Editing X-ray astronomy (section)

==Celestial X-ray sources==
{{main|Astrophysical X-ray source}}
The [[celestial sphere]] has been divided into 88 constellations. The [[International Astronomical Union]] (IAU) constellations are areas of the sky. Each of these contains remarkable X-ray sources. Some of them have been identified from astrophysical modeling to be [[galaxies]] or black holes at the centers of galaxies. Some are [[pulsar]]s. As with sources already successfully modeled by X-ray astrophysics, striving to understand the generation of X-rays by the apparent source helps to understand the Sun, the [[universe]] as a whole, and how these affect us on [[Earth]]. Constellations are an astronomical device for handling observation and precision independent of current physical theory or interpretation. Astronomy has been around for a long time. Physical theory changes with time. With respect to celestial X-ray sources, X-ray astrophysics tends to focus on the physical reason for X-ray brightness, whereas X-ray astronomy tends to focus on their classification, order of discovery, variability, resolvability, and their relationship with nearby sources in other constellations.

[[File:Orion-Eridanus Bubble.gif|thumb|right|This [[ROSAT]] PSPC false-color image is of a portion of a nearby stellar wind superbubble (the [[Orion-Eridanus Superbubble]]) stretching across [[Eridanus (constellation)|Eridanus]] and [[Orion (constellation)|Orion]].]]
Within the constellations Orion and Eridanus and stretching across them is a soft X-ray "hot spot" known as the [[Orion-Eridanus Superbubble]], the '''Eridanus Soft X-ray Enhancement''', or simply the '''Eridanus Bubble''', a 25° area of interlocking arcs of Hα emitting filaments. Soft X-rays are emitted by hot gas (T ~ 2–3 MK) in the interior of the superbubble. This bright object forms the background for the "shadow" of a filament of gas and dust. The filament is shown by the overlaid contours, which represent 100 micrometre emission from dust at a temperature of about 30 K as measured by [[IRAS]]. Here the filament absorbs soft X-rays between 100 and 300 eV, indicating that the hot gas is located behind the filament. This filament may be part of a shell of neutral gas that surrounds the hot bubble. Its interior is energized by [[ultraviolet]] (UV) light and stellar winds from hot stars in the Orion OB1 association. These stars energize a superbubble about 1200 lys across which is observed in the visual (Hα) and X-ray portions of the spectrum.