Autor Wątek: Egzoplanety - badania różne (zbiorczo)  (Przeczytany 20678 razy)

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Offline kanarkusmaximus

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #135 dnia: Lipiec 30, 2017, 19:54 »
Słowo kluczowe w tym przypadku to "kandydat". :)

Offline kanarkusmaximus

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #136 dnia: Lipiec 30, 2017, 23:22 »
Do tej listy co Orionid dał proponuję jeszcze ten artykuł:

Warunki pogodowe i życie na egzoksiężycach – podstawowe założenia

http://kosmonauta.net/2013/03/2013-03-22-exoksiezyce/

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #137 dnia: Lipiec 31, 2017, 17:49 »
Kepler-1625b I – kandydat na egzoksiężyc
BY KRZYSZTOF KANAWKA ON 31 LIPCA 2017

(...) U egzoplanety Kepler 1625b (duży gazowy gigant, o masie około 8 razy większej od Jowisza) wykryto kandydata na księżyc. Może to być bardzo duży egzoksiężyc, być może nawet wielkości Neptuna. Krążyłby on wokół Keplera 1625b w odległości około 350 tysięcy kilometrów. Egzoksiężyc otrzymał oznaczenie Kepler-1625b I.

Dalsze obserwacje układu Kepler 1625 zostaną wykonane m.in przy użyciu kosmicznego teleskopu Hubble (HST). Te obserwacje są zaplanowane na październik tego roku. Wówczas przewidywany jest kolejny tranzyt Keplera 1625b na tle swojej gwiazdy.


Zarejestrowane tranzyty Keplera 1625b / Credits – Teachey et al.

Odkrycie pierwszego egzoksiężyca będzie z pewnością dużym krokiem w rozwoju współczesnej astronomii. (...)

http://kosmonauta.net/2017/07/kepler-1625b-i-kandydat-na-egzoksiezyc/

Offline kanarkusmaximus

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #138 dnia: Lipiec 31, 2017, 23:28 »
Rozumiem, że HST zostanie w obserwacjach Keplera-1625 wykorzystany niczym teleskop Kepler? Ciekawe o ile większa będzie czułość HST w tym przypadku. :)

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #139 dnia: Sierpień 05, 2017, 13:43 »
Wokół gorącego Jowisza WASP-121b przy pomocy HST wykryto stratosferę.

Reporting in the journal Nature, scientists used data from NASA's Hubble Space Telescope to study WASP-121b, a type of exoplanet called a "hot Jupiter." Its mass is 1.2 times that of Jupiter, and its radius is about 1.9 times Jupiter's -- making it puffier. But while Jupiter revolves around our sun once every 12 years, WASP-121b has an orbital period of just 1.3 days. This exoplanet is so close to its star that if it got any closer, the star's gravity would start ripping it apart. It also means that the top of the planet's atmosphere is heated to a blazing 4,600 degrees Fahrenheit (2,500 Celsius), hot enough to boil some metals. The WASP-121 system is estimated to be about 900 light years from Earth - a long way, but close by galactic standards.

https://www.jpl.nasa.gov/news/news.php?feature=6909
http://www.exeter.ac.uk/news/featurednews/title_598443_en.html
http://www.pulskosmosu.pl/2017/08/02/hubble-wykrywa-egzoplanete-ze-swiecaca-wodna-atmosfera/

<a href="http://www.youtube.com/watch?v=fyMd-CJJqoo" target="_blank">http://www.youtube.com/watch?v=fyMd-CJJqoo</a>

Link do materiału: https://www.youtube.com/watch?v=fyMd-CJJqoo
« Ostatnia zmiana: Sierpień 05, 2017, 13:50 wysłana przez Orionid »

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #140 dnia: Wrzesień 02, 2017, 18:14 »
Planety skaliste  obiegające czerwone karły w potencjalnych ekosferach mogą otrzymywać za mało promieniowania ultrafioletowego , by możliwe było zainicjowanie na nich procesów życiowych.

