Dusty Stellar Nurseries from the Dark Side of a Galaxy

The red colours in this image show the galaxy M66 as it appears at the sub-mm wavelength of 850 microns, while the white background shows the galaxy as it appears in visible light. 

Regions of cold dust that appear as dark streaks in the white image glow brightly in the red image. 

The center of the galaxy contains much more dust than is obvious from looking at the visible image and the sub-mm image also picks out an unusual compact cloud in the southern part of the galaxy that is a prime site for future star formation. Credit: VLT/ESO, JAC, G. Bendo.

One of the world's most powerful cameras, SCUBA-2 is producing its first detailed images of our neighbouring galaxies, revealing previously undetected vast pockets of star formation where the next generation of stars is being created.

The light from these stars is usually obscured by dust, but at the sub-millimetre wavelengths that the camera is designed for, these dust lanes actually glow brightly. The images are revealed in the week of the 25th anniversary of the James Clerk Maxwell Telescope, in Hawaii on which SCUBA-2 is mounted.

"This exquisite image from the galaxy M66 in the constellation Leo is exactly the promising start we were hoping for," said Dr. Stephen Serjeant, the team's co-leader from The Open University. "This is a wonderfully exciting taste of things to come."

When looking up at the Milky Way, an irregular pattern of dark regions obscures the light of the stars. The dark patches are caused by clouds of dust trailing through the spiral arms and blocking out the starlight that would otherwise reveal vast pockets of star formation, or stellar nurseries. These dark lanes are not exclusive to the Milky Way, but can be found in all spiral galaxies.

SCUBA-2, led by STFC's UK Astronomy Technology Centre in Edinburgh is the most powerful camera ever developed for observing light at sub-milimetre wavelengths, 1000 times longer than we can see with our eyes.

This makes it possible to detect stellar nurseries usually obscured by dust that are so remote the light they emit left them within the first billion years after the big bang.

University of Edinburgh astrophysicist Professor James Dunlop said: "These beautiful new images from SCUBA-2 show energy conservation in action, as the same dust which absorbs the blue optical light (obscuring the stars in the optical images) can be seen to re-emit at the much longer wavelengths accessible to SCUBA-2."

This image promises to be the first of many stunning results from the James Clerk Maxwell Telescope Nearby Galaxy Legacy Survey (NGLS). The main aim of the survey is to understand how the broader environment of a galaxy affects its gas and dust content.

For example, galaxies in dense clusters can lose their gas and dust through interactions with other galaxies in the cluster or simply by the head wind they feel while moving through the hot gas trapped inside the cluster.

The NGLS is an international collaboration led by astronomers from Canada, the Netherlands, and the United Kingdom which is using SCUBA-2 to observe 150 galaxies in the local universe.

The NGLS team has spent much of the last five years studying molecular hydrogen emission using another instrument on the James Clerk Maxwell Telescope.

"It is very exciting to now see the first results from the SCUBA-2 side of our programme starting to come in," says Professor Christine Wilson, the Principal Investigator from McMaster University in Canada.

"We have a unique sample of galaxies that we are studying and having SCUBA-2 data will let us measure their gas and dust content. Gas and dust usually go hand-in-hand in galaxies, but from time to time, you find a surprise."

STFC is the UK sponsor of astronomy and operates the Joint Astronomy Centre in Hawaii.

ESA Planck study: Cold Gas Pockets May Point to Star Formation, Cosmos Blueprint

(Photo: ESA/Planck)
Distribution of carbon monoxide (CO), a molecule used by astronomers to trace molecular clouds across the sky, as seen by Planck (blue). 

A compilation of previous surveys, which left large areas of the sky unobserved, has been superimposed for comparison (red). The outlines identify the portions of the sky covered by these surveys.
 
Astronomers are closer to uncovering a blueprint of the cosmos after finding islands of cold gas and mysterious microwaves and for the first time map out carbon dioxide through the universe.

The discovery came from the Planck mission from the European Space Agency and was presented at an international conference in Bologna, Italy.

Most people think of carbon monoxide as a poisonous gas sometimes found in households, but an international team mapped out carbon monoxide that is part of the cold clouds in the Milky Way and other galaxies.

Astronomers hypothesized that these hydrogen-rich regions could be the birth places for stars.

"The great advantage of Planck is that it scans the whole sky, allowing us to detect concentrations of molecular gas where we didn't expect to find them," Planck collaborator Jonathan Aumont from the Institut d'Astrophysique Spatiale, Universite Paris XI, Orsay, France, said in a statement.

The microwave haze defied explanation, according to scientists, who are still studying the dataset.

"The results achieved thus far by Planck on the galactic haze and on the carbon monoxide distribution provide us with a fresh view on some interesting processes taking place in our galaxy," Jan Tauber, ESA's Project Scientist for Planck, said in a statement.

