Robert A. Piontek

• Models of Vertically Stratified Two-Phase ISM Disks with MRI-Driven Turbulence, Piontek, R.A. & Ostriker, E.C., 2006, accepted for publication in ApJ
  
  
• Saturated-State Turbulence and Structure from Thermal and Magnetorotational Instability in the ISM: Three-Dimensional Numerical Simulations, Piontek, R.A. & Ostriker, E.C., 2005, 629, 849
  
  
• Thermal and Magnetorotational Instability in the ISM: Two-Dimensional Numerical Simulations, Piontek, R.A, & Ostriker, E.C. 2004, ApJ, 601, 905
  
  
• Phase Dependent Spectroscopy of Mira Variable Stars, Castelaz, M.W., Luttermoser, D. G., Caton, D. B, & Piontek, R.A. 2000, Astronomical Journal, 120, 2627
  
  
• Vanadium Oxide in the Spectra of Mira Variables, Castelaz, M. W., Luttermoser, D. G., & Piontek, R.A. 2000, Astrophysical Journal, 538, 341
  
  
• Teff and Surface Gravity of Mira Variable Stars, Piontek, R. & Luttermoser, D. G. 1998, International Amateur-Professional Photoelectric Photometry Communications, No. 73, p. 59.
  

• Simulations of the ISM - I perform numerical simulations of the interstellar medium, or ISM for short. The ISM is just a fancy name for the gas and dust that is found between the stars of galaxies like our own Milkyway. The total mass of the ISM is pretty small compared to the total mass of stars in a galaxy, but is still very important because the stars we see today formed from this gas. Even today new stars are forming from the interstellar medium. We study the fundamental physical processes that occur in the ISM, and try to understand which processes affect the overall dynamics of the ISM, and how this affects star formation. Since all stars eventually form out of the ISM it is important to have a fundamental understanding of it so that we can complete the more general picture of galaxy formation and evolution. For movies and pictures follow the link above.
  
  
• Hydrodynamics - In my second year of graduate school I worked with Jim Stone, performing simulations of a process called ram pressure stripping. This occurs when the interstellar medium of a galaxy is removed as it passes through a cluster of galaxies, which happens via interaction with the intercluster medium. Here is an image of a related phenomenon, called dynamical friction. This occurs as a massive body passes through a gaseous medium. Due to the force of gravity, material tends to concentrate behind the object as it moves through the medium. The body's own gravitational force acts on this 'wake', which causes it to slow down. This was the main test problem I used to validate the inclusion of a fixed potential to the hydrodynamics code. I have posted a couple movies of simulations at the link above (March 2001).