Madrid, 1 (European Press)
A scientifically mysterious isolated cloud larger than the Milky Way has been placed in a “no-man’s-land” of galaxies by astronomers at the University of Alabama in Huntsville (UAH).
The orphan cloud is filled with hot gas with a temperature of 10,000-10,000,000 degrees K and a total mass of 10,000 times the mass of the Sun. This makes it larger than the mass of smaller galaxies.
The cloud was discovered at Abell 1367 by a group led by Dr. Ming Sun, associate professor of physics at UAH, which is part of the University of Alabama system. Also known as the Leo Cluster, A1367 contains about 70 galaxies and is located about 300 million light-years from Earth.
The cloud was found using the European Space Agency’s XMM-Newton X-ray telescope. The cloud was also observed using the MUSE instrument on the Australian VLT telescope and the Subaru telescope.
“This is an exciting and surprising discovery,” Sun says in a statement. “It shows that there are always new surprises in astronomy, like the oldest natural sciences.” “The ESA seems to agree, as our discovery was chosen as the ESA’s image publication, which was very selective.”
“The cloud was discovered by chance in our XMM data,” Sun says, in a galaxy cluster where thousands of galaxies are associated with hot, thin gas with temperatures of about 100,000,000 K in between.
“However, the cloud is not associated with any galaxy and is in an ‘earth without galaxies,'” he says, adding that the cloud likely originated from a large, unknown galaxy in the cluster.
“The gas in the cloud is removed by compressing the hot gas in the cluster, as the host galaxy rises in the hot gas at a rate of 1,000 to 2,000 kilometers per second.”
This is about 50 times faster than the orbital speed of the Earth around the sun. This level of force can rip the interstellar medium out of the galaxy, and in this case, the researchers found that the cloud’s temperature corresponded to its origin in the galaxy.
“It’s as if your hair and clothes are flying backwards when you’re moving forward against a strong headwind,” Sun says. “Once removed from the host galaxy, the cloud is initially cold and evaporates in the middle within the host group, like ice that melts in summer.”
However, this massive and mysterious cloud is estimated to have survived for hundreds of millions of years after being removed from its host galaxy. “This surprising age is little known, but it may have something to do with the magnetic field in the cloud,” Sun says.
Scientists believe that the field could act to hold the cloud together by suppressing the unstable forces that would cause it to dissipate. Through future studies, the lonely cloud and other yet-to-be-discovered objects could help scientists better understand the bare interstellar media at great distances from their galaxies, as well as the effects of turbulence and thermal conductivity.