Ultraviolet light may be ultra important in search for life
August 31, 2017

Using computer models and the known properties of red dwarfs, the authors estimate that the surface of rocky planets in the potentially habitable zones around red dwarfs would experience 100 to 1,000 times less of the ultraviolet light that may be important to the emergence of life than the young Earth would have. Chemistry that depends on UV light might shut down at such low levels, and even if it does proceed, it could operate at a much slower rate than on the young Earth, possibly delaying the advent of life. (...)

Previous studies have shown that the red dwarf stars in systems such as TRAPPIST-1 may erupt with dramatic flares in UV. If the flares deliver too much energy, they might severely damage the atmosphere and harm life on surrounding planets. On the other hand, these UV flares may provide enough energy to compensate for the lower levels of UV light steadily produced by the star.


https://phys.org/news/2017-08-ultraviolet-ultra-important-life.html
http://www.pulskosmosu.pl/2017/09/01/promieniowanie-uv-niezbedne-do-powstania-zycia/
dublet: https://www.cfa.harvard.edu/news/2017-27

<a href="http://www.youtube.com/watch?v=OK9vcDd9mgk" target="_blank">http://www.youtube.com/watch?v=OK9vcDd9mgk</a>

Link do materiału: https://www.youtube.com/watch?v=OK9vcDd9mgk

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #141 dnia: Wrzesień 15, 2017, 07:23 »
Skąd widać tranzyty Ziemi?
BY KRZYSZTOF KANAWKA ON 14 WRZEŚNIA 2017

(...) Co więcej, astronomom udało się ustalić, że z 68 znanych dziś egzoplanet da się zaobserwować tranzyty przynajmniej jednej planety w naszym Układzie Słonecznym. Dziewięć z tych egzoplanet jest idealnie umiejscowiona, aby obserwować z nich tranzyty Ziemi. Żadna z nich nie krąży blisko ekosfery swoich gwiazd, co oznacza, że szanse na powstanie i utrzymanie się życia na nich są praktycznie zerowe. Wśród nich jak na razie najciekawszym obiektem jest EPIC211913977 b – egzoplaneta, która może być albo super-Ziemią albo mini-Neptunem. (...)

http://kosmonauta.net/2017/09/skad-widac-tranzyty-ziemi/

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #142 dnia: Wrzesień 19, 2017, 13:44 »
Pierwsze wykrycie tlenku tytanu na egzoplanecie.
Gorący Jowisz WASP-19b obiega  gwiazdę macierzystą w 19 godzin.
Temperatura jego atmosfery szacowana jest na 2000 stopni Celsjusza.
Większe stężenie tlenku tytanu w atmosferze blokuje ucieczkę ciepła w przestrzeń kosmiczną.

ESO’s VLT makes first detection of titanium oxide in an exoplanet
13 September 2017

(...) Titanium oxide is rarely seen on Earth. It is known to exist in the atmospheres of cool stars. In the atmospheres of hot planets like WASP-19b, it acts as a heat absorber. If present in large enough quantities, these molecules prevent heat from entering or escaping through the atmosphere, leading to a thermal inversion — the temperature is higher in the upper atmosphere and lower further down, the opposite of the normal situation. Ozone plays a similar role in Earth’s atmosphere, where it causes inversion in the stratosphere.

“The presence of titanium oxide in the atmosphere of WASP-19b can have substantial effects on the atmospheric temperature structure and circulation.” explains Ryan MacDonald, another team member and an astronomer at Cambridge University, United Kingdom. “To be able to examine exoplanets at this level of detail is promising and very exciting.” adds Nikku Madhusudhan from Cambridge University who oversaw the theoretical interpretation of the observations. (...)


https://www.eso.org/public/news/eso1729/

Offline Orionid

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #143 dnia: Październik 13, 2017, 01:37 »
Giant Exoplanet Hunters: Look for Debris Disks
OCTOBER 11, 2017

(...) A new study finds that giant exoplanets that orbit far from their stars are more likely to be found around young stars that have a disk of dust and debris than those without disks. The study, published in The Astronomical Journal, focused on planets more than five times the mass of Jupiter. This study is the largest to date of stars with dusty debris disks, and has found the best evidence yet that giant planets are responsible for keeping that material in check.

