TESS — Transiting Exoplanet Survey Satellite ("Спутник наблюдения за транзитами экзопланет")

Автор Andrey Samoilov, 11.10.2014 00:43:44

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ЦитатаHighlights From TESS's First Year

 NASA Goddard

Опубликовано: 25 июл. 2019 г.

NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered 21 planets outside our solar system and captured data on other interesting events occurring in the southern sky during its first year of science. TESS has now turned its attention to the northern hemisphere to complete the most comprehensive planet-hunting expedition ever undertaken.

TESS began hunting for exoplanets (or worlds orbiting distant stars) in the southern sky in July of 2018, while also collecting data on supernovae, black holes and other phenomena in its line of sight. Along with the planets TESS has discovered, the mission has identified over 800 candidate exoplanets that are waiting for confirmation by ground-based telescopes.

To search for exoplanets, TESS uses four large cameras to watch a 24-by-96-degree section of the sky for 27 days at a time. Some of these sections overlap, so some parts of the sky are observed for almost a year. TESS is concentrating on stars closer than 300 light-years from our solar system, watching for transits, which are periodic dips in brightness caused by an object, like a planet, passing in front of the star.

On July 18, the southern portion of the survey was completed and the spacecraft turned its cameras to the north. When it completes the northern section in 2020, TESS will have mapped over three quarters of the sky.
https://www.youtube.com/watch?v=7LLyFFsY7ZYhttps://www.youtube.com/watch?v=7LLyFFsY7ZY (2:32)

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https://ria.ru/20190729/1556978631.html
ЦитатаАстрономы НАСА открыли три планеты у соседней звезды
18:10

МОСКВА, 29 июл - РИА Новости. Орбитальная обсерватория TESS открыла сразу три планеты, наблюдая за яркой, но небольшой звездой в созвездии Золотой Рыбы, удаленной от нас на 73 световых года. На спутниках одного из этих миров может существовать жизнь, пишут ученые в журнале Nature Astronomy.
Цитата"Звезда TOI-270 отличается очень спокойным характером. Это заметно упрощает последующие поиски возможных следов жизни на ее планетах и их спутниках. Вдобавок, все эти миры синхронизированы друг с другом, что упростит поиски других, более землеподобных планет, если они есть в этой системе", -- заявил Максимилиан Гюнтер (Maximillian Guenther) из Массачусетского технологического института (США).
Телескоп TESS был запущен в апреле прошлого года в качестве замены для его знаменитого предшественника, орбитальной обсерватории "Кеплер", открывшей тысячи экзопланет за восемь лет работы. Запасы топлива на его борту сейчас подходят к концу, и ученые ожидают, что он окончательно прекратит наблюдения в самое ближайшее время.

В отличие от него, TESS будет следить не за одним участком неба, как это делал "Кеплер" в первые четыре года работы на орбите, а за разными уголками космоса, где находятся интересные ученым звезды и планеты.

Еще одним новшеством станет то, что TESS будет следить не за солнцеподобными, а за более яркими звездами, о планетах которых астрономы сегодня практически ничего не знают. Их "перепись", как надеются ученые, покажет, как часто могут формироваться аналоги Земли у более крупных и ярких светил, и насколько вероятно зарождение жизни на их поверхности.

Первое подобное открытие, как отмечают Гюнтер и его коллеги, TESS совершил, наблюдая за светилами в созвездии Золотой Рыбы, которые он изучал в первые месяцы после начала его научной карьеры.

Внимание планетологов привлекла небольшая звезда TOI-270, красный карлик среднего возраста, чья масса примерно в два раза меньше, чем у Солнца. Небольшое расстояние до этого светила, а также его невероятно спокойный характер, помогли TESS "напрямую" открыть сразу три планеты в его окрестностях и точно измерить их свойства.

Все эти миры не похожи на планеты Солнечной системы - они одновременно больше Земли и ее ближайших соседок, но при этом меньше Юпитера, Нептуна и других газовых гигантов. Ближняя к звезде планета, чья масса примерно в два раза больше, чем у нашего мира, относится к числу так называемых "суперземель", а два ее более крупных соседа - к экзотическим "суб-Нептунам".

Так ученые называют достаточно крупные планеты, которые вряд ли могут обладать каменистой поверхностью, но которые при этом заметно уступают "настоящим" газовым гигантам в размерах. Часть исследователей предполагает, что некоторые из них могут представлять причудливые "водные миры", почти полностью состоящие из воды. Планеты TOI-270c и TOI-270d примерно в шесть и пять раз тяжелее Земли, что делает это крайне маловероятным.

Все эти планеты, как отмечают ученые, пока остаются самыми небольшими и близкими к Земле мирами, за которыми можно наблюдать "напрямую", отслеживая то, как они проходят по диску светила. Это позволит ученым очень точно изучить состав их атмосферы, если она существует, а также оценить их пригодность для жизни.

С другой стороны, уже сейчас можно сказать, что все три планеты вряд ли могут быть обитаемыми. Суперземля TOI-270b расположена слишком близко к светилу, из-за чего на ее поверхности царит настоящий ад со средними температурами, превышающими 250 градусов Цельсия.

Две других планеты, скорее всего, обладают слишком густой атмосферой, чтобы в ее верхних слоях могла зародиться жизнь, а температуры на втором мире, TOI-270c, тоже очень высокие - они превышают 150 градусов Цельсия. При определенных условиях, жизнь может скрываться на лунах последнего "суб-Нептуна", где будут царить почти земные температуры.

С другой стороны, если на этих мирах существует жизнь, вероятность ее выживания заметно выше, чем на других кандидатах на роль прибежища инопланетной жизни. Число пятен на поверхности TOI-270, а также уровень ее магнитной активности, как показали замеры TESS, пока остаются на рекордно низком уровне. Это уменьшает вероятность того, что вспышки или корональные выбросы могли уничтожить местную флору и фауну.

Как надеются ученые, первые ответы на подобные вопросы они получат уже в ближайшие годы, когда на орбиту будет выведен телескоп JWST, "наследник" Хаббла. Он будет обладать достаточно высоким разрешением для того, чтобы получить фотографии этих миров и попытаться найти следы жизни в их атмосферах, заключают ученые.

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ЦитатаTESS Helps Reveal Multiple Planets, Including Promising World

NASA Goddard

Опубликовано: 31 июл. 2019 г.

