A hidden dwarf galaxy has been found orbiting our own Milky Way, meaning it could help us solve the much sought after missing satellite problem. The galaxy found is incredibly bleak to spot, being termed one of the faintest satellite galaxy known to mankind. The finding is significant in that it can help us find the so-called missing satellites, which are needed to explain our current theory on the role mysterious dark matter holding everything in our universe together.
Although we already know around 50 galaxies orbiting our own Milky Way, we need hundreds and hundreds more to justify our understanding of the dark matter. This finding suggests that our theory might be right and that maybe these faint galaxies are just hiding in plain sight.
The new satellite, called Virgo I due to its the direction aligning with the Virgo constellation, has been discovered using the 8.2-metre Subaru Telescope in Hawai’i.
Based on the data collected, the incredibly faint dwarf galaxy Virgo I is found to be around 248 light-years across and is located around 280,000 light-years from our Sun.
One of the researchers Daisuke Homma, from Tohoku University in Japan, said on the discovery,
“We have carefully examined the early data of the Subaru Strategic Survey with HSC and found an apparent over density of stars in Virgo with very high statistical significance, showing a characteristic pattern of an ancient stellar system in the colour-magnitude diagram. Surprisingly, this is one of the faintest satellites, with absolute magnitude of –0.8 in the optical waveband. This is indeed a galaxy, because it is spatially extended with a radius of 124 light years – systematically larger than a globular cluster with comparable luminosity.”
The most exciting part is that as we can detect these ultra-faint galaxies, it means that we can also be on the verge of discovering many more of them which couldn’t be seen before.
Lead researcher Masashi Chiba said,
“This discovery implies hundreds of faint dwarf satellites waiting to be discovered in the halo of the Milky Way. How many satellites are indeed there and what properties they have, will give us an important clue of understanding how the Milky Way formed and how dark matter contributed to it.”
The research was published in the Astrophysical Journal, and you can read it in full on arXiv.org.