spanning the period between 1892–2019. All images were consistently processed with an automatic procedure that performs the photometric calibration (if needed) and the limb-darkening compensation. The processing also accounts for artefacts affecting many of the images, including some very specific artefacts, such as bright arcs found in Kyoto and Yerkes data. Our employed methods have previously been tested and evaluated on synthetic data and found to be more accurate than other methods used in the literature to treat a subset of the data analysed here. Results. We produced a plage area time-series from each analysed dataset. We found that the differences between the plage areas derived from individual archives are mainly due to the differences in the central wavelength and the bandpass used to acquire the data at the various sites. We empirically cross-calibrated and combined the results obtained from each dataset to produce a composite series of plage areas. The ’backbone’ approach was used to bridge the series together. We have also shown that the selection of the backbone series has little effect on the final composite of the plage area. We quantified the uncertainty of determining the plage areas with our processing due to shifts in the central wavelength and found it to be less than 0.01 in fraction of the solar disc for the average conditions found on historical data. We also found the variable seeing conditions during the observations to slightly increase the plage areas during the activity maxima. Conclusions. We provide the most complete so far time series of plage areas based on corrected and calibrated historical and modern Ca II K images. Consistent plage areas are now available on 88% of all days from 1892 onwards and on 98% from 1907 onwards.

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Section: Introductionmentioning

confidence: 99%

Analysis of full-disc Ca II K spectroheliograms

Chatzistergos

Ermolli

Krivova

et al. 2020

A&A

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“…Interestingly, the observed planetary relation allows the reconstruction of the direction and eventually the duration of the putative invisible stream. In the present case, the reconstructed direction is at heliocentric longitudes around 155°, and its duration is less than ~6 months; these first rough estimates are a spin-off from this research and may be used in the future, as longer lasting datasets will become available (see, for example, [13,14]).…”

Section: Discussionmentioning

confidence: 77%

“…Furthermore, occasionally planetary gravitational focusing effects can significantly enhance the flux of slow constituents from the dark sector; this implies that the pile-up of a relatively small energy deposition per interaction could trigger energetic events. If the generic IMM has also some preferential incidence direction, future long-lasting observations of the Sun's shape might provide an asymmetry that could be utilized to identify the not isotropic influx of the assumed IMM [13,14]. This research presents the first observation of a planetary relationship for the Sun's radius variation; this would be an additional strong fingerprint from the dark sector since planetary gravitational focusing effects that can occur within the solar system require small velocities, as those are expected for the constituents from the dark Universe (~10 −3 c).…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the Origin of the Rhythmic Sun’s Radius Variation

2022

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Based on helioseismological measurements (1996–2017), the entire Sun shrinks during solar maximum and regrows during the next solar minimum by about a few km (~10−5 effect). Here, we observe, for the first time, that the solar radius variation resembles a 225-day relationship that coincides with Venus’ orbital period. We show that a remote link between planet Venus and Sun’s size must be at work. However, within known realms of physics, this is unexpected. Therefore, we can only speculate about its cause. Notably, the driving idea behind this investigation was some generic as-yet-invisible matter from the dark Universe. In fact, the 11-year solar cycle shows planetary relationships for a number of other observables as well. It has been proposed that the cause must be due to some generic streaming invisible massive matter (IMM). As when a low-speed stream is aligned toward the Sun with an intervening planet, the IMM influx increases temporally due to planetary gravitational focusing, assisted eventually with the free fall of incident slow IMM. A case-specific simulation for Venus’ impact supports the tentative scenario based on this investigation’s driving idea. Importantly, Saturn, combined with the innermost planets Mercury or Venus, unambiguously confirms an underlying planetary correlation with the Sun’s size. The impact of the suspected IMM accumulates with time, slowly triggering the underlying process(es); the associated energy change is massive even though it extends from months to several years. This study shows that the Sun’s size response is as short as half the orbital period of Mercury (44 days) or Venus (112 days). Then, the solar system is the target and the antenna of still unidentified external impact, assuming tentatively from the dark sector. If the generic IMM also has some preferential incidence direction, future long-lasting observations of the Sun’s shape might provide an asymmetry that could be utilized to identify the not isotropic influx of the assumed IMM.

show abstract

“…Whether in physical or digital form, such archives have been used to derive information about the evolution of plage regions (e.g. Antonucci et al 1977;Ermolli et al 2009b;Dorotovič et al 2010;Chatzistergos et al 2016Chatzistergos et al , 2019bBarata et al 2018;Tlatov & Tlatova 2019, and references therein), the solar radius variations (Meftah et al 2018;Hiremath et al 2020), network cell properties (e.g. Berrilli et al 1999;Ermolli et al 2003;Chatterjee et al 2017;Raju 2018), photometric properties of disc features over the solar cycle (e.g.…”

Section: Introductionmentioning

confidence: 99%

Analysis of full disc Ca II K spectroheliograms III. Plage area composite series covering 1892-2019

Chatzistergos,

Ermolli,

Krivova

et al. 2020

Preprint

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Context. Studies of long-term solar activity and variability require knowledge of the past evolution of the solar surface magnetism. An important source of such information are the archives of full-disc Ca II K observations performed more or less regularly at various sites since 1892. Aims. We derive the plage area evolution over the last 12 solar cycles employing data from all Ca II K archives available publicly in digital form known to us, including several as yet unexplored Ca II K archives. Methods. We analyse more than 290,000 full-disc Ca II K observations from 43 datasets spanning the period 1892-2019. All images were consistently processed with an automatic procedure that performs the photometric calibration (if needed) and the limb-darkening compensation. The processing also accounts for artefacts plaguing many of the images, including some very specific artefacts such as bright arcs found in Kyoto and Yerkes data. The employed methods have previously been tested and evaluated on synthetic data and found to be more accurate than other methods used in the literature to treat a subset of the data analysed here. Results. We have produced a plage area time-series from each analysed dataset. We found that the differences between the plage areas derived from individual archives are mainly due to the differences in the central wavelength and the bandpass used to acquire the data at the various sites. We have empirically cross-calibrated and combined the results obtained from each dataset to produce a composite series of plage areas. "Backbone" series are used to bridge all the series together. We have also shown that the selection of the backbone series has little effect on the final plage area composite. We have quantified the uncertainty of determining the plage areas with our processing due to shifts in the central wavelength and found it to be less than 0.01 in fraction of the solar disc for the average conditions found on historical data. We also found the variable seeing conditions during the observations to slightly increase the plage areas during activity maxima. Conclusions. We provide the so far most complete time series of plage areas based on corrected and calibrated historical and modern Ca II K images. Consistent plage areas are now available on 88% of all days from 1892 onwards and on 98% from 1907 onwards.

show abstract

Nearly Century-scale Variation of the Sun’s Radius

Cited by 5 publications

References 47 publications

Analysis of full-disc Ca II K spectroheliograms

Analysis of full-disc Ca II K spectroheliograms

On the Origin of the Rhythmic Sun’s Radius Variation

Analysis of full disc Ca II K spectroheliograms III. Plage area composite series covering 1892-2019

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