Something spectacular happens when two galaxies collide: they give off a massive amount of X-rays.
Just in time for the holiday season this year, galaxies NGC 2207 and IC 2163 are coming together and displaying a festive light show, all captured by NASA's Chandra X-Ray Observatory.
These two spiral galaxies are in the Canis Major constellation, which is about 130 million light-years from Earth. In the past 15 years, the two have experienced three supernova explosions.
These two galaxies are very similar to our Milky Way: not only are they spiral shaped, but they also have many X-ray binary star systems. These are systems that have one star in a tight orbit around a neutron star or black hole. The neutron star or black hole has such strong gravity that it pulls on the other star, sucking some of its material towards it, which heats it up to millions of degrees. This creates super bright X-rays, creating objects called "ultraluminous X-ray sources" (ULXs).
"The new Chandra image contains about five times more observing time than previous efforts to study ULXs in this galaxy pair," writes NASA. "Scientists now tally a total of 28 ULXs between NGC 2207 and IC 2163."
This image suggests that there is a strong link between star formation and these ULXs. For example, the spiral "arms" of the galaxies show areas where astronomers believe that a high number of stars are currently forming.
"Colliding galaxies like this pair are well known to contain intense star formation. Shock waves - like the sonic booms from supersonic aircraft - form during the collision, leading to the collapse of clouds of gas and the formation of star clusters," writes NASA.
This suggests that the primary stars in the galaxies are young, only about 10 million years old (in comparison, our sun is about 5 billion years old). Scientists believe that both galaxies have active star formations, with 24 stars about the mass of our sun created every year. That's about 20 or so more stars per year than the Milky Way creates.
This image is actually a composite of Chandra data, combined with observations from both the Hubble and Spitzer Space Telescopes.
[Photo Credit: X-ray: NASA/CXC/SAO/S.Mineo et al, Optical: NASA/STScI, Infr]
