A new report from ESO (European Southern Observatory):

Celestial Cat Meets Cosmic Lobster 

Astronomers have for a long time studied the glowing, cosmic clouds of gas and dust catalogued as NGC 6334 and NGC 6357, this gigantic new image from ESO’s Very Large Telescope Survey Telescope being only the most recent one. With around two billion pixels this is one of the largest images ever released by ESO. The evocative shapes of the clouds have led to their memorable names: the Cat’s Paw Nebula and the Lobster Nebula, respectively.

This spectacular image from the VLT Survey Telescope shows the Cat’s Paw Nebula (NGC 6334, upper right) and the Lobster Nebula (NGC 6357, lower left). These dramatic objects are regions of active star formation where the hot young stars are causing the surrounding hydrogen gas to glow red. The very rich field of view also includes dark clouds of dust. With around two billion pixels this is one of the largest images ever released by ESO. [Larger views.]

NGC 6334 is located about 5500 light-years away from Earth, while NGC 6357 is more remote, at a distance of 8000 light-years. Both are in the constellation of Scorpius (The Scorpion), near the tip of its stinging tail.

A new image from ESO’s VLT Survey Telescope gives a very detailed view of the star formation regions NGC 6334 and NGC 6357, often called the Cat’s Paw Nebula and the Lobster Nebula, respectively, because of their distinctive shapes. This ESOcast Light takes a quick look at this spectacular vista and explains what it shows. The video is available in 4K UHD.

The British scientist John Herschel first saw traces of the two objects, on consecutive nights in June 1837, during his three-year expedition to the Cape of Good Hope in South Africa. At the time, the limited telescopic power available to Herschel, who was observing visually, only allowed him to document the brightest “toepad” of the Cat’s Paw Nebula. It was to be many decades before the true shapes of the nebulae became apparent in photographs — and their popular names coined.

This montage shows a few of the highlights from a spectacular image from the VLT Survey Telescope showing the Cat’s Paw Nebula (NGC 6334) and the Lobster Nebula (NGC 6357). This part of the sky contains active regions of star formation where hot young stars make their surrounding clouds of hydrogen glow with a characteristic red colour. There are also clouds of dark dust in this rich celestial landscape. [Larger views]

The three toepads visible to modern telescopes, as well as the claw-like regions in the nearby Lobster Nebula, are actually regions of gas — predominantly hydrogen — energised by the light of brilliant newborn stars. With masses around 10 times that of the Sun, these hot stars radiate intense ultraviolet light. When this light encounters hydrogen atoms still lingering in the stellar nursery that produced the stars, the atoms become ionised. Accordingly, the vast, cloud-like objects that glow with this light from hydrogen (and other) atoms are known as emission nebulae.

This video sequence takes the viewer deep into the bright constellation of Scorpius (The Scorpion) and finishes on a new and very detailed view of the star formation regions NGC 6334 and NGC 6357, known as the Cat’s Paw and Lobster Nebulae respectively. Credit: ESO/N. Risinger (skysurvey.org). Music: Nuclearmetal

Thanks to the power of the 256-megapixel OmegaCAM camera, this new Very Large Telescope Survey Telescope (VST) image reveals tendrils of light-obscuring dust rippling throughout the two nebulae. At 49511 x 39136 pixels this is one of the largest images ever released by ESO.

OmegaCAM is a successor to ESO’s celebrated Wide Field Imager (WFI), currently installed at the MPG/ESO 2.2-metre telescope on La Silla. The WFI was used to photograph the Cat’s Paw Nebula in 2010, also in visible light but with a filter that allowed the glow of hydrogen to shine through more clearly (eso1003). Meanwhile, ESO’s Very Large Telescope has taken a deep look into the Lobster Nebula, capturing the many hot, bright stars that influence the object’s colour and shape (eso1226).

This video sequence takes a close look at a spectacular image from the VLT Survey Telescope. It shows the Cat’s Paw Nebula (NGC 6334) and the Lobster Nebula (NGC 6357). These are regions of active star formation where the hot young stars are causing the surrounding hydrogen gas to glow red. The very rich field of view also includes dark clouds of dust. Credit: ESO/N. Bartmann. Music credit: Johan B. Monell

Despite the cutting-edge instruments used to observe these phenomena, the dust in these nebulae is so thick that much of their content remains hidden to us. The Cat’s Paw Nebula is one of the most active stellar nurseries in the night sky, nurturing thousands of young, hot stars whose visible light is unable to reach us. However, by observing at infrared wavelengths, telescopes such as ESO’s VISTA can peer through the dust and reveal the star formation activity within.

Viewing nebulae in different wavelengths (colours) of light gives rise to different visual comparisons on the part of human observers. When seen in longer wavelength infrared light, for example, one portion of NGC 6357 resembles a dove, and the other a skull; it has therefore acquired the additional name of the War and Peace Nebula.

This chart of the bright constellation of Scorpius (The Scorpion) shows the stars visible to the unaided eye on a clear and dark night. It covers a rich part of the sky that is host to many star clusters, glowing clouds of gas and dark dust clouds. Two star formation regions, NGC 6334 (the Cat’s Paw Nebula) and NGC 6357 (the Lobster Nebula) are marked with red circles. Although these clouds appear spectacular in pictures they are very faint and hard to see visually, even with a large telescope. Credit: ESO [Larger versions]

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”.

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