VISTA finds 96 star clusters hidden behind dust

Aug 03, 2011
Using data from the VISTA infrared survey telescope at ESO’s Paranal Observatory, an international team of astronomers has discovered 96 new open clusters hidden by the dust in the Milky Way. Thirty of these clusters are shown in this mosaic. These tiny and faint objects were invisible to previous surveys, but they could not escape the sensitive infrared detectors of the world’s largest survey telescope, which can peer through the dust. This is the first time so many faint and small clusters have been found at once. The images are made using infrared light in the following bands: J (shown in blue), H (shown in green), and Ks (shown in red). Credit: ESO/J. Borissova

This result comes just one year after the start of the VISTA Variables in the Via Lactea programme (VVV) [1], one of the six public surveys on the new telescope. The results will appear in the journal Astronomy & Astrophysics.

"This discovery highlights the potential of VISTA and the VVV survey for finding star clusters, especially those hiding in dusty star-forming regions in the Milky Way's disc. VVV goes much deeper than other surveys," says Jura Borissova, lead author of the study.

The majority of stars with more than half of the mass of our Sun form in groups, called open clusters. These clusters are the building blocks of galaxies and vital for the formation and evolution of galaxies such as our own. However, stellar clusters form in very dusty regions that diffuse and absorb most of the visible light that the young stars emit, making them invisible to most sky surveys, but not to the 4.1-m infrared VISTA .

"In order to trace the youngest star cluster formation we concentrated our search towards known star-forming areas. In regions that looked empty in previous visible-light surveys, the sensitive VISTA infrared detectors uncovered many new objects," adds Dante Minniti, lead scientist of the VVV survey.

By using carefully tuned computer software, the team was able to remove the foreground stars appearing in front of each cluster in order to count the genuine cluster members. Afterwards, they made visual inspections of the images to measure the sizes, and for the more populous clusters they made other measurements such as distance, age, and the amount of reddening of their starlight caused by interstellar dust between them and us.

"We found that most of the clusters are very small and only have about 10-20 stars. Compared to typical open clusters, these are very faint and compact objects -- the dust in front of these clusters makes them appear 10 000 to 100 million times fainter in visible light. It's no wonder they were hidden," explains Radostin Kurtev, another member of the team.

Since antiquity only 2500 open clusters have been found in the Milky Way, but astronomers estimate there might be as many as 30 000 still hiding behind the dust and gas. While bright and large open clusters are easily spotted, this is the first time that so many faint and small clusters have been found at once.

Furthermore, these new 96 open clusters could be only the tip of the iceberg. "We've just started to use more sophisticated automatic software to search for less concentrated and older clusters. I am confident that many more are coming soon," adds Borissova.

Explore further: Astronomers find 'cousin' planets around twin stars

More information: www.eso.org/public/archives/re… /eso1128/eso1128.pdf

Related Stories

Young Star Clusters

Oct 12, 2009

(PhysOrg.com) -- Most stars form in clusters. Recent studies of nearby star forming regions find that about three-quarters of their young stars are located in groups with ten or more members. The formation ...

Antennae Galaxies

May 19, 2008

This image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. During the course of the collision, billions of stars will be formed. The brightest and most compact of these star ...

Colliding galaxies make love, not war

Oct 17, 2006

A new Hubble image of the Antennae galaxies is the sharpest yet of this merging pair of galaxies. As the two galaxies smash together, billions of stars are born, mostly in groups and clusters of stars. The ...

Hubble Sees Star Cluster 'Infant Mortality'

Jan 10, 2007

Astronomers have long known that young or "open" star clusters must eventually disrupt and dissolve into the host galaxy. They simply don't have enough gravity to hold them together, unlike their much more ...

Hubble Eyes Star Birth in the Extreme

Jun 13, 2006

Staring into the crowded, dusty core of two merging galaxies, NASA's Hubble Space Telescope has uncovered a region where star formation has gone wild.

Survey Reveals Building Block Process For Biggest Galaxies

Apr 12, 2006

A new study of the universe's most massive galaxy clusters shows how mergers play a critical role in their evolution. Astronomers used the twin Gemini Observatory instruments in Hawaii and Chile, and the Hubble Space Telescope ...

Recommended for you

How small can galaxies be?

23 hours ago

Yesterday I talked about just how small a star can be, so today let's explore just how small a galaxy can be. Our Milky Way galaxy is about 100,000 light years across, and contains about 200 billion stars. Th ...

The coolest stars

Sep 29, 2014

One way that stars are categorized is by temperature. Since the temperature of a star can determine its visual color, this category scheme is known as spectral type. The main categories of spectral type are ...

Simulations reveal an unusual death for ancient stars

Sep 29, 2014

(Phys.org) —Certain primordial stars—those 55,000 and 56,000 times the mass of our Sun, or solar masses—may have died unusually. In death, these objects—among the Universe's first-generation of stars—would ...

User comments : 6

Adjust slider to filter visible comments by rank

Display comments: newest first

Shootist
not rated yet Aug 03, 2011
These tiny and faint objects were invisible to previous surveys, but they could not escape the sensitive infrared detectors of the worlds largest survey telescope


Open clusters are anything but tiny.
Nikola
not rated yet Aug 03, 2011
Wow 96! What else don't we know?
that_guy
not rated yet Aug 03, 2011
These tiny and faint objects were invisible to previous surveys, but they could not escape the sensitive infrared detectors of the worlds largest survey telescope


Open clusters are anything but tiny.


Size is relative. Out of billions of stars, only a few thousand clusters. I might be able to see where they're coming from.

Their acronym VVV looks a lot like a triple-U (As opposed to a W).
ololo
not rated yet Aug 06, 2011
Amazing
Nik_2213
not rated yet Aug 07, 2011
Another few flecks of the 'Missing Mass' ??
Justsayin
not rated yet Aug 07, 2011
Here is the link to a higher resolution picture...http://www.eso.or...eso1128/