MOMO. IV. The Complete Swift X-Ray and UV/Optical Light Curve and Characteristic Variability of the Blazar OJ 287 during the Last Two Decades

We have been carrying out a dense monitoring of the blazar OJ 287 with Swift since late 2015 as part of our project MOMO (Multiwavelength Observations and Modeling of OJ 287). This is the densest existing monitoring of OJ 287 involving X-ray/UV data. In this latest publication of a sequence, we characterize the multiwavelength variability of OJ 287 based on >4000 Swift single-wave-band data sets including archival data since 2005. A structure function analysis reveals a characteristic timescale of ∼5 days in the optical–UV at epochs of low-level activity and larger during outbursts. The discrete correlation function shows zero lag between optical and UV, with τ = 0 ± 1 day at the epoch of densest cadence. During outbursts (in 2016/17 and 2020) the X-rays follow the UV with near-zero lags. However, during quiescence, the delay is 7–18 days with X-rays leading or lagging, interpreted as due to a different X-ray component dominated by inverse Compton emission. Scaling relations are used to derive the characteristic length scales of the broad-line region and torus in OJ 287. A remarkable, symmetric UV–optical deep fade is identified in late 2017, lasting 2 months. We rule out occultation from the passage of a dusty cloud and a model where the secondary black hole deflects the jet between the primary and observer. We speculate about a temporary dispersion or jet swing event in the core or in a bright quasi-stationary jet feature. The deep fade reveals an additional, spatially distinct X-ray component. The epoch 2020.9–2021.1 was searched for precursor flare activity predicted by the binary black hole model of OJ 287.

Distributed electric current and its relation to ultraviolet radiation of the active region

We utilized full magnetic field vector magnetogramsacquired by the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) to calculate vertical electric currents in the NOAA active region (AR) 12192. The AR was tracked between October 22, 2014 and October 25, 2014 with 720 s cadence. We revealed the presence of a large-scale electric current structure – distributed electric current – with the absolute magnitude varying in the range of (40–90)·1012 A. The distributed electric current is supposed to exist throughout the entire AR, and, extending to the upper layers of the solar atmosphere in one part of the AR, it closes through the chromosphere and corona in the remaining part of the AR. To test this assumption, we have compared the temporal variation of the distributed electric current value with the flare activity level (using GOES-15 data), as well as with intensity of ultraviolet radiation (UV) in the AR (using the Atmospheric Imaging Assembly (AIA/SDO) data in channels 94 Å, 193 Å, 304 Å, and 1600 Å). We found that: i) Time intervals of enhanced flare activity are co-temporal with intervals of increased values of the distributed electric current. The absence of rapid changes in the value of the distributed electric current during solar flares can be explained by high inductance of the current-carrying magnetic loops. ii) Rough estimates of the magnetic energy carried by the distributed electric current into the corona yield the values of about 1033–1034 erg for 12192. Onlya small amount of this energy is released during flare processes in the AR. Most of this energy seems to be consumed during other dissipative processes in the corona. iii) Comparison of the temporal variations of intensity in the 193 Å UV-radiation channel with dynamics of the distributed electric current in the AR reveals a good positive correlation between these values (Pearson’s R = 0.63). The absence of a correlation between the distributed electric current value and the intensity of UV radiation in channels 1600 Å, 304 Å and 94 Å might be explained by a low efficiency of the coronal loop heating by ohmic dissipation of electric currents in the corona due to the strong dependence of plasma conductivity on temperature. iv) Our results may support the concept of equivalent LRC circuit of a current-carrying coronal magnetic loop proposed by Alfven and Carlqvist in 1967 and developed by V.V. Zaitsev, A.V. Stepanov, and others. According to this model, the large-scale electric currents must exist in the upper layers of the solar atmosphere and take part in the coronal plasma heating.

