arXiv subjects

P. C. Schneider

Publications and source records attributed to P. C. Schneider.

76 records · Page 5Linked to original sources

arXiv2009

The Chandra X-ray view of the power sources in Cepheus A

The central part of the massive star-forming region Cepheus A contains several radio sources which indicate multiple outflow phenomena, yet the driving sources of the individual outflows have not been identified. We present a high-resolution Chandra observation of this region that shows the presence of bright X-ray sources, consistent with active pre-main sequence stars, while the strong absorption hampers the detection of less luminous objects. A new source has been discovered located on the line connecting H_2 emission regions at the eastern and western parts of Cepheus A. This source could be the driving source of HH 168. We present a scenario relating the observed X-ray and radio emission.

astro-ph.SR↗

arXiv2009

Chandra observation of Cepheus A: The diffuse emission of HH 168 resolved

X-ray emission from massive stellar outflows has been detected in several cases. We present a Chandra observation of HH 168 and show that the soft X-ray emission from a plasma of 0.55 keV within HH 168 is diffuse. The X-ray emission is observed on two different scales: Three individual, yet extended, regions are embedded within a complex of low X-ray surface brightness. Compared to the bow shock the emission is displaced against the outflow direction. We show that there is no significant contribution from young stellar objects (YSOs) and discuss several shock scenarios that can produce the observed signatures. We establish that the X-ray emission of HH 168 is excited by internal shocks in contrast to simple models, which expect the bow shock to be the most X-ray luminous.

astro-ph.SR↗

arXiv2008

Discovery of X-ray emission from the eclipsing brown-dwarf binary 2MASS J05352184-0546085

The eclipsing brown-dwarf binary system 2MASS J05352184-0546085 is a case sui generis. For the first time, it allows a detailed analysis of the individual properties of young brown dwarfs, in particular, masses, and radii, and the temperature ratio of the system components can be determined accurately. The system shows a "temperature reversal" with the more massive component being the cooler one, and both components are found to be active. We analyze X-ray images obtained by Chandra and XMM-Newton containing 2MASS J05352184-0546085 in their respective field of view. The Chandra observatory data show a clear X-ray source at the position of 2MASS J05352184-0546085, whereas the XMM-Newton data suffer from contamination from other nearby sources, but are consistent with the Chandra detection. No indications of flaring activity are found in either of the observations (together about 70 ks), and we thus attribute the observed flux to quiescent emission. With an X-ray luminosity of 3*10^{28} erg/s we find an L_X/L_{bol}-ratio close to the saturation limit of 10^{-3} and an L_{X}/L_{Hα}-ratio consistent with values obtained from low-mass stars. The X-ray detection of 2MASS J05352184-0546085 reported here provides additional support for the interpretation of the temperature reversal in terms of magnetically suppressed convection, and suggests that the activity phenomena of young brown dwarfs resemble those of their more massive counterparts.

astro-ph↗

arXiv2008

The nature of the soft X-ray source in DG Tau

The classical T Tauri star DG Tau shows all typical signatures of X-ray activity and, in particular, harbors a resolved X-ray jet. We demonstrate that its soft and hard X-ray components are separated spatially by approximately 0.2 arcsec by deriving the spatial offset between both components from the event centroids of the soft and hard photons utilizing the intrinsic energy-resolution of the Chandra ACIS-S detector. We also demonstrate that this offset is physical and cannot be attributed to an instrumental origin or to low counting statistics. Furthermore, the location of the derived soft X-ray emission peak coincides with emission peaks observed for optical emission lines, suggesting that both, soft X-rays and optical emission, have the same physical origin.

astro-ph↗