Radio eyes for the Sun, Heliosphere and Ionosphere: Status and plans for the LOFAR2.0 era.
Abstract
The Low-Frequency Array (LOFAR) has established itself as a formidable instrument in the field of solar physics and spaceweather, providing a unique vantage point for observing the Sun, heliosphere, and ionosphere. As we transition into the LOFAR2.0 era, this abstract outlines the current status and future plans for leveraging LOFAR's capabilities, and the LOFAR IDOLS (Incremental Development of LOFAR Space-weather) project.LOFAR's current work in solar physics involves high-resolution imaging and dynamic spectral analysis, enabling detailed observations of solar radio bursts and other coronal heliosphere and ionosphere phenomena. These observations are critical for understanding the mechanisms behind solar activity and improving our predictive models of space weather events.
The LOFAR IDOLS station, a dedicated space-weather science facility, has been instrumental in advancing this work. It currently provides continuous monitoring of the ionosphere and Sun, tracking disturbances that can affect space wetaher on Earth, but also the astronomical observations of LOFAR itself. The LOFAR2.0 upgrade promises to enhance these capabilities significantly. Plans include improving the sensitivity and spatial resolution of the array, and the simoultaneus observations in LBA and HBA, which will allow for even more precise and broad imaging and tracking of solar phenomena. This will enable researchers to dissect the fine structures within the solar corona and track the development of space weather events with greater accuracy. Furthermore, the LOFAR IDOLS project is set to continue observation during the period of transition to LOFAR2.0 enabling us to test the monitorning capabilities. In conclusion, the LOFAR2.0 era opens a new opportunity for solar and space weather research. With the ongoing work and future plans for the LOFAR IDOLS station and LOFAR2.0 observations, we are preparing to gain deeper insights into the Sun's influence on our space environment and to develop more robust forecasting capabilities for space weather phenomena.
On the Propagation of Shock Waves in the Transition Region and the Corona
Abstract
The chromosphere exhibits various acoustic waves that are generated in
the photosphere or deeper layers due to convective motions. As these
waves encounter the steep density gradient between the photosphere and
the chromosphere, they transform into shock waves, often characterized
by a sawtooth pattern in λ-time plots of chromospheric spectral lines,
such as Hα and Ca II. In this study, we investigate the formation and
propagation of these shock waves in the chromosphere, examining their
possible implications in the higher solar atmosphere using observations
from the Multi Application Solar Telescope (MAST), the Swedish 1-meter
Solar Telescope (SST), the Interface Region Imaging Spectrograph (IRIS),
and the Solar Dynamics Observatory (SDO). Our results show that these
shock waves are predominantly observed in or near magnetic flux
concentration regions and can propagate at least up to the transition
region. In this talk, I will discuss the identification of these shock
waves, their propagation characteristics, and their potential implications
for coronal dynamics.
Electron Density Mapping: Insights from Radio and In-Situ Observations & EUHFORIA Modeling
Abstract
Mapping the coronal electron density remains a challenging task,
as we still rely on rather old 1D electron density models, most of which
are derived from remote sensing observations and lack validation with in
situ measurements. The novel observations from Parker Solar Probe (PSP)
provide a unique opportunity to validate these models and enhance space
weather modeling capabilities.
In this study, we analyze type III radio bursts observed during PSP’s
second perihelion. By employing radio triangulation, we estimate the 3D
radio source positions and map the electron densities along the burst
propagation path. These results are then compared with in situ electron
density measurements from PSP. Additionally, we use EUHFORIA (European
Heliospheric Forecasting Information Asset) to model electron densities at
the PSP location and the radio source positions.
Our findings indicate that bursts occurring within a few minutes from the
same source can exhibit significantly different propagation paths. A
comparison between radio-derived and in situ densities reveals a
discrepancy of one order of magnitude. We also perform simulations using
GONG and ADAPT-GONG magnetic maps as input. Both simulations suggest that
type III bursts propagate along higher-density regions; however, results
obtained with ADAPT-GONG maps show a better match with PSP in situ
densities and predict higher density values overall. These results
highlight the importance of validating remote sensing electron density
models with in situ observations and demonstrate the impact of different
magnetic field inputs on space weather modeling. The improved agreement
with ADAPT-GONG maps suggests that incorporating more dynamic and
data-driven models can enhance the accuracy of electron density
estimations, ultimately improving our understanding of solar wind
structures and radio wave propagation in the heliosphere.