Chandra Release - February 3, 2006

Visual Description: NGC 5746

The X-ray and optical image of the spiral galaxy NGC 5746 features a small bright blue object with a white bulbous core in the center, surrounded by stars and other galaxies in a sea of darkness. The blue object appears to be a large, luminous structure overlays the spiral galaxy seen sharply from the side - in a loose and gaseous flying-saucer like shape. Chandra observations of the massive spiral galaxy revealed a large halo of hot gas (the blue area) surrounding the optical disk of the galaxy (the white core and disk). The halo extends more than 60,000 light years on either side of the disk of the galaxy, which is viewed edge-on. The galaxy shows no signs of unusual star formation, or energetic activity from its nuclear region, making it unlikely that the hot halo is produced by gas flowing out of the galaxy. Hot gas has been detected around spiral galaxies in which vigorous star formation is ejecting matter from the galaxy, but until now, hot halos due to infall of intergalactic matter had not been detected. Indeed, the extensive hot gas halo around NGC 5746 is faint and would be very difficult to detect without a powerful X-ray telescope such as Chandra.