http://sprg.ssl.berkeley.edu/~tohban/nuggets/ RHESSI Nuggets rss-feeden-us 60 H. Jabran Zahid and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=85 2008-09-29 14:00:00 GMT RHESSI makes optical images as well as X-ray and gamma-ray ones. This Nugget explains how. Brian Dennis and Richard Starr http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=84 2008-09-15 14:00:00 GMT MESSENGER is now exploring Mercury. It is also helping RHESSI to understand the solar X-ray spectrum and measure elemental abundances in flares. Hazel Miller Bain and Lyndsay Fletcher http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=83 2008-08-27 14:00:00 GMT Observations during the rise phase of a M5.4 flare suggests that hard x-rays may be associated with a jet observed by TRACE. Hugh Hudson and Beate Stelzer http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=82 2008-08-11 14:00:00 GMT In this nugget, we explore an extrasolar flare (aka stellar flare). These stellar and solar flares are similar but it is often in subtle differences that we may learn the most. Steven Christe and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=81 2008-08-28 14:00:00 GMT Another look at microflare positions... Hugh Hudson and Brian Welsch http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=80 2008-07-14 14:00:00 GMT The sudden energy release of a flare in the solar atmosphere has many consequences. One of them may be the McClymont Jerk. David Long and Peter Gallagher http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=79 2008-06-30 14:00:00 GMT New analyses indicate that the low time cadence of EIT may produce erroneously low values for "EIT wave" speeds, and thus confuse the interpretation of the phenomenon. Jabran Zahid and Steven Christe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=78 2008-06-16 14:00:00 GMT The RHESSI Solar Aspect System is used to observe faculae which are then compared with RHESSI microflares. Yan Xu http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=77 2008-06-04 14:00:00 GMT Evidence for tether-cutting is observed in a flare on October 29, 2003. Lyndsay Fletcher and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=76 2008-05-21 14:00:00 GMT From the original observation made at Carrington's manor house to satellite observatories, the exploration of white-light flares continues... Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=75 2008-05-06 14:00:00 GMT The new solar cycle is coming fast and so are the solar conferences! Jana Kasparova http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=74 2008-04-21 14:00:00 GMT Should we consider new models for solar flares? A study of emission anisotropy may provide the answer. Hugh Hudson and Säm Krucker http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=73 2008-04-10 14:00:00 GMT A joint RHESSI/STEREO observation of the March 25th 2008 flare sends waves through the atmosphere. Antoun Daou and David Alexander http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=72 2008-03-24 14:00:00 GMT This nugget discusses observations that suggest that hard X-rays saturate in intensity in the largest solar flares. Manuela Temmer http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=71 2008-03-10 14:00:00 GMT The relationship between the acceleration of CMEs and flare hard X-ray bursts is found to be closely synchronized and a new flare cartoon is proposed. Iain Hannah http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=70 2008-02-25 14:00:00 GMT An intriguing microflare with simultaneous RHESSI and Hinode observations shows unusual high energy X-ray emission. David Smith http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=69 2008-02-12 14:00:00 GMT Radiation damage has built up in RHESSI's detectors since launch. This nugget describes how the detectors were recently repaired. Lyndsay Fletcher and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=68 2008-02-04 14:00:00 GMT A new theoretical model for the flare impulsive phase turns everything upside down! Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=67 2008-01-15 14:00:00 GMT An introduction to coronal magnetic fields and a happy new year and solar cycle! Gerard Trottet and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=66 2007-12-10 14:00:00 GMT Exploring one of the rare pion-producing flares. Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=65 2007-11-27 14:00:00 GMT This nugget calls attention to a remarkable instrument that in some ways anticipated RHESSI. Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=64 2007-11-12 14:00:00 GMT This article introduces some of the ideas associated with submillimeter and gamma-ray observation of solar flares. Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=63 2007-10-29 14:00:00 GMT The best way to understand how flares happen may be to compare pre and post-flare structures. What conclusions can be drawn from Hinode XRT data using this method? Steven Christe and Säm Krucker http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=62 2007-10-15 14:00:00 GMT Introducing the next generation of hard X-ray spectroscopic imagers, FOXSI. Wei Liu and Vahé Petrosian http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=61 2007-10-01 14:00:00 GMT RHESSI observations strongly suggest that magnetic reconnection and particle acceleration took place between two coronal X-ray sources. Ron Murphy and Gerry Share http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=60 2007-09-17 14:00:00 GMT A description of the uses and analysis of the mysterious 511 keV line produced by the annihilation of positrons with electrons. Hugh Hudson and Lyndsay Fletcher http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=59 2007-09-04 14:00:00 GMT In this Nugget we discuss some of the basic properties of the solar corona as background information, in particular the magnetic field and the Alfven speed in active regions. John Brown and Procheta Mallik http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=58 2007-08-20 14:00:00 GMT We continue with our recombination series. In this part 3, it is found that in dense and hot coronal sources, fast electron recombination can be of vital importance in analyzing data properly. Säm Krucker and Steven Christe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=57 2007-08-06 14:00:00 GMT A problem in imaging the X-class flare of dec 13th, 2006 observed by both RHESSI and the new Hinode is explained and solved! R.T. James McAteer http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=56 2007-07-23 14:00:00 GMT The singular complexity of solar flares is clear at first glance. Thankfully, there exists a theory of complexity. In this nugget, the methods of complexity theory are applied to a solar flare light curve. Ryan Milligan http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=55 2007-07-10 14:00:00 GMT Combining RHESSI and CDS observations gives a new look at the upflows related to chromospheric evaporation. Enrico Landi and Brian Dennis http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=54 2007-06-26 14:00:00 GMT Continuing from the last nugget more technically: the free-bound spectral component is much more important in interpreting the flare emission than had previously been realized, especially as regards Fe abundance. Brian Dennis http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=53 2007-06-13 14:00:00 GMT An introduction to the intricacies of the flare continuum which may not be as simple as we all assume. Enter free-bound emission. Iain Hannah and Steven Christe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=52 2007-05-20 14:00:00 GMT RHESSI has been operating for over five years now and a new flare-finding algorithm has found a total of 24,799 microflares. Some first results show that they are well-associated with magnetic active regions. Linghua Wang http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=51 2007-05-14 14:00:00 GMT Recent results concerning solar-accelerated electrons detected at 1 a.u. imply that low energy electrons provide the seed population for the high energy population. Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=50 2007-04-30 14:00:00 GMT A hypothetical elementary particle - the axion - may be flooding out of the solar core in great profusion. Thankfully, the Primakoff effect can convert axions to X-rays for RHESSI's viewing pleasure. Tom Berger http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=49 2007-04-16 14:00:00 GMT A first comparison between RHESSI and Hinode observations (hopefully many more will follow!). In this case, an initial analysis of a surprising quiet Sun X-class flare. Jeongwoo Lee and Ju Jing http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=48 2007-04-02 14:00:00 GMT How do "footpoints" and "ribbons" differ? A comparison based on the "standard model" theory of Forbes and Priest. Linhui Sui and Gordon Holman http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=47 2007-03-14 14:00:00 GMT A bouncing coronal source motion is found in several early-impulsive flares. Säm Krucker and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=46 2007-03-05 14:00:00 GMT Flares whose spectrum become progressively harder are closely associated with high-energy solar proton events observed in interplanetary space. An analysis of some prominent soft-hard-harder events. Pascal Saint-Hilaire and Gerry Share http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=45 2007-02-20 14:00:00 GMT Another happy birthday but this time for our favorite Solar Spectrometer; RHESSI. At such a significant time, it always helps to take a look back (and forward) in time. Lyndsay Fletcher and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=44 2007-02-08 14:00:00 GMT Happy birthday wishes and a discussion of the pluses and minuses of the thick-target model. Säm Krucker and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=43 2007-01-22 14:00:00 GMT Solar minimum doesn't always have to be boring. Last but not least active region NOAA 10930 gives us something to think about. Eduard Kontar and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=42 2007-01-08 14:00:00 GMT An introductory discussion on the effect of Compton scattering off the solar atmosphere (aka albedo) on the photon spectrum. These albedo x-rays can be used as a dentist's mirror to look at the source from behind. Säm Krucker and Gordon Hurford http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=41 2006-12-04 14:00:00 GMT Gamma-rays from the corona?! Chang Liu http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=40 2006-11-20 14:00:00 GMT Ribbon-like hard X-ray sources match TRACE UV ribbon emissions in an M8.0 flare. Ed Schmahl and Gordon Hurford http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=39 2006-11-06 14:00:00 GMT The introductory visibilities nugget we've been promising! Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=38 2006-10-24 14:00:00 GMT This nugget sets the stage for future discussions of hard radiations (X-rays and gamma-rays) emitted from the corona by flare-associated non-thermal particles. Hugh Hudson and Alec MacKinnon http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=37 2006-10-10 14:00:00 GMT The Sun's global magnetic field during solar minimum is strikingly similar to the Earth's dipole field, raising the question of whether the Sun has its own Van Allen Belts. Marcus Aschwanden http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=36 2006-09-25 14:00:00 GMT Systematically increasing delays are found between thermal and nonthermal emission as a decreasing function of energy. Ed Schmahl and Rick Pernak http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=35 2006-09-11 14:00:00 GMT A trap/precipitation model that suggested that the flux asymmetry of hard X-ray footpoints in flaring loops would be caused by a magnetic asymmetry. Exploring an old model with new data. Steven Christe and Albert Shih http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=34 2006-08-28 14:00:00 GMT We discuss the effects of radiation damage on the RHESSI detectors and the steps currently being taken to fix them. Kyoko Watanabe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=33 2006-08-14 14:00:00 GMT A global network of solar neutron monitors observed a large solar neutron event caused by the hugely energetic X17 flare of 2005 September 7. We report on this solar neutron event and describe some on-going analysis. David Smith http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=32 2006-07-31 14:00:00 GMT Terrestrial gamma-ray flashes are very brief bursts of gamma radiation coming upwards from the Earth's atmosphere. RHESSI electrifies us by identifying these mysterious events with lightning bolts. Paolo Grigis http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=31 2006-07-17 14:00:00 GMT A stochastic acceleration model, endowed with a suitable escape term, reproduces the observed soft-hard-soft behaviour of flare looptop sources and predicts pivot-point type spectral evolution. Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=30 2006-07-03 14:00:00 GMT Every year RHESSI sets out to observe the Crab Nebula during its time of closest (apparent) approach to the Sun. A discussion of the issues involved in using a solar satellite to make non-solar observations and a sneak-peek at results! Nariaki Nitta and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=29 2006-06-19 14:00:00 GMT High-energy particles from the Sun routinely reach the Earth, guided by the heliospheric magnetic field. A quick introduction to the physics (and acronyms) involved. Eduard Kontar http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=28 2006-06-05 14:00:00 GMT The high-quality RHESSI spectrum give us hope for a model-independent inference of the electron spectrum from the photon spectrum. Hugh Hudson and David Smith http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=27 2006-05-22 14:00:00 GMT An introduction to the intricacies behind X-ray and gamma-ray spectroscopy using RHESSIs germanium solid state detectors. Charlie Lindsey and Alina Donea http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=26 2006-05-08 14:00:00 GMT Observations of large RHESSI flares show that the location of impulsive hard X-rays matches that of the source of sunquake waves. Valentina Zharkova and Mykola Gordovskyy http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=25 2006-04-24 14:00:00 GMT Self-induced electric fields and return currents explain the soft-hard soft spectral evolution seen in flares. Marina Battaglia http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=24 2006-04-10 14:00:00 GMT A coronal source shows a soft-hard-soft spectral behavior. Laura Bone http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=23 2006-03-27 14:00:00 GMT The simplest explanations for RHESSI coronal sources is an enhanced coronal density. A discussion of such an interpretation for the 14th April 2002 flare. Cyril Dauphin and Nicole Vilmer http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=22 2006-03-13 14:00:00 GMT An exploration of a trap and precipitation model to explain the observed time delay between gamma-rays and X-rays in the July 23rd event. Alec MacKinnon and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=21 2006-02-27 14:00:00 GMT We continue our quiet Sun series with this nugget on a new component of the hard X-ray emission from the quiet Sun : X-rays produced through the beta decay of cosmic ray-generated neutrons on the Sun. Albert Shih http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=20 2006-02-16 14:00:00 GMT Straight from the horse's mouth: some Browser tips to streamline your RHESSI data perusings from the creator of Browser. Hugh