Credit: ESA/Hubble & NASA
Acknowledgement: Judy Schmidt (Geckzilla)
Acknowledgement: Judy Schmidt (Geckzilla)
At first glance this NASA/ESA Hubble Space Telescope image seems to show an array of different cosmic objects, but the speckling of stars shown here actually forms a single body — a nearby dwarf galaxy known as Leo A. Its few million stars are so sparsely distributed that some distant background galaxies are visible through it. Leo A itself is at a distance of about 2.5 million light-years from Earth and a member of the Local Group of galaxies; a group that includes the Milky Way and the well-known Andromeda galaxy.
Astronomers
study dwarf galaxies because they are very numerous and are simpler in
structure than their giant cousins. However, their small size makes
them difficult to study at great distances. As a result, the dwarf
galaxies of the Local Group are of particular interest, as they are
close enough to study in detail.
As it turns out, Leo A is a
rather unusual galaxy. It is one of the most isolated galaxies in the
Local Group, has no obvious structural features beyond being a roughly
spherical mass of stars, and shows no evidence for recent interactions
with any of its few neighbours. However, the galaxy’s contents are
overwhelmingly dominated by relatively young stars, something that would
normally be the result of a recent interaction with another galaxy.
Around 90% of the stars in Leo A are less than eight billion years old —
young in cosmic terms! This raises a number of intriguing questions
about why star formation in Leo A did not take place on the “usual” timescale, but instead waited until it was good and ready.
Source: ESA/Hubble - Space Telescope
