NASA Hubble Watches Star Clusters on a Collision Course

This is a Hubble Space Telescope image of a pair of star clusters that are believed to be in the early stages of merging.

The clusters lie in the gigantic 30 Doradus nebula, which is 170,000 light-years from Earth.

The Hubble observations, made with the Wide Field Camera 3, were taken Oct. 20-27, 2009.

The blue colour is light from the hottest, most massive stars; the green from the glow of oxygen; and the red from fluorescing hydrogen.

Image Credit: NASA, ESA, R. O'Connell (University of Virginia), and the Wide Field Camera 3 Science Oversight Committee

Astronomers using data from NASA's Hubble Space Telescope have caught two clusters full of massive stars that may be in the early stages of merging.

The clusters are 170,000 light-years away in the Large Magellanic Cloud, a small satellite galaxy to our Milky Way, a small satellite galaxy to our Milky Way.

What at first was thought to be only one cluster in the core of the massive star-forming region 30 Doradus (also known as the Tarantula Nebula) has been found to be a composite of two clusters that differ in age by about one million years.

The entire 30 Doradus complex has been an active star-forming region for 25 million years, and it is currently unknown how much longer this region can continue creating new stars. Smaller systems that merge into larger ones could help to explain the origin of some of the largest known star clusters.

Lead scientist Elena Sabbi of the Space Telescope Science Institute in Baltimore, Md., and her team began looking at the area while searching for runaway stars, fast-moving stars that have been kicked out of their stellar nurseries where they first formed.

"Stars are supposed to form in clusters, but there are many young stars outside 30 Doradus that could not have formed where they are; they may have been ejected at very high velocity from 30 Doradus itself," Sabbi said.

She then noticed something unusual about the cluster when looking at the distribution of the low-mass stars detected by Hubble.

It is not spherical, as was expected, but has features somewhat similar to the shape of two merging galaxies where their shapes are elongated by the tidal pull of gravity.

Hubble’s circumstantial evidence for the impending merger comes from seeing an elongated structure in one of the clusters, and from measuring a different age between the two clusters.

According to some models, the giant gas clouds out of which star clusters form may fragment into smaller pieces.

Once these small pieces precipitate stars, they might then interact and merge to become a bigger system. This interaction is what Sabbi and her team think they are observing in 30 Doradus.

NASA Hubble Image: A Chance Alignment Between Galaxies

The Hubble Space Telescope shows a rare view of a pair of overlapping galaxies, called NGC 3314.

The two galaxies look as if they are colliding, but they are actually separated by tens of millions of light-years, or about ten times the distance between our Milky Way and the neighbouring Andromeda galaxy.

The chance alignment of the two galaxies, as seen from Earth, gives a unique look at the silhouetted spiral arms in the closer face-on spiral, NGC 3314A.

Image Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration, and W. Keel (University of Alabama)

Image of a Very Distant Future: Milky Way Collides with Andromeda Galaxy

This Nasa illustration shows at night just before the predicted merger between our Milky Way galaxy and the neighbouring Andromeda galaxy, which is expected to happen about 3.75 billion years from now

Picture: REUTERS/NASA, ESA, Z. Levay and R. van der Marel (STScI), and A. Mellinger

Dark Matter Ideas Challenged by Galaxy Structures

The galaxy pair UGC 9618 and VV 340, two spiral galaxies at the beginning of a collision.

CREDIT: NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

A sprawling collection of galaxies and star clusters surrounding our own Milky Way is challenging long-standing theories on the existence of dark matter, the mysterious substance thought to pervade the universe.

The structure of satellite galaxies and star clusters around the Milky Way is so vast that it reaches across a million light-years – 10 times as wide as the Milky Way itself, according to astronomers at the University of Bonn in Germany, who made the discovery.

Existing dark matter theories fail to explain the arrangement of these cosmic objects, the scientists say.

"Our model appears to rule out the presence of dark matter in the universe, threatening a central pillar of current cosmological theory," said study team member Pavel Kroupa, a professor of astronomy at the University of Bonn.

"We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit."

NASA Centaur Spacecraft on collision course with Moon

Two NASA spacecraft are barreling toward the moon at twice the speed of a bullet, about to crash into a lunar crater in a search for ice.

If all goes well, the impact will be beamed back live to Earth.

The first and much bigger crash is set for 7:31 a.m. EDT. That's when an empty rocket that weighs 2.2 tons should hit the crater Cabeus and create a minicrater about half the size of an Olympic pool. It should kick up a plume of lunar debris about six miles high.

The idea is to confirm the theory that water — a key resource if people are going to go back to the moon — is hidden below the barren moonscape.

Trailing behind the rocket is the lunar probe LCROSS, short for Lunar Crater Observation and Sensing Satellite and pronounced L-Cross, beaming back to Earth live pictures of the impact and the debris plume using color cameras. It will scour for ice, fly through the debris cloud and then just four minutes later take the fatal plunge itself, triggering a dust storm one-third the size of the first hit.

Telescopes around the world — including the orbiting Hubble Space Telescope — will aim their cameras at the big event to provide more views of the dust-up.