5 research outputs found
The effect of flares on total solar irradiance
Flares are powerful energy releases occurring in stellar atmospheres. Solar
flares, the most intense energy bursts in the solar system, are however hardly
noticeable in the total solar luminosity. Consequently, the total amount of
energy they radiate 1) remains largely unknown and 2) has been overlooked as a
potential contributor to variations in the Total Solar Irradiance (TSI), i.e.
the total solar flux received at Earth. Here, we report on the detection of the
flare signal in the TSI even for moderate flares. We find that the total energy
radiated by flares exceeds the soft X-ray emission by two orders of magnitude,
with an important contribution in the visible domain. These results have
implications for the physics of flares and the variability of our star.Comment: accepted in Nature Physic
Exploiting solar visible-range observations by inversion techniques: from flows in the solar subsurface to a flaring atmosphere
Observations of the Sun in the visible spectral range belong to standard
measurements obtained by instruments both on the ground and in the space.
Nowadays, both nearly continuous full-disc observations with medium resolution
and dedicated campaigns of high spatial, spectral and/or temporal resolution
constitute a holy grail for studies that can capture (both) the long- and
short-term changes in the dynamics and energetics of the solar atmosphere.
Observations of photospheric spectral lines allow us to estimate not only the
intensity at small regions, but also various derived data products, such as the
Doppler velocity and/or the components of the magnetic field vector. We show
that these measurements contain not only direct information about the dynamics
of solar plasmas at the surface of the Sun but also imprints of regions below
and above it. Here, we discuss two examples: First, the local time-distance
helioseismology as a tool for plasma dynamic diagnostics in the near subsurface
and second, the determination of the solar atmosphere structure during flares.
The methodology in both cases involves the technique of inverse modelling.Comment: 29 pages, 15 figures. Accepted for publication in the book "Reviews
in Frontiers of Modern Astrophysics: From Space Debris to Cosmology" (eds
Kabath, Jones and Skarka; publisher Springer Nature) funded by the European
Union Erasmus+ Strategic Partnership grant "Per Aspera Ad Astra Simul"
2017-1-CZ01-KA203-03556