Saturday, 23 February, 2019

Hubble finds dwarf galaxy in our cosmic neighbourhood

Space										
		
																	Hubble just spotted a never-before-seen galaxy hiding in plain sight					
								
			
	
		Mike Wehner			@Mike Space Hubble just spotted a never-before-seen galaxy hiding in plain sight Mike Wehner @Mike
Theresa Hayes | 03 February, 2019, 15:30

While studying the ancient white dwarf stars in the bright globular cluster NGC 6752, in an effort to gain an accurate measure of the cluster's age, they noticed something amiss in the background.

An global team of astronomers recently used the telescope to study white dwarf stars in the NGC 6752. This cluster lies around 13,000 light-years away, and scientists were studying the stars with Hubble to find out how old they are, and in turn, the age of the entire cluster. Analyses of the stars' brightnesses and temperatures indicated that they lay beyond NGC 6752 and were, in fact, part of a previously unknown galaxy.

Our newly discovered cosmic neighbour, nicknamed Bedin 1 by the astronomers, is a modestly sized, elongated galaxy.

The team called the elongated and small galaxy Bedin 1, which measures nearly 3,000 light years, only a fraction of the size of our galaxy. The lunar sample was brought to Earth from the Moon by the Apollo 14 astronauts. In the Local Group of Galaxies, scientists have spotted 36 dwarf spheroidal galaxies, and 22 of them are satellite galaxies of our Milky Way.

Reference: These results will be published online January 31, 2019, in Monthly Notices of the Royal Astronomical Society: Letters [https://academic.oup.com/mnrasl]. Not only is it tiny, but it is also incredibly faint.

The researchers that discovered Bedin-1 were really lucky to have stumbled on it by accident, because it's so small and faint it would probably never have been discovered on objective with current instruments. Not only is it one of just a few dwarf spheroidals that have a well established distance but it is also extremely isolated. It's thought that Bedin 1 is the most isolated dwarf galaxy known to exist.

So if Bedin 1 is gravitationally connected to the distant NGC 6744, the larger galaxy appears to have left its little sibling alone. The galaxy's isolation means it rarely interacted with other galaxies, making it the equivalent of an early universe "living fossil", the space agency explains. But Bedin 1 is special in several ways, according to the discovery team.

[1] While similar to dwarf elliptical galaxies in appearance and properties, dwarf spheroidal galaxies are in general approximately spherical in shape and have a lower luminosity.

The Hubble Space Telescope was launched into orbit in 1990, where it has remained in the decades since.