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Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features  

Scott McIntosh   Submitted: 2014-03-12 23:41

Sunspots are a canonical marker of the Sun's internal magnetic field which flips polarity every ~22-years. The principal variation of sunspots, an ~11-year variation in number, modulates the amount of magnetic field that pierces the solar surface and drives significant variations in our Star's radiative, particulate and eruptive output over that period. This paper presents observations from the Solar and Heliospheric Observatory and Solar Dynamics Observatory indicating that the 11-year sunspot variation is intrinsically tied it to the spatio-temporal overlap of the activity bands belonging to the 22-year magnetic activity cycle. Using a systematic analysis of ubiquitous coronal brightpoints, and the magnetic scale on which they appear to form, we show that the landmarks of sunspot cycle 23 can be explained by considering the evolution and interaction of the overlapping activity bands of the longer scale variability.

Authors: Scott W. McIntosh, Xin Wang, Robert J. Leamon, Alisdair R. Davey, Rachel Howe, Larisza D. Krista, Anna V. Malanushenko, Jonathan W. Cirtain, Joseph B. Gurman, Michael J. Thompson
Projects: SDO-AIA,SDO-HMI

Publication Status: To be submitted ApJ
Last Modified: 2014-03-13 09:28
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Observing Episodic Coronal Heating Events Rooted in Chromospheric Activity  

Scott McIntosh   Submitted: 2009-10-13 12:57

We present results of a multi-wavelength study of episodic plasma injection into the corona of AR 10942. We exploit long-exposure images of the Hinode and Transition Region and Coronal Explorer (TRACE) spacecraft to study the properties of faint, episodic, ''blobs'' of plasma that are propelled upward along coronal loops that are rooted in the AR plage. We find that the source location and characteristic velocities of these episodic upflow events match those expected from recent spectroscopic observations of faint coronal upflows that are associated with upper chromospheric activity, in the form of highly dynamic spicules. The analysis presented ties together observations from coronal and chromospheric spectrographs and imagers, providing more evidence of the connection of discrete coronal mass heating and injection events with their source, dynamic spicules, in the chromosphere.

Authors: Scott W. McIntosh & Bart De Pontieu
Projects: Hinode/SOT

Publication Status: in press ApJL.
Last Modified: 2009-10-14 07:58
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Time-Distance Seismology of the Solar Corona with CoMP  

Scott McIntosh   Submitted: 2009-03-12 05:34

We employ a sequence of Doppler images obtained with the Coronal Multi-channel Polarimeter (CoMP) instrument to perform time-distance seismology of the solar corona. We construct the first k-omega diagrams of the region. These allow us to separate outward and inward propagating waves and estimate the spatial variation of the plane-of-sky projected phase speed, and the relative amount of outward and inward directed wave power. The disparity between outward and inward wave power and the slope of the observed power law spectrum indicate that low-frequency Alfvénic motions suffer significant attenuation as they propagate, consistent with isotropic MHD turbulence.

Authors: Steven Tomczyk & Scott W. McIntosh
Projects: None

Publication Status: ApJ (in press)
Last Modified: 2009-03-12 08:06
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The Inconvenient Truth About Coronal Dimmings  

Scott McIntosh   Submitted: 2008-11-24 13:46

We investigate the occurrence of a CME-driven coronal dimming using unique high resolution spectral images of the corona from the Hinode spacecraft. Over the course of the dimming event we observe the dynamic increase of non-thermal line broadening in the 195.12? emission line of Fe XII as the corona opens. As the corona begins to close, refill and brighten, we see a reduction of the non-thermal broadening towards the pre-eruption level. We propose that the dynamic evolution of non-thermal broadening is the result of the growth of Alfvén wave amplitudes in the magnetically open rarefied dimming region, compared to the dense closed corona prior to the CME. We suggest, based on this proposition, that, as open magnetic regions, coronal dimmings must act just as coronal holes and be sources of the fast solar wind, but only temporarily. Further, we propose that such a rapid transition in the thermodynamics of the corona to a solar wind state may have an impulsive effect on the CME that initiates the observed dimming. This last point, if correct, poses a significant physical challenge to the sophistication of CME modeling and capturing the essence of the source region thermodynamics necessary to correctly ascertain CME propagation speeds, etc.

