X-Ray Morphology,Kinematics and Geometry of the Eridanus Soft X-Ray Enhancement
Session 12 -- Interstellar medium
Display presentation, Monday, 9, 1995, 9:20am - 6:30pm

## [12.15] X-Ray Morphology,Kinematics and Geometry of the Eridanus Soft X-Ray Enhancement

Zhiyu Guo (The Pennsylvanian State University), David N. Burrows (The Pennsylvanian State University), Wilton T. Sanders (University of Wisconsin - Madison), Steve L. Snowden (NASA/GSFC), Bryan E. Penprase (Claremont College)

We present mosaics of X-ray intensity maps and spectral fit results for selected regions of the Eridanus soft X-ray Enhancement (EXE), as well as kinematics of the X-ray absorbing clouds in the EXE region and geometrical properties of this X-ray emitting bubble. The work is based on pointed observations with the ROSAT Position Sensitive Proportional Counter, 21 cm observations with the NRAO 140 foot telescope at Green Bank and interstellar Na D line observations with the NOAO Coud\'{e} Feed telescope at Kitt Peak. The ROSAT pointed observations examine two regions of the EXE. The first is an X-ray absorption lane produced by an IR filament which is located at galactic coordinates of about ($199^{\circ}$, $-45^{\circ}$). The second is in the vicinity of the northern (galactic) boundary of the 1/4 keV EXE, at galactic coordinates of about ($200^{\circ}$, $-25^{\circ}$). Both our spatial and spectral analysis suggest that variations in emission measure and $N_{H}$ are primarily reponsible for the observed variations of the X-ray intensity. Using 100$\mu$ intensities obtained from IRAS maps and $N_{H}$ column densities obtained from our X-ray spectral fits, we find $100 \mu$m/$N_{H}$ ratios across the IR filament that are compatible with typical high latitude values. Maps of the X-ray absorbing clouds in the EXE region at 21 cm reveal that these clouds may belong to two different expanding systems, with one possibly associated with our Local Bubble and the other with the boundary of the EXE. Combination of 21 cm data with interstellar Na D line observations toward stars in the directions of some of the X-ray absorbing clouds along (l,b) $\sim$ ($200^{\circ}$,$-40^{\circ}$) indicate that the near side of the EXE is farther than 151 pc and the distance to the center of the EXE at this latitude is about 226 pc. The density and the thermal pressure found for this X-ray emitting superbubble are 0.015 $cm^{-3}$ and 4.9 $\times$ $10^{4}$ $cm^{-3}$ K.