Revealing the Structure of the Outer Disks of Be Stars
Classical Be stars possess self-ejected gaseous circumstellar disks governed by viscous forces. The structure of the inner parts (<20 stellar radii) of these disks is well explained by the viscous decretion disk model (VDD), which is able to reproduce multi-technique observable properties of most of the so-far studied objects. Due to the nature of the emission mechanism responsible for the IR and radio continuum excess (free-free emission), the outer parts of the disks are observable at radio wavelengths only. A steepening of the spectral slope somewhere between infrared and radio wavelengths was reported for the handful of Be stars that were observed in radio, but the physical reason for this feature remained mostly unknown.
I will present results from the multi-technique modeling of beta CMi, for which we obtained new sub-mm data from the APEX telescope. The SED turndown observed in beta CMi could be reproduced only when assuming a truncated disk. The most plausible explanation for the truncation is the presence of a faint companion, which has been just independently confirmed as predicted via RV analysis of the H-alpha line. Results from the SED modeling of additional stars, for which have new multiband VLA data, will be presented. All the studied disks are found to be truncated, while only one of the objects is a previously known binary. The detailed structure of the radio SED revealed by the VLA observations allow for studying the exact nature of the disk truncation. The truncation is clearly not as sharp as expected, and certain features indicate that the disks may extend beyond the orbits of the companions, thus offering a possibility that Be disks are actually circumbinary disks.
My First 25 Years in PHENIX at RHIC: From Small Science to Big Science
Public holiday in: Alabama, Arizona, Colorado, Connecticut, District of Columbia, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Northern Mariana Islands, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Utah, Virginia, West Virginia
CALICE: Calorimetry Reinvented
Recent developments in calorimetry for high energy physics experiments show
a clear trend towards devices with very fine granularity. In this context,
the CALICE collaboration pioneers the development and study of imaging
calorimeters. After an in-depth introduction into the topic, I will provide
an overview of the collaboration’s activities with a special focus on
possible applications at the planned Electron-Ion Collider.