The primary goal of Jin Koda's research is to understand the gas dynamical evolution of galactic disks, with an emphasis on star formation and interstellar medium (ISM) evolution. He employs both observational and theoretical approaches to explore gas structure, dynamics, and star formation over galactic disks.

Jin Koda uses numerical hydrodynamic simulations and predicts the dramatic evolution of ISM structures in galactic dynamics (e.g. Wada & Koda 2004). The growth of such structures triggers star formation, controlling the formation and evolution of galactic disks. He also observes the evolutionary links among dynamics, ISM structures, and star formation. Recent and upcoming instruments are providing exciting opportunities in resolving ISM structures over global galactic disks. The figure shows an example -- a new image of molecular gas in the Whirlpool galaxy M51 observed with the Combined Array for Research in Millimeter Astronomy (CARMA) and Nobeyama 45m telescope (NRO45). This new map reveals the ISM evolution driven by galactic dynamics: strong shear motions on spiral arms pull apart massive molecular gas associations as they cross the spiral arms, producing filamentary/spur structures in interarm regions (Koda et al. 2009). He is now leading the CARMA & NRO45 survey of nearby galaxies to establish more general picture of ISM evolution and star formation in galaxies. He is also a member of the Herschel key science project (KINGFISH -- Key Insights on Nearby Galaxies: a Far-Infrared Survey with Herschel), which will unveil the immediate sites of star formation that are hidden deeply in the dense ISM.

Stanimir Metchev's research focuses on understanding the physical properties and the dynamical evolution of extrasolar planetary systems and of brown dwarfs - objects with intermediate characteristics between those of stars and gas giant planets. On one hand, he employs the high-contrast imaging capabilities of the Hubble Space Telescope and of ground-based telescopes equipped with adaptive optics systems to resolve dusty disks around young stars. Spatially resolved images of such circumstellar disks allow us to study the formation and architectures of extrasolar planetary systems. On the other hand, he uses sensitive optical to infrared spectroscopy to characterize the atmospheres of brown dwarfs at all ages. The chemical composition and physical structure of brown dwarf atmospheres are not unlike those of gas giant planets in the Solar System, and thus allow us to project the properties of extrasolar giant planets expected to be imaged in the next few years.

Stan's research relies on archival and proprietary data from ground- and space-based telescopes, and uses state of the art technology, such as adaptive optics imaging, integral field spectroscopy, and large-scale database cross-correlation. Research is done on a collaborative basis with scientists across the US and at international institutions, and will often involve students in additional on-site observations at mountain-top observatories.

Deane Peterson's interests are currently focused on the use of the new generation of long baseline Optical Interferometers, specifically the Navy Prototype Optical Interferometer (NPOI), to image the disks of stars. Using this instrument, he and colleagues have resolved the rotationally distorted disk and specifically the asymmetric intensity distribution across the surface of the disk of Altair, one of the three bright A stars making up the so-called summer triangle. He, along with the same colleagues have also discovered that Vega, another of the summer triangle and the principle spectral and photometric standard for Astronomy, is also rotating near breakup, albeit seen nearly pole-on. This means that the wavelength dependence of Vega's emitted light will be substantially different than expected, which will materially affect its use as a standard.

With planned upgrades, particularly increased baseline lengths, the NPOI is contributing to opening a whole new chapter in stellar astrophysics, including how stars accommodate to and evolve while undergoing extreme rotation, the appearance and evolution of sunspots on other solar type stars, the appearance of regions of variable composition on the surface of hotter, but slowly rotating stars, etc. This is a period of rapid advances, observationally driven, in the area of stellar astrophysics.

Mike Simon is interested in the formation of stars, brown dwarfs, and planets, and more specifically in the processes and circumstances that govern the formation of binaries and higher order multiples. At present, he is most involved in using dynamical methods to measure the masses of young stars to measure the masses of very young stars with high precision. The goal of this work is to calibrate calculations of pre-main sequence evolution and thus to improve the accuracy of mass and age estimates of young stars from their location in the HR diagram. Increasingly, this work is leading to similar studies of brown dwarfs.

His research uses state-of-the-art instrumentation in several areas of astronomy (e.g. IR spectroscopy, adaptive optics imaging, and interferometry at Gemini and Keck Observatories, mm-wave interferometry at IRAM). This research is almost always collaborative and offers students the opportunity to work with instruments at the forefront of modern astronomy and with scientists who are expert in their use.

