14 DAY TRIAL // Astronomers operating the NASA/ESA Hubble Space Telescope were recently able to image a runaway galaxy relatively close to the Milky Way, which is traveling through the Universe at an extreme speed. Due to its rapid motion, the galaxy is trailing areas of intense stellar formation.
A runaway galaxy is a formation that travels at immense speeds through the Cosmos. There are several scenarios that can explain this phenomenon, including one where a galaxy has a run-in with another, more massive formation, which results in it being accelerated on its path, rather than a merger.
The object Hubble recently imaged is designated ESO 137-001 and is a member of the barred spiral galaxy group. It is located around 200 million light-years away, in the cluster Abell 3627 (also known as the Norma Cluster). Previous measurements indicate that the formation is heading towards the center of the cluster, most likely on a massive strand of dark matter.
Its extreme speed is stripping away its massive gas reserves, preventing stellar formation inside the galaxy and producing a tail that is no less than 260,000 light-years long. This is 2.6 times longer than the diameter of the Milky Way. What astronomers observed with amazement is that stellar formation does appear to be taking place inside these Tails.
In this sense, ESO 137-001 looks like a dandelion caught in a breeze, spreading its seeds throughout its parent cluster. Interestingly, the Norma Cluster does not feature a lot of intergalactic gas, but the material available is heated to around 100 million degrees Celsius (180 million degrees Fahrenheit).
This extreme heat makes the gas glow at X-ray wavelengths, making it easy to detect with dedicated telescopes. The fact that ESO 137-001 travels through this medium at a speed reaching 7.25 million kilometers (4.5 million miles) per hour is contributing to maintaining this temperature.
Astronomers term the process that leads to the galaxy losing its gas through constant collisions with this intergalactic gas ram pressure stripping. The only reason why the galaxy holds together is the gravitational interactions between its stars. Anything else between these stars is stripped away.
The image above was collected using the Wide Field Camera 3 (WFC3) instrument on Hubble. In addition to the target galaxy, this field of view also includes numerous stars located within the edges of the Milky Way. Also clearly visible are blue, jellyfish-like tendrils trailing ESO 137-001.
The reason these structures are blue is that they are producing an impressive number of new stars, which shine brightly in ultraviolet wavelengths. WFC3 features two UV/visible detecting charge-coupling devices (CCD) and a separate IR detector, meaning it can see these objects as they form.
Based on the new image, astronomers estimate that this galaxy will have a lot of trouble creating new stars in the future. By the time its speed slows down, after it reaches the core of the Norma Cluster, insufficient gas will have remained within ESO 137-001 to allow for meaningful stellar formation.