Dr. Brian R. Dennis was educated in England at Queen Elizabeth's Grammar School, Horncastle, Lincolnshire, and at the University of Leeds, Yorkshire. He received his Ph.D. at Leeds in 1964 and immediately moved to the United States to become a research associate at the University of Rochester, New York. He became a National Research Council Resident Research Associate at Goddard Space Flight Center in 1967, a government employee at GSFC as an astrophysicist in 1969, and a U.S. citizen in 1975. Working in the Solar Physics Branch at Goddard, Dr. Dennis has been involved in designing, building, operating, and analyzing data from several X-ray and gamma-ray instruments for observations of solar flares and cosmic X-ray sources. He was a Co-investigator of the Celestial X-Ray Spectrometer on the 8th Orbiting Solar Observatory and Principal Investigator (PI) of the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission (SMM). He co-chaired the Max 91 program to coordinate observations of solar activity during the solar maximum centered around 1991. He is the Mission Scientist and lead Co-I of the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI), a NASA Small Explorer (SMEX) mission launched on 5 February 2002 and operational until April 2018. In 2004, Dr. Dennis received the Goddard Lindsay Award and a NASA Outstanding Leadership Medal for over two decades of work in high energy solar physics that culminated with the success of RHESSI. He retired from his civil service position in January 2023 and joined the Emeritus program.
Brian R Dennis
(EMERITUS)
| Email: | brian.r.dennis@nasa.gov |
| Phone: | 301.286.7983 |
| Org Code: | 671 |
| Address: |
NASA/GSFC Mail Code 671 Greenbelt, MD 20771 |
| Employer: | EMERITUS |
Brief Bio
Research Interests
Solar Flares
Heliophysics: Transient EventsUnderstand the basic physics of energy release and particle acceleration in solar flares.
Current Projects
Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
Solar Radiation
RHESSI, the sixth of NASA's Small Explorers, was launched in February 2002, operated for over 16 years until April 2018 and reentered.in April 2023. It was designed to investigate particle acceleration and energy release in solar flares through imaging and spectroscopy of X-rays and gamma-rays. It covers hard X-ray and gamma-ray continua emitted by energetic electrons, gamma-ray lines produced by energetic ions, and thermal X-ray emission from plasma at temperatures in excess of ~8 MK,
Fermi GBM and LAT Solar Flare Observations
Solar Radiation
Make Fermi GBM and LAT X-ray and gamma-ray observations readily available for analysis by the international solar physics community.
Positions/Employment
CS Astrophysicist
NASA - GSFC
February 1969 - January 2023
Solar Physics
Emeritus
NASA - GSFC
January 2023 - Present
Continue analyzing RHESSI observations.
Education
Ph. D. (Cosmic Ray Physics), University of Leeds, England, 1964
Selected Publications
Refereed
2019. "A Remarkably Narrow RHESSI X-Ray Flare on 2011 September 25." The Astrophysical Journal 887 (2): 131 [10.3847/1538-4357/ab4f81] [Journal Article/Letter]
2019. "Persistent Quasi-periodic Pulsations during a Large X-class Solar Flare." The Astrophysical Journal 875 (1): 33 [10.3847/1538-4357/ab0ca3] [Journal Article/Letter]
2019. "Always a Farm Boy." solphys 294 (1): 2 [10.1007/s11207-018-1304-7] [Journal Article/Letter]
2017. "Pulsations in the Earth's Lower Ionosphere Synchronized With Solar Flare Emission." Journal of Geophysical Research: Space Physics 122 (10): 9841-9847 [10.1002/2017ja024647] [Journal Article/Letter]
