Some exoplanets have characteristics totally alien to our Solar System. Hot Jupiters are one such type. They can have orbital periods of less than 10 days and surface temperatures that can climb to well over 4,000 K (3,730 \u00b0C or 6,740 \u00b0F). Unlike any planets in our system, they\u2019re usually tidally locked.<\/p>\n
Astronomers probed the atmosphere of one hot Jupiter and found some strange winds blowing. <\/p>\n
<\/p>\n The planet is WASP-121 b, also known as Tylos. It is about 860 light-years away from Earth in the constellation Puppis. It has about 1.16 Jupiter masses and a radius about 1.75 times that of Jupiter. It\u2019s extremely close to its main sequence star and completes an orbit every 1.27 days. Tylos is tidally locked to its star, and its dayside temperature is 3,000 Kelvin (2,730 \u00b0C or 4,940 \u00b0F), qualifying it as an ultra-hot Jupiter. <\/p>\n \u201cIt feels like something out of science fiction.\u201d<\/p>\n Julia Seidel, European Southern Observatory<\/cite><\/p><\/blockquote>\n<\/figure>\n Since its discovery in 2015, Tylos\u2019 atmosphere has been studied many times. Researchers found water in its stratosphere and hints of titanium oxide and vanadium oxide. They\u2019ve also detected iron and chromium, though some subsequent studies failed to replicate some of these findings. <\/p>\n In new research, scientists examined Tylos\u2019 atmosphere in greater detail with the four telescopes that make up the VLT. With help from the VLT\u2019s ESPRESSO instrument, the researchers found powerful winds blowing through the exoplanet\u2019s atmosphere and confirmed the presence of iron and titanium. The results are in two new papers.<\/p>\n \u201cEven the strongest hurricanes in the Solar System seem calm in comparison.\u201d<\/p>\n Julia Seidel, European Southern Observatory<\/cite><\/p><\/blockquote>\n<\/figure>\n The first paper, \u201cVertical structure of an exoplanet\u2019s atmospheric jet stream,\u201d<\/span> was published in Nature. The lead author is Julia Seidel, a researcher at the European Southern Observatory (ESO).<\/p>\n The second is \u201cTitanium chemistry of WASP-121 b with ESPRESSO in 4-UT mode,\u201d which was published in the journal Astronomy and Astrophysics. The lead author is Bibiana Prinoth, a PhD student at Lund University, Sweden, who is also with the European Southern Observatory. <\/p>\n Some of the researchers involved are co-authors of both papers. <\/p>\n \u201cUltra-hot Jupiters, an extreme class of planets not found in our solar system, provide a unique window into atmospheric processes,\u201d the authors of the Nature paper write. \u201cThe extreme temperature contrasts between their day- and night-sides pose a fundamental climate puzzle: how is energy distributed?\u201d<\/p>\n \u201cThis planet\u2019s atmosphere behaves in ways that challenge our understanding of how weather works \u2014 not just on Earth, but on all planets. It feels like something out of science fiction,\u201d said Julia Seidel, the lead author of the study published in Nature.<\/p>\n With the power of the VLT and ESPRESSO, the researchers were able to study Tylos\u2019 atmosphere in detail. No other exoplanet atmosphere has ever been studied in such detail and to such depth. The researchers created a 3D map of the atmosphere, revealing distinct layers and winds.<\/p>\n \u201cWhat we found was surprising: a jet stream rotates material around the planet\u2019s 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,\u201d said Seidel. 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. \u201cEven the strongest hurricanes in the Solar System seem calm in comparison,\u201d she adds.<\/p>\n \u201cIt\u2019s truly mind-blowing that we\u2019re able to study details like the chemical makeup and weather patterns of a planet at such a vast distance.\u201d<\/p>\n Bibiana Prinoth, Lund University and the European Southern Observatory<\/cite><\/p><\/blockquote>\n<\/figure>\n The VLT has an interesting design and is billed by the European Southern Observatory as \u201cthe world\u2019s most advanced visible-light astronomical observatory.