A Bubbly Cosmic Celebration

PR Image eso1521a

The star forming cloud RCW 34

 

PR Image eso1521b

The star-forming cloud RCW 34 in the constellation of Vela

PR Image eso1521c

Around the star-formation region Gum 19 (RCW 34)

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Videos

 

PR Video eso1521a

Zooming in on the star forming cloud RCW 34

PR Video eso1521b

Close-up pan across the star forming cloud RCW 34

In the brightest region of this glowing nebula called RCW 34, gas is heated dramatically by young stars and expands through the surrounding cooler gas. Once the heated hydrogen reaches the borders of the gas cloud, it bursts outwards into the vacuum like the contents of an uncorked champagne bottle — this process is referred to as champagne flow. But the young star-forming region RCW 34 has more to offer than a few bubbles; there seem to have been multiple episodes of star formation within the same cloud.

This new image from ESO’s Very Large Telescope (VLT) in Chile shows a spectacular red cloud of glowing hydrogen gas behind a collection of blue foreground stars. Within RCW 34 — located in the southern constellation of Vela — a group of massive young stars hide in the brightest region of the cloud [1]. These stars have a dramatic effect on the nebula. Gas exposed to strong ultraviolet radiation — as occurs in the heart of this nebula — becomes ionised, meaning that the electrons have escaped the hydrogen atoms.

Hydrogen is treasured by cosmic photographers because it glows brightly in the characteristic red colour that distinguishes many nebulae and allows them to create beautiful images with bizarre shapes. It is also the raw material of dramatic phenomena such as champagne flow. But ionised hydrogen also has an important astronomical role: it is an indicator of star-forming regions. Stars are born from collapsing gas clouds and therefore abundant in regions with copious amounts of gas, like RCW 34. This makes the nebula particularly interesting to astronomers studying stellar birth and evolution.

Vast amounts of dust within the nebula block the view of the inner workings of the stellar nursery deeply embedded in these clouds. RCW 34 is characterised by extremely high extinction, meaning that almost all of the visible light from this region is absorbed before it reaches Earth. Despite hiding away from direct view, astronomers can use infrared telescopes, to peer through the dust and study the nest of embedded stars.

Looking behind the red colour reveals that there are a lot of young stars in this region with masses only a fraction of that of the Sun. These seem to clump around older, more massive stars at the centre, while only a few are distributed in the outskirts. This distribution has led astronomers to believe that there have been different episodes of star formation within the cloud. Three gigantic stars formed in the first event that then triggered the formation of the less massive stars in their vicinity [2].

This image uses data from the FOcal Reducer and low dispersion Spectrograph (FORS) instrument attached to the VLT, which were acquired as part of the ESO Cosmic Gems programme [3].

Notes

[1] RCW 34 is also known as Gum 19 and is centred on the brilliant young star called V391 Velorum.

[2] The most massive very bright stars have short lives — measured in millions of years — but the less massive ones have lives longer than the current age of the Universe.

[3] The ESO Cosmic Gems programme is an outreach initiative to produce images of interesting, intriguing or visually attractive objects using ESO telescopes, for the purposes of education and public outreach. The programme makes use of telescope time that cannot be used for science observations. All data collected may also be suitable for scientific purposes, and are made available to astronomers through ESO’s science archive.

More Information

ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. 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 two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

Links

• ESO Cosmic Gems programme
• Photos of the Very Large Telescope
• Photos from the Very Large Telescope

Contacts

Richard Hook
ESO Public Information Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

Source: ESO

The Light and Dark Face of a Star-Forming Nebula

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Star-forming region Gum 19

PR Image eso1014b

Around Gum 19

PR Video eso1014a

Zoom-in onto Gum 19

Today, ESO is unveiling an image of the little known Gum 19, a faint nebula that, in the infrared, appears dark on one half and bright on the other. On one side hot hydrogen gas is illuminated by a supergiant blue star called V391 Velorum. New star formation is taking place within the ribbon of luminous and dark material that brackets V391 Velorum’s left in this perspective. After many millennia, these fledgling stars, coupled with the explosive demise of V391 Velorum as a supernova, will likely alter Gum 19’s present Janus-like appearance.

Gum 19 is located in the direction of the constellation Vela (the Sail) at a distance of approximately 22 000 light years. The Gum 19 moniker derives from a 1955 publication by the Australian astrophysicist Colin S. Gum that served as the first significant survey of so-called HII (read “H-two”) regions in the southern sky. HII refers to hydrogen gas that is ionised, or energised to the extent that the hydrogen atoms lose their electrons. Such regions emit light at well-defined wavelengths (or colours), thereby giving these cosmic clouds their characteristic glow. And indeed, much like terrestrial clouds, the shapes and textures of these HII regions change as time passes, though over the course of eons rather than before our eyes. For now, Gum 19 has somewhat of a science fiction-esque, “rip in spacetime” look to it in this image, with a narrow, near-vertical bright region slashing across the nebula. Looking at it, you could possibly see a resemblance to a two-toned angelfish or an arrow with a darkened point.

This new image of the evocative Gum 19 object was captured by an infrared instrument called SOFI, mounted on ESO’s New Technology Telescope (NTT) that operates at the La Silla Observatory in Chile. SOFI stands for Son of ISAAC, after the “father” instrument, ISAAC, that is located at ESO’s Very Large Telescope observatory at Paranal to the north of La Silla. Observing this nebula in the infrared allows astronomers to see through at least parts of the dust.

The furnace that fuels Gum 19’s luminosity is a gigantic, superhot star called V391 Velorum. Shining brightest in the scorching blue range of visible light, V391 Velorum boasts a surface temperature in the vicinity of 30 000 degrees Celsius. This massive star has a temperamental nature, however, and is categorised as a variable star accordingly. V391 Velorum’s brightness can fluctuate suddenly as a result of strong activity that can include ejections of shells of matter, which contribute to Gum 19’s composition and light emissions.

Stars on the grand scale of V391 Velorum do not burn bright for long, and after a relatively short lifetime of about ten million years these titans blow up as supernovae. These explosions, which temporarily rival whole galaxies in their light intensity, blast heated matter in surrounding space, an event that can radically change the colour and shape of its enclosing nebula. As such, V391 Velorum’s death throes may well leave Gum 19 unrecognisable.

Within the neighbourhood of this fitful supergiant, new stars nonetheless continue to grow. HII regions denote sites of active star formation wherein great quantities of gas and dust have begun to collapse under their own gravity. In several million years — a blink of an eye in cosmic time — these shrinking knots of matter will eventually reach the high density at their centres necessary to ignite nuclear fusion. The fresh outpouring of energy and stellar winds from these newborn stars will also modify the gaseous landscape of Gum 19.

More information

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 14 countries: Austria, Belgium, 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”.

Contacts

Henri Boffin
ESO ePOD
Garching, Germany
Tel: +49 89 3200 6222
Cell: +49 174 515 43 24
Email: hboffin@eso.org