Extreme Space Weather Events during the First Cycles of Epochs with Decreased Solar Activity

The problem of the distribution of extreme and very strong magnetic storms with intensities (G5, G4) in the first cycles (12 and 24) of epochs of lowered solar activity was considered based on homogeneous series of the geomagnetic index Aa with allowance for the modern scale of the intensity of disturbances in the near-Earth space and the scenario of solar cyclicity. The significant decrease in the number of such events and active solar phenomena in the last cycle may indicate that the sunspot and flare activity in solar cycle 12 was significantly higher than that in cycle 24, but it was significantly lower than in solar cycles of the epoch of increased solar activity.

Social and Clinical Impact of COVID-19 on Patients with Fibrodysplasia Ossificans Progressiva

Background COVID-19, caused by the SARS-CoV-2 virus, is a severe inflammatory condition. Patients with pre-existing conditions including diabetes, hypertension, and cardiovascular disease are at particularly high risk of complications. Fibrodysplasia ossificans progressiva (FOP) is an ultra-rare and debilitating genetic disorder that is characterized by a pro-inflammatory state, which leads to progressive heterotopic ossification and complications after trauma, including intramuscular vaccinations. To better understand the impact of COVID-19 on patients with FOP, we first examined the social impact of the pandemic using data from the FOP Registry managed by the International FOP Association. We also identified patients with FOP who were exposed to or contracted the SARS-CoV-2 virus, or who received a COVID-19 vaccine, to investigate if patients with FOP were at increased risks of complications from SARS-CoV2 exposure. Results Data from 326 individuals in 69 countries were examined in the International FOP Association FOP Connection Registry using patient-reported outcomes measurement information system (PROMIS) global health scale scores. Twenty-six (28.9%) participants aged ≥ 15 years old rated their satisfaction with their social activities and relationships as poor in 2020, which was an increase from 18 (18.9%) in 2019, prior to the SARS-CoV-2 outbreak. Similar trends were noted for physical and mental health in the pediatric population. Frequency of physician visits was not changed, but a larger portion of patients reported missing dental visits in 2020 compared with 2019 (31.5% vs. 41.7%). A second cohort with 32 subjects was tracked after SARS-CoV-2 exposure or vaccination. Ten subjects were positively diagnosed with COVID-19, 15 received a COVID-19 vaccine, and seven had high-risk SARS-CoV-2 exposure but either did not have a confirmed clinical diagnosis or tested negative. Subjects who tested positive for the virus showed no major complications or increased FOP disease activity, though our sample size is very limited. Among the 15 subjects who received a COVID-19 vaccine, using the International Clinical Council on FOP guidelines for prophylaxis with ibuprofen or acetaminophen, only one person experienced flare activity at the injection site. Conclusions Patients with FOP showed a significant decrease in social activities that was reflective of the isolation and mobility changes in this debilitated population. In our limited cohort, the majority of the patients with FOP who tested positive for COVID-19 showed no major complications. Also, although limited in sample size, the majority of patients who received a COVID-19 vaccination and followed guidelines from the FOP International Clinical Council tolerated vaccination well. Only one person experiencing flare activity following their injection. Thus, the risks and benefits of COVID-19 vaccination needs to be discussed carefully so as to support informed decisions.

The Journey to Net Zero: Driving Down Emissions from Bp's North Sea Operations

bp's strategy sets out a decadeof delivery towards becoming a net zero company by 2050 (or sooner) with targets set for emissions from operations to fall by between 30-35% by 2030. In pursuit of this, a North Sea carbonplan has been developed to identify, track, and deliver sustainable emission reductions (SERs) activities. Proactive engagement has been essential in delivery of this plan, helping to empower colleagues to prioritize emissions reduction opportunities. To date, the plan has identified more than 80 SERs across bp's North Seaportfolio and cumulatively reduced carbonemissions by more than 400,000 tonnes from offshore operations. It is on track to reduce almost 70,000tonnes of carbon from operations in 2021 alone. Whilst it is recognised that this represents only part of bp's annual scope 1 emissions in the North Sea; this is a lasting operational improvement. The plan has also significantly reduced sources of unknown flare gas. It also contributed to a 45% reduction in flare activity in 2020 vs 2019as well as achieving zero routine flaringon two of bp's major west of Shetland installations from October 2020 The plan has more deeply embedded emissions tracking in operations on and offshore and helped further improve working practices on flaring and energy efficiency in general.

