The nucleus of the Whirlpool Galaxy (M51). The Cross marks the location of the black hole at the center of the galaxy. The cross was first interpreted as two dust rings circling the nucleus. It was later determined to simply be foreground dust lanes silhouetted by the active nucleus. Bright ionization cones can be seen extending perpendicular to the largest dust feature.
A black hole, surrounded by a ring of dust, is thought to exist at the heart of the spiral. The dust ring stands almost perpendicular to the relatively flat spiral nebula. A secondary ring crosses the primary ring on a different axis, a phenomenon that is contrary to expectations. A pair of ionization cones extend from the axis of the main dust ring.
ABOUT THIS IMAGE:
This image of the core of the nearby spiral galaxy M51, taken with the Wide Field Planetary camera (in PC mode) on NASA's Hubble Space Telescope, shows a striking , dark "X" silhouetted across the galaxy's nucleus. The "X" is due to absorption by dust and marks the exact position of a black hole which may have a mass equivalent to one-million stars like the sun. The darkest bar may be an edge-on dust ring which is 100 light-years in diameter. The edge-on torus not only hides the black hole and accretion disk from being viewed directly from earth, but also determines the axis of a jet of high-speed plasma and confines radiation from the accretion disk to a pair of oppositely directed cones of light, which ionize gas caught in their beam. The second bar of the "X" could be a second disk seen edge on, or possibly rotating gas and dust in MS1 intersecting with the jets and ionization cones.
The size of the image is 1100 light-years.
Object Names: M51, Whirlpool Galaxy
Image Type: Astronomicalhttp://en.wikipedia.org/wiki/Whirlpool_Galaxy.