It's been a good month for cosmic wonderment. The Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile caught the region around the star R Coronae Australis and on June 13th, the Japanese spacecraft Hayabusa returned after 7 years and 1.25 billion miles on a mission to gather material from the comet Itokawa.
It exploded over the Australian outback - intentional, it seems, since it had parachuted its cargo already. At least we hope it has cargo. It experienced some malfunctions on the trip and the researchers will let us know, since they have already picked it up.
But we get cosmic fireworks, so thanks Japan.
Back to extraterrestrial science show-offs, the picture of R Coronae Australis is a combination of twelve separate pictures taken through red, green and blue filters. It shows a section of sky that spans roughly the width of the full Moon. This is equivalent to about four light-years at the distance of the nebula, which is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown).
This pan shows many details in a cosmic watercolour of the star-forming region around the star R Coronae Australis that was captured by the Wide Field Imager (WFI), on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory. Fine details of the bluish reflection nebula and the huge surrounding dust cloud are visible. This star-forming region is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). Credit: ESO
The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength. These complex processes, determined by the physics of the interstellar medium and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles. The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic red colour seen in many star-forming regions.
The huge dust cloud in which the reflection nebula is embedded is here shown in impressively fine detail. The subtle colours and varied textures of the dust clouds make this image resemble an impressionist painting. A prominent dark lane crosses the image from the centre to the bottom left. Here the visible light emitted by the stars that are forming inside the cloud is completely absorbed by the dust. These objects could only be detected by observing at longer wavelengths, by using a camera that can detect infrared radiation.
R Coronae Australis itself is not visible to the unaided eye, but the tiny, tiara-shaped constellation in which it lies is easily spotted from dark sites due to its proximity on the sky to the larger constellation of Sagittarius and the rich star clouds towards the centre of our own galaxy, the Milky Way.
Of course, any time of year is a good time to enjoy the Perseid meteor shower:
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