The talks are in the same order as the Program Schedule.
Hamaguchi, Kenji - Spatially resolving X-ray emission from a Class I Pre-Main Sequence Binary System
Wolk, Scott - Chandra Spitzer and VLA observations of Young Stellar Clusters.
Rachel Osten (University of Maryland/NASA GSFC)
The ability of late-type stellar outer atmospheres to produce X-ray emissions shaped by reconnecting magnetic fields is now known to be a commonplace phenomenon. Such stars are also prolific producers of transient X-ray emissions, but these emissions represent only the tip of the iceberg of flare energetics. The surprising recent detection of a flare from a nearby active binary with the Swift satellite (under the guise of a GRB) has revealed new insights in stellar flare physics, made possible only by the unique design of Swift. I will describe this singular event, and use it as a starting point to discuss new insights gained in stellar flare physics as well as the consequences of large explosive events on stellar environments. The effect of large releases of stellar ionizing radiation, at levels 150,000 times more powerful than the largest solar flares, has implications in a variety of stellar environments, from young hyperactive stars surrounded by a planet-forming disk, to superflares from normal solar-like stars and their effects on terrestrial planet atmospheres (and life!).
Kenji Hamaguchi (NASA/GSFC/ASD) , Minho Choi (International Center for Astrophysics, Korea Astronomy and Space Science Institute), Ken'ichi Tatematsu (National Astronomical Observatory of Japan), Chul-Sung Choi (International Center for Astrophysics, Korea Astronomy and Space Science Institute), Rob Petre (NASA/GSFC), Michael F. Corcoran (CRESST and X-ray Astrophysics Laboratory NASA/GSFC)
Many, if not most, stars are born as a member of a binary system through fragmentation of the parent molecular cloud. Because pre-main sequence (PMS) stars that form as a binary system are the same age, any variation in their X-ray activity would be due to their mass difference or the presence of the companion star. PMS binaries are therefore a useful probe to test models of the dependence of X-ray activity on stellar parameters. Separations of binary PMSs are less than 10” at the typical distance to nearby star forming regions. Chandra’s spatial resolution down to 1” can be used to study the X-ray properties of individual components of PMS binaries for the first time. Using a sub-pixel event repositioning technique, we spatially resolved X-ray emission from the Class I PMS binary system IRS5 in the R Corona Australis molecular cloud with 0.8” separation. As far as we know, this result - obtained from 8 Chandra archival observations between 2000 and 2005 - is the first X-ray study of individual sources in a Class I PMS binary system with a projected separation less than 200AU. We extracted light curves and spectra of the individual sources with a two-dimensional image fitting method using Sherpa. The brighter near-infrared source (IRS 5a) showed three X-ray flares lasting >20 ksec, while the fainter source (IRS 5b) was quiescent almost through the observations. In quiescence, these sources showed almost identical X-ray spectra, with NH 4e22 cm-2, kT 2 keV and Lx 1e30 ergs s-1. Their X-ray properties are typical of Class I protostars although variable cm radio emission with circular polarization from IRS 5 favors it to be a pair of young T-Tauri stars behind a molecular cloud. We discuss their evolutionary stages and the connection between their radio and X-ray activity.
Scott Wolk (Smithsonian Astrophysical Observatory) , R. Osten (UMD), T. Bourke (CfA), S.T. Megeath (U. Toledo), B.D. Spitzbart (CfA), E. Winston (U. Dublin)
We examine the properties of embedded clusters within 2 kpc using new data from the Chandra X-ray Observatory and the Spitzer Space Telescope, as well as data from the VLA for the closest systems. We use surveys of entire molecular clouds to understand the range and distribution of cluster membership, size, and surface density. The data demonstrate clearly that there is a continuum of star-forming environments, from relative isolation to dense clusters. Using the combined Spitzer and CXO data allows a very accurate assessment of cluster size. We have detected differences in the spatial distributions of Class II and Class III objects (a.k.a. classical and naked T Tauri stars). Comparison of the class fraction as a function of cluster age is crucial to understanding disk evolution. The simultaneous radio and X-ray data reveal a disconnect between the two magnetic activity signatures in comparison with nearby active stars and the Sun. This evidence comes from both the lack of correlations of time-averaged luminosities as well as simultaneous measures of radio and X-ray variability which show the absence of the Neupert effect. Further the radio flux is anti-correlated with spectral index in variable sources. Taken together this indicates that the variability in these very young stars is non-solar in nature. We have also detected a radio flare from a Class II object and a score of transition objects in X-rays. These latter data allow us to start the process of understanding the high energy environment in this crucial planet building stage.