Tour the GJ 357 system, located 31 light-years away in the constellation Hydra. Astronomers confirming a planet candidate identified by NASA's Transiting Exoplanet Survey Satellite subsequently found two additional worlds orbiting the star. The outermost planet, GJ 357 d, is especially intriguing to scientists because it receives as much energy from its star as Mars does from the Sun.
https://www.youtube.com/watch?v=6bWra2Wvudkhttps://www.youtube.com/watch?v=6bWra2Wvudk (1:58)

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https://www.nasa.gov/feature/goddard/2019/confirmation-of-toasty-tess-planet-leads-to-surprising-find-of-promising-world
ЦитатаJuly 31, 2019

Confirmation of Toasty TESS Planet Leads to Surprising Find of Promising World

A piping hot planet discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) has pointed the way to additional worlds orbiting the same star, one of which is located in the star's habitable zone. If made of rock, this planet may be around twice Earth's size.

The new worlds orbit a star named GJ 357, an M-type dwarf about one-third the Sun's mass and size and about 40% cooler that our star. The system is located 31 light-years away in the constellation Hydra. In February, TESS cameras caught the star dimming slightly every 3.9 days, revealing the presence of a transiting exoplanet -- a world beyond our solar system -- that passes across the face of its star during every orbit and briefly dims the star's light.
 :
https://www.youtube.com/watch?v=6bWra2Wvudk
Tour the GJ 357 system, located 31 light-years away in the constellation Hydra. Astronomers confirming a planet candidate identified by NASA's Transiting Exoplanet Survey Satellite subsequently found two additional worlds orbiting the star. The outermost planet, GJ 357 d, is especially intriguing to scientists because it receives as much energy fr om its star as Mars does fr om the Sun.
Credits: NASA's Goddard Space Flight Center
Download this video and related multimedia in HD formats fr om NASA Goddard's Scientific Visualization Studio
"In a way, these planets were hiding in measurements made at numerous observatories over many years," said Rafael Luque, a doctoral student at the Institute of Astrophysics of the Canary Islands (IAC) on Tenerife who led the discovery team. "It took TESS to point us to an interesting star wh ere we could uncover them."

The transits TESS observed belong to GJ 357 b, a planet about 22% larger than Earth. It orbits 11 times closer to its star than Mercury does our Sun. This gives it an equilibrium temperature -- calculated without accounting for the additional warming effects of a possible atmosphere -- of around 490 degrees Fahrenheit (254 degrees Celsius).

"We describe GJ 357 b as a 'hot Earth,'" explains co-author Enric Pallé, an astrophysicist at the IAC and Luque's doctoral supervisor. "Although it cannot host life, it is noteworthy as the third-nearest transiting exoplanet known to date and one of the best rocky planets we have for measuring the composition of any atmosphere it may possess."

But while researchers were looking at ground-based data to confirm the existence of the hot Earth, they uncovered two additional worlds. The farthest-known planet, named GJ 357 d, is especially intriguing.


This diagram shows the layout of the GJ 357 system. Planet d orbits within the star's so-called habitable zone, the orbital region wh ere liquid water can exist on a rocky planet's surface. If it has a dense atmosphere, which will take future studies to determine, GJ 357 d could be warm enough to permit the presence of liquid water.
Credits: NASA's Goddard Space Flight Center/Chris Smith

"GJ 357 d is located within the outer edge of its star's habitable zone, wh ere it receives about the same amount of stellar energy from its star as Mars does from the Sun," said co-author Diana Kossakowski at the Max Planck Institute for Astronomy in Heidelberg, Germany. "If the planet has a dense atmosphere, which will take future studies to determine, it could trap enough heat to warm the planet and allow liquid water on its surface."

Without an atmosphere, it has an equilibrium temperature of -64 F (-53 C), which would make the planet seem more glacial than habitable. The planet weighs at least 6.1 times Earth's mass, and orbits the star every 55.7 days at a range about 20% of Earth's distance from the Sun. The planet's size and composition are unknown, but a rocky world with this mass would range from about one to two times Earth's size.


This illustration shows one interpretation of what GJ 357 d may be like.
Credits: NASA's Goddard Space Flight Center/Chris Smith

Even through TESS monitored the star for about a month, Luque's team predicts any transit would have occurred outside the TESS observing window.

GJ 357 c, the middle planet, has a mass at least 3.4 times Earth's, orbits the star every 9.1 days at a distance a bit more than twice that of the transiting planet, and has an equilibrium temperature around 260 F (127 C). TESS did not observe transits from this planet, which suggests its orbit is slightly tilted -- perhaps by less than 1 degree -- relative to the hot Earth's orbit, so it never passes across the star from our perspective.

To confirm the presence of GJ 357 b and discover its neighbors, Luque and his colleagues turned to existing ground-based measurements of the star's radial velocity, or the speed of its motion along our line of sight. An orbiting planet produces a gravitational tug on its star, which results in a small reflex motion that astronomers can detect through tiny color changes in the starlight. Astronomers have searched for planets around bright stars using radial velocity data for decades, and they often make these lengthy, precise observations publicly available for use by other astronomers.

Luque's team examined ground-based data stretching back to 1998 from the European Southern Observatory and the Las Campanas Observatory in Chile, the W.M. Keck Observatory in Hawaii, and the Calar Alto Observatory in Spain, among many others.

A paper describing the findings was published on Wednesday, July 31, in the journal Astronomy & Astrophysics and is available online.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

By Francis Reddy
NASA's Goddard Space Flight Center, Greenbelt, Md.
 

Last Updated: July 31, 2019
Editor: Rob Garner

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ЦитатаTESS Catches its First Star-destroying Black Hole

 NASA Goddard

25 сент. 2019 г.

For the first time, NASA's planet-hunting Transiting Exoplanet Survey Satellite (TESS) watched a black hole tear apart a star from start to finish, a cataclysmic phenomenon called a tidal disruption event.

The blast, named ASASSN-19bt, was found on Jan. 29 by the All-Sky Automated Survey for Supernovae (ASAS-SN), a worldwide network of 20 robotic telescopes. Shortly after the discovery, ASAS-SN requested follow-up observations by NASA's Swift satellite, ESA's (European Space Agency's) XMM-Newton and ground-based 1-meter telescopes in the global Las Cumbres Observatory network.

The disruption occurred in TESS's continuous viewing zone, which is always in sight of one of the satellite's four cameras. This allowed astronomers to view the explosion from beginning to end.