2017. "Detection and Interpretation of Long-lived X-Ray Quasi-periodic Pulsations in the X-class Solar Flare on 2013 May 14." The Astrophysical Journal 836 (1): 84 [10.3847/1538-4357/836/1/84] [Journal Article/Letter]
2016. "A LARGE-SCALE SEARCH FOR EVIDENCE OF QUASI-PERIODIC PULSATIONS IN SOLAR FLARES." The Astrophysical Journal 833 (2): 284 [10.3847/1538-4357/833/2/284] [Journal Article/Letter]
2016. "Quasi-periodic Pulsations during the Impulsive and Decay phases of an X-class Flare." The Astrophysical Journal Letters 827 (2): L30 [10.3847/2041-8205/827/2/L30] [Journal Article/Letter]
2015. "High-temperature differential emission measure and altitude variations in the temperature and density of solar flare coronal X-ray sources." A&A 584 A89 [10.1051/0004-6361/201526665] [Journal Article/Letter]
2015. "FLARE FOOTPOINT REGIONS AND A SURGE OBSERVED BYHINODE/EIS,RHESSI, ANDSDO/AIA." The Astrophysical Journal 813 (1): 32 [10.1088/0004-637x/813/1/32] [Journal Article/Letter]
2015. "SOLAR FLARE ELEMENT ABUNDANCES FROM THE SOLAR ASSEMBLY FOR X-RAYS (SAX) ON MESSENGER." The Astrophysical Journal 803 (2): 67 [10.1088/0004-637x/803/2/67] [Journal Article/Letter]
2015. "Misidentification of the source of a neutron transient detected by MESSENGER on 4 June 2011." Journal of Geophysical Research: Space Physics 120 (1): 1-11 [10.1002/2014ja020663] [Journal Article/Letter]
2014. "THREE-DIMENSIONAL MAGNETIC RESTRUCTURING IN TWO HOMOLOGOUS SOLAR FLARES IN THE SEISMICALLY ACTIVE NOAA AR 11283." The Astrophysical Journal 795 (2): 128 [10.1088/0004-637x/795/2/128] [Journal Article/Letter]
2014. "THE RADIATED ENERGY BUDGET OF CHROMOSPHERIC PLASMA IN A MAJOR SOLAR FLARE DEDUCED FROM MULTI-WAVELENGTH OBSERVATIONS." ASTROPHYSICAL JOURNAL 793 [10.1088/0004-637X/793/2/70] [Journal Article/Letter]
2013. "Imaging coronal magnetic-field reconnection in a solar flare." Nature Physics 9 (8): 489-493 [10.1038/nphys2675] [Journal Article/Letter]
2013. "Estimating the Properties of Hard X-Ray Solar Flares by Constraining Model Parameters." The Astrophysical Journal 769 [89-10.1088/0004-637X/769/2/89] [Journal Article/Letter]
2013. "Solar Eruptive Events (SEE) 2020 Mission Concept." ArXiv e-prints arXiv:1311.5243- [Journal Article/Letter]
2012. "GLOBAL ENERGETICS OF THIRTY-EIGHT LARGE SOLAR ERUPTIVE EVENTS." The Astrophysical Journal 759 (1): 71 [10.1088/0004-637x/759/1/71] [Journal Article/Letter]
2012. "OBSERVATIONS OF A TWO-STAGE SOLAR ERUPTIVE EVENT (SEE): EVIDENCE FOR SECONDARY HEATING." The Astrophysical Journal 746 (1): L5 [10.1088/2041-8205/746/1/l5] [Journal Article/Letter]
2011. "Bayesian Analysis of RHESSI Flare Data: Effect of Prior Information on Determining the Low-energy Cutoff and the Total Electron Content." Bulletin of the American Astronomical Society 2228- [Journal Article/Letter]
2011. "Multi-thermal observations of the 2010 October 16 flare:heating of a ribbon via loops, or a blast wave?." Bulletin of the American Astronomical Society 2237- [Journal Article/Letter]
2011. "Pulsations In Two-ribbon Flares: Waves, Reconnection Or Both?." Bulletin of the American Astronomical Society 1204- [Journal Article/Letter]
2011. "Solar Eruptive Events (SEE) Mission for the Next Solar Maximum." Bulletin of the American Astronomical Society 2204- [Journal Article/Letter]
2011. "Transient phenomena and thermal evolution during the Boss' Day flare of 2010 October 16 with AIA, EVE and RHESSI." AGU Fall Meeting Abstracts A1902- [Journal Article/Letter]
