Spying a spiral through a cosmic lens

In the centre is an elliptical galaxy, seen as an oval-shaped glow around a small bright core. Around this is wrapped a broad band of light, appearing like a spiral galaxy stretched and warped into a ring, with bright blue lines drawn through it where the spiral arms have been stretched into circles. A few distant objects are visible around the ring on a black background. Credit: ESA/Webb, NASA & CSA, G. Mahler. Acknowledgement: M. A. McDonald

This new NASA/ESA/CSA James Webb Space Telescope Picture of the Month features a rare cosmic phenomenon called an Einstein ring. What at first appears to be a single, strangely shaped galaxy is actually two galaxies that are separated by a large distance. The closer foreground galaxy sits at the center of the image, while the more distant background galaxy appears to be wrapped around the closer galaxy, forming a ring.

Einstein rings occur when light from a very distant object is bent (or ‘lensed’) about a massive intermediate (or ‘lensing’) object. This is possible because spacetime, the fabric of the Universe itself, is bent by mass, and therefore light travelling through space and time is bent as well. This effect is much too subtle to be observed on a local level, but it sometimes becomes clearly observable when dealing with curvatures of light on enormous, astronomical scales, such as when the light from one galaxy is bent around another galaxy or galaxy cluster.

When the lensed object and the lensing object line up just so, the result is the distinctive Einstein ring shape, which appears as a full circle (as seen here) or a partial circle of light around the lensing object, depending on the precision of the alignment. Objects like these are the ideal laboratory in which to research galaxies too faint and distant to otherwise see.

The lensing galaxy at the center of this Einstein ring is an elliptical galaxy, as can be seen from the galaxy’s bright core and smooth, featureless body. This galaxy belongs to a galaxy cluster named SMACSJ0028.2-7537. The lensed galaxy wrapped around the elliptical galaxy is a spiral galaxy. Even though its image has been warped as its light travelled around the galaxy in its path, individual star clusters and gas structures are clearly visible.

The Webb data used in this image were taken as part of the Strong Lensing and Cluster Evolution (SLICE) survey (programme 5594), which is led by Guillaume Mahler at University of Liège in Belgium, and consists of a team of international astronomers. This survey aims to trace 8 billion years of galaxy cluster evolution by targeting 182 galaxy clusters with Webb’s Near-InfraRed Camera instrument. This image also incorporates data from two of the NASA/ESA Hubble Space Telescope’s instruments, the Wide Field Camera 3 and the Advanced Camera for Surveys.

Links

• Pan Video: Einstein ring in galaxy cluster SMACSJ0028.2-7537
• Image on ESA website

Source: ESA/Webb/potm

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Colourful clouds of a nearby neighbour

SMC 13

An area of space that is filled with stars. Most of the stars are small, distant dots in orange colours; closer stars shine with a bright glow and four thin spikes around them. These closer stars appear in both bluish and reddish colours. Clouds from a nebula cover the left half of the scene, giving it a blue-greenish cast. More pieces of cloud drift over the black background of space on the right. Credit: ESA/Hubble & NASA, C. Murray

Say hello to one of the Milky Way’s neighbours! Today’s NASA/ESA Hubble Space Telescope Picture of the Week features a scene from one of the closest galaxies to the Milky Way, the Small Magellanic Cloud (SMC). The SMC is a dwarf galaxy located about 200 000 light-years away. Most of the galaxy resides in the constellation Tucana, but a small section crosses over into the neighbouring constellation Hydrus.

Thanks to its proximity, the SMC is one of only a few galaxies that can be seen from Earth without the help of a telescope or binoculars. For viewers in the southern hemisphere and some latitudes in the northern hemisphere, the SMC resembles a piece of the Milky Way that has broken off, though in reality it’s much farther away than any part of our own galaxy.

With its 2.4-metre ‘eye’ and sensitive instruments, Hubble’s view of the SMC is far more detailed and vivid than what humans can see. Researchers used Hubble’s Wide Field Camera 3 instrument to observe this scene through four different filters. Each filter admits different wavelengths of light, creating a multicoloured view of dust clouds drifting across a field of stars. Hubble’s view, however, is much more zoomed-in than our eyes, the better for it to observe very distant objects. This image captures a small region of the SMC near the centre of NGC 346, a star cluster that is home to dozens of massive young stars.

Source: ESA/Hubble/potw

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