Category Archives: Astronomy

Tylos (or WASP-121b) is a gaseous, giant exoplanet located some 900 light-years away in the constellation Puppis. Using the ESPRESSO instrument on ESO’s Very Large Telescope (VLT), scientists have been able to prove into its atmosphere, revealing its 3D structure. This is the first time that this has been possible on a planet outside of the Solar System. The atmosphere of Tylos is divided into three layers, with iron winds at the bottom, followed by a very fast jet stream of sodium, and finally an upper layer of hydrogen winds. This kind of climate has never been seen before on any planet.

Astronomers have peered through the atmosphere of a planet beyond the Solar System, mapping its 3D structure for the first time. By combining all four telescope units of the European Southern Observatory’s Very Large Telescope (ESO’s VLT), they found powerful winds carrying chemical elements like iron and titanium, creating intricate weather patterns across the planet’s atmosphere. The discovery opens the door for detailed studies of the chemical makeup and weather of other alien worlds.

“This planet’s atmosphere behaves in ways that challenge our understanding of how weather works — not just on Earth, but on all planets. It feels like something out of science fiction,”

says Julia Victoria Seidel, a researcher at the European Southern Observatory (ESO) in Chile and lead author of the study, published today in Nature.

The planet, WASP-121b (also known as Tylos), is some 900 light-years away in the constellation Puppis. It’s an ultra-hot Jupiter, a gas giant orbiting its host star so closely that a year there lasts only about 30 Earth hours. Moreover, one side of the planet is scorching, as it is always facing the star, while the other side is much cooler.

The team has now probed deep inside Tylos’s atmosphere and revealed distinct winds in separate layers, forming a map of the atmosphere’s 3D structure. It’s the first time astronomers have been able to study the atmosphere of a planet outside our Solar System in such depth and detail.

“What we found was surprising: a jet stream rotates material around the planet’s equator, while a separate flow at lower levels of the atmosphere moves gas from the hot side to the cooler side. This kind of climate has never been seen before on any planet,”

says Seidel, who is also a researcher at the Lagrange Laboratory, part of the Observatoire de la Côte d’Azur, in France. The observed jet stream spans half of the planet, gaining speed and violently churning the atmosphere high up in the sky as it crosses the hot side of Tylos.

“Even the strongest hurricanes in the Solar System seem calm in comparison,”

she adds.

This diagram shows the structure and motion of the atmosphere of the exoplanet Tylos (WASP-121b). The exoplanet is shown from above in this figure, looking at one of its poles. The planet rotates counter-clockwise, in such a way that it always shows the same side to its parent star, so it’s always day on one half of the planet and night on the other. The transition between night and day is the “morning side” while the “evening side” represents the transition between day and night; its morning side is to the right and its evening side to the left. As the planet crosses in front of its host star, atoms in the planet’s atmosphere absorb specific colours or wavelengths of the star’s light, which can be measured with a spectrograph. From this data –– obtained in this case with the ESPRESSO instrument on ESO’s Very Large Telescope –– astronomers can reconstruct the composition and velocity of different layers in the atmosphere. The deepest layer is a wind of iron that blows away from the point of the planet where the star is directly overhead. Above this layer there is a very fast jet of sodium that moves faster than the planet rotates. This jet actually accelerates as it moves from the morning side to the evening side of the planet. Finally, there is an upper layer of hydrogen wind blowing outwards. This hydrogen layer overlaps with the sodium jet below it.

To uncover the 3D structure of the exoplanet’s atmosphere, the team used the ESPRESSO instrument on ESO’s VLT to combine the light of its four large telescope units into a single signal. This combined mode of the VLT collects four times as much light as an individual telescope unit, revealing fainter details. By observing the planet for one full transit in front of its host star, ESPRESSO was able to detect signatures of multiple chemical elements, probing different layers of the atmosphere as a result.

“The VLT enabled us to probe three different layers of the exoplanet’s atmosphere in one fell swoop,”

says study co-author Leonardo A. dos Santos, an assistant astronomer at the Space Telescope Science Institute in Baltimore, United States. The team tracked the movements of iron, sodium and hydrogen, which allowed them to trace winds in the deep, mid and shallow layers of the planet’s atmosphere, respectively.

“It’s the kind of observation that is very challenging to do with space telescopes, highlighting the importance of ground-based observations of exoplanets,”

he adds.

Interestingly, the observations also revealed the presence of titanium just below the jet stream, as highlighted in a companion study published in Astronomy and Astrophysics. This was another surprise since previous observations of the planet had shown this element to be absent, possibly because it’s hidden deep in the atmosphere.

“It’s truly mind-blowing that we’re able to study details like the chemical makeup and weather patterns of a planet at such a vast distance,”

says Bibiana Prinoth, a PhD student at Lund University, Sweden, and ESO, who led the companion study and is a co-author of the Nature paper.