2011. "Evidence for the Full Hard X-ray Spectral Signature of Nonuniform Ionization in a Solar Flare." The Astrophysical Journal 731 106 [Full Text] [10.1088/0004-637X/731/2/106] [Journal Article/Letter]
2010. "Cloudy Solar Software - Enhanced Capabilities for Finding, Pre-processing, and Visualizing Solar Data." Bulletin of the American Astronomical Society 41 #407.05- [Journal Article/Letter]
2010. "Cloudy Solar Software - Enhanced Capabilities for Finding, Pre processing, and Visualizing Solar Data." Bulletin of the American Astronomical Society 41 #407.05- [Journal Article/Letter]
2010. "Observing Solar Hard X-rays from Heliospheric Orbits." Bulletin of the American Astronomical Society 41 #404.16- [Journal Article/Letter]
2010. "Fermi GBM and LAT Solar Flare X Ray and γ Ray Observations." Bulletin of the American Astronomical Society 41 #404.06- [Journal Article/Letter]
2010. "Science Objectives for an X-Ray Microcalorimeter Observing the Sun." ArXiv e-prints arXiv:1011.4052- [Journal Article/Letter]
2010. "Evidence of Enhanced Particle Acceleration During a Plasmoid-Looptop Collision Observed with RHESSI." Bulletin of the American Astronomical Society 41 #404.26- [Journal Article/Letter]
2009. "EPISODIC X-RAY EMISSION ACCOMPANYING THE ACTIVATION OF AN ERUPTIVE PROMINENCE: EVIDENCE OF EPISODIC MAGNETIC RECONNECTION." The Astrophysical Journal 698 (1): 632-640 [10.1088/0004-637x/698/1/632] [Journal Article/Letter]
2009. "Bayesian analysis of RHESSI spectra." AGU Fall Meeting Abstracts 8- [Journal Article/Letter]
2009. "Observation Of Inflows And Collapsing X-point During CME Initiation Using STEREO And RHESSI." AAS/Solar Physics Division Meeting #40 40 #21.10- [Journal Article/Letter]
2009. "Velocity Characteristics of Evaporated Plasma Using Hinode/EIS." AAS/Solar Physics Division Meeting #40 40 #36.02- [Journal Article/Letter]
2009. "VSO For Dummies." AAS/Solar Physics Division Meeting #40 40 #15.10- [Journal Article/Letter]
2009. "GRB Polarimetry with POET." American Institute of Physics Conference Series 1133 64-66 [10.1063/1.3155969] [Journal Article/Letter]
2008. "Extending the Virtual Solar Observatory (VSO) to Incorporate Data Analysis Capabilities (III)." AGU Fall Meeting Abstracts 1618- [Journal Article/Letter]
2008. "Extending the Virtual Solar Observatory to Incorporate Data Analysis Capabilities (II)." AGU Spring Meeting Abstracts 19- [Journal Article/Letter]
2007. "Extending the Virtual Solar Observatory (VSO) to Incorporate Data Analysis Capabilities." AGU Fall Meeting Abstracts 5- [Journal Article/Letter]
2006. "Motion of Nonthermal Sources Along Flare Loop." 36th COSPAR Scientific Assembly 36 1797- [Journal Article/Letter]
2005. "RHESSI soft X-ray imaging spectroscopy of a flare." AGU Spring Meeting Abstracts A3- [Journal Article/Letter]
2004. "Multi-Wavelength Study of a Strong Impulsive Solar Limb Flare on 2002 August 3." 35th COSPAR Scientific Assembly 35 1080- [Journal Article/Letter]
2004. "Thermal and nonthermal contributions to the solar flare x-ray flux." 35th COSPAR Scientific Assembly 35 1284- [Journal Article/Letter]
2004. "Energy partition in two solar flare/CME events." Journal of Geophysical Research (Space Physics) 109 10104 [10.1029/2004JA010571] [Journal Article/Letter]
2003. "High-Resolution Observation of the Solar Positron-Electron Annihilation Line." The Astrophysical Journal 595 L85 [Full Text] [10.1086/378174] [Journal Article/Letter]
