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Some potentially inhabited worlds may not have “zones of life”

An artistic representation of a tidal trapped potentially inhabited exoplanet, with the open ocean of liquid water surrounded by a global ice shell covering the rest of the extra-solar world on the day side.

They may be completely covered in ice and their oceans do not receive starlight.

Some of the potentially inhabited exoplanets orbiting red dwarfs may be completely covered in ice and not have open surface oceans of liquid water even on the side facing the star, which, under certain conditions, makes them unsuitable for life, scientists say in a study presented in Nature Astronomy.

planet

“Perhaps some of the tidal traps of extrasolar worlds that were previously considered potentially inhabitable are frozen snowballs and have no open areas with liquid water. As a result, the starlight necessary for photosynthetic organisms does not reach the ocean, sealed under a global ice shell, which greatly limits the chances of the development and prosperity of life, ”says Jun Yan, lead author of the study from Peking University (China).

Potentially inhabited tidal rocky extra-solar worlds in red dwarf systems, especially the Proxima b, TRAPPIST-1e, and LHS 1140b, which are especially close to us, are the main goals for future studies of exoplanetary atmospheres, which can provide clues about their ability to support life.

planet

Current models predict that if such a planet contains a vast surface ocean, then on its warmer day side there should be an ice-free area, locked on all sides by a global ice shell. However, as noted by Jun Yan, previous simulations did not fully take into account the important component of the climate system – ice dynamics – which did not allow revealing the issue of ocean resilience to global glaciation.

“In our work, we show that ice drifting from the night side of the exoplanet flows into an open area, gradually cooling, reducing, and ultimately completely sealing it.

It should be noted that such a scenario is applicable only to worlds living in the outer and, possibly, in the middle regions of the inhabited zone, but not to those located at its inner edge, since for them the flux of stellar radiation is high enough to melt ice and snow on the surface and maintain liquid water on the day and even night sides. In addition, the presence of greenhouse gases in the atmosphere plays a small role, since a large number of them will save the exoplanet from turning into a snowball, ”Jun Yan explained.

But, in spite of the fact that planets completely covered with ice are extremely inhospitable for life, one should not put an end to their potential for habitability, because the Earth itself in the past twice experienced periods of global glaciation: 2.2 billion years ago and 630 million years ago.

“For example, photosynthetic organisms can develop in areas with thin ice, where stellar radiation nevertheless reaches liquid water, or in local unsealed areas where active geothermal processes occur, or, finally, in some“ bays, ”where access to drifting ice is limited.” – concluded Jun Yan.

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Space

What did Mars look like millions of years ago? New theory

At the moment, Mars is considered the most suitable planet for human life. It is in many ways similar to our native Earth: the surface is solid, the day lasts almost the same 24 hours and periodically there is a change of seasons. 

Scientists are sure that millions of years ago between our planet and Mars there were even more similarities, such as the presence of water and living organisms. He has one snag – in time immemorial the sun was much weaker than it is now, and Mars was quite far from it and was not going to approach. It turns out that the planet was cold and there could not be rivers and oceans on it. 

But how, then, can explain the presence of valleys and depressions on its surface, which were clearly formed as a result of the flow of water? Canadian scientists have started looking for an explanation for this mysterious phenomenon. 

In the course of scientific work, they managed to put forward a theory that greatly changes the idea of ​​scientists about the past of the Red Planet. Perhaps Mars looked like a giant snowball.

Millions of years ago, Mars was hardly a warm place

Water on Mars

The essence of the theory was published in the scientific journal Nature Geoscience . According to one of the study’s authors, Anna Grau Galofre , over the past 40 years, the scientific community has believed that irregularities on the surface of Mars were formed by the movement of rivers. 

However, there are distinctive features between valleys and depressions in different regions of the planet. To find out what factors could affect the structure of the irregularities, scientists decided to find a place on Earth, the surface of which is as close as possible to the Martian landscape. However, researchers have long known about the existence of such a place.

Mars on Earth

One of the most Mars-like places on our planet is considered the uninhabited island of Devon, located in northern Canada. Almost all of its surface is a cold and dry desert. If you look at the island from a bird’s eye view or even from a satellite, you will notice that its surface is really very similar to the vastness of the Red Planet. 

It is also full of all kinds of irregularities and scientists are well aware of how they were formed. Since Devon Island is a rather cold place, most of the rivers there flow under a layer of ice. Part of the ice sheet melted over time and the valleys left by the rivers are now clearly visible to us. In their structure, they are very different from the valleys formed by rivers that flow in the open.

