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Scientists crack mystery of black holes

BANGALORE: A scientist from Indian Institute of Science (IISc) Bangalore, and his student have successfully applied Albert Einstein’s gravity theory to unlock the mysteries of black holes.

Banibrata Mukhopadhyay, associate professor, department of physics, IISc, and his student Indrani Banerjee worked for over two years for their landmark discovery. Their study on black holes has been acknowledged by the scientific community across the globe, including professors from Harvard University. The duo has published its findings in the international journal Physical Review Letters.

Black holes, as stars are known postdeath, are not visible to the plain eye. Though not visible, black holes devour everything in their neighbourhood given the gravitational pulls they exercise. It was hitherto believed that mass and spin are the determining properties of black holes and they would go a long way in determining the influence of black holes on their neighbourhood as well as their pre-death star existence.

Their new study, says Banibrata, who worked in Harvard for three years before joining IISc in 2007, throws more light on black holes and their properties, particularly the correlation between mass and spin or rotation. They have proved that mass and spin are not independent of each other but actually interdependent. They have established that mass of the star could be used to calculate the spin.

“The spin of the observed black holes is still a debatable issue — the exact value of the spin is not known. On the other hand mass can be determined more easily. Rotation of the black hole is determined by the mass and rotation of the initial star. The larger the mass of the initial star the greater it tends to have a high rotational speed and turn into swiftly spinning black holes. The smaller the mass of the initial star the slower its rotation and spin. This property shows that spin and mass are correlated. Hence if mass is known, the spin can be predicted. Eventually, only one fundamental parameter characterizes the black hole,” Banibrata explained.

Indrani, a PhD student of physics, said, “First we were working on how stars collapse and end up into black holes. During the research, the thought of discovering the properties emerged,” she said.

WHAT ARE BLACK HOLES?

Black holes are formed when stars exhaust their ‘nuclear fuel’ or are ‘dead’. They are abyssinian spaces that exert strong gravitational force on everything in their vicinity. The hole is called ‘black’ because it absorbs all the light that hits the horizon, reflecting nothing. The largest black holes are called ‘supermassive’. These black holes have masses that are more than 1 million suns together.

Source : timesofindia.indiatimes.com

Space

It’s a good start: TESS orbiting telescope discovers the first habitable world, with oceans

The TESS Space Telescope has discovered a planet on which oceans may exist. In addition, the exoplanet revolves around a quiet star, and this compares favorably with other candidates for the title of the cradle of extraterrestrial life. This is the first, but certainly not the last potentially inhabited world discovered by the TESS Observatory.

The space telescope was launched in 2018. Its task is to search for exoplanets, including those similar to Earth.

TESS has discovered 17 Earth-like planets orbiting 11 stars so far, according to a press release for the new study. All these luminaries are red dwarfs, which are smaller and colder than the Sun.

The TESS team divided almost the entire sky into sectors, each of which is observed for 27 days. However, these areas partially overlap, so some luminaries remain in the field of view of the device for much longer.

The TOI-700 star (aka TIC 150428135) is one of those “lucky ones”. Thanks to this, astronomers have discovered as many as three exoplanets about the size of the Earth.

The first of them (TOI-700b) has a radius almost equal to that of the Earth and revolves around its sun in 10 Earth days. The next planet, TOI-700c, is much larger than its neighbor (2.7 times the Earth’s radius). It makes a complete revolution in 16 days.

However, the most interesting of all is the third exoplanet from the planet TOI-700d. Its radius is 1.1 terrestrial, and its orbital period is 37 terrestrial days. It is this orbit around the cool local sun that makes the TOI-700d “right to life.” 

According to scientists, the planet receives 86% of the heat that goes to the Earth. This means that the temperature on this celestial body allows for the existence of liquid water and, therefore, the biosphere. According to experts, the exoplanet is in the habitable zone.

Planetary system TOI-700. The habitable zone is shown in green. One astronomical unit (AU) is equal to the distance from the Earth to the Sun. Illustration by Rodriguez et al. / Astronomical Journal (2020).

Three scientific articles published in the Astronomical Journal are devoted to the newly discovered world.

The first describes the discovery of this planet using the TESS telescope.

The second publication is devoted to the observation of an exoplanet using the Spitzer space infrared observatory. The telescope received this data in October 2019 and January 2020, shortly before the termination of its mission.

Finally, the authors of the third research paper simulated the possible climate of TOI-700d.

The researchers examined two dozen scenarios that differ from each other in the composition of the planet’s atmosphere, the amount of water on it, and other characteristics. Their conclusion is optimistic: a climate suitable for life is obtained in a fairly wide range of conditions.

It is important that TOI-700, unlike most other red dwarfs, is a calm star, not prone to catastrophic flares. That is, TOI-700d has every chance of preserving the atmosphere and hydrosphere for billions of years.

