Research Highlights
Research Highlights
A selection of highlights culled from publications by HAO staff.
Atomic structure calculations of Land ́e g factors of astrophysical interest with direct applications for solar coronal magnetometry
We perform a detailed theoretical study of the atomic structure of ions with ns2npm ground configurations and focus on departures from LS coupling which directly affect the Land ́e g factors of magnetic dipole lines between levels of the ground terms.
Investigation of a neutral ‘tongue’ observed by GOLD during the geomagnetic storm on May 11,2019
The National Aeronautics and Space Administration Global-scale observations of the Limb and Disk (GOLD) mission observed a unique structure of thermospheric column density ratio of O to N2 (∑O/N2) during a geomagnetic storm on day of year (DOY) 130 (May 10) to DOY 132 in 2019. The percentage difference of ∑O/N2 between the storm time (DOY 131) and the quiet time (DOY 128) had a relatively enhanced ∑O/N2 region sandwiched by two depleted regions over North America and the Atlantic Ocean in the Northern Hemisphere.
Measuring the magnetic origins of solar flares, CMEs and Space Weather
We take a broad look at the problem of identifying the magnetic solar causes of space weather. The challenges are best met through a combination of near UV lines of bright Mg II, and lines of Fe II and Fe I (mostly within the 4s − 4p transition array) which form in the chromosphere up to 20,000 K.
A comparison of Fabry-Perot interferometer and meteor radar wind measurements near the polar mesopause region
The neutral winds in the Mesosphere and Lower Thermosphere (MLT) region have been observed at King Sejong Station, Antarctica using a meteor radar and a Fabry-Perot interferometer (FPI) simultaneously. These two independent MLT wind measurements are compared to each other to identify the characteristics of FPI measurement.
Ultra-Fast Kelvin Wave (UFKW) Variations in the Surface Magnetic Field
Kelvin waves are large scale wave that is important for Earth’s atmosphere. The Ultra-Fast Kelvin waves (UFKW) are a subset of the Kelvin waves that can propagate to the mesosphere and lower thermosphere (MLT) ~100km and above due to their high zonal phase speeds.
Magnetic structure of the solar chromosphere-corona transition regions
The bulk of the emission from the plasma called "transition region" plasma originates from structures energetically connected both to the chromosphere and corona. This result resolves decades of debate and opens the door to measuring magnetic energy and its evolution in the corona using transition region emission lines.
On single-point inversions of magnetic dipole lines in the corona
Prompted by a recent paper by Dima and Schad, we re-consider the problem of inferring magnetic properties of the corona using polarimetric observations of magnetic dipole (M1) lines.
Deciphering Deep-Origin of Active Regions From Analysis Of Magnetograms
Dikpati, et. al., derive magnetic toroids from surface magnetograms by employing a novel optimization method based on Trust Region Reflective algorithm.
Design of a Highly Efficient Polychromatic Full-Stokes Polarization Modulator for the CRISP Imaging Spectrometer
In 2014 HAO built a polarimetric modulator for the CRISP instrument on the Swedish 1-m Solar Telescope in La Palma, using the principles of polychromatic modulation previously developed by HAO scientists. This paper discusses the processes by which the modulator was designed, built, and tested. The modulator was installed and had been in use since 2015. It is working at close to optimal efficiency and has produced considerable scientific output.