Authors: Scott W. McIntosh
Projects: Hinode/EIS

Publication Status: Submitted ApJ - rerouted to ApJL
Last Modified: 2008-11-25 05:50
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A Coherence-Based Approach for Tracking Waves inthe Solar Corona  

Scott McIntosh   Submitted: 2008-08-19 17:09

We consider the problem of automatically (and robustly) isolating and extracting information about waves and oscillations observed in EUV image sequences of the solar corona with a view to near real-time application to data from the Atmospheric Imaging Array (AIA) on the Solar Dynamics Observatory (SDO). We find that a simple coherence / travel-time based approach detects and provides a wealth of information on transverse and longitudinal wave phenomena in the test sequences provided by the Transition Region and Coronal Explorer (TRACE). The results of the search are "pruned" (based on diagnostic errors) to minimize false-detections such that the remainder provides robust measurements of waves in the solar corona, with the calculated propagation speed allowing automated distinction between various wave modes. In this paper we discuss the technique, present results on the TRACE test sequences, and describe how our method can be used to automatically process the enormous flow of data (~1Tb/day) that will be provided by SDO/AIA after launch in late 2008.

Authors: Scott W. McIntosh, Bart De Pontieu & Steven Tomczyk
Projects: TRACE

Publication Status: Solar Physics (in press)
Last Modified: 2008-09-23 20:51
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Observations Supporting the Role of Magnetoconvection in Energy Supply to the Quiescent Solar Atmosphere  

Scott McIntosh   Submitted: 2006-07-17 11:42

Identifying the two physical mechanisms behind the production and sustenance of the quiescent solar corona and solar wind poses two of the outstanding problems in solar physics today. We present analysis of spectroscopic observations from the Solar and Heliospheric Observatory (SOHO) that are consistent with a single physical mechanism being responsible for a significant portion of the heat supplied to the lower solar corona and the initial acceleration of the solar wind; the ubiquitous action of magnetoconvection-driven reprocessing and reconnection of the Sun's magnetic field. We deduce that the reconnection released plasma can either provide thermal input to the quiet solar corona or become a tributary to the solar wind is simply related to the global magnetic environment in which it is rooted.

Authors: Scott W. McIntosh, Alisdair R. Davey and Donald M. Hassler
Projects: SoHO-MDI,SoHO-SUMER

Publication Status: Submitted
Last Modified: 2006-07-17 11:43
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Simple Magnetic Flux Balance as an Indicator of Neon VIII Doppler Velocity Partitioning in an Equatorial Coronal Hole  

Scott McIntosh   Submitted: 2006-07-17 11:38

We present a novel investigation into the relationship between simple estimates of magnetic flux balance and the Ne VIII Doppler velocity partitioning of a large equatorial coronal hole observed by the Solar Ultraviolet Measurements of Emitted Radiation spectrometer (SUMER) on the Solar and Heliospheric Observatory (SOHO) in November 1999. We demonstrate that a considerable fraction of the large scale Doppler velocity pattern in the coronal hole can be qualitatively described by simple measures of the local magnetic field conditions, i.e., the relative unbalance of magnetic polarities and the radial distance required to balance local flux concentrations with those of opposite polarity.

Authors: Scott W. McIntosh, Alisdair R. Davey and Donald M. Hassler
Projects: SoHO-MDI,SoHO-SUMER

Publication Status: In Press
Last Modified: 2006-07-17 11:38
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Abstracts by Author
Deciphering Solar Magnetic Activity I: On The Relationship Between The Sunspot Cycle And The Evolution Of Small Magnetic Features
Observing Episodic Coronal Heating Events Rooted in Chromospheric Activity
Time-Distance Seismology of the Solar Corona with CoMP
The Inconvenient Truth About Coronal Dimmings
A Coherence-Based Approach for Tracking Waves in the Solar Corona
Observations Supporting the Role of Magnetoconvection in Energy Supply to the Quiescent Solar Atmosphere
Simple Magnetic Flux Balance as an Indicator of Neon VIII Doppler Velocity Partitioning in an Equatorial Coronal Hole

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

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