Cartwheel Galaxy
The Cartwheel Galaxy (also referred to as ESO 350-40 or PGC 2248) may be a convexo-convex galaxy and ring galaxy concerning five hundred million light-years away within the constellation Sculptor. It is an estimated 150,000 light-years diameter, and has a mass of about 2.9–4.8 × 109 solar masses; its outer ring has a circular velocity of 217 km/s.
It was discovered by Fritz Zwicky in 1941.Zwicky considered his discovery to be "one of the most complicated structures awaiting its explanation on the basis of stellar dynamics."
An estimation of the galaxy's span resulted during a conclusion of one hundred fifty,000 light years, which is slightly larger than the Milky Way.
- Structures
The Cartwheel galaxy shows non-thermal radio and optical spokes, but they are not the same spokes.
- Evolution
The galaxy was once a traditional galaxy before it apparently underwent a head-on collision with a smaller companion just about two hundred million years agony (i.e., 200 million years prior to the image). When the nearby galaxy passed through the Cartwheel Galaxy, the force of the collision caused a powerful shock wave through the galaxy, like a rock being tossed into a sanded. Moving at high speed, the shock wave swept up gas and dust, creating a starburst around the galaxy's center portion that were unscathed. This explains the blue ring round the center, brighter portion.It can be seen that the galaxy is beginning to retake the form of a normal spiral galaxy, with arms spreading out from a central core.
Alternatively, a model based on the gravitational Jeans instability of both axisymmetric (radial) and nonaxisymmetric (spiral) small-amplitude gravity perturbations allows an association between growing clumps of matter and the gravitationally unstable axisymmetric and nonisometric waves which take on the appearance of a ring and spokes
- X-ray sources
The unusual form of the Cartwheel Galaxy is also because of a collision with a smaller galaxy like those within the lower left of the image. The most recent star burst (star formation due to compression waves) has lit up the Cartwheel rim, which has a diameter larger than the Milky Way. Star formation via starburst galaxies, such as the Cartwheel Galaxy, results in the formation of large and extremely luminous stars. When huge stars explode as supernovas, they leave behind neutron stars and black holes. Some of these nucleon stars and black holes have near companion stars, and become powerful sources of X-rays as they pull matter off their companions (also known as ultra and hyper luminous X-ray sources).The brightest X-ray sources square measure doubtless black holes with companion stars, and seem because the white dots that lie on the rim of the X-ray image. The Cartwheel contains associate degree exceptionally sizable amount of those region binary X-ray sources, as a result of several large stars shaped within the ring.
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