Related papers: Stellar Cosmic Rays in a Habitable Zone
We present the results of a search for stellar flares from stars neighbouring the target sources in the Kepler short cadence data. These flares have been discarded as contaminants in previous surveys and therefore provide an unexplored…
Magnetic fields on hot stars can produce a variety of interesting effects on the velocity, density, and temperature structure in the winds from the stars. The fields can produce a longitudinal dependence of the mass flux, which would lead…
The theory of radiatively driven winds successfully explains the key points of the stellar winds of hot massive stars. However, there is an apparent break-down of this paradigm at L/Lsun<5.2: the stellar wind momentum is smaller than…
A young and energetic pulsar powers the well-known Crab Nebula. Here we describe two separate gamma-ray (photon energy >100 MeV) flares from this source detected by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. The…
X-rays have significant impacts on cold, weakly ionized protoplanetary disks by increasing the ionization rate and driving chemical reactions. Stellar flares are explosions that emit intense X-rays and are the unique source of hard X-rays…
The mechanism accelerating cosmic rays in the Milky Way Galaxy and galaxy clusters is identified and described. The acceleration of cosmic rays is a purely electrostatic process which operates up to the maximum energies of $10^{23}$ eV in…
Starspots and stellar flares are indicators of stellar magnetic activity.The magnetic energy stored around spots is thought to be the origin of flares, but the connection is not completely understood. To investigate the relation between…
We characterize the magnetic activity of M dwarfs to provide the planet community with information on the energy input from the star; in particular, in addition to the frequency of optical flares directly observed with TESS, we aim at…
One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic inter-cloud medium (ICM) which has density nH ~ 1 per cubic cm, gas must accumulate from a volume several hundred pc…
How do the characteristics of starspots influence the triggering of stellar flares? Here we investigate the activity of two K-type stars, similar in every way from mass to rotation periods and planetary systems. Both stars exhibit about a…
We have analyzed a number of intense X-ray flares observed in the Chandra Orion Ultradeep Project (COUP), a 13 days observation of the Orion Nebula Cluster (ONC). Analysis of the flare decay allows to determine the size, peak density and…
About 10% of hot stars host a fossil magnetic field on the pre-main sequence and main sequence. However, the first magnetic evolved hot stars have been discovered only recently. An observing program has been set up to find more such…
Recently, two nearby prominent starburst galaxies, M82 and NGC253, have been detected as point-like sources with gamma-ray telescopes at TeV energies [1] [2]. It has been claimed that these detections show that the cosmic ray intensity in…
Strong magnetic fields in magnetospheres of neutron stars (especially magnetars) and other astrophysical objects may release their energy in violent, intense episodes of magnetic reconnection. While reconnection has been studied…
Pulsars can act as an excellent probe of the Milky Way magnetic field. The average strength of the Galactic magnetic field component parallel to the line of sight can be estimated as $\langle B_\parallel \rangle = 1.232 \,…
We investigated how the magnetic field in solar active regions (ARs) controls flare activity, i.e., whether a confined or eruptive flare occurs. We analyzed 44 flares of GOES class M5.0 and larger that occurred during 2011--2015. We used 3D…
Main sequence M stars pose an interesting problem for astrobiology: their abundance in our galaxy makes them likely targets in the hunt for habitable planets, but their strong chromospheric activity produces high energy radiation and…
Approximately 10% of B-type stars possess strong magnetic fields, and of these, 25% host centrifugal magnetospheres (CMs) in which the radiative wind, magnetic field, and rotational support interact to form a dense circumstellar plasma…
The recent discoveries of several reliable events of high energy cosmic rays at an energy above 10^20 eV raise questions about their path through the nearby universe. The two analyses of the Haverah Park data set and the Akeno data set…
Observations have suggested that some low-mass stars have larger radii than predicted by 1-D structure models. Some theoretical models have invoked very strong interior magnetic fields (of order 1 MG or more) as a possible cause of such…