The surface of Devon Island is very similar to the Martian landscape

So, scientists became aware of the distinctive features of the two types of valleys. Based on this data, they developed an algorithm that was able to quickly study photographs of 10,000 Martian irregularities. 

Among them, the researchers found many valleys, which clearly formed under a thick layer of ice. Most of them were formed about 3.8 billion years ago. It turns out that once upon a time, although not all, but most of Mars, was covered with ice and snow. But scientists assumed that it was very similar to our blue-green Earth.

Above is the surface of Mars, and below is the surface of Devon Island

Life on Mars

If Mars really was covered with layers of ice, then the probability of the existence of living organisms on it increases markedly. The fact is that microorganisms could well inhabit the waters hidden under the ice sheet. And this shield, in turn, could perfectly protect them from cosmic radiation. 

Indeed, the Red Planet has a very weak magnetic field, which is precisely what serves to protect against harmful radiation. So, despite the changes in the idea of ​​the appearance and conditions of ancient Mars, the probability that at least primitive creatures lived on it remained. Maybe someday their traces will be discovered by devices like InSight and we will gain confidence that life on other planets can exist.

According to the new theory, 3.8 billion years ago Mars looked something like this

The computer algorithm created within the framework of scientific work will not disappear. According to the developers, it can be useful for studying the past of the Earth. 

Technologies existing at the moment allow us to look at history no further than 5 million years, and a new algorithm can reconstruct the history of glaciations on our planet over the past 35 million years. It sounds intriguing, so we can only hope that new discoveries will not be long in coming.

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Neutron star formed in front of astronomers

Astronomers fought their way through the dusty curtain to the newborn neutron star

Thirty-three years ago, astronomers recorded a supernova explosion, 1987A. And just recently they found a neutron star formed in this cataclysm. This is the youngest such object in the history of observations. For some time, scientists doubted that they were observing exactly a neutron star, but fresh scientific work has provided very convincing evidence of this.

On February 23, 1987, male astronomers (and also female astronomers) received a gift from the Universe. On this day, supernova 1987A was discovered, which exploded in the Large Magellanic Cloud – a nearby dwarf galaxy, a satellite of the Milky Way.

As you know, a star dying in a supernova explosion (or rather, what is left of it) turns either into a black hole or into a neutron star. Scientists were confident that in the case of 1987A, the second option was realized. This was indicated by the flux of neutrinos recorded by terrestrial detectors simultaneously with the light of the flash.

Recall that a neutron star is a celestial body with a diameter of only a few kilometers, which, at the same time, is comparable in mass to the Sun. Due to the monstrous density and the most powerful magnetic field, the matter inside such an object is in states that cannot be reproduced in terrestrial laboratories. Therefore, neutron stars are of great interest to physicists. And, of course, astronomers who seek to figure out the ins and outs of every object and process in the universe.

The 1987A explosion gave researchers the first chance to study the neutron star that formed before their eyes and understand what these celestial bodies are like immediately after birth. All other known neutron stars are much older.

So, the second place belongs to the recently discovered object , which is 240 years old, and even it is surprisingly young compared to its counterparts millions of years old.

Let us clarify that new supernova explosions are discovered regularly and in large numbers , but in galaxies that are too distant to make out the formed neutron star. And the 1987A flare occurred only 168 thousand light years from Earth. It was the closest supernova explosion seen since the invention of the telescope.

Supernova Remnant 1987A at different wavelengths. The inset shows the radiation of a hot central object.Illustration ALMA (ESO / NAOJ / NRAO), P. Cigan, R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA.

Alas, by pointing telescopes at the site of the 1987A flare, astronomers saw only a dense cloud of dust formed during a supernova explosion. For more than thirty years, using increasingly powerful instruments, scientists have tried to discern at least some trace of the central body. And finally they succeeded.

In 2019, the ALMA radio telescope helped astronomers see the supernova remnant 1987A in unprecedented detail. Thanks to this, astronomers discovered that there is a compact and very hot object in the center of the dust cloud. Although the “heater” itself remains hidden behind the dust curtain, the telescope records the radiation of the dust heated by it.

“We were very surprised to see this hot ball formed in a thick cloud of dust in a supernova remnant,” says co-author Mikako Matsuura of Cardiff University. “There must be something in the cloud that heats the dust and makes it glow This is why we assumed there was a neutron star hiding inside the dust cloud.

However, the radiation power seemed suspicious to scientists. Could a neutron star be so hot? Or is there something else lurking in the center of the dust cloud?

