Dr. Ricky Egeland
MSU Physics Graduate
- Ricky Egeland
- Telephone (office ext.)
- Telephone (skype)
- (612) 326-5362
I entered the MSU physics graduate program in the Fall of 2011 and earned my PhD in 2017 with my dissertation "Long Term Variability of the Sun in the Context of Solar Analog Stars". This work uses Sun-like stars as independent "dynamo experiments" to provide observational clues on the workings of the stellar magnetic dynamo. I was awarded the Newkirk Fellowship in 2014 and performed much of the work at the NCAR High Altitude Observatory in Boulder, Colorado.
I received my B.S. in physics in 2003 from the University of Minnesota, Twin Cities followed by seven years of software development work for the Compact Muon Solenoid project at CERN. After leaving CERN in 2010 I worked briefly at the Observatório Nacional in Rio de Janeiro before coming to Montana to resume my studies.
Long Term Variability of the Sun in the Context of Solar Analog Stars
The Sun is the best observed object in astrophysics, but despite this distinction the nature of its well-ordered generation of magnetic field in 11-year activity cycles remains a mystery. In this work, we place the solar cycle in a broader context by examining the long-term variability of solar analog stars within 5% of the solar effective temperature, but varied in rotation rate and metallicity. Emission in the Fraunhofer H & K line cores from singly-ionized calcium in the lower chromosphere is due to magnetic heating, and is a proven proxy for magnetic flux on the Sun. We use Ca H & K observations from the Mount Wilson Observatory HK project, the Lowell Observatory Solar Stellar Spectrograph, and other sources to construct composite activity time series of over 100 years in length for the Sun and up to 50 years for 26 nearby solar analogs. Archival Ca H & K observations of reflected sunlight from the Moon using the Mount Wilson instrument allow us to properly calibrate the solar time series to the S-index scale used in stellar studies. We find the mean solar S-index to be 5–9% lower than previously estimated, and the amplitude of activity to be small compared to active stars in our sample. A detailed look at the young solar analog HD 30495, which rotates 2.3 times faster than the Sun, reveals a large amplitude ∼12-year activity cycle and an intermittent short-period variation of 1.7 years, comparable to the solar variability time scales despite its faster rotation. Finally, time series analyses of the solar analog ensemble and a quantitative analysis of results from the literature indicate that truly Sun-like cyclic variability is rare, and that the amplitude of activity over both long and short timescales is linearly proportional to the mean activity. We conclude that the physical conditions conducive to a quasi-periodic magnetic activity cycle like the Sun’s are rare in stars of approximately the solar mass, and that the proper conditions may be restricted to a relatively narrow range of rotation rates.
As a primary author
- R. Egeland, W. Soon, S. Baliunas, J. C. Hall, and G. W. Henry "Evolution of Long Term Variability in Solar Analogs." In D. Nandi, A. Valio, and P. Petit, editors, Living Around Active Stars, Proceedings of the 328th Symposium of the International Astronomical Union Held in Maresias, Brazil. Cambridge University Press (2017) [ADS]
- R. Egeland, W. Soon, S. Baliunas, J. C. Hall, A. A. Pevtsov, L. Bertello "The Mount Wilson Observatory S-index of the Sun." The Astrophysical Journal (2017) [DOI] [ADS] [CDS]
- R. Egeland, W. Soon, S. Baliunas, J. C. Hall, A. A. Pevtsov, G. W. Henry "Dynamo Sensitivity in Solar Analogs with 50 Years of Ca II H & K Activity." Proceedings of The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS19), Uppsala, Sweden, 6-10 June 2016, editor G. A. Felden (2016) [DOI] [ADS] [CDS]
- T. S. Metcalfe, R. Egeland, J. van Saders. "Stellar Evidence That the Solar Dynamo May Be in Transition." The Astrophysical Journal Letters 826.1 (2016) [DOI] [ADS] [CDS]
- R. Egeland, T. S. Metcalfe, J. C. Hall, G. W. Henry "Sun-like Magnetic Cycles in the Rapidly Rotating Young Solar Analog HD 30495"; The Astrophysical Journal Vol. 812, Num 1 (2015) [DOI] [ADS]
- P. Judge and R. Egeland "Century-long monitoring of solar irradiance and Earth's albedo using a stable scattering target in space"; Monthly Notices of the Royal Astronomical Society: Letters, Volume 448, Issue 1, p.L90-L93; (2015) [DOI] [ADS]
- A. Sanchez-Hernandez et al. "From toolkit to framework – the past and future evolution of PhEDEx"; Journal of Physics: Conference Series, Volume 396, Issue 3, article id. 032118 (2012) [DOI] [ADS] [CDS]