Periodic Variation of Solar Flare Index for the Last Solar Cycle (Cycle 24)

In this study, we used the flare index (FI) data taken from Kandilli Observatory for the period of 2009–2020. The data sets are analyzed in three categories as Northern Hemisphere, Southern Hemisphere, and total FI data sets. Total FI data set is obtained from the sum of Northern and Southern Hemispheric values. In this study, the periodic variations of abovementioned three categories FI data sets were investigated by using the MTM and Morlet wavelet analysis methods. The wavelet coherence (XWT) and cross wavelet (WTC) analysis methods were also performed between these data sets. As a result of our analysis, the following results were found: (1) long- and short-term periodicities ( 2048 ± 512 day and periodicities smaller than 62 days) exist in all data sets without any exception at least with 95 % confidence level; (2) all periodic variations were detected maximum during the solar cycle, while during the minima, no meaningful period is detected; (3) some periodicities have data preference that about 150 days Rieger period appears only in the whole data set and 682-, 204-, and 76.6-day periods appear only in the Northern Hemisphere data sets; (4) During the Solar Cycle 24, more flare activity is seen at the Southern Hemisphere, so the whole disk data periodicities are dominated by this hemisphere; (5) in general, there is a phase mixing between Northern and Southern Hemisphere FI data, except about 1024-day periodicity, and the best phase coherency is obtained between the Southern Hemisphere and total flare index data sets; (6) in case of the Northern and Southern Hemisphere FI data sets, there is no significant correlation between two continuous wavelet transforms, but the strongest correlation is obtained for the total FI and Southern Hemisphere data sets.

A PULSATING FLARE STAR IN THE NEW PLANETARY SYSTEM: KOI-258

We present findings about the nature of KOI-258. Its temperature was found to be 6500 ± 200 K from its spectrum, which also indicates that the target is a single main sequence star despite the existence of a radial velocity variation with a small amplitude. Ca II H, K lines indicate the existence of magnetic activity, though there is no remarkable excess or variation in the Hα line. We found 51 flares with a frequency of 0.00186 h−1, whose plateau value is 0.659 s. Apart from the flares, we found 420 frequencies due to solar-like oscillations at out-of-eclipses. Removing these 420 frequencies, we demonstrated three different transits caused by three exo-planets. Their radii were found to be 2.33 R_⊕ for the first planet, 0.53 R_⊕ for the second one, and 1.15 R_⊕ for the third planet. Consequently, KOI-258 is an oscillating, single, main sequence star, with in a planetary system and remarkable flare activity.

The effect of a solar flare on chromospheric oscillations

ABSTRACT Oscillations in the solar atmosphere have long been observed both in quiet conditions and during solar flares. The chromosphere is known for its 3-min signals, which are strong over sunspot umbrae, and have periods determined by the chromosphere’s acoustic cut-off frequency. A small number of observations have shown the chromospheric signals to be affected by energetic events such as solar flares, however the link between flare activity and these oscillations remains unclear. In this work, we present evidence of changes to the oscillatory structure of the chromosphere over a sunspot which occurs during the impulsive phase of an M1 flare. Using imaging data from the CRISP instrument across the H α and Ca ii 8542 Å spectral lines, we employed a method of fitting models to power spectra to produce maps of where there is evidence of oscillatory signals above a red-noise background. Comparing results taken before and after the impulsive phase of the flare, we found that the oscillatory signals taken after the start of the flare differ in two ways: the locations of oscillatory signals had changed and the typical periods of the oscillations had tended to increase (in some cases increasing from <100 s to ∼200 s). Both of these results can be explained by a restructuring of the magnetic field in the chromosphere during the flare activity, which is backed up by images of coronal loops showing clear changes to magnetic connectivity. These results represent one of the many ways that active regions can be affected by solar flares.