This video shows images of a tidal disruption event called ASASSN-19bt taken by NASA's Transiting Exoplanet Survey Satellite (TESS) and Swift missions, along with an animation illustrating how it unfolded. Because ASASSN-19bt occurred in the TESS continuous viewing zone, the satellite observed the full duration of the event.
https://www.youtube.com/watch?v=85tdoDt1Qh0https://www.youtube.com/embed/85tdoDt1Qh0 (1:46)

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ЦитатаDive Into TESS's Southern Sky Panorama

 NASA Goddard

5 нояб. 2019 г.

The glow of the Milky Way -- our galaxy seen edgewise -- arcs across a sea of stars in a new mosaic of the southern sky produced from a year of observations by NASA's Transiting Exoplanet Survey Satellite (TESS). Constructed from 208 TESS images taken during the mission's first year of science operations, completed on July 18, the southern panorama reveals both the beauty of the cosmic landscape and the reach of TESS's cameras.

Within this scene, TESS has discovered 29 exoplanets, or worlds beyond our solar system, and more than 1,000 candidate planets astronomers are now investigating.
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TESS divided the southern sky into 13 sectors and imaged each one of them for nearly a month using four cameras, which carry a total of 16 charge-coupled devices (CCDs). Remarkably, the TESS cameras capture a full sector of the sky every 30 minutes as part of its search for exoplanet transits. Transits occur when a planet passes in front of its host star from our perspective, briefly and regularly dimming its light. During the satellite's first year of operations, each of its CCDs captured 15,347 30-minute science images. These images are just a part of more than 20 terabytes of southern sky data TESS has returned, comparable to streaming nearly 6,000 high-definition movies.

In addition to its planet discoveries, TESS has imaged a comet in our solar system, followed the progress of numerous stellar explosions called supernovae, and even caught the flare from a star ripped apart by a supermassive black hole. After completing its southern survey, TESS turned north to begin a year-long study of the northern sky.
https://www.youtube.com/watch?v=P3KevBr4go4https://www.youtube.com/embed/P3KevBr4go4 (3:29)


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https://www.nasa.gov/feature/goddard/2020/nasa-planet-hunter-finds-its-1st-earth-size-habitable-zone-world
Цитата

Jan. 7, 2020

NASA Planet Hunter Finds its 1st Earth-size Habitable-zone World

NASA's Transiting Exoplanet Survey Satellite (TESS) has discovered its first Earth-size planet in its star's habitable zone, the range of distances where conditions may be just right to allow the presence of liquid water on the surface. Scientists confirmed the find, called TOI 700 d, using NASA's Spitzer Space Telescope and have modeled the planet's potential environments to help inform future observations.

TOI 700 d is one of only a few Earth-size planets discovered in a star's habitable zone so far. Others include several planets in the TRAPPIST-1 system and other worlds discovered by NASA's Kepler Space Telescope.

"TESS was designed and launched specifically to find Earth-sized planets orbiting nearby stars," said Paul Hertz, astrophysics division director at NASA Headquarters in Washington. "Planets around nearby stars are easiest to follow-up with larger telescopes in space and on Earth. Discovering TOI 700 d is a key science finding for TESS. Confirming the planet's size and habitable zone status with Spitzer is another win for Spitzer as it approaches the end of science operations this January."

TESS monitors large swaths of the sky, called sectors, for 27 days at a time. This long stare allows the satellite to track changes in stellar brightness caused by an orbiting planet crossing in front of its star fr om our perspective, an event called a transit.

TOI 700 is a small, cool M dwarf star located just over 100 light-years away in the southern constellation Dorado. It's roughly 40% of the Sun's mass and size and about half its surface temperature. The star appears in 11 of the 13 sectors TESS observed during the mission's first year, and scientists caught multiple transits by its three planets.

The star was originally misclassified in the TESS database as being more similar to our Sun, which meant the planets appeared larger and hotter than they really are. Several researchers, including Alton Spencer, a high school student working with members of the TESS team, identified the error.

"When we corrected the star's parameters, the sizes of its planets dropped, and we realized the outermost one was about the size of Earth and in the habitable zone," said Emily Gilbert, a graduate student at the University of Chicago. "Additionally, in 11 months of data we saw no flares from the star, which improves the chances TOI 700 d is habitable and makes it easier to model its atmospheric and surface conditions."

Gilbert and other researchers presented the findings at the 235th meeting of the American Astronomical Society in Honolulu, and three papers -- one of which Gilbert led -- have been submitted to scientific journals.

The innermost planet, called TOI 700 b, is almost exactly Earth-size, is probably rocky and completes an orbit every 10 days. The middle planet, TOI 700 c, is 2.6 times larger than Earth -- between the sizes of Earth and Neptune -- orbits every 16 days and is likely a gas-dominated world. TOI 700 d, the outermost known planet in the system and the only one in the habitable zone, measures 20% larger than Earth, orbits every 37 days and receives from its star 86% of the energy that the Sun provides to Earth. All of the planets are thought to be tidally locked to their star, which means they rotate once per orbit so that one side is constantly bathed in daylight.

A team of scientists led by Joseph Rodriguez, an astronomer at the Center for Astrophysics | Harvard & Smithsonian in Cambridge, Massachusetts, requested follow-up observations with Spitzer to confirm TOI 700 d.

"Given the impact of this discovery -- that it is TESS's first habitable-zone Earth-size planet -- we really wanted our understanding of this system to be as concrete as possible," Rodriguez said. "Spitzer saw TOI 700 d transit exactly when we expected it to. It's a great addition to the legacy of a mission that helped confirm two of the TRAPPIST-1 planets and identify five more."

The Spitzer data increased scientists' confidence that TOI 700 d is a real planet and sharpened their measurements of its orbital period by 56% and its size by 38%. It also ruled out other possible astrophysical causes of the transit signal, such as the presence of a smaller, dimmer companion star in the system.

Rodriguez and his colleagues also used follow-up observations from a 1-meter ground-based telescope in the global Las Cumbres Observatory network to improve scientists' confidence in the orbital period and size of TOI 700 c by 30% and 36%, respectively.

Because TOI 700 is bright, nearby, and shows no sign of stellar flares, the system is a prime candidate for precise mass measurements by current ground-based observatories. These measurements could confirm scientists' estimates that the inner and outer planets are rocky and the middle planet is made of gas.

Future missions may be able to identify whether the planets have atmospheres and, if so, even determine their compositions.