- R. Egeland, C-H. Huang, P. Rossman, P. Sundarrajan, T. Wildish "The PhEDEx next-gen website"; Journal of Physics: Conference Series, Volume 396, Issue 3, article id. 032117 (2012) [DOI] [ADS] [CDS]
- T. Chwalek et al. "No file left behind – monitoring transfer latencies in PhEDEx"; Journal of Physics: Conference Series Volume 396, Issue 3, article id. 032089 (2012) [DOI] [ADS][CDS]
- R. Egeland, T. Wildish, C. Huang "PhEDEx Data Service"; Journal of Physics: Conference Series Volume 219, Issue 6, article id. 062010 (2010) [DOI] [ADS] [CDS]
- R. Egeland, T. Wildish, S. Metson "Data transfer infrastructure for CMS data taking"; Proceedings of XII Advanced Computing and Analysis Techniques in Physics Research. November 3-7, 2008. Erice, Italy (2008) [conf] [PDF] [ADS]
- R. Egeland et al. "Database requirements for the CMS ECAL"; CMS internal note IN-2005/ 029 (2005)
As contributing author
- P. G. Beck et al. "Lithium abundance and rotation of seismic solar analogues." Astronomy & Astrophysics (2016; pending)
- P. G. Beck et al. "Probing seismic solar analogues through observations with the NASA Kepler space telescope and HERMES high-resolution spectrograph." Proceedings of The 19th Cambridge Workshop on Cool Stars, Stellar Systems, and the Sun (CS19), Uppsala, Sweden, 6-10 June 2016, editor G. A. Felden (2016) [DOI] [ADS]
- D. Salabert et al. "The solar-stellar connection: Magnetic activity of seismic solar analogs." Proceedings of The 19th Cambridge Workshop on Cool Stars, Stellar Sys- tems, and the Sun (CS19), Uppsala, Sweden, 6-10 June 2016, editor G. A. Felden (2016) [DOI] [ADS]
- D. Salabert et al. "Photospheric and chromospheric magnetic activity of seismic solar analogs. Observational inputs on the solar-stellar connection from Kepler and Hermes." Astronomy & Astrophysics, Vol. 596, id.A31 (2016) [DOI] [ADS]
- D. Salabert et al. "Magnetic variability in the young solar analog KIC 10644253. Observations from the Kepler satellite and the HERMES spectrograph" Astronomy & Astrophysics Volume 589, id.A118 (2016) [DOI] [ADS]
- The CMS Collaboration "A New Boson with a Mass of 125 GeV Observed with the CMS Experiment at the Large Hadron Collider"; Science, Volume 338, Issue 6114, pp. 1569-1575 (2012) [DOI] [ADS] [CDS]
- The CMS Collaboration "Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC"; Physics Letters B (2012) [DOI] [ADS] [CDS]
- S. Metson, D. Bonacorsi, M. Dias Ferreira, R. Egeland "SiteDB: Marshalling people and resources available to CMS"; Journal of Physics: Conference Series, Volume 219, Issue 7, article id. 072044, 8 pp. (2010) [DOI] [ADS]
- A. Fanfani et al. "Distributed Analysis in CMS"; Journal of Grid Computing, Volume 8, Issue 2, pp 159-179 (2010) [CDS] [journal]
- G. Organtini et al. "The CMS ECAL Database Services for Detector Control and Monitoring"; Journal of Physics: Conference Series, Volume 219, Issue 2, article id. 022016, 8 pp. (2010) [DOI] [ADS] [CDS]
- N. Magini et al. "The CMS data transfer test environment in preparation for LHC data taking"; Proc. IEEE Dresden 2008, Dresden, Germany; Nuclear Science Symposium Conference Record, 2008. NSS’08. IEEE (2008) [IEEE]
- L. Tuura et al. "Scaling CMS data transfer system for LHC start-up"; Journal of Physics: Conference Series, Volume 119, Issue 7, article id. 072030, 10 pp. (2008) [DOI] [ADS] [CDS]
- S. Metson et al. "CMS offline web tools"; Journal of Physics: Conference Series, Volume 119, Issue 8, article id. 082007, 5 pp. (2008) [DOI] [ADS] [CDS]
- A. Delgado Peris et al. "Data Location, Transfer and Bookkeeping in CMS"; Nuclear Physics B (Proceedings Supplements), Volume 177, p. 279-280 (2008) [DOI] [ADS] [CDS]
- The CMS Collaboration "The CMS experiment at the CERN LHC"; Journal of Instrumentation, Volume 3, Issue 08, pp. S08004 (2008) [DOI] [ADS] [CDS]
- A. Fanfani et al. "CMS data and workflow management system"; Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications, Volume 4, pp.441-445 (2008) [DOI] [ADS] [CDS]
- F. Cavallari et al. "CMS ECAL intercalibration of ECAL crystals using laboratory measurements"; CMS Note (2006) [CDS]
- E. Auffray et al. "CMS ECAL Barrel channel numbering"; CMS internal note IN-2005/021 (2005)
- D. Bailleux et al. "Hamamatsu APD for CMS ECAL: Quality Insurance"; Nuclear Instruments and Methods in Physics Research Section A, Volume 518, Issue 1-2, p. 622-625 (2004) [DOI] [ADS] [CDS]
- A. Kuznetsov et al. "Radiation hard avalanche photodiodes for CMS ECAL"; Nuclear Instruments and Methods in Physics Research Section A, Volume 504, Issue 1-3, p. 44-47 (2003) [DOI] [CDS]
The following topics are interests for my PhD thesis research.
