Photo de la semaine

24 avril 2023: This Picture of the Week shows a newly-formed planet with a mass similar to Jupiter’s orbiting the star HD 169142. The star has a disc around it, and as the protoplanet moves it carves a circular gap in the disc, as seen in the first image. But how was this planet found? Astronomers observed the system over several years with the SPHERE instrument at ESO’s Very Large Telescope in Chile. A new re-analysis of this data, led by Iain Hammond from Monash University in Australia, confirmed the presence of this protoplanet, which moves around the star at a distance somewhat larger than that between Neptune and the Sun. They also identified a spiral wake that the protoplanet leaves behind as it rearranges part of the material in the disc, much like a boat can create a wake as it moves through water. A protoplanet forms during the early stages of ...

17 avril 2023: This Picture of the Week shows the young stellar object 244-440 in the Orion Nebula observed with ESO’s Very Large Telescope (VLT) –– the sharpest image ever taken of this object. That wiggly magenta structure is a jet of matter launched close to the star, but why does it have that shape? Very young stars are often surrounded by discs of material falling towards the star. Some of this material can be expelled into powerful jets perpendicularly to the disc. The S-shaped jet of 244-440 suggests that what lurks at the center of this object isn’t one but two stars orbiting each other. This orbital motion periodically changes the orientation of the jet, similar to a water sprinkler. Another possibility is that the strong radiation from the other stars in the Orion cloud could be altering the shape of the jet. These observations, presented in a new paper led by ...

10 avril 2023: Don’t worry, no planets were harmed in the making of this Picture of the Week! The powerful laser beams seen here are installed in one of the four 8.2-m telescopes of ESO’s Very Large Telescope (VLT) in Chile. They allow astronomers to obtain very sharp images of the cosmos by correcting the blur caused by turbulence in the atmosphere, but how? The lasers are tuned to a very specific colour that excites sodium atoms floating 90 km above the ground, making them glow. This creates artificial “stars” high up in the sky, whose rapid twinkling is monitored in real time by special sensors. Then, instructions are sent to the telescope’s deformable secondary mirror, which quickly reshapes itself to counteract the atmospheric distortion. And all of this happens at millisecond speeds! This technique, known as adaptive optics, can also use real stars as a reference to measure the turbulence. But there ...

3 avril 2023: From the long eastward shadows of the telescopes in this Picture of the Week we can see that it’s almost the beginning of a long night shift of stargazing for the telescopes at ESO’s La Silla Observatory. In the foreground of this picture is the BlackGEM array, designed to hunt for the visible light of gravitational wave sources. If you then follow the road up to the summit of La Silla you will pass several ESO telescopes including the 1-metre Schmidt telescope and the New Technology Telescope, until you finally reach the 3.6-metre telescope at the top, home to the HARPS planet hunter. La Silla mountain is ideally situated for an observatory as its isolated location means there is very little light pollution. It is also in Chile’s extremely dry Atacama desert at an altitude of 2400 metres, meaning there’s hardly ever a cloud in the sky and almost every ...

29 mars 2023: The circled spot in this Picture of the Week has almost disappeared. What happened? This sequence of images, taken in optical light with ESO’s Very Large Telescope, shows the gamma-ray burst GRB 221009A fading away. Gamma-ray bursts are the most luminous phenomena that we know of in the universe, and GRB 221009A is the brightest one yet as seen from Earth. The burst was detected in October 2022 by several gamma-ray space telescopes, such as NASA's Swift and Fermi and ESA’s INTEGRAL. Then, a few hours after the initial detection, ESO’s X-shooter instrument at the VLT took a spectrum, which provided the first distance measurement to the explosion of approximately 2400 million light years. Thanks to this distance measurement, a team of astronomers led by Daniele Bjørn Malesani (Radboud University, the Netherlands; DAWN/Niels Bohr Institute, Denmark) ruled out an origin in the Milky Way, although the burst is still much ...

