The Hubble Space Telescope has discovered a previously undetected dwarf galaxy in the Milky Way’s backyard. It’s a mere 30 million light-years away (the seeable universe is 93 billion light-years across!), and so old that scientists have deemed it a “living fossil” right in our neighborhood. Space.com reported on Thursday.
The galaxy was found by accident, as so many things in space are. Researchers were using Hubble to study white dwarves (super-dense “stellar corpses”) in the globular cluster NGC 6752. NGC 6752 is in the Milky Way itself. But as they were analyzing the images they got back, they realized that the stars they were looking at existed beyond NGC 6752. Their brightness and temperature indicated that they, in fact, lay in another galaxy all together.
Astronomers determined that this new galaxy is small. Very small. It is only 3,000 light-years wide. By way of comparison, the Milky Way is 100,00 light-years wide across the diameter of its famous spiral disc. Named Bedin 1, after the discovery team leader L. R. Bedin of the INAF-Osservatorio Astronomico di Padova in Italy, it is a “spheroidal dwarf”. Many galaxies of its kind (more than 20) are known satellite galaxies around the Milky Way. But this one is different.
Bedin 1 is 2 million light-years from any galaxy that might be its host (in this case, NGC 6744). It’s unusually far. That makes Bedin 1 the most isolated small dwarf galaxy known. And it is very, very old. In a statement, the Hubble team noted, “From the properties of its stars, astronomers were able to infer that the galaxy is around 13 billion years old — nearly as old as the universe itself,” and “Because of its isolation — which resulted in hardly any interaction with other galaxies — and its age, Bedin 1 is the astronomical equivalent of a living fossil from the early universe.”
Exciting, right!?! It’s like finding a dinosaur femur underneath your deck while you’re pulling weeds! What will we learn next!?!
The researchers published their findings online Jan. 31 in the journal Monthly Notices of the Royal Astronomical Society: Letters.