While the exact conditions on TOI 700 d are unknown, scientists can use current information, like the planet's size and the type of star it orbits, to generate computer models and make predictions. Researchers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, modeled 20 potential environments of TOI 700 d to gauge if any version would result in surface temperatures and pressures suitable for habitability.

Their 3D climate models examined a variety of surface types and atmospheric compositions typically associated with what scientists regard to be potentially habitable worlds. Because TOI 700 d is tidally locked to its star, the planet's cloud formations and wind patterns may be strikingly different from Earth's.

One simulation included an ocean-covered TOI 700 d with a dense, carbon-dioxide-dominated atmosphere similar to what scientists suspect surrounded Mars when it was young. The model atmosphere contains a deep layer of clouds on the star-facing side. Another model depicts TOI 700 d as a cloudless, all-land version of modern Earth, wh ere winds flow away from the night side of the planet and converge on the point directly facing the star.

When starlight passes through a planet's atmosphere, it interacts with molecules like carbon dioxide and nitrogen to produce distinct signals, called spectral lines. The modeling team, led by Gabrielle Engelmann-Suissa, a Universities Space Research Association visiting research assistant at Goddard, produced simulated spectra for the 20 modeled versions of TOI 700 d.

"Someday, when we have real spectra from TOI 700 d, we can backtrack, match them to the closest simulated spectrum, and then match that to a model," Engelmann-Suissa said. "It's exciting because no matter what we find out about the planet, it's going to look completely different from what we have here on Earth."

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes and observatories worldwide are participants in the mission.

The Jet Propulsion Laboratory in Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate in Washington. Science operations are conducted at the Spitzer Science Center at Caltech in Pasadena. Space operations are based at Lockheed Martin Space in Littleton, Colorado. Data are archived at the Infrared Science Archive housed at IPAC at Caltech. Caltech manages JPL for NASA.

The modeling work was funded through the Sellers Exoplanet Environments Collaboration at Goddard, a multidisciplinary collaboration that brings together experts to build comprehensive and sophisticated computer models to better analyze current and future exoplanet observations.

Banner image: The three planets of the TOI 700 system orbit a small, cool M dwarf star. TOI 700 d is the first Earth-size habitable-zone world discovered by TESS. Credit: NASA's Goddard Space Flight Center

By Jeanette Kazmierczak
NASA's Goddard Space Flight Center, Greenbelt, Md.​


Last Updated: Jan. 7, 2020
Editor: Rob Garner

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https://nauka.tass.ru/nauka/7475037
Цитата7 ЯНВ, 15:14
Телескоп TESS впервые открыл землеподобную планету у далекой звезды
Планета удалена от Земли на 100 световых лет

ТАСС, 7 января. Американская орбитальная обсерватория TESS при наблюдении за небольшой звездой в созвездии Золотой Рыбки открыла землеподобную планету, потенциально пригодную для жизни, планета удалена от Земли на 100 световых лет. Это первое подобное открытие в истории данного телескопа, сообщила во вторник пресс-служба Центра космических полетов NASA имени Роберта Годдарда (GSFC).

"Обсерватория TESS была запущена в том числе и для поиска землеподобных планет, вращающихся вокруг близлежащих звезд. Поэтому открытие планеты TOI 700d стало одним из важнейших достижений как для этого аппарата, так и для обсерватории "Спитцер", подтвердившей то, что этот мир находится в зоне жизни", - заявил глава астрофизического подразделения NASA Пол Герц (Paul Hertz), чьи слова приводит пресс-служба GSFC.

Как отмечают исследователи, планета TOI 700d в целом похожа на другие землеподобные миры, открытые в последние годы. В частности, она вращается вокруг красного карлика, чьи масса и размеры примерно в два раза меньше, чем у Солнца. За 11 месяцев наблюдений астрономы не зафиксировали ни одной вспышки на поверхности этой звезды, что характерно для других звезд, у которых были найдены похожие миры. Это значительно повышает вероятность существования жизни на ее поверхности.

Помимо TOI 700d, в этой звездной системе присутствуют еще планеты TOI 700b и TOI 700c, чьи орбиты находятся далеко за пределами зоны жизни. Первый мир, обладающий почти земными размерами, находится слишком близко к звезде, а вторая представляет собой небольшой газовый гигант из числа так называемых горячих нептунов.

Как предполагают ученые, по своему климату и условиям на поверхности планета TOI 700d больше напоминает ранний Марс, чем Землю. Ее атмосфера, как показывает предварительный анализ спектра, должна почти полностью состоять из углекислоты, а поверхность этого двойника Земли получает чуть меньше энергии от светила (86%), чем Земля.

Главным препятствием для существования жизни на ее поверхности, по мнению ученых NASA, может быть то, что эта планета всегда "смотрит" одной и той же стороной на звезду. Это может резко повысить температуру на ее освещаемой стороне, а также непредсказуемым образом повлиять на характер движения ветров в атмосфере. Планетологи надеются, что дальнейшие наблюдения за TOI 700d помогут им понять, как эта особенность может влиять на обитаемость подобных миров.

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ЦитатаTESS Satellite Discovered Its 1st World Orbiting 2 Stars

NASA Goddard

6 янв. 2020 г.

Researchers working with data from NASA's Transiting Exoplanet Survey Satellite (TESS) have discovered the mission's first circumbinary planet, a world orbiting two stars. The planet, called TOI 1338b, is around 6.9 times larger than Earth, or between the sizes of Neptune and Saturn. It lies in a system 1,300 light-years away in the constellation Pictor.

The stars in the system make an eclipsing binary, which occurs when the stellar companions circle each other in our plane of view. One is about 10% more massive than our Sun, while the other is cooler, dimmer and only one-third the Sun's mass.

TOI 1338b's transits are irregular, between every 93 and 95 days, and vary in depth and duration thanks to the orbital motion of its stars. TESS only sees the transits crossing the larger star -- the transits of the smaller star are too faint to detect. Although the planet transits irregularly, its orbit is stable for at least the next 10 million years. The orbit's angle to us, however, changes enough that the planet transit will cease after November 2023 and resume eight years later.
https://www.youtube.com/watch?v=8FrlhrtVEW8https://www.youtube.com/embed/8FrlhrtVEW8 (1:32)

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ЦитатаTESS Shows Ancient North Star Has Eclipses

NASA Video

6 янв. 2020 г.

