PETRUS (PIET) C MARTENS
Research Professor in Physics
Office: EPS 247
Petrus C. Martens
Montana State University
PO BOX 173840
Bozeman, MT 59717-3840
The Astrophysical Journal Letters
Chair, NASA Living with a Star Focus Group on "Solar Modulation of the Galactic Cosmic Rays and the Production
of Cosmogenic Isotope Archives of Long-term Solar Activity, Used to Interpret Past Climate Changes."
Winner of the 2011 MSU College of Letters and Science Award for Meritorious Research and Creativity
Publications: Links to Preprints,
Reprints, and the
Presentations: A List of Seminars and
Conference Papers, 1999 - present
Recent News Items: Press Conferences, Articles, Interviews
Joint Publications with Students and Postdocs
MSU Personnel involved: Piet Martens,
Rafal Angryk (Computer Science)
Postdocs: Juan Banda and Jason Scott. Students: Mike Schuh, and Karthik Pillai Ganesan (Computer Science), Alexander Engell (Physics), Ricky Egeland (Physics),
The Solar Dynamics Observatory (SDO) feature finding team is a large international consortium tasked by NASA to produce a comprehensive system for automated feature recognition for SDO. We are producing robust and very efficient software modules that can keep up with the SDO data stream and detect, trace, and analyze a large number of phenomena, including flares, sigmoids, filaments, and coronal dimmings.
Main publication: "Computer Vision for the Solar Dynamics Observatory" (Invited Paper), P.C.H. Martens, G.D.R. Attrill, A.R. Davey, A. Engell, S. Farid, P.C. Grigis, J. Kasper, K. Korreck, S.H. Saar, A. Savcheva, Y. Su, P. Testa, M. Wills-Davey, P.N. Bernasconi, N.-E. Raouafi, V.A. Delouille, J.F. Hochedez, J.W. Cirtain, C.E. DeForest, R.A. Angryk, I. De Moortel, T. Wiegelmann, M.K. Georgoulis, R.T.J. McAteer, R.P. Timmons 2012, Solar Phys., SDO Mission Issue, 275, 79-113.
We use a new and innovative stellar dynamo simulation code, developed by former graduate student Andrés Muñoz, to explore the origins of, and decipher the evolution of solar magnetic activity over multiple time scales ranging from centuries to stellar and planetary evolutionary time scales. The results from that dynamo code are as input for a surface magnetic flux transport code developed by our collaborators at the University of St. Andrews in Scotland to produce accurate predictions for the Sun's surface magnetic fields and open magnetic flux. The former regulates the variations in the total solar irradiance and the latter the amount of Cosmic Rays that penetrate the atmosphere of the Earth, both of which are key physical agents of the solar influence on the Earth's climate.
The most recent, and exciting, result is a clear explanation for the unusual length and depth of the most recent solar minimum, "The Unusual Minimum of Sunspot Cycle 23 a Consequence of Meridional Plasma Flow Variations", Dibyendu Nandy, Andres Munoz-Jaramillo, and Petrus C. H. Martens 2011, Nature 471, 80-82.
Personnel involved: Piet Martens, Dibyendu Nandi (Iiserkol, India), Anthony Yeates (Univ. of Durham), Duncan Mackay (St Andrews), Andrés Muñoz (Jack Eddy postdoc at Harvard-Smithsonian). Graduate Student: Ernest Amouzou (Physics)
The geological and biological record support that the Earths biosphere was considerably warmer than currently during the origin of life on Earth and for several billions of years thereafter. Yet, stellar evolution calculations support the Sun reaching the Zero Age Mean Sequence at about 75% of its present luminosity, and linearly increasing in time up to its current level. Climate models predict a Snowball Earth for such a low solar constant. That is the paradox: Solving this puzzle is our objective.
One recent presentation: "The Faint Young Sun Paradox", (Invited Public Lecture), P.C.H. Martens, International Symposium on Solar-Terrestrial Physics, November 6-9, 2012, Indian Institute of Science, Education and Research, Pune, India.
