Related papers: Intense geomagnetic storm during Maunder minimum p…
Geomagnetic storms are an important aspect of space weather and can result in significant impacts on space- and ground-based assets. The majority of strong storms are associated with the passage of interplanetary coronal mass ejections…
Forecasting geomagnetic storms is highly important for many space weather applications. In this study we review performance of the geomagnetic storm forecasting service StormFocus during 2011--2016. The service was implemented in 2011 at…
The Sun experienced a period of unprecedented activity during the 20th century, now called the Modern Maximum (MM). The decay of the MM after cycle 19 has changed the Sun, the heliosphere, and the planetary environments in many ways.…
Recent work has revealed an phenomenological picture of the how the $\sim$11-year sunspot cycle of Sun arises. The production and destruction of sunspots is a consequence of the latitudinal-temporal overlap and interaction of the toroidal…
Magnetic fields emerging from the Sun's interior carry information about physical processes of magnetic field generation and transport in the convection zone. Soon after appearance on the solar surface the magnetic flux gets concentrated in…
We present observations of the formation process of a small-scale filament on the quiet Sun during 5-6 February 2016 and investigate its formation cause. Initially, a small dipole emerged and its associated arch filament system was found to…
Observations of rapidly-rotating cool stars often show coronal slingshot prominences that remove mass and angular momentum when they are ejected. The derived masses of these prominences show a scatter of some two orders of magnitude. In…
We investigate the solar origin and heliospheric evolution of an intense geomagnetic storm that occurred on March 23-24, 2023. Despite multiple candidate CMEs observed between March 19-21, a weak CME detected on March 19 at 18:00 UT was…
HD 166620 was recently identified as a Maunder Minimum candidate based on nearly 50 years of Ca II H & K activity data from Mount Wilson and Keck-HIRES (Baum et al. 2022). These data showed clear cyclic behavior on a 17-year timescale…
Fluctuations in the Sun's magnetic activity, including episodes of grand minima such as the Maunder minimum have important consequences for space and planetary environments. However, the underlying dynamics of such extreme fluctuations…
Magnetic storms on stars manifest as remarkable, randomly occurring changes of the luminosity over durations that are tiny in comparison to the normal evolution of stars. These stellar flares are bursts of electromagnetic radiation from…
Recent studies of radioisotopes in tree rings or ice cores suggest that extreme space weather events occurred in the pre-telescope age. Observational records of naked-eye sunspots and low-latitude auroras in historical documents in…
We present an analysis of a Suzaku observation taken during the geomagnetic storm of 2005 August 23-24. We found time variation of diffuse soft X-ray emission when a coronal mass ejection hit Earth and caused a geomagnetic storm. The…
Like the solar cycle, stellar activity cycles are also irregular. Observations reveal that rapidly rotating (young) Sun-like stars exhibit a high level of activity with no Maunder-like grand minima and rarely display smooth regular activity…
The Carrington storm in 1859 is considered to be the major geomagnetic disturbance related to solar activity. In a recent paper, Cid et al. (2015) discovered a geomagnetic disturbance case with a profile extraordinarily similar to the…
(adapted)Considering recent observations challenging the traditional magnetar model, we explore the wind braking of magnetars. There is evidence for strong multipole magnetic fields in active magnetars, but the dipole field inferred from…
Strong coronal magnetic field, when present, manifests itself as bright microwave sources at high frequencies produced by gyroresonant (GR) emission mechanism in thermal coronal plasma. The highest frequency at which this emission is…
We could infer a secular decreasing trend in the poloidal to toroidal solar magnetic flux amplification factor ( Af) using geomagnetic observations ( classic and IHV corrected aa indices) during the sunspot cycles 9-23. A similar decreasing…
Recently, a transient localized brightness enhancement has been observed in Jupiter's main auroral emission close to noon by Palmaerts et al. (2014). We use results from three-dimensional global MHD simulations to understand what is causing…
Space weather events produce variations in the electric current in the Earth's magnetosphere and ionosphere. From these high altitude atmospheric regions, resulting geomagnetically induced currents (GICs) can lead to fluctuations in ground…