Computer simulations conducted by Japanese scientists provide convincing evidence for the existence of a liquid subsurface ocean on Pluto and similar worlds, and suggests that there are many more exoplanets and exomoons in the Universe, under the icy shells of which the environment can potentially live.
Our work showed that if there is an insulating layer of gas hydrates on Pluto between the subsurface ocean and the ice shell, it protects the ocean from freezing, and the water in it can remain liquid for billions of years.
In July 2015, the NASA spacecraft New Horizons made a historic flight through the Pluto system, providing the world’s first images of this distant dwarf planet and its satellites. In these photographs, Pluto appeared unexpectedly as a living world with interesting landscapes and surface features, among which the ellipsoidal snow-white Sputnik Planitia plain stands out, located near the equator and having a diameter of almost 1.5 kilometers.
Because of its location and topography, scientists believe that under the ice shell of Pluto, which is thinning in Sputnik Planitia, there is an underground ocean. However, these observations contradict the age of the dwarf planet, because any ocean on it had to freeze for a long time, and the inner surface of the ice shell, facing the ocean, evened out.
To resolve the inconsistency of models and observations, the researchers tried to find out what could keep warm in the subsurface ocean and not flatten the inner surface of the ice shell, leaving it frozen and uneven.
We hypothesized that there is an“ insulating layer ”of gas hydrates under the ice surface of Sputnik Planitia. Gas hydrates are crystalline, ice-like solids that are formed from water and gas under certain conditions. They have high viscosity, low thermal conductivity and can provide insulating properties.
In order to test their assumption, scientists conducted a computer simulation covering 4.6 billion years of the evolution of Pluto since the inception of the solar system, considering two scenarios: the first, where an insulating layer of gas hydrates existed between the ocean and the ice shell, and the second without it. The simulation revealed the thermal and structural evolution of the depths of the dwarf planet and the time required for freezing the hidden ocean and for the formation of a homogeneous thick ice shell.
Modeling showed that without an insulating layer the ocean would completely freeze hundreds of millions of years ago, while it would take only one million years to form a uniform thick ice crust. However, when the gas hydrates layer was included in the simulation, the ocean did not freeze at all, and a billion years were spent on the formation of an even layer.
-Shunichi Kamata, lead author of the study from Hokkaido University
The team believes that the most likely gas in the proposed insulating layer is methane, which originates from the stone core of Pluto. This theory, according to which methane is captured as a gas hydrate, is consistent with the unusual composition of the atmosphere of a dwarf planet, which is almost devoid of methane and rich in nitrogen.
Our results may mean that there are many more worlds with oceans in the Universe than previously thought. This makes the existence of extraterrestrial life more likely.
The conditions for liquid ocean existence on Pluto and similar worlds Click To Tweet
The Hubble space telescope took a fresh look at the impressive galaxy NGC 4485, which was twisted and tightened by its larger neighbor. Gravity of the second galaxy disrupted an orderly set of stars, gas and dust, giving rise to a disorderly region of newborns and hot blue giants, chaotic clusters and streams.
Galaxy NGC 4485 was involved in a dramatic gravitational interaction with the large galactic neighbor NGC 4490. Discovered at a distance of about 30 million light years from Earth in the direction of the Hounds Dog constellation, the strange result of the interaction of the galactic duet led to the appearance of the object Arp 269 in the Atlas of peculiar galaxies.
Leaving behind their closest approach, NGC 4485 and NGC 4490 are now moving apart, significantly different from the original structures. Still involved in a destructive, but artistic dance, the gravitational force between them continues to distort each of the participants beyond recognition, while at the same time creating conditions for huge areas of intense star formation.
Galactic tug-of-war created a stream of material about 25,000 light-years long that connects two galaxies. The stream consists of bright knots and huge gas pockets, as well as impressive star-forming areas where young massive blue stars are born. However, these short-lived stars are quickly depleted and end their lives with dramatic explosions, which in turn enrich the space environment with heavier elements and release material for the formation of a new generation of stars.
There are two completely different areas in NGC 4485 today: hints on the original spiral structure of the galaxy on the left, and a part torn out of the spiral in the direction of its larger neighbor and overflowing with hot blue stars and streams of dust and gas.
Small, strong planets are more likely to survive the death of a parent star.
Astrophysicists modeled the probability of destruction of various planets by tidal forces when their stars become white dwarfs, and identified the most significant factors by which they can avoid death. The resulting survival guide of exoplanets will help detect potential worlds around dead stars, for which a new generation of powerful telescopes is being developed.
