A group of astronomers headed by Professor Tomoharu Oka of Japan’s Keio University has detected a mysterious gas cloud, known as CO-0.40-0.22, just at a distance of 200 light years from the center of the Milky Way. The surprisingly wide velocity dispersion of CO-0.40-0.22 made it unusual. The cloud consists of gas having a quite broad range of speeds.

The team has discovered this baffling feature using two radio telescopes, Japan’s Nobeyama 45-m Telescope and Chile’s ASTE Telescope. Both are operated by Japan’s National Astronomical Observatory.

For investigating a clear picture and a detailed structure, the astronomers observed CO-0.40-0.22 using the Nobeyama 45-m Telescope again to get 21 emission lines from 18 molecules. The findings showed that the cloud has an elliptical shape. It consists of two components: a compact but low density component having a quite broad velocity dispersion of 100 km/s, and a dense component that extends 10 light years with narrow velocity dispersion.

The cloud has no holes. And, X-ray and infrared observations haven’t found any compact objects. The features have indicated that the velocity dispersion isn’t the result of a local energy input, like supernova explosions.

The researchers carried out a simple simulation of gas clouds hurled by a strong gravity source. During the simulation, the gas clouds were first attracted by the source, and then, their speed went up when they approached it, and reached maximum at the nearest point to the object.

The speed of clouds decreased after they continue past the object. The researchers discovered that a model, using a gravity source that had 100 thousand times the Sun’s mass inside a region with a radius of 0.3 light years, gave the best fit to the observed data.

Oka, said, “Considering the fact that no compact objects are seen in X-ray or infrared observations, as far as we know, the best candidate for the compact massive object is a black hole”.