The astronomers plan to release the Planck dataset in 2013.

For more details click here.

Exotic Galaxies Reveal Tantalising Tales

Optical SDSS image of the galaxies in yellow: Low resolution radio image from NVSS in blue; High resolution radio image from GMRT in red. Credit: Hota et al., SDSS, NCRA-TIFR, NRAO/AUI/NSF.

A galaxy with a combination of characteristics never seen before is giving astronomers a tantalizing peek at processes they believe played key roles in the growth of galaxies and clusters of galaxies early in the history of the Universe.

The galaxy, dubbed Speca by the researchers, is only the second spiral, as opposed to elliptical, galaxy known to produce large, powerful jets of subatomic particles moving at nearly the speed of light. It also is one of only two galaxies to show that such activity occurred in three separate episodes.

Giant jets of superfast particles are powered by supermassive black holes at the cores of galaxies. Both elliptical and spiral galaxies harbor such black holes, but only Speca and one other spiral galaxy have been seen to produce large jets. The jets pour outward from the poles of rapidly-rotating disks of material orbiting the black hole.

The on-and-off jet episodes have been seen in a dozen ellipticals, but only one other elliptical shows evidence, like Speca, for three such distinct episodes.

"This is probably the most exotic galaxy with a black hole ever seen. It has the potential to teach us new lessons about how galaxies and clusters of galaxies formed and developed into what we see today," said Ananda Hota, of the Academia Sinica Institute of Astronomy and Astrophysics (ASIAA), in Taiwan.

The scientists believe that Speca, about 1.7 billion light-years from Earth, and the 60-some other galaxies in a cluster with it are providing a look at what young galaxies and clusters may have been like when the Universe was much younger.

In the young Universe, galaxies in such clusters would have been gathering up additional material, colliding with each other, undergoing bursts of star formation, and interacting with primordial material falling into the cluster from outside.

"Speca is showing evidence for many of these phenomena," Ananda said, adding that "We hope to find many more galaxies like it with future observations, and to learn more about the processes and an environment that were much more common when the Universe was a fraction of its current age."

Speca (an acronym for Spiral-host Episodic radio galaxy tracing Cluster Accretion) first came to Ananda's attention in an image that combined data from the visible-light Sloan Digital Sky Survey and the FIRST survey done with the National Science Foundation's Very Large Array (VLA) radio telescope.

Followup observations with the Lulin optical telescope in Taiwan and ultraviolet data from NASA's GALEX satellite confirmed that the giant lobes of radio emission, usually seen coming from elliptical galaxies, were coming from a spiral galaxy with ongoing star formation.

Ananda's team also examined the galaxy in images from the NRAO VLA Sky Survey (NVSS), then made new observations with the Giant Meterwave Radio Telescope (GMRT) in India, which observes at longer wavelengths than the VLA and is the premier telescope for observing at those long wavelengths.

With this impressive variety of data from across the electromagnetic spectrum, the researchers unraveled the galaxy's complex and fascinating history.

VISTA comes online (the Visible and Infrared Survey Telescope for Astronomy)

A new telescope - VISTA (Visible and Infrared Survey Telescope for Astronomy) - has just started it's working life at ESO's Paranal Observatory and has made its first release of pictures.

VISTA is a survey telescope working at infrared wavelengths and is the world's largest telescope dedicated to mapping the sky.

Its large mirror, wide field of view and very sensitive detectors will reveal a completely new view of the southern sky. Spectacular new images of the Flame Nebula, the centre of our Milky Way galaxy and the Fornax Galaxy Cluster show that it is working extremely well.

VISTA is the latest telescope to be added to ESO's Paranal Observatory in the Atacama Desert of northern Chile. It is housed on the peak adjacent to the one hosting the ESO Very Large Telescope (VLT) and shares the same exceptional observing conditions.

VISTA's main mirror is 4.1 metres across and is the most highly curved mirror of this size and quality ever made - its deviations from a perfect surface are less than a few thousandths of the thickness of a human hair - and its construction and polishing presented formidable challenges.

VISTA was conceived and developed by a consortium of 18 universities in the United Kingdom [1] led by Queen Mary, University of London and became an in-kind contribution to ESO as part of the UK's accession agreement. The telescope design and construction were project-managed by the Science and Technology Facilities Council's UK Astronomy Technology Centre (STFC, UK ATC).

Provisional acceptance of VISTA was formally granted by ESO at a ceremony at ESO's Headquarters in Garching, Germany, attended by representatives of Queen Mary, University of London and STFC, on 10 December 2009 and the telescope will now be operated by ESO.

"VISTA is a unique addition to ESO's observatory on Cerro Paranal. It will play a pioneering role in surveying the southern sky at infrared wavelengths and will find many interesting targets for further study by the Very Large Telescope, ALMA and the future European Extremely Large Telescope," says Tim de Zeeuw, the ESO Director General.

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