20 mars 2023: This Picture of the Week shows a beautiful meeting between the Swedish–ESO Submillimetre Telescope (SEST) and the Milky Way, apparently almost touching each other. This shot was taken at ESO’s La Silla Observatory, located on the outskirts of the Chilean Atacama Desert, at an altitude of 2400 metres. Light and darkness shape the Milky Way as it stretches across the night sky. The dark patches are dust clouds blocking the light behind them, coming from millions of stars in the central region of our galaxy. SEST was built on behalf of the Swedish Natural Science Research Council (NFR) and ESO in 1987. It is a 15-m radio telescope, and it was the only large sub-millimetre telescope in the southern hemisphere at the time of first light. In 2003, the telescope was decommissioned as it was superseded by the Atacama Pathfinder EXperiment telescope (APEX) and the Atacama Large Millimeter/submillimeter Array (ALMA) ...

13 mars 2023: This picture of the week shows the Sun’s path on the sky as seen from ESO’s Paranal Observatory in Chile. The picture was taken with a pinhole camera with an exposure of 8 months, from 17 April to 11 December 2018. The tall structure in the foreground is the “seeing monitor”, which measures the blur/twinkling of the stars due to the atmospheric turbulence. In the background we can see several domes; the ones to the centre-left are part of the Very Large Telescope, and the rightmost one is the VLT Survey Telescope. But what are those bright coloured lines behind them? They are created by the Sun as it moves in the sky throughout the day, leaving an imprint on the sheet of photographic paper placed inside the pinhole camera. The camera was facing west, so here we see hundreds of sunsets. But as the Earth moves around the Sun, ...

6 mars 2023: In this Picture of the Week, we take a deep plunge into the ocean of stars in the IC4701 nebula. This nebula is located in the Sagittarius constellation, and it is twice as wide as the full Moon in the sky. The energetic light from newly-born stars ionizes the hydrogen gas in the nebula, causing it to emit the intense reddish hue seen in this picture. The dark clouds in this image contain large amounts of interstellar dust, too dense for the light of the background stars to pierce through it. The IC4701 nebula is part of a rich and vast complex of dust and gas within which new stars spring to life. When stars are born, most of them are cooler, redder, and less massive than our own Sun. Hotter, more massive stars are much rarer, and they quickly burn through all their fuel and die. This makes these ...

27 février 2023: Sur cette image de la semaine, Vénus brille au-dessus de l'observatoire de La Silla de l'ESO au Chili. La photo a été prise juste avant l'aube, vers l'est, et montre également la lumière zodiacale diffuse, c'est-à-dire la lumière du soleil dispersée par les particules de poussière dans le système solaire. Les trois dômes à gauche de la route sont les télescopes BlackGEM, construits par l'université Radboud, la Netherlands Research School for Astronomy (NOVA) et la KU Leuven. BlackGEM recherchera la rémanence de quelques-uns Les ondulations de l'espace et du temps générées par ces événements violents peuvent être détectées par les observatoires LIGO et Virgo. Grâce à leur grand champ de vision, les télescopes BlackGEM peuvent localiser la source de lumière visible provenant de la rémanence de ces événements, et ainsi localiser l'endroit où la collision a eu lieu. Les astronomes peuvent ainsi étudier plus en détail ce qui se passe ...

20 février 2023: No, you’re not seeing double: this Picture of the Week shows two images of a Jupiter-like planet that orbits the star AF Leporis. The planet has been imaged by two independent groups of astronomers using the SPHERE instrument on ESO’s Very Large Telescope (VLT) in Chile. But why did they target this particular star? The two groups, led by Dino Mesa (INAF, Italy) and Robert De Rosa (ESO, Chile), studied star catalogues from the European Space Agency’s Hipparcos and Gaia satellites. Over the years, these two space missions have accurately pinpointed the position and motion of stars in our galaxy using astrometry. Planets exert a gravitational tug on their host stars, perturbing their trajectory on the sky. The two teams found that the star AF Leporis exhibited such a disturbed trajectory, a telltale sign that a planet could be hiding there. As the two groups took a closer look at ...

