Antipodal Flares
From RHESSI Wiki
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[http://stereo.gsfc.nasa.gov/spacecraft.shtml STEREO]. | [http://stereo.gsfc.nasa.gov/spacecraft.shtml STEREO]. | ||
RHESSI of course can only see such events at the exact limb, as illustrated | RHESSI of course can only see such events at the exact limb, as illustrated | ||
- | Figure 1, since otherwise an antipodal flare counterpart would be occulted, and hence not be observable. | + | Figure 1, since otherwise an antipodal flare counterpart would be occulted, and hence not be readily observable. |
[[File:197f1.png|thumb|center|800px| | [[File:197f1.png|thumb|center|800px| | ||
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collision with a much larger mass. | collision with a much larger mass. | ||
]] | ]] | ||
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Prior to these RHESSI results, it had not been realized that the antipodal | Prior to these RHESSI results, it had not been realized that the antipodal | ||
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intensely near a point, where one could imagine the triggering of energy | intensely near a point, where one could imagine the triggering of energy | ||
release in a unstable region could occur. | release in a unstable region could occur. | ||
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Another problem with the known properties of the flare-induced seismic waves | Another problem with the known properties of the flare-induced seismic waves | ||
- | is the fact of their existence in the first place. | + | is the mere fact of their existence in the first place. |
An apt analogy of a coronal disturbance and a photospheric response might be | An apt analogy of a coronal disturbance and a photospheric response might be | ||
found in the thought-experiment of bouncing a table-tennis ball off of a | found in the thought-experiment of bouncing a table-tennis ball off of a | ||
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and yet the observed energy in flare seismic waves may be of order | and yet the observed energy in flare seismic waves may be of order | ||
10<sup>-3</sup> (e.g., ref. [3]) of the flare total! | 10<sup>-3</sup> (e.g., ref. [3]) of the flare total! | ||
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+ | Something more is needed, and the RHESSI signatures noted above may well provide | ||
+ | the necessary clue. | ||
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+ | == Heliogammonium == | ||
We believe that RHESSI's observations of hard photons in antipodal | We believe that RHESSI's observations of hard photons in antipodal | ||
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[http://www.universetoday.com/53563/who-discovered-helium/ discovery of helium] | [http://www.universetoday.com/53563/who-discovered-helium/ discovery of helium] | ||
itself in the Sun. | itself in the Sun. | ||
- | The properties of the new heliogammonium particle remain to be elucidated, along with | + | The properties of the new heliogammonium particle remain to be elucidated, along with those of |
- | many other | + | many other exotic new particles that have been proposed in the world of particle physics |
+ | (see our earlier [http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=50 axion] Nugget). | ||
== References == | == References == |
Revision as of 17:02, 30 March 2013
Nugget | |
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Number: | 197 |
1st Author: | W. Pecos |
2nd Author: | B. Paul |
Published: | 2013 April 1 |
Next Nugget: | TBD |
Previous Nugget: | Observational evidence for breakout reconnection |
List all |
Contents |
Introduction
Antipodal flares
The RHESSI field of vew covers the whole Sun all the time, but its images can only extend to a few arc min (nominal FWHM about 3 arc min) (see a previous Nugget or the actual specifications for details). This means that very large-scale features, such as those noted recently in SDO/AIA observations (e.g., Ref. [1]), may at first glance have eluded discovery. We report here an analysis of large-scale variations that suggest the common occurrence of flares with an antipodal orientation, ie at opposite ends of a solar diameter. These events may have escaped earlier notice because of the uniqueness of our vantage point at Earth, prior to the adevnt of STEREO. RHESSI of course can only see such events at the exact limb, as illustrated Figure 1, since otherwise an antipodal flare counterpart would be occulted, and hence not be readily observable.
In Figure 1, the arc of the limb gives a rough idea of the flare location in azimuth around the limb. The existence of polar antipodal flares (lower row) was an unexpected result of the search described here.
Excitation of seismic disturbances
The near-simultaneous occurence of these antipodal pairs of events implies a causal connection, via Occam's Razor, in the body of the Sun - rather than in its tenuous corona. If so the best-known such link is the excitation of interior acoustic waves, first observed in 1997, but having been predicted by C. Wolff long before that time (Ref. [2]). Figure 2 (left) illustrates how the interior of the Sun refracts acoustic waves, allowing their propagation between opposite hemispheres. Because of the high temperature of the solar interior, the wave propagation time is only some tens of minutes.
Prior to these RHESSI results, it had not been realized that the antipodal focusing of waves induced by a flare at one point, could in fact trigger a comparably large energy release at the antipode. Note that in Figure 2 (left) the waves clearly disperse and do not focus intensely near a point, where one could imagine the triggering of energy release in a unstable region could occur.
Another problem with the known properties of the flare-induced seismic waves is the mere fact of their existence in the first place. An apt analogy of a coronal disturbance and a photospheric response might be found in the thought-experiment of bouncing a table-tennis ball off of a bowling ball (see sketch in Figure 2, right panel). In such a collision between disparate masses, the requirement for conservation of momentum dictates that very little energy be coupled. The mass ratio of a flare and the Sun may be of order 10-19), and yet the observed energy in flare seismic waves may be of order 10-3 (e.g., ref. [3]) of the flare total!
Something more is needed, and the RHESSI signatures noted above may well provide the necessary clue.
Heliogammonium
We believe that RHESSI's observations of hard photons in antipodal flares, as illustrated above, points to a solution to this problem: a heretofore-unrecognized and weakly-interacting particle, created during the flare gamma-ray energy release, could serve to concentrate and transport the momentum associated with the flare eruption through the solar interior as a focused beam, enabling a resonance with the chance unstable region at the antipodal location. We tentatively call this new particle heliogammonium, noting the earlier discovery of helium itself in the Sun. The properties of the new heliogammonium particle remain to be elucidated, along with those of many other exotic new particles that have been proposed in the world of particle physics (see our earlier axion Nugget).
References
[2] "Free Oscillations of the Sun and Their Possible Stimulation by Solar Flares"
[3] "Seismic Emission from the Solar Flares of 2003 October 28 and 29"
RHESSI Nugget Date | 1 April 2013 + |
RHESSI Nugget First Author | W. Pecos + |
RHESSI Nugget Index | 197 + |
RHESSI Nugget Second Author | B. Paul + |