Starship Asterisk*

Credit: ESO/A. Tudorică

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The rugged terrain of the Chilean Atacama Desert offers a truly striking backdrop for photographs — as evidenced by this snap of ESO’s Visible and Infrared Survey Telescope for Astronomy (VISTA), taken by ESO Photo Ambassador Alexandru Tudorică at ESO’s Paranal Observatory.

Although it is by far Tudorică’s most prominent subject, VISTA is not the only telescope visible in this image. The snaking path trailing off to the right side of the image leads to the inconspicuous enclosure of the Next Generation Transit Survey (NGTS) — the enclosure itself is just about visible to the far right of the frame, illuminated by a sliver of sunlight.

The NGTS comprises an array of small robotic telescopes that constantly and precisely monitor the brightness of nearby stars. By doing so, it hopes to catch exoplanets the size of Neptune in the act of blocking out light from their parent stars as they transit across the face of their star and cross the line of sight to Earth.

Credit: ESA/Hubble, NASA Acknowledgement: Sarajedini et al

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This image from the NASA/ESA Hubble Space Telescope reveals a glistening and ancient globular cluster named NGC 3201 — a gathering of hundreds of thousands of stars bound together by gravity. NGC 3201 was discovered in 1826 by the Scottish astronomer James Dunlop, who described it as a “pretty large, pretty bright” object that becomes “rather irregular” towards its centre.

Globular clusters are found around all large galaxies, but their origin and role in galaxy formation remain tantalisingly unclear. Astronomers recently discovered a black hole lurking at the heart of NGC 3201 — its position was revealed by the strange movements of a star being quickly flung around a massive, invisible counterpart. This sparkling group of stars also has some strange properties which make it unique amongst the over 150 globular clusters belonging to the Milky Way. NGC 3201 has an extremely fast velocity with respect to the Sun and its orbit is retrograde, meaning that it moves speedily in the opposite direction to the galactic centre, which it orbits.

The unusual behaviour of this cluster suggests that it may have extragalactic origins, but at some point was captured by the Milky Way’s gravity. However, the chemical makeup of this intriguing cluster tells a different story — the stars within NGC 3201 are chemically very similar to those of other galactic globular clusters, implying that they formed at a similar location and time to their neighbours.

Whether this mysterious cluster was adopted by our galaxy or has for some reason evolved very differently to the family of clusters it grew up with, it is certainly an unusual astronomical beauty.

[img3="Credit: ESO/M. Bellazzini et al"]https://cdn.eso.org/images/thumb700x/potw1805a.jpg[/img3][hr][/hr]

Squint or you’ll miss it! At the very centre of this image, taken with the VIMOS instrument attached to ESO’s Very Large Telescope (VLT), you can just about see the faint and fuzzy blue form of a distant galaxy known as the Sagittarius Dwarf Irregular Galaxy.

Discovered in 1977 with the ESO 1-metre Schmidt telescope, situated at ESO’s La Silla observatory, the irregularly shaped — hence the name — dwarf galaxy is approximately 3 million light-years away in the constellation of Sagittarius (The Archer). It is the most distant member of the Local Group of galaxies, of which the Milky Way is a member.

Unlike normal galaxies, dwarf galaxies are typically smaller and host a relatively small number of stars. Gravitational tugs from nearby galaxies can often distort the spherical and disc-like shapes of these fragile galaxies — this very process may be responsible for the slightly rectangular shape of this particular dwarf galaxy.

[img3="Credit: NASA/ESA/Hubble/D. Milisavljevic (Purdue)"]https://cdn.spacetelescope.org/archives ... w1805a.jpg[/img3][hr][/hr]

This NASA/ESA Hubble Space Telescope image shows a spiral galaxy known as NGC 7331. First spotted by the prolific galaxy hunter William Herschel in 1784, NGC 7331 is located about 45 million light-years away in the constellation of Pegasus (The Winged Horse). Facing us partially edge-on, the galaxy showcases it’s beautiful arms which swirl like a whirlpool around its bright central region.

Astronomers took this image using Hubble’s Wide Field Camera 3 (WFC3), as they were observing an extraordinary exploding star — a supernova — which can still be faintly seen as a tiny red dot near the galaxy’s central yellow core. Named SN 2014C, it rapidly evolved from a supernova containing very little Hydrogen to one that is Hydrogen-rich — in just one year. This rarely observed metamorphosis was luminous at high energies and provides unique insight into the poorly understood final phases of massive stars.

NGC 7331 is similar in size, shape, and mass to the Milky Way. It also has a comparable star formation rate, hosts a similar number of stars, has a central supermassive black hole and comparable spiral arms. The primary difference between our galaxies is that NGC 7331 is an unbarred spiral galaxy — it lacks a “bar” of stars, gas and dust cutting through its nucleus, as we see in the Milky Way. Its central bulge also displays a quirky and unusual rotation pattern, spinning in the opposite direction to the galactic disc itself.

By studying similar galaxies we hold a scientific mirror up to our own, allowing us to build a better understanding of our galactic environment which we cannot always observe, and of galactic behaviour and evolution as a whole.

Adaptive optics facility extended to HAWK-I instrument

[c][imghover=https://cdn.eso.org/images/screen/ann18006a.jpg]https://cdn.eso.org/images/screen/ann18006b.jpg[/imghover][hr][/hr]Tarantula Nubula by HAWK-I with AOF (image 1) and without AOF (image 2)[/c]

ESO’s Very Large Telescope (VLT) now has a second instrument working with the powerful Adaptive Optics Facility (AOF). The infrared instrument HAWK-I (High Acuity Wide-field K-band Imager) [1] is now also benefiting from sharper images and shorter exposure times. This follows the successful integration of the AOF with MUSE (the Multi Unit Spectroscopic Explorer).

The Adaptive Optics Facility (AOF) is a long-term project that is nearing completion on ESO’s Very Large Telescope (VLT). It provides adaptive optics correction for all the instruments attached to one of the VLT Unit Telescopes (UT4, also known as Yepun).

Adaptive optics works to compensate for the blurring effect of the Earth’s atmosphere. This upgrade now enables HAWK-I to obtain sharper images, needing shorter exposure times than before to obtain similar results. By using the AOF, astronomers can now get good image quality with HAWK-I, even when the weather conditions are not perfect. ...