13 février 2023: The Atacama Desert of Chile is one of the driest places on Earth, with extremely reliable weather, making it an excellent site to explore the Universe. So it’s not strange that this is the place ESO has chosen to place the flagship facilities for European ground-based astronomy. At 2635 meters above sea level in the Atacama Desert, we find ESO’s Paranal Observatory, seen on the far mountain top in this image. It hosts several world-class telescopes like the Very Large Telescope (VLT), and the Visible and Infrared Survey Telescope for Astronomy (VISTA), the latter located on its own peak, seen here to the right of the main one. But the desert is good for other astronomy related sciences as well: Mars explorations! The red and rocky environment around Paranal has a strong resemblance to Mars, making it a perfect site for the European Space Agency (ESA) to test their Mars ...

6 février 2023: Fall deeper into the entrancing NGC 4303, a spiral galaxy located approximately 55 million light-years from Earth in the constellation Virgo. This image combines data taken at radio and visible wavelengths, and is helping astronomers understand how stars form in galaxies. The hypnotising golden glow drawing you into the image corresponds to clouds of molecular gas, the raw material out of which stars form. The data was taken with the Atacama Large Millimeter/submillimeter Array (ALMA), co-operated by ESO in the Chilean Andes. The blueish regions in the background, on the other hand, were imaged with the Multi-Unit Spectroscopic Explorer (MUSE) instrument on ESO’s Very Large Telescope (VLT), also in Chile, and they reveal already formed stars. By comparing the distribution of gas and stars astronomers are able to study what triggers, enhances or hampers the birth of new stars. This image is part of the Physics at High Angular resolution ...

30 janvier 2023: This Picture of the Week shows the grand skies of the Chajnantor plateau in the Chilean Atacama desert. The rare sight of clouds in this typically dry and arid region creates a dramatic display of reds and blues, as well as a sun pillar –– an optical phenomenon caused by ice crystals in the atmosphere –– that emanates from the Sun in line with a telescope. This large antenna is a part of the Atacama Large Millimeter/submillimeter Array (ALMA), which is co-owned by ESO. ALMA is one of the most powerful observatories in the world for radio astronomy. Its collection of 66 antennae — like the one pictured above — has been responsible for many incredible ground-breaking discoveries, including contributing to the creation of the first image of a black hole.

23 janvier 2023: In this Picture of the Week, a three hour long photographic sequence shows the path of a lunar eclipse over ESO’s Very Large Telescope (VLT) at Paranal, Chile. This eclipse, which took place on 20-21 January 2019, was visible from the Americas. As the Moon moves into the Earth’s shadow, it becomes darker and acquires a red hue. This reddening, which is due to sunlight being scattered by Earth’s atmosphere before reaching the Moon, can be seen in the middle of the trail. This trail, and those of the stars in the background, are due to the Earth’s rotation and are a ubiquitous feature in long exposure photographs of the night sky. The stars above ESO’s telescopes can be seen clearly because of the high altitude at the Paranal mountain and the lack of light pollution from human settlements. But the bright lunar light can still disturb astronomical observations done ...

16 janvier 2023: Since 1979, the 1.54-metre Danish telescope at ESO’s La Silla observatory has been unveiling intricate details about our home galaxy. Stretching over the telescope in this image is the Milky Way and its galactic heart, lighting up the night sky in the Chilean desert. The Danish 1.54-m was used in a 15-year long survey published in 2004 to study 14,000 stars in our galaxy, providing the first clues to the turbulent and violent history of the Milky Way. The survey measured the motions of these stars and their distances, as well as their ages and chemical composition. This allowed the creation of a historical map of the Milky Way which revealed a far more complex history of the galaxy than previously expected. The Milky way cruises the Chilean night sky and looks peaceful in this image, but the survey found traces of a much more dynamic activity in the past. ...