To uncover the atmosphere of smaller, Earth-like planets, though, larger telescopes will be needed. They will include ESO’s Extremely Large Telescope (ELT), which is currently under construction in Chile’s Atacama Desert, and its ANDES instrument.

“The ELT will be a game-changer for studying exoplanet atmospheres,” says Prinoth. “This experience makes me feel like we’re on the verge of uncovering incredible things we can only dream about now.”

Links

Research paper (Nature)
Research paper (A&A)
Photos of the VLT
Find out more about ESO’s Extremely Large Telescope on our dedicated website and press kit
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Night sky highlights for February 2025

February 3, 2025 TopSpacer

Check out the night sky this month, February 2025. Here are videos and links to websites highlighting the top sights to observe.

** What’s Up: February 2025 Skywatching Tips from NASA – NASA JPL

What are some skywatching highlights in February 2025?

Venus blazes at its brightest in the early evening, despite being only a slim crescent through the telescope eyepiece. Mars and Jupiter to rule the night sky after Venus sets, amid the menagerie of bright winter stars in Orion, Taurus, and Gemini. And enhance your astronomy IQ by knowing the difference between a conjunction and an appulse.

0:00 Intro
0:13 Moon & planets
0:41 Appulses
1:39 Venus at maximum
2:51 February Moon phases

Additional information about topics covered in this episode of What’s Up, along with still images from the video, and the video transcript, are available at https://solarsystem.nasa.gov/skywatch….

Sky chart showing Jupiter and Mars high overhead after nightfall in February. Credits:
NASA/JPL-Caltech

** Venus and Mars dominate the sky. What’s in the night sky tonight, February 2025 – BBC Sky at Night Magazine

Pete Lawrence and Paul Abel reveal what’s visible in the night sky this month, including bright Venus dominating the sky in February 2025. Look out for Venus, Saturn and Uranus near the crescent Moon on the evening of 1 February.

Mars and Jupiter continue to dazzle, a particular highlight being a meeting between Mars and the Moon on 9 February 2025.

Also, February marks a final chance to enjoy and explore the constellation Orion before it disappears from view.

** February Podcast: Planets Amid Winter’s Stars – Sky & Telescope

Night sky highlights for January 2025

January 3, 2025 TopSpacer

Check out the night sky this month, January 2025. Here are videos and links to websites highlighting the top sights to observe.

** What’s Up: January 2025 Skywatching Tips from NASA – NASA JPL

What are some skywatching highlights in January 2025?

This month, four bright planets greet you in the early evening. Venus and Saturn cozy up on the 17th and 18th, while Mars is at its brightest in the past two years. The Moon occults Mars for those in the U.S. and Eastern Canada on Jan. 13. Plus, the Quadrantid meteors peak on the morning of Jan. 3 before dawn.

0:00 Intro
0:14 Four planets at once
1:02 Venus & Saturn Get Close
1:39 Mars at Opposition
2:31 Quadrantid Meteors Peak
3:07 January Moon phases

** What to see in the night sky: January 2025 – BBC Sky at Night Magazine

Pete Lawrence and Paul Abel reveal their pick of the best things to see in the night sky this month, including:

Mars at opposition, Jupiter near Orion, a lunar occultation of Saturn, the Quadrantid meteor shower, the Moon and the Pleiades, and the best deep-sky objects.

** Sky & Telescope’s Sky Tour Podcast – January 2025 – Sky & Telescope Youtube

Our monthly Sky Tour #astronomy #podcast provides an informative and entertaining 12-minute guided tour of the #night #sky. Join us for the January 2025 episode and start the year with a strong #meteor shower, keep tabs on four bright #planets, watch #Mars disappear behind the full Wolf Moon, and focus on #Orion the Hunter and the #Pleiades star cluster. So grab your curiosity, and come along on this month’s Sky Tour.

ESO: First ever binary star found near Milky Way’s supermassive black hole

December 17, 2024 TopSpacer

A new report from the European Southern Observatory (ESO):

First ever binary star found near
our galaxy’s supermassive black hole

This image indicates the location of the newly discovered binary star D9, which is orbiting Sagittarius A*, the supermassive black hole at the centre of our galaxy. It is the first star pair ever found near a supermassive black hole. The cut-out shows the binary system as detected by the SINFONI spectrograph on ESO’s Very Large Telescope. While the two stars cannot be discerned separately in this image, the binary nature of D9 was revealed by the spectra captured by SINFONI over several years. These spectra showed that the light emitted by hydrogen gas around D9 oscillates periodically towards red and blue wavelengths as the two stars orbit each other.

An international team of researchers has detected a binary star orbiting close to Sagittarius A*, the supermassive black hole at the centre of our galaxy. It is the first time a stellar pair has been found in the vicinity of a supermassive black hole. The discovery, based on data collected by the European Southern Observatory’s Very Large Telescope (ESO’s VLT), helps us understand how stars survive in environments with extreme gravity, and could pave the way for the detection of planets close to Sagittarius A*.