Modeling the effect of star gravity changes on rotating rocky bodies, the researchers identified the most likely factors that would cause the planet to be within the radius of destruction, where an object held only by its own gravity disintegrates due to tidal forces, dolphin this area with its fragments.
Although the survival of the planet depends on many factors, models show that the more massive it is, the higher the likelihood of its death from tidal interaction.
But destruction also depends in part on viscosity, measures of resistance to deformation: low-viscosity exo-earths are easily attracted by a white dwarf, even if they are at a distance of five times the radius of destruction.
Exotic earths with high viscosity are easily swallowed only if they are closer than two radii of destruction. Such planets should consist entirely of heavier elements, such as the planetesimal in orbit of a white dwarf SDSS J122859.93 + 104032.9, previously discovered by another group of astronomers from the University of Warwick, who avoided absorption only by their small size.
Our study, although sophisticated in some respects, concerns only homogeneous stony planets. A multi-layered planet such as Earth is much more difficult to compute, but we are exploring the possibility of doing this.
-Dr. Dimitri Veras from the University of Warwick
The distance from the star, like the mass of the planet, has a strong correlation with survival or absorption. The safe distance depends on many parameters. In general, a small rocky homogeneous planet, which is three times closer to a white dwarf than Mercury to the Sun, is guaranteed not to be destroyed by tidal forces.
Thousands of young faults found on images taken by NASA’s Lunar Reconnaissance Orbiter (LRO) spacecraft camera indicate the recent tectonic activity of the Moon, but the extent of these faults was not clear. In addition, seismometers placed by American astronauts in the framework of the Appolon program also recorded minor lunar earthquakes, the source of which was also not known.
However, now the Apollo seismic data analysis has linked some “moonquakes” to recent faults. This indicates that the Moon, like the Earth, is tectonically active.
This is a strong testimony to the importance of the Apollo program, because seismic data collected more than 40 years ago helps confirm that the modern moon is tectonically active. The relationship between the location and time of shallow moonquakes and well-known young faults is further evidence that our satellite is a dynamic world.
-Thomas Watters, senior fellow at the Smithsonian Institution (USA), the lead author of the study
The astronauts of the Apollo 11, 12, 14, 15 and 16 missions installed seismometers on the moon — instruments that measured the shaking of the lunar crust. Four seismometers operated from 1969 to 1977 and recorded 28 small shocks. In order to accurately determine the location of vibrations, a mathematical model was developed, and the analysis provided provided the best estimate.
Using revised estimates of moonquake sites, the team found that 8 out of 28 crust tremors occurred within 30 kilometers of faults. This is close enough to associate vibrations with cracks in the crust, since modeling taking into account the size of the faults shows that a strong seismic crust is expected at this distance.
We believe that the eight moonquakes were caused by cracks in the crust caused by the accumulation of stress, when the lunar crust was compressed and stretched by tidal forces. This indicates that the Moon is still tectonically active.
M 42 or the Orion Nebula is a complex region of active star formation, where some hot and young stars merge together. Consisting of glowing gas and dust, the nebula is part of a much larger area — the Orion Cloud, which also includes the Horsehead Nebula, located south of Orion, the easternmost star in the Orion belt.
The red glow in the Orion Nebula is due to ionized hydrogen. Located deep in the trapezium nebula is a dense group of the four brightest stars of the Orion Nebula. The trapezoid can be seen in a small telescope, but the Orion Nebula itself can be seen with the naked eye in the form of a fuzzy spot, which has an apparent magnitude of 4.0. M 42 is located in the Orion arm of the Milky Way galaxy and is 1600 light-years away from Earth.
To the north of M 42, M 43 is located, which seems to be separated from M 42 by a dark strip of dust. However, M 43 is physically part of the Orion Nebula.
The blue nebula above the Orion Nebula is an interstellar cloud of dust that reflects light from hot young stars. It consists of three regions, known as NGC 1977, NGC 1975 and NGC 1973, which are physically connected to the Orion Nebula and lie at approximately the same distance.
Take a close look at the photo of the Orion Nebula below the Orion Belt, or use the site’s online telescope and 3D models, which display the stars of galaxies and famous high-quality constellations. Do not forget to use a star map in independent searches.
This image, from ESO’s Very Large Telescope, shows a reflection nebula nestled at the heart of the constellation — NGC 2023. Located close to the well-known Horsehead and Flame Nebulae.
