Hubble Captures a Dwarf Galaxy Shaped by a Grand Design

Image Credit: ESA/NASA

The subject of this Hubble image is NGC 5474, a dwarf galaxy located 21 million light-years away in the constellation of Ursa Major (The Great Bear).

This beautiful image was taken with Hubble's Advanced Camera for Surveys (ACS).

The term "dwarf galaxy" may sound diminutive, but don't let that fool you, NGC 5474 contains several billion stars!

However, when compared to the Milky Way with its hundreds of billions of stars, NGC 5474 does indeed seem relatively small.

NGC 5474 itself is part of the Messier 101 Group. The brightest galaxy within this group is the well-known spiral Pinwheel Galaxy (also known as Messier 101).

This galaxy's prominent, well-defined arms classify it as a "grand design galaxy," along with other spirals Messier 81 and Messier 74.

Also within this group are Messier 101's galactic neighbors. It is possible that gravitational interactions with these companion galaxies have had some influence on providing Messier 101 with its striking shape.

Similar interactions with Messier 101 may have caused the distortions visible in NGC 5474.

Both the Messier 101 Group and our own Local Group reside within the Virgo Supercluster, making NGC 5474 something of a neighbour in galactic terms.

ESA Hubble View: NGC 4303 A Hungry Starburst Galaxy

This new ESA Hubble picture is the sharpest ever image of the core of spiral galaxy Messier 61. 

Taken using the High Resolution Channel of Hubble's Advanced Camera for Surveys (ACS), the central part of the galaxy is shown in striking detail.

Credit: European Space Agency

Also known as NGC 4303, this galaxy is roughly 100,000 light-years across, comparable in size to our galaxy, the Milky Way.

Both Messier 61 and our home galaxy belong to a group of galaxies known as the Virgo Supercluster in the constellation of Virgo (The Virgin), a group of galaxy clusters containing up to 2,000 spiral and elliptical galaxies in total.

Messier 61 is a type of galaxy known as a starburst galaxy, one that experiences an incredibly high rate of star formation, hungrily using up their reservoir of gas in a very short period of time (in astronomical terms).

But this is not the only activity going on within the galaxy; deep at its heart there is thought to be a supermassive black hole that is violently spewing out radiation.

Despite its inclusion in the Messier Catalogue, Messier 61 was actually discovered by Italian astronomer Barnabus Oriani in 1779.

Charles Messier also noticed this galaxy on the very same day as Oriani, but mistook it for a passing comet, the comet of 1779.