Related papers: Superflares and Giant Planets
We report the latest statistical analyses of superflares on solar-type (G-type main-sequence; effective temperature is 5100 - 6000 K) stars using all of the $Kepler$ primary mission data, and $Gaia$-DR2 (Data Release 2) catalog. We updated…
We present a theoretical model describing magnetar giant flares on the basis of solar flare/coronal mass ejection theory. In our model, a preflare activity plays a crucial role in driving evaporating flows and supplying baryonic matters…
We study the energy release process of a set of 51 flares (32 confined, 19 eruptive) ranging from GOES class B3 to X17. We use H$\alpha$ filtergrams from Kanzelh\"ohe Observatory together with SDO HMI and SOHO MDI magnetograms to derive…
Magnetic reconnection is a rapid energy release process that is believed to be responsible for flares on the Sun and stars. Nevertheless, such flare-related reconnection is mostly detected to occur in the corona, while there have been few…
Solar CMEs and flares have a statistically well defined relation, with more energetic X-ray flares corresponding to faster and more massive CMEs. How this relation extends to more magnetically active stars is a subject of open research.…
Sunspots and solar flares are two different manifestations of magnetic activity on the surface of the Sun. On the Sun, flares typically occur close to spots. In this paper we test this the connection between spots and flares on other stars.…
White-light flares are magnetically driven localized brightenings on the surfaces of stars. Their temporal, spectral, and statistical properties present a treasury of physical information about stellar magnetic fields. The spatial…
Massive stars (those larger than 8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7\% of massive stars have…
Observations of nearby star forming clouds with imaging X-ray telescopes have revealed that X-ray emission is elevated $10^1-10^4$ above main sequence levels in low-mass pre-main sequence (PMS) stars. The variability and spectral X-ray…
Solar-type stars exhibit their highest levels of magnetic activity during their early convective pre-main sequence (PMS) phase of evolution. The most powerful PMS flares, super-flares and mega-flares, have peak X-ray luminosities of…
An investigation of the G-type stellar population with Kepler (as done by Maehara et al.) shows that less than 1 per cent of those stars show superflares. Due to the large pixel scale of Kepler ($\sim4 arcsec \: px^{-1}$), it is still not…
Recent observations of solar type stars with the Kepler satellite by Maehara et al. have revealed the existence of superflares (with energy of 10^33 - 10^35 erg) on Sun-like stars, which are similar to our Sun in their surface temperature…
We report on the results of high dispersion spectroscopy of two `superflare stars', KIC 9766237, and KIC 9944137 with Subaru/HDS. Superflare stars are G-type main sequence stars, but show gigantic flares compared to the Sun, which have been…
Magnetic-field reconnection is believed to play a fundamental role in magnetized plasma systems throughout the Universe1, including planetary magnetospheres, magnetars and accretion disks around black holes. This letter present extreme…
We analyze the correlation between starspots and superflares on solar-type stars using observations from the Kepler mission. The analysis shows that the observed fraction of stars with superflares decreases as the rotation period increases…
Solar flares sometimes lead to coronal mass ejections that directly affect the Earth's environment. However, a large fraction of flares, including on solar-type stars, are confined flares. What are the differences in physical properties…
Solar flares are often accompanied by filament/prominence eruptions ($\sim10^{4}$ K and $\sim 10^{10-11}$ cm$^{-3}$), sometimes leading to coronal mass ejections (CMEs) that directly affect the Earth's environment. `Superflares' are found…
High-mass microquasars are binary systems composed by a massive star and a compact object from which relativistic jets are launched. Regarding the companion star, observational evidence supports the idea that winds of hot stars are formed…
We analyzed the occurrence rates of flares on stars of spectral types K, G, F, and A, observed by Kepler. We found that the histogram of occurrence frequencies of stellar flares is systematically shifted towards a high-energy tail for…
In many star-planet systems discovered so far, the innermost planet orbits within only a few stellar radii. In these systems, planets could become in-situ probes of the extended stellar magnetic field. Because they disturb the field as they…