Of course, not without a fly in the ointment. TOI-700 is more than a hundred light years from Earth. It’s too far away to directly study the atmosphere of a small planet like TOI-700d, even with the future James Webb telescope .

However, the capabilities of astronomical instruments are growing rapidly. Perhaps in a few decades, scientists will carefully study the mysterious exoplanet and (who knows?) will find signs of the existence of life on it.

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Space

Apophis: A dangerous phenomenon was noticed on an asteroid threatening Earth

The asteroid Apophis, potentially dangerous for the Earth, experiences the Yarkovsky effect, as a result of which it gains acceleration and shifts to more and more threatening orbits with a collision with the Earth.

The asteroid Apophis, 325 meters in size, was discovered in 2004. The discovery caused a stir – calculations showed that there is a 2.7 percent probability that Apophis, named after the ancient Egyptian god of evil and destruction, will collide with the Earth in 2029. Then scientists ruled out this threat, calculating that on April 13, 2029, the asteroid will fly at a distance of 37.6 thousand kilometers from the center of the Earth.

The report on the detected displacement was presented at the Planetological Section of the Virtual Meeting of the American Astronomical Society in 2020 by a specialist from the Institute of Astronomy, University of Hawaii, Dave Tholen. According to the speaker and his colleagues, the asteroid Apophis is strongly susceptible to the Yarkovsky effect, which consists in a weak force effect on an object moving in space due to the inhomogeneity of thermal radiation.

All asteroids emit in the form of heat the energy of the sunlight they absorb in order to remain in a state of thermal equilibrium – and as a result of this process, the asteroid’s orbit changes weakly. Until now, it was believed that collisions of the asteroid Apophis during its approach to Earth in 2029 and 2068 are impossible. Taking into account the Yarkovsky effect with respect to a 325-meter potentially dangerous asteroid means that the scenario of its collision with the Earth in 2068 is updated again.

Apophis is the most likely candidate for a collision from the aton asteroids passing near the Earth, was discovered in 2004 and received its own name on July 19, 2005 in honor of the ancient Egyptian god Apop (Apophis) – a huge destroyer snake living in the darkness of the underworld and trying to destroy Sun (Ra).

During its approach to Earth on Friday, April 13, 2029, this asteroid will be visible to the naked eye as it passes within the orbits of Earth’s communications satellites.

One of the discoverers of Apophis, David Jay Tolen, in particular, said:

“We already know that the collision of this cosmic stone with our planet is impossible during the approach of 2029. However, the quality of our new observations with the Subaru telescope was high enough to reveal the acceleration resulting from the Yarkovsky effect on this asteroid.

Calculations have shown that the asteroid is annually displaced from a “purely gravitational” orbit by about 170 meters, and this displacement is enough to return the scenario of a collision with the Earth in 2068 among the probable outcomes .”

There are a number of services on Earth that track the potentially dangerous approaches of our planet with asteroids, but significant in body size, such as Apophis, attract the attention of scientists.

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Space

US professor said that the space expansion of earthlings will lead to the spread of totalitarianism

Political scientist Daniel Dodney believes that the foundation for future space conflicts is being laid on Earth today.

Space exploration is one of the main priorities for humanity in the 21st century. But not everyone agrees that the exit of our civilization beyond the boundaries of the globe will do more good than harm. For example, Daniel Dodney, professor of political science at Johns Hopkins University in the United States, believes that we should not attempt space expansion at all.

Dewdney is confident that the emergence of new habitats for people, in addition to the Earth, will lead to the emergence of interplanetary totalitarian empires. And if mankind somehow manages to master at least a few planets of the solar system, then nuclear weapons will become the “gold standard” in all wars (which, according to the professor, will not stop).

Although many colleagues consider Daniel’s arguments too pessimistic, the political scientist himself generally believes that people should abandon the exploration of outer space and search for a new home. 

“The large-scale expansion of human activity into space <…> must be included in the growing list of catastrophic existential threats to humanity,” Dodni insists.

No matter how gloomy the views of the American political scientist may look, they have certain grounds. So, in 2019, the United States announced the creation of a new type of its Armed Forces – space: they are “designed to protect the interests of the United States in space, deter aggression at long distances and conduct operational and consistent space operations.”

Daniel Dodney / The Brown Daily Herald
Daniel Dodney / The Brown Daily Herald

Other countries followed the American example: France, Canada and Japan announced their intentions to create similar troops. According to Dodnya, all this testifies to laying the foundation for future “near-earth conflicts.” According to his forecasts, space special forces will one day be able to control asteroids and comets to destroy settlements on rival planets or change the climate there, causing total extinction.

At the same time, the political scientist notes that he has nothing against “using space in ways that will benefit the Earth.” However, he doubts that this is possible.

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