E-Print Archive

There are 4396 abstracts currently viewable.


Advanced Search
Main Page Add New E-Print Submitter
News Help/FAQ About Preferences
Manage Key Phrase
ALMA observations of the variability of the quiet Sun at millimeter wavelengths View all abstracts by submitter

Alexander Nindos   Submitted: 2021-06-14 01:28

Aims. We address the variability of the quiet solar chromosphere at 1.26 mm and 3 mm with a focus on the study of spatially resolved oscillations and transient brightenings, i.e. small, weak events of energy release. Both phenomena may have a bearing on the heating of the chromosphere. Methods. We used Atacama Large Millimeter/submillimeter Array (ALMA) observations of the quiet Sun at 1.26 mm and 3 mm. The spatial and temporal resolution of the data were 1-2" and 1 s, respectively. The concatenation of light curves from different scans yielded a frequency resolution in spectral power of 0.5-0.6 mHz. At 1.26 mm, in addition to power spectra of the original data, we degraded the images to the spatial resolution of the 3 mm images and used fields of view of equal area for both data sets. The detection of transient brightenings was made after the effect of oscillations was removed. Results. At both frequencies we detected p-mode oscillations in the range 3.6-4.4 mHz. The corrections for spatial resolution and field of view at 1.26 mm decreased the rms of the oscillations by factors of 1.6 and 1.1, respectively. In the corrected data sets, the oscillations at 1.26 mm and 3 mm showed brightness temperature fluctuations of ~1.7-1.8% with respect to the average quiet Sun, corresponding to 137 and 107 K, respectively. We detected 77 transient brightenings at 1.26 mm and 115 at 3 mm. Although their majority occurred in cell interior, the occurrence rate per unit area of the 1.26 mm events was higher than that of the 3 mm events and this conclusion does not change if we take into account differences in spatial resolution and noise levels. The energy associated with the transient brightenings ranged from 1.8 x 1023 to 1.1 x 1026 erg and from 7.2 x1023 to 1.7 x 1026 erg for the 1.26 mm and 3 mm events, respectively. The corresponding power-law indices of the energy distribution were 1.64 and 1.73. We also found that ALMA bright network structures corresponded to dark mottles/spicules seen in broadband Hα images from the GONG network. Conclusions. The fluctuations associated with the p-mode oscillations represented a fraction of 0.55-0.68 of the full power spectrum. Their energy density at 1.26 mm was 3 x 10-2 erg cm-3. The computed low-end energy of the 1.26 mm transient brightenings is among the smallest ever reported, irrespective of the wavelength of observation. Although the occurrence rate per unit area of the 1.26 mm transient brightenings was higher than that of the 3 mm events their power per unit area is smaller probably due to the detection of many weak 1.26 mm events.

Authors: A. Nindos, S. Patsourakos, C.E. Alissandrakis, T.S. Bastian
Projects: ALMA

Publication Status: A&A accepted for publication
Last Modified: 2021-06-16 08:40
Go to main E-Print page  Investigating Remote-sensing Techniques to Reveal Stealth Coronal Mass Ejections  The Poissonian origin of power laws in solar flare waiting time distributions  Edit Entry  Download Preprint  Delete Entry 

Go to main E-Print pageGo to main E-Print page.
Previous AbstractPrevious Abstract.
Next AbstractNext Abstract.
Download PreprintDownload Preprint.
Submitter's HomepageSubmitters Homepage.
Edit EntryEdit Entry.
View All Abstracts By SubmitterView all abstracts by submitter.
Delete AbstractDelete abstract.

Latest Entries
The Solar Memory From Hours to Decades
Solar chromosphere heating and generation of plasma outflows by impulsively generated two-fluid Alfvén waves
Radio evidence for a shock wave reflected by a coronal hole
Hemispheric sunspot numbers 1874 - 2020
Temperature in Solar Sources of 3He-rich Solar Energetic Particles and Relation to Ion Abundances
The long period of 3He-rich solar energetic particles measured by Solar Orbiter 2020 November 1723
Tracing Hα Fibrils through Bayesian Deep Learning
Energetics and 3-D Structure of Elementary Events in Solar Coronal Heating
Forecasting the Remaining Duration of an Ongoing Solar Flare
A fundamental mechanism of solar eruption initiation
Thermal Trigger for Solar Flares III: Effect of the Oblique Layer Fragmentation
Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops
Characteristic time of stellar flares on Sun-like stars
M-dwarf's Chromosphere, Corona and Wind Connection via the Nonlinear Alfvén Wave
Bayesian evidence for a nonlinear damping model for coronal loop oscillations
Small-scale Turbulent Motion of the Plasma in a Solar Filament as the Precursor of Eruption
Validation of the PDFI_SS method for electric field inversions using a magnetic flux emergence simulation
Investigation on the Spatiotemporal Structures of Supra-Arcade Spikes
Magnetic helicity and energy budget around large confined and eruptive solar flares
One dimensional prominence threads: I. Equilibrium models

Related Pages
MSU Solar Physics.
Max Millennium Science Mail Archive.
Max Millennium Message of the Day Mail Archive.
Max Millennium Flare Catalog

Archive Maintainer
Alisdair Davey

© 2000-2020 Solar Physics Group - Montana State University