- The solar cycle. The roughly 11-year solar cycle modulates many solar phenomenon including the number of sunspots, the solar irradiance, as well as the frequency of flares and CMEs. What is responsible for this cycle, and for the subtle variations of it? What determines the period of the cycle, and did the period vary throughout the life of the Sun? What has its impact been on the history of the Earth and the Solar System?
- Sun-like stars. Are there any solar twins out there, with comparable mass, composition, spectral features, and magnetic cycle? In this context, is the Sun's variability normal or abnormal? What are the essential parameters which determine the magnetic activity of Sun-like stars?
- Helio/Astro-seismology. Like regular seismology, we use the acoustic waves travelling through the object to learn about the conditions of the interior, which can't otherwise be measured. Astroseismology allows measurement of stellar parameters crucial to the working of the magnetic dynamo.
- Magnetic cycle Grand Minnima. During the "Maunder Minima" the 11-year solar cycle inexplicably stopped between 1645 and 1715, as sunspots became exceedingly rare. How frequent are these cessations of activity? What causes their onset, and what causes the cycle to later start up again?
- The faint young Sun paradox. Stellar models predict that the ancient young Sun was only 70% as intense as it is today, and would provide insufficient energy for the Earth to have a liquid ocean. However, geological and paleontological evidence show that the Earth did have a liquid ocean and at times was quite warm and humid. What is the explanation for this contradiction?
These topics are also interesting to me, but not closely related to my thesis reseach. Maybe I'll look into it someday?
- Large-scale scientific computing. Every sub-field of science is transitioning into a new era where increases in data volume necessitate new approaches to data analysis, as well as opening up new possibilities for discovery. For solar physics, I am interested in finding ways to use expansive datasets such as from the SDO mission to do large-scale statistical studies that were not possible in previous decades.
- Acceleration of particles by the Sun. The Sun has the largest and most active magnetic field in the solar system and is the best place for us to study natural particle acceleration processes in detail. The same events which are responsible for impressive solar flares and coronal mass ejections are responsible for accelerating particles anywhere from 1 MeV up to the GeV scale. These mechanisms are likely analogous to those which accelerate ultra-high-energy cosmic rays, where kinetic energies exceeding 10^20 eV have been observed.
- Coronal mass ejections, solar wind, and the space environment. Coronal mass ejections are solar events whose effects may be felt here on Earth. The acceleration of asteroid-sized amounts of material into space and the subsequent impact with the Earth's magnetic field is responsible for the auroras as well as for radio and satellite disturbances which have an impact on our modern way of life.
- Structure of the heliosphere. The interaction between the heliosphere and the interstellar medium is only recently being made available to direct observation. Measurements from the still-going Voyager probes and energetic neutral particle measurements from the IBIX spacecraft have brought forth new questions about the size, shape and structure of the outer edge of our Sun's influence.
- Exoplanet remote sensing. Kepler and other exoplanet efforts are expanding the catalog of known worlds. Some planets with wide orbits have already been imaged, and the atmospheres of eclipsing planets can be investigated via spectral analysis of the host star. We are just beginning to understand what variety of worlds are possible in our galaxy.
When I'm not working on physics or writing some computer program I like to...
- Play guitar. I play mostly classical guitar, though I dabble in blues, jazz, rock, folk and country as well as Brazilian styles bossa nova and choro. I also like to experiment with a lot of different sounds, and for this I have a Brian Moore MIDI guitar and tons of software instruments like those from the Native Instruments Komplete 8 package.
- Go outside. Montana is great for this. I like biking, hiking, and canoeing, though I suspect Minnesota was better for canoeing.
- Travel. I've lived in Switzerland and Brazil and seen a lot of nice places along with my wonderful wife, Patricia. I suspect we'll see a lot more interesting places as time goes on.
- Take photos. When I'm outside or traveling I like to take pictures. Sometimes I even take good ones. When I do, I put them on my flickr photostream. A few random pictures are shown below.