000005698 001__ 5698
000005698 005__ 20220314092751.0
000005698 037__ $$aSCART-2022-0046
000005698 100__ $$aTiwari, S. K.
000005698 245__ $$aSolO/EUI Observations of Ubiquitous Fine-scale Bright Dots in an  Emerging Flux Region: Comparison with a Bifrost MHD Simulation
000005698 260__ $$c2022
000005698 520__ $$a We report on the presence of numerous tiny bright dots in and around an emerging flux region (an X-ray/coronal bright point) observed with SolO's EUI/\hri\ in 174 \AA. These dots are roundish, have a diameter of 675$\pm$300 km, a lifetime of 50$\pm$35 seconds, and an intensity enhancement of 30\% $\pm$10\% above their immediate surroundings. About half of the dots remain isolated during their evolution and move randomly and slowly ($<$10 \kms). The other half show extensions, appearing as a small loop or surge/jet, with intensity propagations below 30\,\kms. Many of the bigger and brighter \hri\ dots are discernible in SDO/AIA 171 \AA\ channel, have significant emissivity in the temperature range of 1--2 MK, and are often located at polarity inversion lines observed in HMI LOS magnetograms. Although not as pervasive as in observations, Bifrost MHD simulation of an emerging flux region do show dots in synthetic \fe\ images. These dots in simulation show distinct Doppler signatures -- blueshifts and redshifts coexist, or a redshift of the order of 10 \kms\ is followed by a blueshift of similar or higher magnitude. The synthetic images of \oxy\ and \siiv\ lines, which represent transition region radiation, also show the dots that are observed in \fe\ images, often expanded in size, or extended as a loop, and always with stronger Doppler velocities (up to 100 \kms) than that in \fe\ lines. Our observation and simulation results, together with the field geometry of dots in the simulation, suggest that most dots in emerging flux regions form in the lower solar atmosphere (at $\approx$1 Mm) by magnetic reconnection between emerging and pre-existing/emerged magnetic field. Some dots might be manifestations of magneto-acoustic shocks through the line formation region of \fe\ emission.
000005698 594__ $$aSTCE
000005698 6531_ $$aEUI
000005698 6531_ $$aEUV
000005698 6531_ $$aactive regions
000005698 700__ $$aHansteen, V. H.
000005698 700__ $$aDe Pontieu, B.
000005698 700__ $$aBerghmans, D.
000005698 773__ $$pApJ$$y2022
000005698 8560_ $$fdavid.berghmans@observatoire.be
000005698 85642 $$ahttp://arxiv.org/abs/2203.06161
000005698 905__ $$aaccepted to be published in
000005698 980__ $$aREFERD