Mörk nebulosa

A reproduction of a composite colour image of the Horsehead Nebula and its immediate surroundings - Eso0202a.jpg
Författare/Upphovsman: European Southern Observatory, Licens: CC BY 4.0
A reproduction of a composite colour image of the Horsehead Nebula and its immediate surroundings. It is based on three exposures in the visual part of the spectrum with the FORS2 multi-mode instrument at the 8.2-m KUEYEN telescope at Paranal. It was produced from three images, obtained on February 1, 2000, with the FORS2 multi-mode instrument at the 8.2-m KUEYEN Unit Telescope and extracted from the VLT Science Archive Facility . The frames were obtained in the B-band (600 sec exposure; wavelength 429 nm; FWHM 88 nm; here rendered as blue), V-band (300 sec; 554 nm; 112 nm; green) and R-band (120 sec; 655 nm; 165 nm; red). The original pixel size is 0.2 arcsec. The photo shows the full field recorded in all three colours, approximately 6.5 x 6.7 arcmin 2 . The seeing was about 0.75 arcsec. This image is available as a mounted image in the ESOshop. #L

A Hole in the Sky.jpg
Författare/Upphovsman: ESO, Licens: CC BY 4.0
Rather than showing spectacular objects, some of the most surprising images of the Universe instead focus on emptiness. This new image from the 2.2-metre MPG/ESO telescope shows dark tentacles swirling outwards from a dark, blank spot of space in the centre of the frame, particularly conspicuous against the dense peppering of bright gold and red stars across the rest of the image.

This region is not a hole in the cosmos, or an empty patch of sky. The dark lanes are actually made up of thick, opaque dust lying between us and the packed star field behind it. This obscuring dust forms part of a dark molecular cloud, cold and dense areas where large quantities of dust and molecular gas mingle and block the visible light emitted by more distant stars.

It is still unclear how these clouds form, but they are thought to be the very early stages of new star formation — in the future, the subject of this image may well collapse inwards on itself to form a new star system.

Although the cloud in this image is a fairly anonymous resident of the nearby Universe — catalogued as LDN1774 — one of the most famous examples of a molecular cloud is the very similar Barnard 68, which lies some 500 light-years away from us. Barnard 68 has been observed extensively using ESO telescopes, both in visible (eso9924a) and infrared light (eso9934, eso0102a). As shown in these different images, it is possible to probe through dark cosmic dust using infrared light, but visible-light observations such as those shown in this VLT image cannot see beyond the smokescreen.

This image was taken by the Wide Field Imager, an instrument mounted on ESO’s 2.2-metre MPG/ESO telescope at La Silla, Chile.

The Dark Cloud Lupus 4.jpg
Författare/Upphovsman: ESO, Licens: CC BY 4.0
The Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile captured this view of dark cloud Lupus 4 blotting out background stars. Lupus 4 is a dense pocket of gas and dust where new stars are expected to form. The cloud is located about 400 light-years away from Earth, on the border between the constellations of Lupus (The Wolf) and Norma (The Carpenter's Square).

All Quiet in the Nursery?.jpg
Författare/Upphovsman: ESO, Licens: CC BY 4.0
The dark patch snaking across this spectacular image of a field of stars in the constellation of Ophiuchus (The Serpent-bearer) is not quite what it appears to be.

Although it looks as if there are no stars here, they are hidden behind this dense cloud of dust that blocks out their light. This particular dark cloud is known as LDN 1768.

Despite their rather dull appearance, dark nebulae like LDN 1768 are of huge interest to astronomers, as it is here that new stars form. Inside these vast stellar nurseries there are protostars — stars at the earliest stage of their lives, still coalescing out of the gas and dust in the cloud.

Protostars are relatively cold and have not yet begun to produce enough energy to emit visible light. Instead, they emit radiation at submillimetre wavelengths, which human eyes cannot see. Luckily, unlike visible light, light at submillimetre wavelengths is not absorbed by the surrounding dust. By using special telescopes that are sensitive to submillimetre radiation, like the Atacama Large Millimeter/submillimeter Array (ALMA) observatory, we can see through the dust and find out more about the protostars within the cloud.

Eventually, the protostars will become dense and hot enough to start the nuclear reactions that will produce visible light and they will start to shine. When this happens, they will blow away the cocoon of dust surrounding them and cause any remaining gas to emit light as well, creating the spectacular light show known as an HII region.

The dark nebula LDN 483.jpg
Författare/Upphovsman: ESO, Licens: CC BY 4.0
The Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile snapped this image of the dark nebula LDN 483. The object is a region of space clogged with gas and dust. These materials are dense enough to effectively eclipse the light of background stars. LDN 483 is located about 700 light-years away in the constellation of Serpens (The Serpent).