Orion constellation is one of the most recognizable combinations of stars in the night sky. People noticed it at least tens of thousands of years ago, and most likely, much earlier. Chinese astronomers called this constellation Shen, literally three stars, because of its three bright stars in a row, forming the Orion Belt. The ancient Egyptians imagined the Sah and Sopde gods at this place, the incarnations of Osiris and Isis, respectively, while the Greek astrologers saw a brave hunter with a raised sword above his head, ready to strike, that is, Orion.
But apart from the mythology, Orion is a wonderful part of the sky. The picture presented on the Very Large Telescope (VLT) of the European Southern Observatory (ESO) as part of the ESO Space Treasures program shows one of the largest reflective nebulae in the sky – NGC 2023. It lives in the center of the constellation at a distance of about 1.5 thousands of light years from Earth and is located next to the well-known Nebula Horsehead and Flame.
Reflective nebulae are clouds of interstellar dust, reflecting the light of sources of light shining nearby or inside them, just as fog disperses the light of car headlights. In this case, NGC 2023 is illuminated by a massive young star HD 37903, which is several times hotter than the Sun.
Such nebulae are often the places of birth of stars and contain ragged gas clouds that are significantly more dense than the environment. Under the action of gravity, these clouds attract each other and merge, which leads to the formation of a new star. So after a few million years, another star may appear in the Orion Belt!
Approximately every two Earth years, when summer arrives in the southern hemisphere of Mars, a window opens in its atmosphere, through which water vapor can rise from the lower layers of the planet’s gas to the upper layers. Most of it is carried away by the winds to the north pole, where it settles on the surface, but a certain amount of water vapor still disintegrates and disappears into space.
Scientists from the Moscow Institute of Physics and Technology and the Institute of Solar System Studies describes this unusual Martian water cycle in a study presented in the journal Geophysical Research Letters. Their computer simulation shows how water vapor overcomes the cold air barrier in the middle atmosphere of Mars and reaches higher layers. This, according to the authors of the work, will help to understand why Mars, unlike Earth, has lost most of its water.
Billions of years ago, Mars was a planet rich in water, rivers flowed on it and oceans raged. Since then, it has changed a lot: today there are very few areas with frozen water on its surface, and in the atmosphere water vapor is found only in trace amounts. In general, Mars may have lost at least 80 percent of its original water.
The reason for this lies in the fact that in the upper atmosphere of the Red Planet, the ultraviolet radiation of the Sun splits water molecules into hydrogen (H) and hydroxyl radicals (OH). From there, hydrogen irrevocably evaporates into space. Measurements using probes and space telescopes show that even today water continues to be lost in this way. But how is this possible? The layer of the middle atmosphere of Mars, like the tropopause of the Earth, should practically block the escape of gas, since this region is usually so cold that water vapor turns into ice.
In order to reveal this secret, Russian and German researchers conducted a simulation that revealed a previously unknown mechanism resembling a pump. Their simulation comprehensively describes the flows in the entire atmosphere enveloping Mars: from the surface to an altitude of 160 kilometers. Calculations show that the icy middle layer of the gas envelope becomes permeable to water vapor twice a day, but only in a certain place and at a certain time of the year.
The orbit of Mars plays a crucial role in this process: the path of the planet around the Sun, which lasts about two Earth years, is much more elliptical than that of the Earth. At the point closest to the Sun (approximately coincides with summer in the southern hemisphere) Mars is approximately 42 million kilometers closer to it than at the farthest point of the orbit, therefore summer in the southern hemisphere is noticeably warmer than in the northern.
When summer arrives in the southern hemisphere, water vapor can rise locally with warmer air masses at certain times of the day and reach the upper layers of the atmosphere. There the air flows carry gas to the north pole, where it cools again and settles. However, part of the water vapor is excluded from this cycle: under the influence of solar radiation, water molecules disintegrate, and hydrogen escapes into space.
-Paul Hartog, co-author of the work of the Institute for Solar System Research
This unusual hydrological cycle is enhanced by another feature of the Red Planet: huge dust storms that cover all of Mars at intervals of several years. The last such storms occurred in 2007 and 2018 and were extensively documented by orbital probes.
The amount of dust circulating in the atmosphere during such a storm facilitates the transport of water vapor to the upper layers of the atmosphere.
-Alexander Medvedev, co-author of the work of the Institute for Solar System Research
Scientists estimate that during the 2007 dust storm, twice as much water vapor fell into the upper atmosphere than it does in calm times for Mars. As the dust particles absorb sunlight and thus heat up, the temperature in the entire atmosphere rises to 30 degrees.