Astronomers using data from NASA's Transiting Exoplanet Survey Satellite (TESS) have shown that Alpha Draconis, a well-studied star visible to the naked eye, and its fainter companion star regularly eclipse each other. While astronomers previously knew this was a binary system, the mutual eclipses came as a complete surprise.
https://www.youtube.com/watch?v=oynnkyDbOPMhttps://www.youtube.com/embed/oynnkyDbOPM (0:29)

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ЦитатаNASA's TESS Delivers New Insights Into an Ultrahot World

 NASA Goddard

30 июн. 2020 г.

Measurements from NASAs Transiting Exoplanet Survey Satellite (TESS) have enabled astronomers to greatly improve their understanding of the bizarre environment of KELT-9 b, one of the hottest planets known. 
 Скрытый текст:
Located about 670 light-years away in the constellation Cygnus, KELT-9 b was discovered in 2017 because the planet passed in front of its star for a part of each orbit, an event called a transit. Transits regularly dim the stars light by a small but detectable amount.
 
Between July 18 and Sept. 11, 2019, as part of the mission's yearlong campaign to observe the northern sky, TESS observed 27 transits of KELT-9 b, and these observations allowed the team to model the systems unusual star and its impact on the planet.
 
KELT-9 b is a gas giant world about 1.8 times bigger than Jupiter, with 2.9 times its mass. Tidal forces have locked its rotation so the same side always faces its star. The planet swings around its star in just 36 hours on an orbit that carries it almost directly above both of the star's poles. 
 
The close orbit means the planet's dayside temperature is around 7,800 degrees Fahrenheit (4,300 C), hotter than the surfaces of some stars. This intense heating also causes the planets atmosphere to stream away into space.
 
Its odd host star is about twice the size of the Sun and averages about 56 percent hotter. But it spins 38 times faster than the Sun, completing a full rotation in just 16 hours. Its rapid spin distorts the stars shape, flattening it at the poles and widening its midsection. This causes the stars poles to heat up and brighten while its equatorial region cools and dims, a phenomenon called gravity darkening. The result is a temperature difference across the stars surface of almost 1,500 F (800 C).
 
With each orbit, KELT-9 b twice experiences the full range of stellar temperatures, producing what amounts to a peculiar seasonal sequence. The planet experiences summer when it swings over each hot pole and winter when it passes over the stars cooler midsection. So KELT-9 b experiences two summers and two winters every year, with each season about nine hours.
 
KELT-9 b begins its transit near the star's bright poles, and then blocks less and less light as it travels over the star's dimmer equator. This asymmetry provides clues to the temperature and brightness changes across the stars surface, and they permitted the team to reconstruct the stars out-of-round shape, how its oriented in space, its range of surface temperatures, and other factors impacting the planet.

youtu.be/bLMIo9Q5mDA

https://www.youtube.com/watch?v=bLMIo9Q5mDA (2:01)

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ЦитатаTESS Completes its Primary Mission

 NASA Goddard

11 авг. 2020 г.

On July 4, NASA's Transiting Exoplanet Survey Satellite (TESS) completed its primary mission, a two-year-long survey that imaged about 75% of the starry sky. In capturing this giant mosaic, TESS has found 66 new exoplanets, or worlds beyond our solar system, as well as nearly 2,100 candidates astronomers are working to confirm.
 Скрытый текст:
TESS monitors 24-by-96-degree strips of the sky, called sectors, for about a month using its four cameras. The mission spent its first year observing 13 sectors comprising the southern sky and then spent another year imaging the northern sky.

Now in its extended mission, TESS has turned around to resume surveying the south. In addition, the TESS team has introduced improvements to the way the satellite collects and processes data. Its cameras now capture a full image every 10 minutes, or three times faster than during the primary mission. The faster measurements will allow TESS to better resolve brightness changes caused by stellar oscillations and to capture explosive flares from active stars in greater detail.

These changes will remain in place for the duration of the extended mission, which will be completed in September 2022. After spending a year imaging the southern sky, TESS will take another 15 months to collect additional observations in the north and to survey areas along the ecliptic – the plane of Earth's orbit around the Sun – that have not yet been imaged by TESS.

TESS looks for transits, the telltale dimming of a star caused when an orbiting planet passes in front of it from our point of view. During its primary mission, TESS also  observed the outburst of a comet in our solar system, as well as numerous exploding stars, and even watched as a black hole in a distant galaxy shredded a Sun-like star.

youtu.be/uOxuTLPAlzI

https://www.youtube.com/watch?v=uOxuTLPAlzI (2:57)

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https://www.nasa.gov/feature/goddard2020/nasa-s-planet-hunter-completes-its-primary-mission

ЦитатаAug. 11, 2020

NASA's Planet Hunter Completes Its Primary Mission

On July 4, NASA's Transiting Exoplanet Survey Satellite (TESS) finished its primary mission, imaging about 75% of the starry sky as part of a two-year-long survey. In capturing this giant mosaic, TESS has found 66 new exoplanets, or worlds beyond our solar system, as well as nearly 2,100 candidates astronomers are working to confirm. 

"TESS is producing a torrent of high-quality observations providing valuable data across a wide range of science topics," said Patricia Boyd, the project scientist for TESS at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "As it enters its extended mission, TESS is already a roaring success."

youtu.be/uOxuTLPAlzI
NASA's Transiting Exoplanet Survey Satellite (TESS) has completed its two-year primary mission and is continuing its search for new worlds. Watch to review some of TESS's most interesting discoveries so far.
Credits: NASA's Goddard Space Flight Center
Download high-resolution video and images from NASA's Scientific Visualization Studio

TESS monitors 24-by-96-degree strips of the sky called sectors for about a month using its four cameras. The mission spent its first year observing 13 sectors comprising the southern sky and then spent another year imaging the northern sky.

Now in its extended mission, TESS has turned around to resume surveying the south. In addition, the TESS team has introduced improvements to the way the satellite collects and processes data. Its cameras now capture a full image every 10 minutes, three times faster than during the primary mission. A new fast mode allows the brightness of thousands of stars to be measured every 20 seconds, along with the previous method of collecting these observations from tens of thousands of stars every two minutes. The faster measurements will allow TESS to better resolve brightness changes caused by stellar oscillations and to capture explosive flares from active stars in greater detail.

These changes will remain in place for the duration of the extended mission, which will be completed in September 2022. After spending a year imaging the southern sky, TESS will take another 15 months to collect additional observations in the north and to survey areas along the ecliptic - the plane of Earth's orbit around the Sun - that the satellite has not yet imaged.

