NC State is one of the leading institutions in the world in the field of supernova remnants, from both an observational and a theoretical perspective. Steve Reynolds, John Blondin, Kazik Borkowski, and Don Ellison all are active in the field. At left is an image of SNR N132D in the Large Magellanic Cloud. This is a 24 µm image from the Spitzer Space Telescope showing emission from dust grains that have been heated in the outward moving shockwave from a 2500 year-old supernova. This image is just one of many that were obtained as part of a successful observing proposal (PI Borkowski) to observe more than 40 SNRs in the Magellanic Clouds during cycle 1 of Spitzer. See the "Papers" link on the left for some recent publications on this and other research done at NC State.

Steve Reynolds

Dr. Reynolds' research has spanned the electromagnetic spectrum throughout his career. From his early work involving SNR studies in radio waves, he moved on to higher energy regimes when he suggested that synchrotron radiation could be observed in hard X-rays from the shock edges of supernova remnants. His current research involves further study of SNRs in X-rays, particularly in modeling X-ray spectra. He is also involved in the somewhat newer field of infrared astronomy, and along with Kazik Borkowski has been Co-invesitgator on several successful observing proposals for Spitzer. His most recent claim to fame was being PI on a 750,000 second observation of Kepler's Supernova Remnant with Chandra. The image on the right contains approximately 30 million X-ray photons, and is one of the deepest X-ray images ever recorded. Analysis of this image led Dr. Reynolds and his collaborators to conclude that Kepler's SNR is the result of a type Ia supernova, and possibly an unusual class of Ia. Dr. Reynolds has also done research on pulsar-wind nebulae, specifically the broadband synchrotron spectra of such objects.

John Blondin

Much of Dr. Blondin's work is focused on the computational problem of getting supernovae to explode in the first place. He was one of the principal investigators of the Terascale Supernova Initiative, a multi-facility collaboration to use some of the world's most powerful computers to simulate supernova explosions. Dr. Blondin's work focuses on getting the post-bounce shock-wave to break out of the star and propel the remains of the star into the interstellar medium. His hydrodynamics codes can be adapted to a variety of different astrophysical situations, including the expansion of a shock-wave from a supernova into the ISM, thus creating a supernova remnant. The image on the left is a frame from a VH-1 simulation showing the oscillations of shockwaves created by a supernova. He has modeled the transitions between various phases of an SNR's evolution. Recently, Dr. Blondin and his collaborators found that it may be possible to impart the angular momentum needed to spin a pulsar, not from the initial angular momentum of the progenitor star (as had been previously assumed), but from instabilities in the accretion shock as it attempts to break out of the star. You can read more about this here.

Kazimierz Borkowski

Kazik Borkowski is a research professor who specializes in the interaction of supernova remnants with the ISM. From his early days of optical studies of planetary nebulae, he has now migrated on to the fields of X-ray and infrared astronomy. Some of his recent work has been in researching a possible "new-class" of supernovae by examining properties of their remnants. "Prompt" type Ia supernovae would be stars that exploded in much less time than originally thought for a type Ia supernova. The image at right is an example of one such object, DEM L238. In addition to specializing in the modeling of X-ray spectra from SNRs, he also has research interests in the physics of interstellar dust grains. He has led several succesful proposals to observe SNRs in the infrared, where warm dust grains heated by the blast-wave from a supernova emit thermal radiation. Modeling this emission gives valuble information on dust abundance and composition in the medium of outer space.

Don Ellison

Dr. Ellison's work involves the acceleration of cosmic rays by shock waves in supernova remnants. Cosmic rays were discovered in the early 20th century, but their origin has remained a mystery to astronomers. Since cosmic rays are protons, alpha particles, and electrons, they have charge, and are thus constrained to move when they encounter the ambient magnetic field in the galaxy, making a determination of their source nearly impossible. It is also a mystery how cosmic rays get accelerated to the enormous energies they are observed as having. One of the few mechanisms capable of doing this is a shock-wave in a supernova remnant. Dr. Ellison's research has been on the methods that could provide the acceleration. One promising possibility is Diffusive Shock Acceleration (DSA). The essence of DSA is that charged particles move in tangled magnetic fields present in these shocks, and trajectories of these particles are so complex that some of thermal particles can cross the shock back and forth multiple times. Due to the difference in flow speeds across the shock, these particles gain energy and may leave the shock and be detected as cosmic rays (CR) on Earth. Clicking on the image to the left will launch a video, which illustrates acceleration of a particle in a shock by this process.