"Our research is important for how future missions will plan which stars to observe," said Tiffany Meshkat, lead author and assistant research scientist at IPAC/Caltech in Pasadena, California. Meshkat worked on this study as a postdoctoral researcher at NASA's Jet Propulsion Laboratory in Pasadena. "Many planets that have been found through direct imaging have been in systems that had debris disks, and now we know the dust could be indicators of undiscovered worlds." (...)

https://www.jpl.nasa.gov/news/news.php?feature=6970

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #144 dnia: Wczoraj o 19:46 »
Nowy model badania warunków występowania wody na egzoplanetach powinien zaowocować większą ilością takich, na których mogą  istnieć potencjalne warunki sprzyjające życiu.

New NASA Study Improves Search for Habitable Worlds
Oct. 19, 2017 Bill Steigerwald

New NASA research is helping to refine our understanding of candidate planets beyond our solar system that might support life.

“Using a model that more realistically simulates atmospheric conditions, we discovered a new process that controls the habitability of exoplanets and will guide us in identifying candidates for further study,” said Yuka Fujii of NASA’s Goddard Institute for Space Studies (GISS), New York, New York and the Earth-Life Science Institute at the Tokyo Institute of Technology, Japan, lead author of a paper on the research published in the Astrophysical Journal Oct. 17.

Previous models simulated atmospheric conditions along one dimension, the vertical. Like some other recent habitability studies, the new research used a model that calculates conditions in all three dimensions, allowing the team to simulate the circulation of the atmosphere and the special features of that circulation, which one-dimensional models cannot do. The new work will help astronomers allocate scarce observing time to the most promising candidates for habitability.

Liquid water is necessary for life as we know it, so the surface of an alien world (e.g. an exoplanet) is considered potentially habitable if its temperature allows liquid water to be present for sufficient time (billions of years) to allow life to thrive. If the exoplanet is too far from its parent star, it will be too cold, and its oceans will freeze. If the exoplanet is too close, light from the star will be too intense, and its oceans will eventually evaporate and be lost to space. This happens when water vapor rises to a layer in the upper atmosphere called the stratosphere and gets broken into its elemental components (hydrogen and oxygen) by ultraviolet light from the star. The extremely light hydrogen atoms can then escape to space. Planets in the process of losing their oceans this way are said to have entered a “moist greenhouse” state because of their humid stratospheres.

In order for water vapor to rise to the stratosphere, previous models predicted that long-term surface temperatures had to be greater than anything experienced on Earth – over 150 degrees Fahrenheit (66 degrees Celsius). These temperatures would power intense convective storms; however, it turns out that these storms aren’t the reason water reaches the stratosphere for slowly rotating planets entering a moist greenhouse state.

“We found an important role for the type of radiation a star emits and the effect it has on the atmospheric circulation of an exoplanet in making the moist greenhouse state,” said Fujii. For exoplanets orbiting close to their parent stars, a star’s gravity will be strong enough to slow a planet’s rotation. This may cause it to become tidally locked, with one side always facing the star – giving it eternal day – and one side always facing away –giving it eternal night.

When this happens, thick clouds form on the dayside of the planet and act like a sun umbrella to shield the surface from much of the starlight. While this could keep the planet cool and prevent water vapor from rising, the team found that the amount of near-Infrared radiation (NIR) from a star could provide the heat needed to cause a planet to enter the moist greenhouse state. NIR is a type of light invisible to the human eye. Water as vapor in air and water droplets or ice crystals in clouds strongly absorbs NIR light, warming the air. As the air warms, it rises, carrying the water up into the stratosphere where it creates the moist greenhouse.