TESS looks for transits, the telltale dimming of a star caused when an orbiting planet passes in front of it from our point of view. Among the mission's newest planetary discoveries are its first Earth-size world, named TOI 700 d, which is located in the habitable zone of its star, the range of distances where conditions could be just right to allow liquid water on the surface. TESS revealed a newly minted planet around the young star AU Microscopii and found a Neptune-size world orbiting two suns.

In addition to its planetary discoveries, TESS has observed the outburst of a comet in our solar system, as well as numerous exploding stars. The satellite discovered surprise eclipses in a well-known binary star system, solved a mystery about a class of pulsating stars, and explored a world experiencing star-modulated seasons. Even more remarkable, TESS watched as a black hole in a distant galaxy shredded a Sun-like star

Missions like TESS help contribute to the field of astrobiology, the interdisciplinary research on the variables and conditions of distant worlds that could harbor life as we know it, and what form that life could take.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center. Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA's Ames Research Center in California's Silicon Valley; the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts; MIT's Lincoln Laboratory; and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

Last Updated: Aug. 11, 2020
Editor: Francis Reddy

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https://tass.ru/kosmos/9176949

Цитата11 АВГ, 19:53
Орбитальная обсерватория TESS успешно завершила основную миссию
Как сообщили в NASA, телескоп открыл несколько десятков ранее неизвестных планет вне Солнечной системы

ТАСС, 11 августа. Орбитальный телескоп TESS решил все задачи, поставленные в рамках основной миссии, получив детальную карту 75% ночного неба и открыв несколько десятков ранее неизвестных планет вне Солнечной системы. Об этом во вторник сообщила пресс-служба Центра космических полетов NASA имени Годдарда (GSFC).

"Наш телескоп уже два года подряд проводит очень качественные наблюдения, получая данные, которые будут интересны многим нашим коллегам, изучающим самые разные научные проблемы. Запуская расширенную миссию TESS, мы уже сейчас можем сказать, что ее основная часть завершилась крайне успешно", - сообщила научный руководитель проекта TESS в Центре космических полетов NASA имени Годдарда Патрисия Бойд, чьи слова приводит пресс-служба GSFC.

Орбитальный телескоп TESS, предназначенный для наблюдений за экзопланетами, был выведен в космос в апреле 2018 года. Он стал заменой для его предшественника, обсерватории Kepler, запущенной в 2009 году и открывшей свыше 4 тыс. экзопланет за восемь лет работы.

В отличие от Kepler, наблюдавшего на первом этапе своей работы за одним участком неба, расположенном на стыке созвездий Лебедя и Лиры, TESS во время основной и расширенной миссии будет работать в "свободном режиме", наблюдая за разными уголками Галактики.

В частности, за первые два года работы он уже успел открыть 66 подтвержденных экзопланет и обнаружить свыше двух тысяч кандидатов на эту роль. Часть из них была найдена в окрестностях очень ярких светил, за которыми в принципе не мог наблюдать Kepler. Как ожидают ученые, ему удастся открыть еще больше объектов во время расширенной миссии, которая завершится в сентябре 2022 года.

В ее рамках он сначала повторно изучит южную половину небесной сферы, а затем попытается впервые обнаружить планеты у звезд, на которые мы смотрим через плоскость Солнечной системы. Эти наблюдения, как надеются астрономы, помогут им найти аналоги Земли у других звезд и понять, как часто на их поверхности возникает жизнь.

Salo

https://nauka.tass.ru/nauka/9293097
Цитата: undefined26 авг, 13:53
Искусственный интеллект подтвердил существование 50 экзопланет
Новый алгоритм машинного обучения может такие объекты гораздо быстрее людей или классических методов обработки информации
ТелескопТелескоп "Кеплер"
© NASA via AP
ТАСС, 26 августа. Британские астрономы разработали алгоритм машинного обучения, который может анализировать снимки с телескопов TESS и "Кеплер" и проверять, действительно ли у далеких звезд существуют экзопланеты. В частности, он уже подтвердил существование 50 экзопланет, проанализировав данные "Кеплера". Результаты их работы опубликовал научный журнал Monthly Notices of the Royal Astronomical Society.
"Благодаря этому алгоритму мы перевели в категорию подтвержденных экзопланет сразу 50 кандидатов. Раньше никто не использовал для этого системы машинного обучения. Теперь мы не просто можем сказать, какой из кандидатов, скорее всего, представляет из себя планету, но и можем точно вычислить вероятность этого", - пояснил один из авторов исследования, планетолог из Уорикского университета (Великобритания) Дэвид Армстронг.
За последние несколько лет астрономы нашли более тысячи экзопланет и несколько тысяч кандидатов на эту роль. Большинство из них относится к так называемым горячим юпитерам - планетам размером с Юпитер, которые при этом находятся на порядок ближе к своей звезде, чем Меркурий к Солнцу. При этом среди экзопланет все чаще встречаются менее крупные планеты, которые по размеру сопоставимы с Землей.
Большую часть известных экзопланет открыл телескоп "Кеплер". На протяжении почти четырех лет он непрерывно следил за сотнями тысяч звезд, которые находятся на границе созвездий Лебедя и Лиры. Если на его снимках было видно, что у какой-то звезды периодически снижается яркость, то это могло быть знаком, что ее время от времени "загораживала" от телескопа вращающаяся вокруг светила планета. Такое явление астрономы называют прохождением или транзитом.
Впрочем, причиной этого могут быть и другие явления, в том числе процессы внутри самих светил. Как правило, длительные наблюдения позволяют отделить одно от другого, однако для этого нужно очень долго и кропотливо сравнивать изображения и анализировать все доступные научные данные об активности звезды.

Подсказки искусственного разума

Британские ученые разработали алгоритм машинного обучения, который может решить эту задачу быстрее и качественнее человека или классических статистических методов анализа информации. Он представляет собой многослойную нейросеть, которая может отыскивать скрытые закономерности в серии снимков звезд.
Для тренировки этого искусственного интеллекта ученые использовали набор данных, которые "Кеплер" собрал при открытии уже подтвержденных экзопланет, а также объектов, существование которых впоследствии не подтвердилось. Всего для обучения через искусственный интеллект прогнали более 30 тыс. транзитов.
Работу алгоритма ученые проверили на нескольких сотнях еще не подтвержденных планет из каталога "Кеплера". Алгоритм выделил 50 объектов, которые с вероятностью более чем 99% представляют из себя экзопланеты. Впоследствии астрономы подтвердили это с помощью других методов анализа данных.
Исследователи считают, что их разработку можно использовать для автоматизированного и очень быстрого поиска новых экзопланет. Алгоритм может анализировать данные с TESS и других телескопов в режиме реального времени. В частности, Армстронг и его коллеги надеются, что их методику используют в работе строящейся европейской космической обсерватории PLATO, запуск которой намечен на 2026 год.
"Были когда-то и мы рысаками!!!"

