The wilds of the local group

March 23, 2016
This image, captured by ESO's OmegaCAM on the VLT Survey Telescope, shows a lonely galaxy known as Wolf-Lundmark-Melotte, or WLM for short. Although considered part of our Local Group of dozens of galaxies, WLM stands alone at the group's outer edges as one of its most remote members. In fact, the galaxy is so small and secluded that it may never have interacted with any other Local Group galaxy -- or perhaps even any other galaxy in the history of the Universe. Credit: ESO

Rather like an uncontacted tribe living deep in the Amazon rainforest or on an island in Oceania, WLM offers a rare insight into the primordial nature of galaxies that have been little disturbed by their environment.

WLM was discovered in 1909 by German astronomer Max Wolf, and identified as a galaxy some fifteen years later by astronomers Knut Lundmark and Philibert Jacques Melotte—explaining the galaxy's unusual moniker. The dim galaxy is located in the constellation of Cetus (The Sea Monster) about three million light-years away from the Milky Way, which is one of the three dominant spiral in the Local Group.

WLM is quite small and lacks structure, hence its classification as a dwarf irregular galaxy. WLM spans about 8000 light-years at its greatest extent, a measurement that includes a halo of extremely old stars discovered in 1996.

Astronomers think that comparatively small primeval galaxies gravitationally interacted with each other and in many cases merged, building up into larger composite galaxies. Over billions of years, this merging process assembled the large spiral and that now appear to be common in the modern Universe. Galaxies congregating in this manner is similar to the way in which human populations have shifted over thousands of years and intermixed into larger settlements, eventually giving rise to today's megacities.

WLM has instead developed on its own, away from the influence of other galaxies and their stellar populations. Accordingly, like a hidden human population with limited contact with outsiders, WLM represents a relatively unperturbed "state of nature", where any changes occurring over its lifetime have taken place largely independent of activity elsewhere.

This small galaxy features an extended halo of very dim red stars, which stretches out into the inky blackness of the surrounding space. This reddish hue is indicative of advanced stellar age. It is likely that the halo dates back to the original formation of the galaxy itself, helpfully offering clues about the mechanisms that spawned the very first galaxies.

The stars at the centre of WLM, meanwhile, appear younger and bluer in colour. In this image, pinkish clouds highlight areas where the intense light from young stars has ionised ambient hydrogen gas, making it glow in a characteristic shade of red.

This detailed image was captured by the OmegaCAM wide-field imager, a huge camera mounted on ESO's VLT Survey Telescope (VST) in Chile—a 2.6-metre telescope exclusively designed to survey the night sky in visible light. OmegaCAM's 32 CCD detectors create 256-megapixel images, offering a very detailed wide-field view of the cosmos.

Explore further: Image: Hubble's compact blue dwarf galaxy UGC 11411

Related Stories

A shy galactic neighbor

September 16, 2015

The Sculptor Dwarf Galaxy, pictured in this new image from the Wide Field Imager camera, installed on the 2.2-metre MPG/ESO telescope at ESO's La Silla Observatory, is a close neighbour of our galaxy, the Milky Way. Despite ...

Hubble views a young elliptical galaxy

November 23, 2015

At the center of this amazing Hubble image is the elliptical galaxy NGC 3610. Surrounding the galaxy are a wealth of other galaxies of all shapes. There are spiral galaxies, galaxies with a bar in their central regions, distorted ...

Image: Hubble views two galaxies merging

December 31, 2015

This image, taken with the Wide Field Planetary Camera 2 on board the NASA/ESA Hubble Space Telescope, shows the galaxy NGC 6052, located around 230 million light-years away in the constellation of Hercules.

Hubble sees a legion of galaxies

March 11, 2016

Peering deep into the early universe, this picturesque parallel field observation from the NASA/ESA Hubble Space Telescope reveals thousands of colorful galaxies swimming in the inky blackness of space. A few foreground stars ...

Recommended for you

NASA's Juno to soar closest to Jupiter this Saturday

August 26, 2016

This Saturday at 5:51 a.m. PDT, (8:51 a.m. EDT, 12:51 UTC) NASA's Juno spacecraft will get closer to the cloud tops of Jupiter than at any other time during its prime mission. At the moment of closest approach, Juno will ...

Spitzer Space Telescope begins 'Beyond' phase

August 26, 2016

Celebrating the spacecraft's ability to push the boundaries of space science and technology, NASA's Spitzer Space Telescope team has dubbed the next phase of its journey "Beyond."

Rosetta captures comet outburst

August 25, 2016

In unprecedented observations made earlier this year, Rosetta unexpectedly captured a dramatic comet outburst that may have been triggered by a landslide.

ALMA finds unexpected trove of gas around larger stars

August 25, 2016

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) surveyed dozens of young stars—some Sun-like and others approximately double that size—and discovered that the larger variety have surprisingly ...

Rocky planet found orbiting habitable zone of nearest star

August 24, 2016

An international team of astronomers including Carnegie's Paul Butler has found clear evidence of a planet orbiting Proxima Centauri, the closest star to our Solar System. The new world, designated Proxima b, orbits its cool ...

2 comments

Adjust slider to filter visible comments by rank

Display comments: newest first

Bigbangcon
1.8 / 5 (5) Mar 23, 2016
This is typical broken-record narrative of official Big Bang cosmology. How can lost amazon tribe still exist without breeding new members? Where does "younger blue stars" in WLM galaxy and the "ionized ambient hydrogen gas" in it come from; without new hydrogen gas forming (from the virtual particles of the quantum vacuum) specially at the core of the galaxy, according to Arp-Malek hypothesis? Ambartsumian, Arp and the Breeding Galaxies: http://redshift.v...2MAL.pdf
EnsignFlandry
5 / 5 (1) Mar 23, 2016
Its not new hydrogen.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.