This process is especially relevant for planets around low-mass stars that are cooler and much dimmer than the Sun. To be habitable, planets must be much closer to these stars than our Earth is to the Sun. At such close range, these planets likely experience strong tides from their star, making them rotate slowly. Also, the cooler a star is, the more NIR it emits. The new model demonstrated that since these stars emit the bulk of their light at NIR wavelengths, a moist greenhouse state will result even in conditions comparable to or somewhat warmer than Earth's tropics. For exoplanets closer to their stars, the team found that the NIR-driven process increased moisture in the stratosphere gradually. So, it’s possible, contrary to old model predictions, that an exoplanet closer to its parent star could remain habitable.

This is an important observation for astronomers searching for habitable worlds, since low-mass stars are the most common in the galaxy. Their sheer numbers increase the odds that a habitable world may be found among them, and their small size increases the chance to detect planetary signals.

The new work will help astronomers screen the most promising candidates in the search for planets that could support life. “As long as we know the temperature of the star, we can estimate whether planets close to their stars have the potential to be in the moist greenhouse state,” said Anthony Del Genio of GISS, a co-author of the paper. “Current technology will be pushed to the limit to detect small amounts of water vapor in an exoplanet’s atmosphere. If there is enough water to be detected, it probably means that planet is in the moist greenhouse state.”

In this study, researchers assumed a planet with an atmosphere like Earth, but entirely covered by oceans. These assumptions allowed the team to clearly see how changing the orbital distance and type of stellar radiation affected the amount of water vapor in the stratosphere. In the future, the team plans to vary planetary characteristics such as gravity, size, atmospheric composition, and surface pressure to see how they affect water vapor circulation and habitability.


This is a plot of what the sea ice distribution could look like on a synchronously rotating ocean world. The star is off to the right, blue is where there is open ocean, and white is where there is sea ice.
Credits: Anthony Del Genio/GISS/NASA


The research was funded by the NASA Astrobiology Program through the Nexus for Exoplanet System Science; the NASA Postdoctoral Program, administered by Oak Ridge Affiliated Universities, Oak Ridge, Tennessee, and Universities Space Research Association, Columbia, Maryland; and a Grant-in-Aid from the Japan Society for the Promotion of Science, Tokyo, Japan (No.15K17605).

https://www.nasa.gov/feature/goddard/2017/nasa-improves-search-for-habitable-worlds

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Odp: Egzoplanety - badania różne (zbiorczo)
« Odpowiedź #145 dnia: Dzisiaj o 08:55 »
Wokół HD 32297 w odległościach 75 - 200 AU z milionów komet mogą się tworzyć zalążki planet , które w przyszłości rozmiarowo mają przypominać Urana czy Neptuna .

Scientist Sees Evidence of Planetary Formation in Narrow Rings of Other Solar Systems
By Amit Malewar - October 21, 2017

Instead of finding a planet built from one big "construction site," researchers are observing planets rising from many small construction sites, which will eventually merge their work into the final product.(...)

In Fomalhaut and HD 32297, researchers expect that millions of comets are contributing to form the cores of ice giant planets like Uranus and Neptune—although without the thick atmospheres enveloping the cores of Uranus and Neptune, since the primordial gas disks that would form such atmospheres are gone. In HR 4796A, with its warmer dust ring, even the ices normally found in the rings' comets evaporated over the last million years or so, leaving behind core building blocks that are rich only in leftover carbon and rocky materials.

"These systems appear to be building planets we don't see in our solar system—large multi-Earth mass ones with variable amounts of ice, rock and refractory organics," Lisse said. "This is very much like the predicted recipe for the super-Earths seen in abundance in the Kepler planet survey."

"Much still has to happen, though, before these rings could become planets the size of the gas giants," he continued. "Why it's taking so long to make outer planets in these systems—after their primordial gas disks have been stripped away—is a big mystery."

https://www.techexplorist.com/scientist-sees-evidence-planetary-formation-narrow-rings-solar-systems/

<a href="http://www.youtube.com/watch?v=cgVuBD2XM_w" target="_blank">http://www.youtube.com/watch?v=cgVuBD2XM_w</a>
https://www.youtube.com/watch?v=cgVuBD2XM_w