Personnel Involved: Piet Martens
Contributers: Jeremy Drake, Steve Saar, Leon Golub, Steven Cramner, and Andres Munoz (all CfA), and John Priscu (MSU)
Students: I would like to see some involved!
The Virtual Solar Observatory (VSO) has been developed to allow researchers, educators, and the general public to access data and images from the major sources of on-line solar data. The VSO substantially reduces the effort required to locate disparate data sets, and removes the need for the user to locate the data and learn multiple interfaces. The VSO provides a single interface to more than 60 geographically distributed data sets including space- and ground-based sources. These data sets incorporate several physical variables including magnetic field, intensity, Doppler velocity, etc., and all wavelengths from X-ray to radio. All layers of the Sun, from the interior to the corona, are included. In the linked paper we describe the system and present the interface that the user will encounter. Future enhancements are planned for the system, and student participation is encouraged.
Main publication: "The Virtual Solar Observatory -- A Resource for International Heliophysics Research" (Invited Contribution), Frank Hill, Piet Martens, Keiji Yosimura, Joseph Gurman, Joseph Hourcle, George Dimitoglou, Igor Suarez-Sola, Steve Wampler, Kevin Reardon, Alisdair Davey, Richard S. Bogart, and Karin Q. Tian, in: "Proceedings of the UN/ESA/NASA/Japan Workshop", 2009, eds. Guenter Eichhorn and Hans Haubold, Earth, Moon, and Planets 104(10), 315-330.
Personnel involved: Piet Martens and Keiji Yosimura at MSU, list of authors above
Founders of the VSO (1999) are: Frank Hill (NSO),
Joe Gurman (NASA-Goddard),
Rick Bogart (Stanford), and Piet Martens (MSU)
Students: Students (Physics and Computer Science) are welcome for research credit.
The building blocks of X-ray and EUV emission in the solar corona are so-called coronal loops. These loops, it is believed, follow the magnetic field lines and they are brighter than the surrounding corona because coronal heating -- the conversion of free magnetic to thermal energy -- is concentrated inside them. Solar coronal loops are now being observed with unprecedented spatial, spectral and temporal resolution by the AIA instrument on the Solar Dynamics Observatory. We have developed analytical models for quasi-static solar coronal loops, an advanced numerical code for simulating the thermal structure and dynamics of steady and flaring loops, and sophisticated techniques for analyzing the observations of such loops. Diagnosis and modeling of loops is an ongoing effort involving several students.
"Outflow and Dark Bands at Arcade-like Active Region Boundaries", J.T. Scott, P. C. H. Martens, and L. Tarr 2013, Astrophys. J., accepted.
"Fast Differential Emission Measure Inversion of Solar Coronal Data", Joseph Plowman, Charles Kankelborg, and Petrus Martens 2013, Astrophys. J., accepted.
"EUV Analysis of a Dynamic Coronal Loop Structure", J.T. Scott, P. C. H. Martens, and D. McKenzie 2012, Solar Phys., 276, 113.
On the Anti-correlation between Spectral Line Broadening and Intensity in Coronal Structures Observed with EIS", J.T. Scott and P. C. H. Martens 2011, Astrophys. J., 742, 101.
"Simulating the Effects of Initial Pitch-angle Distribution on Solar Flares", Henry D. Winter, Petrus Martens, Katherine K. Reeves 2011, Astrophys. J., 735, 103-116.
"Scaling Laws and Temperature Profiles for Solar and Stellar Coronal Loops with Non-uniform Heating", P.C.H. Martens 2010, Astrophys. J., 714, 1290-1304.
Henry (Trae) Winter defended his thesis on November 4th 2008 (Election day), and won his election to PhD as well. Trae is now an Astrophysicist in the Solar and Stellar X-ray Group of the Harvard-Smithsonian Center for Astrophysics. At the 2005 AGU meeting in New Orleans, Trae won "Outstanding Student Paper Award" twice, one for a research paper and another one for an educational paper. Trae and I continue to collaborate on simulations and analysis of EUV and X-ray coronal loops.
