Dragonfly 44 Galaxy is almost entirely made up of invisible dark matter, study suggests

Astronomers have discovered a new galaxy which they believe is almost entirely made of dark matter, and is so faint that it has remained hidden from the eyes of researchers for the past so many decades. Dubbed Dragonfly 44, this galaxy is located in the Coma Cluster, approximately 330 million light years away from Earth and is made up of approximately 99.99% dark matter.

Why is dark matter so mysterious?

Scientists have been searching for the mysterious dark matter in the universe for past so many decades, but this invisible stuff has never been really seen, most likely because it doesn't emit any observable light or radiation which could be detected by any scientific instrument.  Scientists have however detected the gravitational force exerted by the invisible matter, suggesting that this matter does exist and is probably vital for the Universe to remain stable. Scientists also estimate that about 27% of all the energy and mass in the observable Universe consists of dark matter.

How was Dragonfly 44 discovered?

Dragonfly 44 was actually found two years back in 2014 by a team of researchers from Keck Observatory (Hawaii), Yale University, and University of Toronto. The galaxy was discovered when researchers were using the WM Keck Observatory and Gemini North Telescope in Manuakea in Hawaii to observe a group of galaxies in Coma Cluster region in the Universe. Astronomers were able to detect the galaxy by observing the movement of its stars, which appeared to be influenced by presence of black matter in the galaxy. The team noted that stars in the Dragonfly 44 were moving very fast, suggesting a big discrepancy and presence of black matter in the galaxy.

Mass of Dragonfly 44

Based on their observations, the researchers hypothesised that the invisible dark matter 'shield' was probably protecting the galaxy from ripping apart. The team tested out their hypothesis by calculating the mass of Dragonfly 44. They first measured the velocity of the stars in the galaxy for about 34 hours and then used this data to estimate the total mass of the galaxy. The team calculated that the mass of Dragonfly 44 is about 1 trillion times more than the mass of our Sun. According to researchers, this mass is so big that the stars of Dragonfly alone can't protect it from ripping itself apart, and there must be about 99.99 percent dark matter in this galaxy to keep this galaxy intact.

The detailed findings of the study have been published in the journal Astrophysical Journal Letters.