“Black holes are not as destructive as we thought”

says Florian Peißker, a researcher at the University of Cologne, Germany, and lead author of the study published today in Nature Communications. Binary stars, pairs of stars orbiting each other, are very common in the Universe, but they had never before been found near a supermassive black hole, where the intense gravity can make stellar systems unstable.

This new discovery shows that some binaries can briefly thrive, even under destructive conditions. D9, as the newly discovered binary star is called, was detected just in time: it is estimated to be only 2.7 million years old, and the strong gravitational force of the nearby black hole will probably cause it to merge into a single star within just one million years, a very narrow timespan for such a young system.

“This provides only a brief window on cosmic timescales to observe such a binary system — and we succeeded!”

explains co-author Emma Bordier, a researcher also at the University of Cologne and a former student at ESO.

For many years, scientists also thought that the extreme environment near a supermassive black hole prevented new stars from forming there. Several young stars found in close proximity to Sagittarius A* have disproved this assumption. The discovery of the young binary star now shows that even stellar pairs have the potential to form in these harsh conditions.

“The D9 system shows clear signs of the presence of gas and dust around the stars, which suggests that it could be a very young stellar system that must have formed in the vicinity of the supermassive black hole”

explains co-author Michal Zajaček, a researcher at Masaryk University, Czechia, and the University of Cologne.

The newly discovered binary was found in a dense cluster of stars and other objects orbiting Sagittarius A*, called the S cluster. Most enigmatic in this cluster are the G objects, which behave like stars but look like clouds of gas and dust.

It was during their observations of these mysterious objects that the team found a surprising pattern in D9. The data obtained with the VLT’s ERIS instrument, combined with archival data from the SINFONI instrument, revealed recurring variations in the velocity of the star, indicating D9 was actually two stars orbiting each other.

“I thought that my analysis was wrong,” Peißker says, “but the spectroscopic pattern covered about 15 years, and it was clear this detection is indeed the first binary observed in the S cluster.”

The results shed new light on what the mysterious G objects could be. The team proposes that they might actually be a combination of binary stars that have not yet merged and the leftover material from already merged stars.

The precise nature of many of the objects orbiting Sagittarius A*, as well as how they could have formed so close to the supermassive black hole, remain a mystery. But soon, the GRAVITY+ upgrade to the VLT Interferometer and the METIS instrument on ESO’s Extremely Large Telescope (ELT), under construction in Chile, could change this. Both facilities will allow the team to carry out even more detailed observations of the Galactic centre, revealing the nature of known objects and undoubtedly uncovering more binary stars and young systems.

“Our discovery lets us speculate about the presence of planets, since these are often formed around young stars. It seems plausible that the detection of planets in the Galactic centre is just a matter of time”

concludes Peißker.

This chart shows the location of the field of view within which Sagittarius A* resides — the black hole is marked with a red circle within the constellation of Sagittarius (The Archer). This map shows most of the stars visible to the unaided eye under good conditions.

Links

Research paper
Photos of the VLT
Find out more about ESO’s Extremely Large Telescope on our dedicated website and press kit
For journalists: subscribe to receive our releases under embargo in your language
For scientists: got a story? Pitch your research

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Night sky highlights for December 2024

December 2, 2024 TopSpacer

Check out the night sky this month, December 2024. Here are videos and links to websites highlighting the top sights to observe.

** What’s Up: December 2024 Skywatching Tips from NASA – NASA JPL

What are some skywatching highlights in December 2024?

This month, enjoy dazzling views of Venus as the “Evening Star,” Jupiter at its brightest during opposition, and Mars doubling in brightness, and look for the Winter Triangle. The Geminid meteor shower peaks under challenging moonlight conditions, but you might get lucky and catch a shooting star that week before sunrise!

0:00 Intro
0:14 December planet highlights
1:31 The Winter Stars
1:57 The Winter Triangle
2:42 Geminid Meteor Shower
3:14 December Moon phases

** What to see in the night sky: December 2024 – BBC Sky at Night Magazine

Pete Lawrence and Paul Abel reveal their pick of the best things to see in the night sky this month.

** Sky & Telescope’s Sky Tour Podcast – December 2024 | Jupiter Shines, Winter Stars, and Many Meteors – Sky & Telescope Youtube

Our monthly Sky Tour #astronomy #podcast provides an informative and entertaining 10-minute guided tour of the #night #sky. Join us for the December 2024 episode and mark the #solstice, be amazed by #Jupiter, welcome the arrival of winter’s bright #stars, and prep for what’s usually the year’s best #meteorshower.

Listen and subscribe to this podcast at https://skyandtelescope.org/observing/ and don’t forget to subscribe to S&T’s YouTube channel to get alerts about new videos, including this monthly podcast.