E-Print Archive

There are 3872 abstracts currently viewable.


Search:

Advanced Search
Options
Main Page Add New E-Print Submitter
Information
Feedback
News Help/FAQ About Preferences
Manage Key Phrase
Notification
High-wavenumber solar f-mode strengthening prior to active region formation View all abstracts by submitter

Axel Brandenburg   Submitted: 2017-10-21 07:56

We report a systematic strengthening of the local solar surface or fundamental f-mode 1-2 days prior to the emergence of an active region (AR) in the same (corotating) location. Except for a possibly related increase in the kurtosis of the magnetic field, no indication can be seen in the magnetograms at that time. Our study is motivated by earlier numerical findings of Singh et al. (2014) which showed that, in the presence of a nonuniform magnetic field that is concentrated a few scale heights below the surface, the f-mode fans out in the diagnostic kω diagram at high wavenumbers. Here we explore this possibility using data from the Helioseismic and Magnetic Imager on board the Solar Dynamics Observatory and show for six isolated ARs, 11130, 11158, 11242, 11105, 11072, and 11768, that at large latitudinal wavenumbers (corresponding to horizontal scales of around 3000 km), the f-mode displays strengthening about two days prior to AR formation and thus provides a new precursor for AR formation. Furthermore, we study two ARs, 12051 and 11678, apart from a magnetically quiet patch lying next to AR~12529, to demonstrate the challenges in extracting such a precursor signal when a newly forming AR emerges in a patch that lies in close proximity of one or several already existing ARs which are expected to pollute neighboring patches. We then discuss plausible procedures for extracting precursor signals from regions with crowded environments. The idea that the f-mode is perturbed days before any visible magnetic activity occurs at the surface can be important in constraining dynamo models aimed at understanding the global magnetic activity of the Sun.

Authors: Singh, N. K., Raichur, H., & Brandenburg, A.
Projects: None

Publication Status: Astrophys. J. 832, 120 (2017)
Last Modified: 2017-10-21 18:40
Go to main E-Print page  Magnetic swirls and associated fast magnetoacoustic kink waves in a solar chromospheric flux tube  Block-induced complex structures building the flare-productive solar active region 12673  Edit Entry  Download Preprint  Submitter's Homepage Delete Entry 

Key
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
Two Episodes of Magnetic Reconnections During a Confined Circular-ribbon Flare
Enhanced stellar activity for slow antisolar differential rotation?
Quasi-periodic pulsations in the most powerful solar flare of Cycle 24
GONG Catalog of Solar Filament Oscillations Near Solar Maximum
Chromospheric response during the precursor and the main phase of a B6.4 flare on August 20, 2005
Unambiguous Evidence of Coronal Implosions During Solar Eruptions and Flares
Two Types of Long-duration Quasi-static Evolution of Solar Filaments
Oscillations of cometary tails: a vortex shedding phenomenon?
Observations of Running Penumbral Waves Emerging in a Sunspot
Reconnection in the Post-Impulsive Phase of Solar Flares
Temperature of source regions of 3He-rich impulsive solar energetic particles events
3He-rich Solar Energetic Particles in Helical Jets on the Sun
On the importance of the nonequilibrium ionization of Si IV and O IV and the line-of-sight in solar surges
Was the cosmic ray burst detected by the GRAPES-3 on 22 June 2015 caused by transient weakening of geomagnetic field or by an interplanetary anisotropy?
Connecting Coronal Mass Ejections to Their Solar Active Region Sources: Combining Results from the HELCATS and FLARECAST Projects
Studies of Isolated and Non-isolated Photospheric Bright Points in an Active Region Observed by the New Vacuum Solar Telescope
Fermi-LAT observations of the 2017 September 10th solar flare
Propagation of a global coronal wave and its interaction with large-scale coronal magnetic structures
A New Tool for CME Arrival Time Prediction Using Machine Learning Algorithms: CAT-PUMA
Solar Magnetoseismology with Magnetoacoustic Surface Waves in Asymmetric Magnetic Slab Waveguides

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



© 2003 Solar Physics Group - Montana State University