Starship Asterisk*

Credit: ESA/Hubble & NASA, J. Kalirai, A. Milone

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This Picture of the Week shows an open cluster known as NGC 2164, which was first discovered in 1826 by a Scottish astronomer named James Dunlop. NGC 2164 is located within one of the Milky Way galaxy's closest neighbours — the satellite galaxy known as the Large Magellanic Cloud. The Large Magellanic Cloud is a relatively small galaxy that lies about 160 000 light-years from Earth. It is considered a satellite galaxy because it is gravitationally bound to the Milky Way. In fact, the Large Magellanic Cloud is on a very slow collision course with the Milky Way — it’s predicted that they will collide 2.4 billion years from now.

The Large Magellanic Cloud only contains about one hundredth as much mass as the Milky Way, but it still contains billions of stars. The open cluster NGC 2164 is in good company in the Large Magellanic Cloud — the satellite galaxy is home to roughly 700 open clusters, alongside about 60 globular clusters. This image of NGC 2164 was taken by the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3), which has previously imaged many other open clusters, including NGC 330 and Messier 11.

Image Credit: ESO/Petr Horálek

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How does a fish see the Milky Way? We can get a pretty good idea thanks to this picture of our galaxy, taken with a fisheye lens from the entrance of the Paranal Residencia at the Paranal Observatory’s Base Camp, located 3 km away from ESO’s Very Large Telescope (VLT).

The Paranal Residencia is a true “oasis for astronomers”. Located in the Atacama desert, one of the driest regions on our planet, it is a comfortable and modern building where ESO staff and visitors can rest during their long shifts and withstand the extreme local climatic conditions. The Residencia is a subterranean construction with a 35-metre wide glass-covered dome, which brings in natural light, and a swimming pool, which helps the staff to relax and also contributes to the building’s humidification system. The building’s facade opens towards the Pacific Ocean, just 12 kilometres away.

From its southern latitude, Paranal offers a unique view of the Milky Way. It is estimated that the Milky Way contains a few hundred billions of stars. Most of them lie on the galactic plane, with their light giving rise to the luminous band stretching across the night sky which we can admire from Earth.

Image Credit: ESA/Hubble & NASA, B. Nisini

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This striking image features a relatively rare celestial phenomenon known as a Herbig–Haro object. This particular Herbig–Haro object is named HH 111, and was imaged by Hubble’s Wide Field Camera 3 (WFC3). These spectacular objects are formed under very specific circumstances. Newly formed stars are often very active, and in some cases they expel very narrow jets of rapidly moving ionised gas — gas that is so hot that its molecules and atoms have lost their electrons, making the gas highly charged. The streams of ionised gas then collide with the clouds of gas and dust surrounding newly-formed stars at speeds of hundreds of kilometres per second. It is these energetic collisions that create Herbig–Haro objects such as HH 111.

WFC3 takes images at optical and infrared wavelengths, which means that it observes objects at a wavelength range similar to the range that human eyes are sensitive to (optical) and a range of wavelengths that are slightly too long to be detected by human eyes (infrared). Herbig–Haro objects actually release a lot of light at optical wavelengths, but they are difficult to observe because their surrounding dust and gas absorb much of the visible light. Therefore, the WFC3’s ability to observe at infrared wavelengths — where observations are not as affected by gas and dust — is crucial to observing Herbo–Haro objects successfully.