Showing posts with label Messier 80. Show all posts
Showing posts with label Messier 80. Show all posts

Wednesday, January 05, 2011

VISTA Stares Deeply into the Blue Lagoon

PR Image eso1101a
VISTA's infrared view of the Lagoon Nebula (Messier 8)

PR Image eso1101b
Infrared/visible light comparison of views of the Lagoon Nebula (Messier 8)

PR Image eso1101c
The star formation region Messier 8 in the constellation of Sagittarius

PR Image eso1101d
VISTA’s infrared view of the Lagoon Nebula (Messier 8)

Zooming in on the VISTA view of the Lagoon Nebula (Messier 8)

IR/visible crossfade of the Lagoon Nebula (Messier 8)

This new infrared image of the Lagoon Nebula was captured as part of a five-year study of the Milky Way using ESO’s VISTA telescope at the Paranal Observatory in Chile. This is a small piece of a much larger image of the region surrounding the nebula, which is, in turn, only one part of a huge survey.

Astronomers are currently using ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA) to scour the Milky Way’s central regions for variable objects and map its structure in greater detail than ever before. This huge survey is called VISTA Variables in the Via Lactea (VVV) [1]. The new infrared image presented here was taken as part of this survey. It shows the stellar nursery called the Lagoon Nebula (also known as Messier 8, see eso0936), which lies about 4000–5000 light-years away in the constellation of Sagittarius (the Archer).

Infrared observations allow astronomers to peer behind the veil of dust that prevents them from seeing celestial objects in visible light. This is because visible light, which has a wavelength that is about the same size as the dust particles, is strongly scattered, but the longer wavelength infrared light can pass through the dust largely unscathed. VISTA, with its 4.1-metre diameter mirror — the largest survey telescope in the world — is dedicated to surveying large areas of the sky at near-infrared wavelengths deeply and quickly. It is therefore ideally suited to studying star birth.

Stars typically form in large molecular clouds of gas and dust, which collapse under their own weight. The Lagoon Nebula, however, is also home to a number of much more compact regions of collapsing gas and dust, called Bok globules [2]. These dark clouds are so dense that, even in the infrared, they can block the starlight from background stars. But the most famous dark feature in the nebula, for which it is named, is the lagoon-shaped dust lane that winds its way through the glowing cloud of gas.

Hot, young stars, which give off intense ultraviolet light, are responsible for making the nebula glow brightly. But the Lagoon Nebula is also home to much younger stellar infants. Newborn stars have been detected in the nebula that are so young that they are still surrounded by their natal accretion discs. Such new born stars occasionally eject jets of matter from their poles. When this ejected material ploughs into the surrounding gas short-lived bright streaks called Herbig–Haro objects [3] are formed, making the new-borns easy to spot. In the last five years, several Herbig–Haro objects have been detected in the Lagoon Nebula, so the baby boom is clearly still in progress here.

Notes

[1] This survey, one of six VISTA surveys currently in progress, will image the central parts of the Milky Way many times over a period of five years and will detect huge numbers of new variable objects.

[2] Bart Bok was a Dutch-American astronomer who spent most of his long career in the United States and Australia. He first noticed the dark spots that now bear his name, in star formation regions and speculated that they may be associated with the earliest stages of star formation. The hidden baby stars were only observed directly when infrared imaging was possible several decades later.

[3] Although not the first to see such objects, the astronomers George Herbig and Guillermo Haro were the first to study the spectra of these strange objects in detail and realise that they were not just clumps of gas and dust that reflected light, or glowed under the influence of the ultraviolet light from young stars, but were a new class of objects associated with star formation.

More information
The science team for VVV includes Dante Minniti (Universidad Catolica, Chile), Phil Lucas (University of Hertfordshire, UK), Ignacio Toledo (Universidad Catolica) and Maren Hempel (Universidad Catolica). ESO, the European Southern Observatory, is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive astronomical observatory. It is supported by 15 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Portugal, Spain, Sweden, Switzerland and the United Kingdom. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and VISTA, the world’s largest survey telescope. ESO is the European partner of a revolutionary astronomical telescope ALMA, the largest astronomical project in existence. ESO is currently planning a 42-metre European Extremely Large optical/near-infrared Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links:
Photos of VISTA
VVV survey main page

Contacts :
Richard Hook

ESO, La Silla, Paranal, E-ELT and Survey Telescopes Public Information Officer

Garching bei München, Germany

Tel: +49 89 3200 6655

Cell: +49 151 1537 3591

Email:
rhook@eso.org

Wednesday, September 22, 2010

PR Image heic1015a
Image credit: NASA, ESA

PR Video heic1015a
Zooming in on the Lagoon Nebula

PR Video heic1015b
Panning across the Lagoon Nebula

A spectacular new NASA/ESA Hubble Space Telescope image reveals the heart of the Lagoon Nebula. Seen as a massive cloud of glowing dust and gas, bombarded by the energetic radiation of new stars, this placid name hides a dramatic reality.

The Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope has captured a dramatic view of gas and dust sculpted by intense radiation from hot young stars deep in the heart of the Lagoon Nebula (Messier 8). This spectacular object is named after the wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula.

This structure is prominent in wide-field images, but cannot be seen in this close-up. However the strange billowing shapes and sandy texture visible in this image make the Lagoon Nebula’s watery name eerily appropriate from this viewpoint too.

Located four to five thousand light-years away, in the constellation of Sagittarius (the Archer), Messier 8 is a huge region of star birth that stretches across one hundred light-years. Clouds of hydrogen gas are slowly collapsing to form new stars, whose bright ultraviolet rays then light up the surrounding gas in a distinctive shade of red.

The wispy tendrils and beach-like features of the nebula are not caused by the ebb and flow of tides, but rather by ultraviolet radiation’s ability to erode and disperse the gas and dust into the distinctive shapes that we see.

In recent years astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous proof that star formation by accretion of matter from the gas cloud is ongoing in this region.

Young stars that are still surrounded by an accretion disc occasionally shoot out long tendrils of matter from their poles. Several examples of these jets, known as Herbig-Haro objects, have been found in this nebula in the last five years, providing strong support for astronomers’ theories about star formation in such hydrogen-rich regions.

The Lagoon Nebula is faintly visible to the naked eye on dark nights as a small patch of grey in the heart of the Milky Way. Without a telescope, the nebula looks underwhelming because human eyes are unable to distinguish clearly between colours at low light levels.

Charles Messier, the 18th century French astronomer, observed the nebula and included it in his famous astronomical catalogue, from which the nebula’s alternative name comes. But his relatively small refracting telescope would only have hinted at the dramatic structures and colours now visible thanks to Hubble.

Notes

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

Contacts

Oli Usher
Junior ESA/Hubble Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Email: ousher@eso.org

Tuesday, February 23, 2010

Alien invaders pack the Milky Way

A Hubble Space Telescope image of the typical globular cluster Messier 80, an object made up of hundreds of thousands of stars and located in the direction of the constellation of Scorpius. The Milky Way galaxy has an estimated 160 globular clusters of which one quarter are thought to be ‘alien’. Image: NASA / The Hubble Heritage Team / STScI / AURA. JPEG (524 kb)

Around a quarter of the star clusters in our Milky Way galaxy are invaders from other galaxies, according to a team of scientists from Swinburne University of Technology in Australia. In a paper accepted for publication in Monthly Notices of the Royal Astronomical Society, Swinburne astronomer Professor Duncan Forbes has shown that many of our galaxy’s globular star clusters are actually foreigners - having been born elsewhere and then migrated to our Milky Way.

“It turns out that many of the stars and globular star clusters we see when we look into the night sky are not natives, but aliens from other galaxies,” said Forbes. “They have made their way into our galaxy over the last few billion years.”

Previously astronomers had suspected that some globular star clusters, which each contain between 10000 and several million stars were foreign to our galaxy, but it was difficult to positively identify which ones.

Using Hubble Space Telescope data, Forbes, along with his Canadian colleague Professor Terry Bridges, examined globular star clusters within the Milky Way galaxy.

They then compiled the largest ever high-quality database to record the age and chemical properties of each of these clusters.

“Using this database we were able to identify key signatures in many of the globular star clusters that gave us tell-tale clues as to their external origin,” Forbes said.

“We determined that these foreign-born globular star clusters actually make up about one quarter of our Milky Way globular star cluster system. That implies tens of millions of accreted stars – those that have joined and grown our galaxy – from globular star clusters alone.”

The researchers’ work also suggests that the Milky Way may have swallowed up more dwarf galaxies than was previously thought.

“We found that many of the foreign clusters originally existed within dwarf galaxies - that is ‘mini’ galaxies of up to 100 million stars that sit within our larger Milky Way.

“Our work shows that there are more of these accreted dwarf galaxies in our Milky Way than was thought. Astronomers had been able to confirm the existence of two accreted dwarf galaxies in our Milky Way – but our research suggests that there might be as many as six yet to be discovered.

"Although the dwarf galaxies are broken-up and their stars assimilated into the Milky Way, the globular star clusters of the dwarf galaxy remain intact and survive the accretion process."

“This will have to be explored further, but it is a very exciting prospect that will help us to better understand the history of our own galaxy.”

Forbes’ research was carried out in Canada as part of an Australian Research Council International Fellowship.

The research paper can be accessed at: http://hdl.handle.net/1959.3/77578

MEDIA CONTACTS

Crystal Ladiges
Press Office
Swinburne University of Technology
Tel: +61 3 9214 5064
Mob: +61 416 174 880
E-mail:
cladiges@swin.edu.au

Dr Robert Massey
Press and Policy Officer
Royal Astronomical Society
Tel: +44 (0)20 7734 3307 / 4582
Mob: +44 (0)794 124 8035
E-mail:
rm@ras.org.uk

NOTES FOR EDITORS

THE ROYAL ASTRONOMICAL SOCIETY

The Royal Astronomical Society (RAS: http://www.ras.org.uk), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognises outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3000 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others.