10 janvier 2023: In this Picture of the Week we peer closer into the galaxy UGC 4211, where astronomers have discovered two supermassive black holes on the verge of merging, separated by just 750 lightyears — the closest to have been found to date using multiple wavelengths and less than half of the previous record. They used ESO’s Very Large Telescope (VLT), the Atacama Large Millimeter/submillimeter Array (ALMA), of which ESO is a partner, and other telescopes to detect the bright light produced as the black holes engulf material in their vicinity. Both of the images shown here were made using data from the MUSE instrument on ESO’s VLT in Chile. The left image shows a classical view of this galaxy, with dust lanes obscuring starlight. The image on the right shows emission from oxygen, nitrogen and hydrogen in blue, green and red respectively. Red indicates areas of star formation, and the bright ...

2 janvier 2023: The technical and engineering achievement behind the astronomical images and discoveries produced by scientists using ESO facilities is exceptionally marvelous. Here we see the fourth Unit Telescope (Yepun) of ESO’s Very Large Telescope (VLT) in Chile, which hosts several advanced instruments, such as MUSE, HAWK-I and ERIS. These instruments, engineered to study the mysteries of the Universe, such as planets, stellar nurseries, and supermassive black holes, would never be able to do so without the Adaptive Optics Facility (AOF). One of the components of the AOF is the 4 Laser Guide Star Facility (4LGSF). The lasers are emitted from the four black tubes seen in this image around the telescope’s 8.2-m mirror. Each laser beam is 30 centimeters wide and carries 22 watts of power! As the lasers reach about 90 kilometers into Earth’s atmosphere, they excite sodium atoms, making them glow, just like a star. Special sensors in each ...

27 décembre 2022: Cette image de la semaine montre les tout premiers stades d'un système d'étoiles binaires avec quelques caractéristiques intrigantes. Il s'agit d'une image radio prise par le télescope Atacama Large Millimeter/submillimeter Array (ALMA) au Chili, dont l'ESO est partenaire. Les deux jeunes étoiles, ou proto-étoiles -- marquées par des symboles d'étoile -- sont entourées d'un disque de poussière. La couleur représente la distribution de la température des proto-étoiles et de la zone environnante, les couleurs jaunes plus vives représentant des températures plus élevées. Il y a trois amas de poussière chaude loin des proto-étoiles, marqués par des croix, mais qu'est-ce qui les chauffe ? Une étude récente, dirigée par Maria Jose Maureira de l'Institut Max Planck de physique extraterrestre en Allemagne, suggère que ces régions ne sont pas seulement chauffées par les proto-étoiles, mais aussi, très probablement, par des ondes de choc, similaires à celles produites lorsqu'un avion se déplace dans ...

19 décembre 2022: As we are closing in on 2022, we want to send our best wishes to each and every one of you out there, from all of us at ESO, for the holidays and the new year. This year marked our 60th anniversary –– follow #ESO60Years to find out more –– and we want to thank you for following along our journey of exploring the Universe. We wish you a healthy end of the year and a wonderful start to 2023!

12 décembre 2022: La galaxie NGC 3627, également connue sous le nom de Messier 66, semble expulser des flammes de ses majestueux bras spiraux dans cette image de la semaine. Le "feu" marque en fait des nuages de gaz moléculaire froid, qui est la matière à partir de laquelle les étoiles se forment, et a été capturé à l'aide de l’observatoire Atacama Large Millimeter/submillimeter Array (ALMA) au Chili, dont l'ESO est partenaire. Les régions bleutées à l'arrière-plan révèlent la position d'étoiles plus anciennes, déjà formées, imagées par le spectrographe Multi-Unit Spectroscopic Explorer (MUSE) du Very Large Telescope (VLT) de l'ESO, également au Chili. Située à environ 31 millions d'années-lumière de la Terre dans la constellation du Lion, NGC 3627 est l'une des nombreuses galaxies observées dans le cadre du projet PHANGS (Physics at High Angular resolution in Nearby GalaxieS). PHANGS effectue des observations à haute résolution des galaxies proches à l'aide de télescopes ...