Anand Sivaramakrishnan and his collaborators helped develop the theory, design, and use of high contrast coronagraphic instrumentation on 4-8 meter telescopes with "extreme" adaptive optics (ExAO) systems, constructing and fielding the first such instrument, the Lyot Project. He is making coronagraphs for two next-generation ExAO systems, Palomar's P1640 and the Gemini Planet Imager, with the goal of direct detection and spectral characterization of young, warm exosolar jovian planets. Anand pioneered the use of non-redundant masking (NRM) on the James Webb Space Telescope (JWST), which he intends to use to detect and characterize protoplanets in the constellation of Taurus, for example. He is on the science team of one of its instruments, the Fine Guidance Sensor Tunable Filter Imager (FGS-TFI). The NRM technique improves JWST's angular resolution by a factor of at least 8 over its conventional coronagraphs. This field offers students and postdoctoral scholars opportunities in hardware, optics, developing new instrumentation and observing techniques, and conducting searches for planets and protoplanetary disks outside our solar system. He also uses the National Synchrotron Light Source at Brookhaven National Laboratory to characterize his high contrast optics and develop innovative instrumentation.

Fred Walter has eclectic interests in galactic astronomy. His main interests are in star formation in the Galaxy, stellar coronae and chromospheres, and compact objects. The overarching theme to his present research is the astrophysics of accretion, from star formation (T Tauri stars), to white dwarfs (polars and novae). He is a multiwavelength observer, working in X-rays (Chandra and XMM), UV (FUSE), optical (HST; SMARTS) and the near-IR (IRTF). Current projects include

• Accretion and activity in the T Tauri stars S CrA and RU Lupi
• The eruptive pre-main sequence stars (EXORs) V1118 Ori and V1647 Ori
• Spectrophotometry of recent novae, including YY Dor and N LMC 2005
• Coronal structure in rapidly rotating stars: XY UMa and V471 Tau
• Star formation in OB associations, concentrating on the low mass stars and brown dwarfs in the Orion OB1 association
• properties of isolated neutron stars
• activity cycles in magnetic cataclysmic variables (POLARS)

(image credit: Stella Kafka/CTIO)

Alan Calder studies a variety of nuclear astrophysics problems as well as the basic physical processes involved in these problems. He has investigated core collapse supernovae and coalescing neutron stars, events thought to be sites of r-process nucleosynthesis, and problems involving thermonuclear explosions, classical novae and thermonuclear runaway (Type Ia) supernovae in particular. Calder is also interested in the challenging problem of radiation hydrodynamics, which has numerous applications in astrophysics. His research involves large-scale, multi-physics simulations of astrophysical events, and he is very interested in the validation of codes and simulations by comparing simulations to actual laboratory experiments.

Jim Lattimer studies the structure, composition, formation and evolution of neutron stars by working at the crossroads between nuclear theory and astrophysics. He also researches gravitational collapse supernovae, the mergers of neutron star-neutron star and neutron star-black hole binaries, and neutrino emission from proto-neutron stars. He is interested in the nuclear matter equation of state and the constraints that can be placed on it by laboratory nuclear measurements as well as by pulsar-timing observations and optical and X-ray studies of neutron stars. He has published, and continues to develop, tabulated equations of state that are frequently used throughout the world in large-scale computational simulations of supernovae and neutron star mergers.

Doug Swesty is interested in a variety of nuclear astrophysical and radiation-hydrodynamic phenomena. He is working on neutrino radiation-hydrodynamic models of stellar core-collapse and type II supernova explosions. This work utilizes large-scale parallel computers to carry out high-resolution models of the neutrino-radiating fluid that is present in proto-neutron stars formed at the endpoint of the collapse of a massive stellar core. His research also focuses on the role of the equation of state of hot, dense matter in facilitating the supernova explosion associated with the stellar core collapse. Swesty also actively works with colleagues at national laboratories, such as Lawrence Livermore National Laboratory, on the development of new radiation transport and radiation-hydrodynamic algorithms and codes. This includes the development of verification tests as well as validation testing strategies using data from high energy density laboratory experiments.

Mike Zingale is interested in computational astrophysics and its application to astrophysical thermonuclear explosions, in particular, Type Ia supernovae, Type I X-ray bursts, and Classical novae. Type Ia supernovae are the largest thermonuclear explosions in the Universe. The physical processes leading up to the explosion involve a wide range of length and timescales, making these events extremely challenging to simulate. Working with colleagues at LBL, Zingale is developing a low Mach number hydrodynamic code, MAESTRO, appropriate to the conditions in these explosions. MAESTRO filters soundwaves from the system, allowing for the efficient simulation of long timescale processes, such as astrophysical convection. This method was recently used to model the final hours of 'smoldering' preceding the explosion of a Type Ia supernovae. This type of calculation is critical to determining the distribution of the initial flames for the subsequent explosion.

Together with other members of the nuclear astrophysics group, Zingale is also interested in verification and validation of astrophysical hydrodynamics codes.