Our model with unprecedented accuracy shows how dust in the atmosphere affects the microphysical processes associated with the transformation of ice into water vapor.
-Dmitry Shaposhnikov, lead author of a study from the Moscow Institute of Physics and Technology
The authors of the paper conclude that, apparently, the atmosphere of Mars is more permeable to water vapor than the Earth’s, and the opened seasonal water cycle largely contributes to the continuing loss of water by the Red Planet.
Observing two areas of the sky with NASA’s Spitzer Space Telescope, the astronomers were surprised to find that some of the very first galaxies in the universe were brighter than models predict. The discovery, according to the authors of the study, could potentially unleash the driving force of the Epoch of Reionization, the main cosmic event that turned an opaque cosmos into a brilliant star landscape visible today.
We have observed some of the first galaxies that were formed less than a billion years after the Big Bang, or a little more than 13 billion years ago. The data showed that at some specific wavelengths of infrared light, galaxies are much brighter than expected. Our work is the first to confirm this phenomenon for a large sample of galaxies of that period, and shows that even ordinary ancient galaxies at these wavelengths were much brighter than those that we see today.
Today it is not precisely known when the first stars in the Universe were lit, however, some data indicate that approximately 100–200 million years after the Big Bang, the space was mostly filled with neutral hydrogen, which, perhaps, only began to unite into the first luminaries that became building blocks of the most ancient galaxies.
About 1 billion years after birth, the universe flashed. And something else has changed: the electrons of the omnipresent neutral hydrogen were removed during a process known as ionization. The epoch of reionization – the transition from the space filled with neutral hydrogen to the space with ionized hydrogen – is well documented.
Before this transformation, long-wave forms of light, such as radio waves and visible light, passed through the Universe more or less freely. But shorter wavelengths of light, including ultraviolet light, X-rays and gamma rays, were trapped by neutral hydrogen atoms. These collisions deprived them of electrons, that is, ionized.
But what could produce enough ionizing radiation to affect all the hydrogen from that era? These were individual stars? Giant galaxies? If the culprits were these objects, then those early cosmic settlers would be different from most modern stars and galaxies, which usually do not emit a large amount of ionizing radiation. On the other hand, perhaps something else could provoke this event, for example, quasars – galaxies with incredibly bright hearts, driven by supermassive black holes with a huge amount of material rotating around them.
This is one of the biggest open questions in observational cosmology. We know that it happened, but what caused it? Our results can be a great hint.
-Stefan de Barros, lead author of a study from the University of Geneva (Switzerland)
To look into the past by the time shortly before the end of the Eon of Reionization, Spitzer looked at two areas of the sky for about 200 hours, collecting light that had traveled to us for more than 13 billion years.
Galaxies circled in red circles are identified by Spitzer observations. The inset shows one of them. Credit: NASA, JPL-Caltech, ESA, Spitzer
Using these ultra-deep observations, astronomers identified 135 distant galaxies, which turned out to be particularly bright at two specific wavelengths of infrared light produced by ionizing radiation interacting with hydrogen and oxygen in them. This means that young massive stars predominated in the population of these galaxies, consisting mainly of hydrogen and helium and containing a very small amount of heavy elements (such as nitrogen, carbon and oxygen) compared with the stars found in average modern galaxies.
We did not expect that Spitzer with a mirror that does not exceed the diameter of the hoop, will be able to get close to the origins of the Universe. But nature is full of surprises, and the unexpected brightness of early galaxies, along with the excellent telescope characteristics, makes them available to our small but powerful observatory.
-Michael Werner, a scientist at the Spitzer project at NASA’s Jet Propulsion Laboratory
The NASA James Webb space telescope, which is scheduled to launch in 2021, will explore the Universe at many wavelengths observed by Spitzer. But, considering that the diameter of the main Spitzer mirror is only 85 centimeters, and the heir of Hubble is 6.5 meters, which is about 7.5 times larger, this will allow the future telescope to study the first galaxies in much more detail. In fact, James Webb will try to detect light from the first stars and galaxies in the universe, and the data obtained show that because of their brightness, this will be easier to do than previously thought.
The Spitzer data is certainly another step towards unraveling the mystery of cosmic reionization. Now we know that the physical conditions in the early galaxies were very different from those observed in typical galaxies today, and the James Webb space telescope will have to determine the cause of this discrepancy.