2003. "RHESSI Observation of the Solar Annihilation Line." Proceedings of the 28th International Cosmic Ray Conference. July 31-August 7, 2003. Trukuba, Japan. Under the auspices of the International Union of Pure and Applied Physics (IUPAP). Editors: T. Kajita, Y. Asaoka, A. Kawachi, Y. Matsubara and M. Sasaki, p.3199 6 3199 [Full Text] [Journal Article/Letter]
2003. "Rapid Acceleration of a Coronal Mass Ejection in the Low Corona and Implications for Propagation." Bulletin of the American Astronomical Society 35 816- [Journal Article/Letter]
2003. "RHESSI and non-thermal solar physics in the IHY." EGS - AGU - EUG Joint Assembly 7939- [Journal Article/Letter]
2003. "The Unusual Hard X-ray Spectrum of the Flare of 20 August 2002." AGU Fall Meeting Abstracts A171- [Journal Article/Letter]
2003. "The Relationship Between Large Solar Flares and Very Fast Coronal Mass Ejections - Physics and Causality." AGU Fall Meeting Abstracts 7- [Journal Article/Letter]
2003. "Evidence for the Formation of Large-Scale Current Sheets in Three Solar Flares." AGU Fall Meeting Abstracts 5- .. [Journal Article/Letter]
2002. "The Reuven Ramaty High-Energy Solar Spectroscopic Imager (RHESSI)." Solar Physics 210 3-32 [10.1023/A:1022428818870] [Journal Article/Letter]
2002. "A Search and Analysis Tool for RHESSI Complementary Observations." Bulletin of the American Astronomical Society 34 757- [Journal Article/Letter]
2002. "Tracing the Sun-Earth Connection: The Solar Particle Chain in April 2002." AGU Fall Meeting Abstracts 3- [Journal Article/Letter]
2002. "Preface." Solar Physics 210 1-1 [10.1007/s11207-004-0827-2] [Journal Article/Letter]
2002. "Antiferromagnetism in CaCu3Ti4O12 studied by magnetic Raman spectroscopy." Physical Review B 65 [052406-10.1103/PhysRevB.65.052406] [Journal Article/Letter]
2002. "RHESSI and TRACE Observations of an X-class Flare." 34th COSPAR Scientific Assembly 34 - [Journal Article/Letter]
2002. "The energetic importance of accelerated electrons in solar flares." 34th COSPAR Scientific Assembly 34 - [Journal Article/Letter]
2002. "RHESSI Investigations of the Neupert Effect in Solar Flares." Bulletin of the American Astronomical Society 35 #141.01- [Journal Article/Letter]
2001. "A Search and Analysis Tool for HESSI Ancillary Observations." AGU Fall Meeting Abstracts A775- [Journal Article/Letter]
2001. "The High Energy Solar Spectroscopic Imager (HESSI) Mission." AGU Spring Meeting Abstracts 42- [Journal Article/Letter]
1997. "Evidence for a Cutoff in the Frequency Distribution of Solar Flares from Small Active Regions." The Astrophysical Journal 475 (1): 338-347 [10.1086/303532] [Journal Article/Letter]
1996. "A Study of the Thermal/Nonthermal Electric Field Model in Solar Flares Using Spectral and Spatial X-Ray Data from Compton Gamma Ray Observatory and YOHKOH." ApJ 466 1067 [10.1086/177576] [Journal Article/Letter]
1994. "Studying Solar Flares with YOHKOH and the Compton Gamma-Ray Observatory." Proceedings of Kofu Symposium 221-224 [Journal Article/Letter]
1994. "Impulsive behavior in solar soft X-radiation." The Astrophysical Journal 422 L25-L27 [10.1086/187203] [Journal Article/Letter]
1994. "Precise Localizations and Counterpart Searches of GRBs from the 2nd Interplanetary Network." Gamma-Ray Bursts 307 359- [Journal Article/Letter]
1994. "Evidence for Impulsive Soft-X Bursts during Flares." X-ray solar physics from Yohkoh 65- [Journal Article/Letter]
1993. "Impulsive Soft X-Ray Emission in Solar Flares." Bulletin of the American Astronomical Society 25 1177- [Journal Article/Letter]