Andrés Muñoz, jointly mentored by Dibyendu Nandi and myself, defended his thesis in June 2010. He did exceptionally well, authoring three first author ApJ papers for this thesis, and co-authoring a paper in Nature (see my list of joint publications with students). Andrés now has joined Trae as a Jack Eddy postdoctoral fellow in the Solar and Stellar X-ray Group of the Harvard-Smithsonian Center for Astrophysics. Andrés' just published a paper on his work in the Spanish language version of Scientific American, and, most impressively, he recently won the 2011 Fred L. Scarf Award from the Space Physics and Aeronomy Section of the American Geophysical Union, for the best thesis in North-America in this field. Andrés will receive the award and present an invited talk at the 2011 Fall AGU in San Francisco.
Jason Scott defended his thesis with success in November 2011. The thesis includes three first author papers, plus a fourth one in draft form. Jason graduated from MSU in December 2004 and won the "2005 Dean's Award for Excellence as the Outstanding Graduating Senior in Sciences". Both he and Jonathan Cirtain also won NASA Graduate Student Research Program fellowships to support their graduate studies. Jason's research concentrates on the EUV and X-ray emission of solar coronal loops, using images and spectra from TRACE, Hinode, and SDO.
Current Graduate Students
started working with me in January of 2010. He is interested in the solar interior
(helioseismology) and the solar dynamo.
Alexander Engell became a graduate student at MSU in the fall of 2011. He is interested in magnetic fields, prominences, feature recognition, and space hardware.
Ricky Egeland started working with me in the fall of 2012, after starting his graduate studies in the fall of 2011. He is interested in working on the cusp between Solar Physics and Computer Science, data mining in particular.
I was the original PI of our NSF supported
Research Opportunities for
Undergraduates program, ten weeks of solar research during the summer.
I also started up the
Solar Physics REU program at the Harvard-Smithsonian Center for Astrophysics in
2008. In the summer of 2011 I worked with REU students
(St Andrews) and
Rahul Sharma (Udaipur). Their joint final presentation is
here. In 2012 Dibyendu Nandi and I worked with Sushant Mahajan on the development of a
code for solar surface magnetic flux transport simulations, see
In previous years I have worked with Kudzanayi Munetsi-Mugomba from Lincoln University determining the accuracy and stability of analytical solutions for the temperature structure in coronal loops. Before that Antonia Wilmot-Smith, from St. Andrews University in Scotland worked with Dibyendu Nandi and me on a project to simulate solar and stellar cycles through sets of nonlinear ordinary differential equations, while in the summer of 2003 Dibyendu and I worked with Andrés Muñoz from the Universidad de los Andes in Colombia on a project to simulate stellar dynamo cycles. Another succesful project within this program was with Paul Wood from St. Andrews in the summer of 2000. At Harvard-Smithsonian, in 2009, I supervised St Andrews REU student Jonathan Constable, jointly with Anthony Yeates, which also led to a joint publication.
Missions I am and have been involved with:
Atmospheric Imaging Assembly (AIA): We are partners with the Lockheed-Martin Solar & Astrophysics Lab and the Harvard-Smithsonian Center for Astrophysics to build an assembly of six EUV telescopes to fly on NASA's Solar Dynamics Observatory. SDO was launched in February 2010, and the mission is designed to last until 2020. Prof. David McKenzie and myself are the MSU Co-I's. MSU plays a significant role in AIA's design and calibration, science & data analysis, and the Education & Public Outreach program.
Thus the Sun is a unique astrophysical laboratory for magnetic fields. The instruments that Solar physicists have built to study Solar magnetic fields routinely produce stunning imagery. A personal selection, result of the work of a high school summer student some time ago, and pertinent to the research interests of our Solar group, is shown here.
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Please contact me for comments, questions, and contributions.
Solar and Heliospheric NASA Heliophysics Management Operations Working Group, 2008-2009
Member, NASA Living with a Star Management Operations Working Group, 2009-2010