-Pascal Osh, co-author of the study from the University of Geneva
The space industry is agitated by the new project of the richest man in the world, Jeff Bezos, called Kuiper. The plan is to place in orbit a constellation of 3,236 satellites to provide high-speed Internet around the globe.
The provision of broadband Internet services to digital deserts is also the goal of another company called OneWeb, which intends this summer in Florida, USA, to build two satellites per day to create a constellation of more than 600 satellites. These satellites will be commissioned until 2021, the company said.
SpaceX billionaire Ilona Mask also demonstrates activity in this field: the company recently received permission to deploy 12,000 satellites in orbit at various altitudes as part of the Starlink constellation.
In addition, in the modern world there are a large number of other projects that are in the initial stages of development or are limited to lower levels of funding.
At the international conference Satellite 2019, held in Washington this week, industry professionals expressed concerns about the invasion of Bezos, the founder of the Amazon Internet platform, into the satellite Internet market. According to the experts, Bezos can arrange a bloodbath for the players of this market, squeezing them out of the sector at low prices.
Satellite Internet is practically not used in large cities, where cable and fiber optic data transmission methods dominate, but it is needed in remote corners of our planet. In addition, satellite Internet is used on airplanes and watercraft, therefore, the expansion of the satellite Internet market will provide an opportunity to use high-speed data transmission during flights and sea travel.
Blue supergiants look like rock and roll stars: these massive stars live a short life and die young. Therefore, these stars are rare in the universe, and their study is difficult even with the help of modern telescopes.
Before the advent of space telescopes, astronomers could observe only a few blue supergiants in the night sky, so our knowledge of the stars of this spectral class was very limited.
Astrophysicist Dr. Tamara Rogers of the University of Newcastle, United Kingdom, has worked with her team over the past five years to model such stars, trying to understand why their surface looks exactly as we see it during observations.
Modeling the structure of the stars, the team predicted that hydrodynamic gravitational waves, similar to those we see in the ocean, are breaking at the surface of the blue giant.
In addition, a second type of wave was predicted. These coherent waves resemble seismic waves on Earth and are generated deep in the depths of a star.
Now, using data collected by NASA space telescopes, a team of researchers led by Dr. Dominic Bowman from the Institute of Astronomy, Catholic University of Leuven, Belgium, for the first time conducted a detailed analysis of stars of this spectral class and found that almost all blue supergiants flicker reason for the presence of waves of these two types on the surface.
As predicted, these waves form deep in the depths of the star and can be a source of valuable information about the structure of stars of this class. This direction of studying the structure of stars is called astroseismology.
Although earlier we predicted the existence of these waves, but only now we were able to confirm their presence by observations. This is indeed a very inspiring moment for us!
-Dr. Rogers, co-author of the study
Blue supergiants are factories of metals of our Universe. In the depths of these stars all elements of the Periodic Table D.I. are formed. Mendeleev – which turns 150 years old this year – is heavier than helium, the authors note.
Astronomers have only recently been able to get the world’s first photographs of a black hole, and now researchers are faced with the task of obtaining clearer images that will help test Einstein’s General Theory of Relativity. Scientists from the University of Nijmegen, the Netherlands, together with colleagues from the European Space Agency and other scientific institutions, offer the concept of taking clearer images of a black hole based on the use of special space radio telescopes.
The idea is to place two or three satellites in a circular orbit around the Earth to observe black holes. This concept is called the Event Horizon Imager (EHI). In their study, scientists published black-hole images from simulations that show how high-resolution images from the EHI telescope system will look.
Using satellites instead of ground-based telescopes, such as the Event Horizon Telescope (EHT) radio telescope, has several advantages. In space, observations can be made at higher frequencies, at which observations from the Earth are difficult due to the filtering of these frequencies by the atmosphere. In addition, in space, you can significantly increase the distance between telescopes. This allows you to make a big step forward. We will be able to take pictures with a resolution greater than 5 times the resolution of the EHT telescope.
-the main author of the new study, Freek Roelofs of the University of Nijmegen
The study also considered a possible way to transfer data for analysis. Data obtained using the ground-based telescope EHT, currently delivered to the analytical centers using aircraft on hard drives. Of course, such a delivery method is not possible with the use of space telescopes, so data can be transmitted to Earth using a laser data transmission system, while the primary data processing will be done already on board these satellites, the authors point out.
Space telescopes will help to get clearer black holes pictures Click To Tweet