1993. "Studying Flare Models with Yohkoh and GRO/BATSE." Bulletin of the American Astronomical Society 25 1186- [Journal Article/Letter]
1993. "Evidence for Both Electron Acceleration and Direct Heating in Solar Flares." Bulletin of the American Astronomical Society 25 1177- [Journal Article/Letter]
1993. "Precise Localizations of Gamma-Ray Bursts from the 2nd Interplanetary Network." Bulletin of the American Astronomical Society 25 846- [Journal Article/Letter]
1993. "Survey of Loop-Footpoint Brightenings During the Impulsive Phase of Flares." Bulletin of the American Astronomical Society 25 1187- [Journal Article/Letter]
1993. "Frequency distributions of solar X-ray flare parameters." Advances in Space Research 13 179-182 [10.1016/0273-1177(93)90474-P] [Journal Article/Letter]
1993. "Solar X-Ray and Gamma-Ray Burst Instrumentation for the Argentine SAC-B Spacecraft." Small Instruments for Space Physics 17- [Journal Article/Letter]
1992. "The Compton Observatory Science Workshop. Proceedings." The Compton Observatory Science Workshop. Proceedings.; by Shrader C. R.; Gehrels N.; Dennis B.; National Aeronautics and Space Administration; Washington DC (USA); National Aeronautics and Space Administration; Greenbelt MD (USA). Goddard Space Flight Center 1992 566 [Journal Article/Letter]
1991. "Atmospheric Occultation of a Solar Flare in Hard X-Rays." Bulletin of the American Astronomical Society 23 1388- [Journal Article/Letter]
1990. "A 3rd Catalog of Cosmic Gamma-Ray Bursts: 1981-1983 Localizations from the Second Interplanetary Network." International Cosmic Ray Conference 1 52- [Journal Article/Letter]
1989. "The SMM/HXRBS Gamma Ray Burst Catalogue." Bulletin of the American Astronomical Society 21 1176- [Journal Article/Letter]
1987. "The discovery of a source of repeated soft short gamma bursts in Sagittarius." Pisma v Astronomicheskii Zhurnal 13 987-994 [Journal Article/Letter]
1987. "Localization, time histories, and energy spectra of a new type of recurrent high-energy transient source." The Astrophysical Journal 320 L105-L110 [10.1086/184984] [Journal Article/Letter]
1985. "Characteristics of gamma-ray line flares." The Astrophysical Journal 292 699-715 [10.1086/163202] [Journal Article/Letter]
1983. "Characteristics of gamma-ray line flares." NASA STI/Recon Technical Report N 84 14098- [Journal Article/Letter]
1980. "Changes in the Characteristics of the Coronal Plasma During Two Impulsive Flares." Bulletin of the American Astronomical Society 12 911- [Journal Article/Letter]
1980. "Microwave and Hard X-ray Observations of the Flare on 1980 June 29 0230 UT." Bulletin of the American Astronomical Society 12 903- [Journal Article/Letter]
Non-Refereed
2022. "Hard X-ray Imaging of Solar Flares." Springer Imprint 164 [https://doi.org/10.1007/978-3-030-87277-9] [Book]
2021. "Improved RHESSI Imaging Spectroscopy Of Extended Hard X-ray Sources." American Astronomical Society Meeting Abstracts 53 313.08 [Proceedings]
2018. "Comparisons of Three Solar Eruptive Gamma-Ray Events." AGU Fall Meeting Abstracts 2018 SH11D-2896 [Proceedings]
2018. "Solar X-Ray and Gamma-Ray Imaging Spectroscopy." Deep Space Gateway Concept Science Workshop 2063 3186 [Proceedings]
2016. "Quasi-Periodic Pulsations (QPP) in a Long-Duration Flare." AAS/Solar Physics Division Meeting 47 #6.05 [Proceedings]
2012. "The Relationship Between Hard X-ray Pulse Timings and the Locations of Footpoint Sources During Solar Flares." American Astronomical Society Meeting Abstracts #220 220 #204.10- [Proceedings]