Hudson and Martin Fivian http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=19 2006-02-02 14:00:00 GMT Did you know that RHESSI also observes the Sun in white light? There is more than one use for the RHESSI aspect system. Anna Watts and Tod Strohmayer http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=18 2006-01-16 14:00:00 GMT Results from more in-depth analysis of the most powerful cosmic gamma-ray burst ever observed may imply the first direct detection of vibrations in a neutron star crust. Säm Krucker and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=17 2006-01-05 14:00:00 GMT The soft-hard-soft spectral evolution may be very popular among flares but every once in a while a flare stands out of the crowd by being different or soft-hard-harder. Iain Hannah http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=16 2005-12-19 14:00:00 GMT The Sun is now entering its quiet phase and solar flares are becoming more and more infrequent. This is the first of a series of nuggets exploring the quiet sun spectrum as seen by RHESSI. Ken Phillips and Cristina Chifor http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=15 2005-12-05 14:00:00 GMT Part two and conclusion of an exploration of the status of the Fe and Fe/Ni line analysis. RHESSI observes some tantalizing discrepancies between the lines and the continuum. Gordon Holman http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=14 2005-11-21 14:00:00 GMT Magnetic loops associated a with solar flare are often observed to expand after the explosive phase. New RHESSI observations show that magnetic loops can contract first before expanding as usual. Ken Phillips and Cristina Chifor http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=13 2005-11-07 14:00:00 GMT Who would have thought that a gamma-ray telescope could observe X-ray emission lines? But RHESSI does... Iain Hannah http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=12 2005-10-24 14:00:00 GMT If pirates have taught us anything it is that one should look for an X if one is looking for treasure...or a simple explanation for particle acceleration. Hugh Hudson and Tom Metcalf http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=11 2005-10-10 14:00:00 GMT Since the original white-light flare observation by Carrington back in 1859, what have we learned about these prototypical flares? Brian Dennis http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=10 2005-09-26 14:00:00 GMT Since the 1970s, the conventional wisdom was that a CME carried far more energy than was released during its associated flare. Recent observations by SORCE show that the energy released in a flare is not inconsequential and, in fact, may be comparable to the energy of the CME. Marina Battaglia http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=9 2005-09-12 14:00:00 GMT Are small flares simply scaled down versions of large flares? Or are they fundamentally different? Gordon Hurford and Steven Christe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=8 2005-08-29 14:00:00 GMT RHESSI makes images without the use of lenses or mirrors. How does it do that? Claire Foullon http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=7 2005-08-16 14:00:00 GMT Giant loops interconnecting the northern and southern hemispheres may explain some remarkable oscillatory structures observed by RHESSI. This is an unexpected application of imaging spectroscopy, but with the spectroscopy in the time domain, rather than in energy. Arnold Benz http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=6 2005-08-04 14:00:00 GMT As experienced prospectors know, nuggets are often found in close proximity to one another. Thus, in the same flare containing the nugget presented by Paolo Grigis, we found another nugget. Säm Krucker and Hugh Hudson http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=5 2005-07-18 14:00:00 GMT As is (strangely) usual, Bastille day 2005 produced yet another large (X-class) solar flare. The Sun seems willing to disregard the solar cycle in order to celebrate the French revolution. Paolo Grigis http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=4 2005-07-11 14:00:00 GMT Flare hard X-rays can show us both where magnetic energy is stored, and also where it is released. The RHESSI observations therefore give us some leverage on acceptable theories. Hugh Hudson and Kevin Hurley http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=3 2005-07-05 14:00:00 GMT By an extraordinary coincidence, the most powerful gamma-ray burst ever observed occurred quite close to the solar direction. Accordingly RHESSI got unique observations of a relativistic blackbody. Steven Christe http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=2 2005-04-09 14:00:00 GMT Do the solar energetic particles that we see in space near the Earth make X-rays on the way out? This nugget uses the RHESSI spectrogram tool, plus hard X-ray imaging, to study this problem. Hugh Hudson and Säm Krucker http://sprg.ssl.berkeley.edu/~tohban/nuggets/?page=article&article_id=1 2005-03-21 14:00:00 GMT This nugget introduces X-ray spectrograms, a rather neat tool that encapsulates the time variation of the solar X-ray spectrum and thus reveals many interesting effects.