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ЦитатаTESS, Spitzer Spot Potential Giant World Circling Tiny Star

 NASA Goddard

16 сент. 2020 г.

youtu.be/fDhG0ppvQ2g

https://www.youtube.com/watch?v=fDhG0ppvQ2g (2:10)

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https://www.nasa.gov/press-release/nasa-missions-spy-first-possible-survivor-planet-hugging-white-dwarf-star

ЦитатаSept. 16, 2020
RELEASE 20-086

NASA Missions Spy First Possible 'Survivor' Planet Hugging White Dwarf Star


In this illustration, WD 1856 b, a potential Jupiter-size planet, orbits its much smaller host star, a dim white dwarf.
Credits: NASA's Goddard Space Flight Center

An international team of astronomers using NASA's Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope has reported what may be the first intact planet found closely orbiting a white dwarf, the dense leftover of a Sun-like star, only 40% larger than Earth.

The Jupiter-size object, called WD 1856 b, is about seven times larger than the white dwarf, named WD 1856+534. It circles this stellar cinder every 34 hours, more than 60 times faster than Mercury orbits our Sun.

"WD 1856 b somehow got very close to its white dwarf and managed to stay in one piece," said Andrew Vanderburg, an assistant professor of astronomy at the University of Wisconsin-Madison. "The white dwarf creation process destroys nearby planets, and anything that later gets too close is usually torn apart by the star's immense gravity. We still have many questions about how WD 1856 b arrived at its current location without meeting one of those fates."

A paper about the system, led by Vanderburg and including several NASA co-authors, appears in the Sept. 17 issue of Nature and is now available online.

TESS monitors large swaths of the sky, called sectors, for nearly a month at a time. This long gaze allows the satellite to find exoplanets, or worlds beyond our solar system, by capturing changes in stellar brightness caused when a planet crosses in front of, or transits, its star.

The satellite spotted WD 1856 b about 80 light-years away in the northern constellation Draco. It orbits a cool, quiet white dwarf that is roughly 11,000 miles (18,000 kilometers) across, may be up to 10 billion years old, and is a distant member of a triple star system.

When a Sun-like star runs out of fuel, it swells up to hundreds to thousands of times its original size, forming a cooler red giant star. Eventually, it ejects its outer layers of gas, losing up to 80% of its mass. The remaining hot core becomes a white dwarf. Any nearby objects are typically engulfed and incinerated during this process, which in this system would have included WD 1856 b in its current orbit. Vanderburg and his colleagues estimate the possible planet must have originated at least 50 times farther away from its present location.

youtu.be/fDhG0ppvQ2g
Watch to learn how a possible giant planet may have survived its tiny star's chaotic history. Jupiter-size WD 1856 b is nearly seven times larger than the white dwarf it orbits every day and a half. Astronomers discovered it using data from NASA's Transiting Exoplanet Survey Satellite (TESS) and now-retired Spitzer Space Telescope.
Credits: NASA/JPL-Caltech/Goddard Space Flight Center

"We've known for a long time that after white dwarfs are born, distant small objects such as asteroids and comets can scatter inward towards these stars. They're usually pulled apart by a white dwarf's strong gravity and turn into a debris disk," said co-author Siyi Xu, an assistant astronomer at the international Gemini Observatory in Hilo, Hawaii, which is a program of the National Science Foundation's NOIRLab. "That's why I was so excited when Andrew told me about this system. We've seen hints that planets could scatter inward, too, but this appears to be the first time we've seen a planet that made the whole journey intact."

The team suggests several scenarios that could have nudged WD 1856 b onto an elliptical path around the white dwarf. This trajectory would have become more circular over time as the star's gravity stretched the object, creating enormous tides that dissipated its orbital energy.

"The most likely case involves several other Jupiter-size bodies close to WD 1856 b's original orbit," said co-author Juliette Becker, a 51 Pegasi b Fellow in planetary science at Caltech (California Institute of Technology) in Pasadena. "The gravitational influence of objects that big could easily allow for the instability you'd need to knock a planet inward. But at this point, we still have more theories than data points."

Other possible scenarios involve the gradual gravitational tug of the two other stars in the system, red dwarfs G229-20 A and B, over billions of years and a flyby from a rogue star perturbing the system. Vanderburg's team thinks these and other explanations are less likely because they require finely tuned conditions to achieve the same effects as the potential giant companion planets.

Jupiter-size objects can occupy a huge range of masses, from planets only a few times more massive than Earth to low-mass stars thousands of times Earth's mass. Others are brown dwarfs, which straddle the line between planet and star. Usually scientists turn to radial velocity observations to measure an object's mass, which can hint at its composition and nature. This method works by studying how an orbiting object tugs on its star and alters the color of its light. But in this case, the white dwarf is so old that its light has become both too faint and too featureless for scientists to detect noticeable changes.

Instead, the team observed the system in the infrared using Spitzer, just a few months before the telescope was decommissioned. If WD 1856 b were a brown dwarf or low-mass star, it would emit its own infrared glow. This means Spitzer would record a brighter transit than it would if the object was a planet, which would block rather than emit light. When the researchers compared the Spitzer data to visible light transit observations taken with the Gran Telescopio Canarias in Spain's Canary Islands, they saw no discernible difference. That, combined with the age of the star and other information about the system, led them to conclude that WD 1856 b is most likely a planet no more than 14 times Jupiter's size. Future research and observations may be able to confirm this conclusion.

Finding a possible world closely orbiting a white dwarf prompted co-author Lisa Kaltenegger, Vanderburg, and others to consider the implications for studying atmospheres of small rocky worlds in similar situations. For example, suppose that an Earth-size planet were located within the range of orbital distances around WD 1856 where water could exist on its surface. Using simulated observations, the researchers show that NASA's upcoming James Webb Space Telescope could detect water and carbon dioxide on the hypothetical world by observing just five transits.

