Unveiling the magnetic nature of chromospheric vortices
Journal
Date Issued
2020
Author(s)
•
Shetye, J.
•
•
Verwichte, E.
•
Arber, T.
•
•
•
Goffrey, T.
Abstract
Vortex structures in the Sun's chromosphere are believed to channel energy
between different layers of the solar atmosphere. We investigate the nature and
dynamics of two small-scale quiet-Sun rotating structures in the chromosphere.
We analyse two chromospheric structures that show clear rotational patterns in
spectropolarimetric observations taken with the Interferometric Bidimensional
Spectrometer (IBIS) at the Ca II 8542 \AA~ line. We present the detection of
spectropolarimetric signals that manifest the magnetic nature of rotating
structures in the chromosphere. Our observations show two long-lived structures
of plasma that each rotate clockwise inside a 10 arcsec$^{2}$~ quiet-Sun
region. Their circular polarization signals are 5-10 times above the noise
level. Line-of-sight Doppler velocity and horizontal velocity maps from the
observations reveal clear plasma flows at and around the two structures. An MHD
simulation shows these two structures are plausibly magnetically connected.
Wave analysis suggests that the observed rotational vortex pattern could be due
to a combination of slow actual rotation and a faster azimuthal phase speed
pattern of a magneto-acoustic mode. Our results imply that the vortex
structures observed in the Sun's chromosphere are magnetic in nature and that
they can be connected locally through the chromosphere.
Volume
639
Start page
A59
Issn Identifier
0004-6361
Rights
open.access
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