“We thought that such a neutron star might be too bright to exist. But then Dani Page and his team published a study that showed that a neutron star could actually be so bright because it is so young,” Matsuura says.

Supernova Remnant 1987A. Imaging in radio waves, visible light and X-rays. Translated by Vesti.Ru.Illustration ALMA (ESO / NAOJ / NRAO), P. Cigan, R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA.

The scientific article , published in the edition of the Astrophysical Journal by Dany Page of the National Autonomous University of Mexico and his colleagues, set the record straight. Experts have shown that the dust-heating object at the center of Supernova remnant 1987A not only could be a neutron star, but could hardly be anything else.

According to the calculations of Page and his co-authors, the temperature of a neutron star 30 years after its birth should be five million degrees. This is just enough to explain the observed heating of the dust.

In addition, the central object is located exactly where the neutron star should have been thrown by the explosion (by the way, at the time of the cataclysm, it was moving at a speed of hundreds of kilometers per second).

Finally, recall that the neutrinos recorded in 1987 indicate that a neutron star was formed during a supernova explosion, not a black hole.

However, theoretically, the central object can be a black hole, onto which a dense stream of matter falls. But this requires a fantastically accurate adjustment of its properties to observational data, which is extremely unlikely. So experts are confident that they have finally “groped” for a newborn neutron star.

We now see the 1987A supernova remnant as it was 33 years after the explosion. Perhaps, after a few more decades, the dust cloud dispersed a little and began to transmit the radiation from the central object. Scientists are looking forward to the moment when these rays will reach the Earth.

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Scientists have confirmed that something else existed before our universe

American scientists, using mathematical tools, described the inhomogeneities of the cosmic relic radiation that arose immediately after the origin of the Universe. 

The authors believe that their results confirm the correctness of the Big Bounce hypothesis, according to which the emergence of our universe was the result of the collapse of some “previous” universe. The results are published in the journal Physical Review Letters.

While Einstein’s theory of general relativity explains a wide range of astrophysical and cosmological phenomena, some properties of the universe remain a mystery. In particular, it cannot explain the uneven distribution of galaxies and dark matter in space.

Since the 1980s, Pennsylvania State University researchers have been developing a cosmological paradigm based on the concept of loop quantum gravity. This paradigm, called loop quantum cosmology, describes all modern large structures in the Universe as quantum fluctuations of space-time that took place at the birth of the world.

According to the generally accepted theory of the Big Bang, it all started with a singularity – a state in which all matter and energy were compressed into one point. Then, in the first fraction of a second, during a period called inflation, space swelled to enormous proportions. But the Big Bang theory does not explain what happened before the singularity, so this state cannot be described in terms of the laws of physics and mathematics.

Scientists at Pennsylvania State University hold the alternative Big Bounce hypothesis, according to which the current expanding universe arose from the supercompressed mass of the universe of the previous phase. To describe this state, they use a universal mathematical apparatus that combines quantum mechanics and the theory of relativity.

The authors trace the origin of the structure of the Universe to the smallest inhomogeneities recorded against the background of microwave relict cosmic radiation, which was emitted when the Universe was only 380 thousand years old.

But this radiation itself has three mysterious anomalies that are difficult to explain using classical physics. These deviations are so serious that many physicists began to talk about a crisis in cosmology.

In a new study, scientists argue that, from a loop quantum cosmology perspective, describing inflation removes two major anomalies in the CMB distribution.

“Using quantum loop cosmology, we naturally resolved two of these anomalies, avoiding a potential crisis,” co-author Donghui Jeong, associate professor in the Department of Astronomy and Astrophysics, said in a university press release. anomalies suggests that we live in an exclusive universe.”

The authors believe that the inhomogeneities of the CMB are the result of inevitable quantum fluctuations in the early Universe. During the accelerated phase of expansion – inflation – these initially tiny fluctuations were stretched by gravity, reflected in the observed irregularities.

“The standard inflationary paradigm, based on general relativity, views spacetime as a smooth continuum,” says the first author, Professor Abhay Ashtekar, director of the Pennsylvania State Institute of Gravity and Space. but upon closer inspection, you can see that it is woven from densely packed one-dimensional strands. And quantum strands are woven into the fabric of spacetime. With these strands, loop quantum cosmology allows us to go beyond the continuum described by general relativity.”

Scientists hope that new satellite missions such as LiteBIRD and Cosmic Origins Explorer, aimed at detecting traces of primary gravitational waves in the background of the background radiation, will confirm their findings.

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