The results of these calculations, led by Kaltenegger and Ryan MacDonald, both at Cornell University in Ithaca, New York, have been published in The Astrophysical Journal Letters and are available online.

"Even more impressively, Webb could detect gas combinations potentially indicating biological activity on such a world in as few as 25 transits," said Kaltenegger, the director of Cornell's Carl Sagan Institute. "WD 1856 b suggests planets may survive white dwarfs' chaotic histories. In the right conditions, those worlds could maintain conditions favorable for life longer than the time scale predicted for Earth. Now we can explore many new intriguing possibilities for worlds orbiting these dead stellar cores."

There is currently no evidence suggesting there are other worlds in the system, but it's possible additional planets exist and haven't been detected yet. They could have orbits that exceed the time TESS observes a sector or are tipped in a way such that transits don't occur. The white dwarf is also so small that the possibility of catching transits from planets farther out in the system is very low.

TESS is a NASA Astrophysics Explorer mission led and operated by MIT in Cambridge, Massachusetts, and managed by NASA's Goddard Space Flight Center in Greenbelt, Maryland. Additional partners include Northrop Grumman, based in Falls Church, Virginia, NASA's Ames Research Center in California's Silicon Valley, the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, MIT's Lincoln Laboratory, and the Space Telescope Science Institute in Baltimore. More than a dozen universities, research institutes, and observatories worldwide are participants in the mission.

NASA's Jet Propulsion Laboratory (JPL) in Southern California managed the Spitzer mission for the agency's Science Mission Directorate in Washington. Spitzer science data continue to be analyzed by the science community via the Spitzer data archive, located at the Infrared Science Archive housed at the Infrared Processing and Analysis Center (IPAC) at Caltech. Science operations were conducted at the Spitzer Science Center at Caltech. Spacecraft operations were based at Lockheed Martin Space in Littleton, Colorado. Caltech manages JPL for NASA.

-end-

Last Updated: Sept. 16, 2020
Editor: Sean Potter

tnt22

ЦитатаTESS's Northern Sky Vista

 NASA Goddard

5 окт. 2020 г.

Familiar stars shine, nebulae glow, and nearby galaxies tantalize in a new panorama of the northern sky assembled from 208 images from NASA's Transiting Exoplanet Survey Satellite (TESS).

Within this starry scene, TESS has discovered 67 new exoplanets. Astronomers are sifting through some 1,200 additional exoplanet candidates, potential new worlds that await confirmation. More than 600 of these candidates lie in the northern sky.

The northern mosaic covers less of the sky than its southern counterpart, which was imaged during the mission's first year of operations. For about half of the northern sectors, the team decided to angle the cameras further north to minimize the impact of scattered light from Earth and the Moon. This results in an obvious gap along the mosaic's outer edge.

TESS has now begun its extended mission, during which it will spend another year imaging the southern sky. The satellite will revisit planets discovered in its first year, discover new worlds, and fill in coverage gaps from its initial survey. Improvements to the satellite's data collection and processing now allow TESS to return full sector images every 10 minutes and measure the brightness of thousands of stars every 20 seconds - all while continuing its previous strategy of measuring the brightness of tens of thousands of stars every two minutes.

youtu.be/aKSvBJz_CdU

https://www.youtube.com/watch?v=aKSvBJz_CdU (3:58)

Salo

https://nauka.tass.ru/nauka/12236061

Цитата27 авг, 16:40
Телескоп TESS засек пять необычных коричневых карликов. Они в 70-90 раз тяжелее Юпитера
Благодаря этому ученые узнали, что по мере старения коричневые карлики постепенно сжимаются

Орбитальный телескоп TESS  NASA via APОрбитальный телескоп TESS
© NASA via AP

ТАСС, 27 августа. С помощью орбитального телескопа TESS ученые обнаружили пять объектов, занимающих положение между полноценными звездами и коричневыми карликами. Их изучение поможет определить минимальную массу светил, считают ученые. Результаты исследования опубликовал научный журнал Astronomy & Astrophysics.

"Мы до сих пор не знаем точного предела массы, который отделяет коричневые карлики от самых небольших звезд, которые могут сжигать водород на протяжении многих миллиардов лет. Чтобы ее определить, нам нужно будет найти еще много других крупных коричневых карликов, кроме этих пяти объектов", - объяснил один из авторов исследования, научный сотрудник Женевского университета (Швейцария) Нолан Гривс.
Коричневыми карликами астрономы называют несостоявшиеся звезды, которые слабо светятся в инфракрасном диапазоне и постепенно гаснут по мере охлаждения их недр. Они возникают, если ядро протозвезды, которая формируется в облаке из газа и пыли, не более чем в 70-100 раз тяжелее массы Юпитера. Точное положение границы между звездами и коричневыми карликами пока не известно.
Гривс и его коллеги приблизились к ее определению. В ходе нового исследования они анализировали снимки орбитального телескопа TESS. Он предназначен для поиска экзопланет в окрестностях звезд размером с Солнце, но при этом достаточно чувствителен, чтобы изучать и открывать коричневые карлики.

Крупнейшие неудавшиеся звезды

Ученые обратили внимание, что коричневых карликов можно искать в окрестностях других звезд так же, как TESS ищет экзопланеты. Он отслеживает периодические колебания яркости светила, которые возникают из-за того, что тусклые или не светящиеся объекты проходят между телескопом и звездой.
Руководствуясь подобными соображениями, астрономы проанализировали данные TESS и попытались найти в них следы необычно крупных объектов массой больше самых крупных известных экзопланет. Необычно большими коричневыми карликами оказались сразу пять из них. Их масса, предположительно, превышает юпитерианскую в 70-90 раз.
Их изучение помогло Гривсу и его коллегам узнать одну необычную черту подобных крупных коричневых карликов. Эти "неудавшиеся звезды" по мере старения сжимаются. Это связано с тем, что изначально в их центре происходят термоядерные реакции с участием дейтерия, однако порождаемых ими температур не хватает для запуска аналогичных процессов с участием обычного водорода.
В результате коричневый карлик начинает быстро остывать и уменьшаться в размерах после того, как запасы дейтерия в его недрах подходят к концу. Эту особенность крупных и пожилых коричневых карликов следует учитывать при дальнейших поисках этих объектов и оценке их возраста, подытожили астрономы.
"Были когда-то и мы рысаками!!!"