\u201d It has four main units with 8.2-meter primary mirrors and four smaller, movable auxiliary \u2018scopes with 1.8-meter primary mirrors. When working together with the ESPRESSO instrument, the VLT operates as a single, powerful telescope. This combined power meant that the VLT gathered ample data during a single transit of Tylos in front of its star. <\/p>\n \u201cThe VLT enabled us to probe three different layers of the exoplanet\u2019s atmosphere in one fell swoop,\u201d said study co-author Leonardo A. dos Santos, an assistant astronomer at the Space Telescope Science Institute. The researchers traced the movement of the winds by tracking the movements of different elements: iron, sodium, and hydrogen correspond to the deep, mid, and shallow layers of the atmosphere. \u201cIt\u2019s the kind of observation that is very challenging to do with space telescopes, highlighting the importance of ground-based observations of exoplanets,\u201d he adds. <\/p>\n The observations revealed an exoplanet atmosphere with unusual complexity. <\/p>\n When Tylos crosses in front of its host star, known as a transit, atoms in the planet\u2019s atmosphere absorb specific wavelengths of starlight, which was measured with the VLT\u2019s ESPRESSO instrument. With that data, astronomers reconstructed the composition and velocity of different layers in the atmosphere. An iron wind blows in the deepest layer, away from the point of the planet where the star is directly overhead. Above the iron layer is a very fast jet of sodium that moves faster than the planet rotates. The sodium jet accelerates as it moves from the planet\u2019s morning side to its evening side. The upper layer is made of hydrogen, where the wind blows outwards. The hydrogen layer overlaps with the sodium jet below it.<\/p>\n The authors explain that this unusual planet is more than just an oddity. Its unusual characteristics make it a great testbed for Global Circulation Models. \u201cBy resolving the vertical structure of atmospheric dynamics, we move beyond integrated global snapshots of the atmosphere, enabling more accurate identification of flow patterns and allowing for a more nuanced comparison to models,\u201d the authors explain. <\/p>\n The study published in Astronomy and Astrophysics is also based on data from the VLT and ESPRESSO. It uncovered more details of Tylos\u2019 atmosphere, including its chemistry. \u201cThe transmission spectrum of WASP-121 b has been extensively studied using the cross-correlation technique, resulting in detections and confirmations for various atoms and ions, including H I, Mg I, Ca I, V I, Cr I, Fe I, Ni I, Fe II, Ca II, and K I, Ba II,\u201d the authors write. \u201cWe confirm all these detections and additionally report detections for Ti\u00a0I, Mn\u00a0I, Co\u00a0I\u00a0Sr\u00a0I, and Sr\u00a0II.\u201d<\/p>\n \u201cThis experience makes me feel like we\u2019re on the verge of uncovering incredible things we can only dream about now.\u201d<\/p>\n Bibiana Prinoth, Lund University and the European Southern Observatory<\/cite><\/p><\/blockquote>\n<\/figure>\n The researchers found titanium just below the jet stream. This finding is interesting because previous research detected titanium and subsequent research refuted that. \u201cWe attribute the capability of detecting Ti I to the superior photon-collecting power enabled by using ESPRESSO in 4-UT mode compared to a single 1-UT transit and to improvements in the application of the cross-correlation technique,\u201d the authors explain. <\/p>\n The cross-correlation technique is a powerful method for studying exoplanet atmospheres. Light from the atmosphere is much fainter than light from the star and can be obscured by the much stronger starlight. The cross-correlation technique helps overcome this by comparing the observed spectrum with the known \u201ctemplate\u201d spectrum of specific molecules and atoms expected to be present in the atmosphere. <\/p>\n \u201cIt\u2019s truly mind-blowing that we\u2019re able to study details like the chemical makeup and weather patterns of a planet at such a vast distance,\u201d said Bibiana Prinoth, lead author of the Astronomy and Astrophysics paper. <\/p>\n \u201cThe 4-UT mode of ESPRESSO, with its effective photon collecting area equivalent to that of a 16-meter class telescope, serves as a valuable test-bed for pushing the limits of S\/N on relatively faint targets,\u201d the authors write in their conclusion. <\/p>\n The study of exoplanet atmosphere with ground-based telescopes will soon get a big boost. In 2028, the long-awaited Extremely Large Telescope should begin operations. It will have a 39.3-metre-diameter primary mirror, giving it 250 times more light-gathering area than the Hubble. It will also feature powerful instruments to probe exoplanet atmospheres. <\/p>\n \u201cThe present analysis also allows us to anticipate the observational capabilities of the soon-to-be-commissioned ELT, particularly with regard to time-resolved studies of exoplanet atmospheres,\u201d the authors write. <\/p>\n Who knows what further strangeness is waiting to be discovered in exoplanet atmospheres? <\/p>\n \u201cThe ELT will be a game-changer for studying exoplanet atmospheres,\u201d said Prinoth. \u201cThis experience makes me feel like we\u2019re on the verge of uncovering incredible things we can only dream about now.\u201d<\/p>\n \n\n
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