Black holes are getting stranger — even to astronomers. They’ve now detected the signal from a long ago violent collision of two black holes that created a new one of a size that had never been seen before.
“It’s the biggest bang since the Big Bang observed by humanity,” said Caltech physicist Alan Weinstein, who was part of the discovery team.
Researchers with the University of British Columbia were also on that team.
Black holes are compact regions of space so densely packed that not even light can escape. Until now, astronomers only had observed them in two general sizes. There are “small” ones called stellar black holes that are formed when a star collapses and are about the size of small cities. And there are supermassive black holes that are millions, maybe billions, of times more massive than our sun and around which entire galaxies revolve.
According to astronomers’ calculations, anything in between didn’t quite make sense, because stars that grew too big before collapse would essentially consume themselves, leaving no black holes.
Star collapses couldn’t create stellar black holes much bigger than 70 times the mass of our sun, scientists thought, according to physicist Nelson Christensen, research director of the French National Centre for Scientific Research.
Then in May 2019 two detectors picked up a signal that turned out to be the energy from two stellar black holes — each large for a stellar black hole — crashing into each other. One was 66 times the mass of our sun and the other a husky 85 times the mass of the sun.
The end result: The first ever discovered intermediate black hole, at 142 times the mass of the sun.
Lost in the collision was an enormous amount of energy in the form of a gravitational wave, a ripple in space that travels at the speed of light. It was that wave that physicists in the United States and Europe, using detectors called LIGO and Virgo, captured last year. After deciphering the signal and checking their work, scientists published the results Wednesday in Physical Review Letters and Astrophysical Journal Letters.
Because the detectors allow scientists to pick up the gravitational waves as audio signals, scientists actually heard the collision. For all the violence and drama, the signal lasted only one-tenth of a second.
“It just sounds like a thud,” Weinstein said. “It really doesn’t sound like much on a speaker.”
This crash happened about 7 billion years ago, when the universe was about half its current age, but is only being detected now because it is incredibly far away.
Black hole collisions have been observed before, but the black holes involved were smaller to begin with and even after the merger didn’t grow beyond the size of typical stellar black holes.
Scientists still don’t know how supermassive black holes at the centre of galaxies formed, Christensen said, but this new discovery may offer a clue.
Perhaps, like playing Legos, smaller blocks combine to make bigger ones and those combine to make even bigger ones, said Harvard astronomer Avi Loeb, who wasn’t part of the study but said the results chart new astronomical territory.
And indeed the bigger of the two black holes involved in this crash could have been the result of an earlier merger, both Weinstein and Christensen said, further bolstering that theory.
“It’s conceivable that this pair of black holes formed entirely differently, possibly in a dense system with lots of dead stars whizzing about, which allows one black hole to capture another during a fly by,” said Barnard College astronomer Janna Levin, who wasn’t part of the research and is author of the book Black Hole Survival Guide.
On the other hand, scientists can’t quite explain how merged black holes, flying around the universe, would meet so many others to merge again and grow ever bigger. It could instead be that supermassive black holes were formed in the immediate aftermath of the Big Bang.
“In astrophysics we’re always faced with surprises,” Weinstein said.
Source:- Global News
Buried lakes of salty water on Mars may provide conditions for life – MENAFN.COM
(MENAFN – The Conversation) In 2018 a team of Italian scientists announced to the world that there was a lake on Mars . Using satellite radar data, the team detected a very bright area approximately 20 kilometres across located about 1.5 kilometres deep under the ice and dust of the south polar cap.
After analysis, they concluded that the bright area was a subglacial lake filled with liquid water. The discovery raised some fundamental questions.
Was this the only lake hidden beneath the ice on Mars? How could liquid water exist in the extreme cold of the Martian south polar region, where the average surface temperatures are lower than -100 °C?
After acquiring additional satellite data, my colleagues and I have discovered three more distinct ‘lakes’ near the one found in 2018 and confirmed that all four bodies contain liquid water.
Read more: Mars: mounting evidence for subglacial lakes, but could they really host life?
How can we see lakes under the ice on Mars?
The radar sounder MARSIS (Mars Advanced Radar for Subsurface and Ionosphere Sounding) is one of eight instruments on board the European Space Agency orbiter Mars Express. This scientific spacecraft has been circling the red planet since December 2003.
The orbiting radar directs radio ‘chirps’ toward the planetary surface. These signals are partly reflected back by the surface, and partly penetrate deeper, where they may be absorbed, scattered, or reflected back to the radar. Liquid water reflects radar signals better than many other materials, so the surface of a body of liquid water shines brightly in a radar image.
Radar sounders are used on Earth to detect subglacial lakes in Antarctica, Greenland and Canada. Here, a technique called radio-echo sounding (RES) is commonly used to analyse the signals.
There are some obvious differences between how radar sounding is used on Earth and on Mars. For a start, MARSIS operates from altitudes between 250 km and 900 km above the surface, it has a 40-metre long antenna, and it operates at much lower frequencies (1.8-5 MHz) than Earth-based radar sounders.
These differences meant we had to do some work to adapt standard radio-echo sounding techniques for use with signals from MARSIS. However, we were able to analyse data from 134 MARSIS tracks acquired between 2010 and 2019 over an area 250 km wide and 300 km long near the south pole of Mars.
In this area, we identified three distinct bright patches around the lake already ‘seen’ in 2018. We then used an unconventional probabilistic method to confirm that the bright patches really do represent bodies of liquid water.
We also obtained a much clearer picture of the shape and extent of the lake discovered in 2018. It is still the largest of the bodies of water, measuring 20 km across on its shortest axis and 30 km on its longest.
How could liquid water exist beneath the Martian ice?
The surface temperatures in our study area are around -110 °C on average. The temperatures at the base of the ice cap may be slightly warmer, but still way below the freezing point of pure water.
So how can bodies of liquid water exist here, let alone persist for periods of time long enough for us to detect them?
After the first lake was found in 2018, other groups had suggested the area might be warmed from below by magma within the planet crust. However, there is to date no evidence this is the case, so we think extremely high salt levels in the water are a more likely explanation.
Read more: What on Earth could live in a salt water lake on Mars? An expert explains
Perchlorate salts, which contain chlorine, oxygen, and another element, such as magnesium or calcium, are everywhere in the Martian soil. These salts absorb moisture from the atmosphere and turn to liquid (this process is termed ‘deliquescence’), producing hypersaline aqueous solutions (brines), which crystallise at temperatures far below the freezing point of pure water. Furthermore, laboratory experiments have shown that solutions formed by deliquescence can stay liquid for long periods even after temperatures drop below their own freezing points.
We therefore suggested in our paper that the waters in the south polar subglacial lakes are ‘salty’. This is particularly fascinating, because it has been shown that brines like these can hold enough dissolved oxygen to support microbial life.
Could conditions be right for life beneath the ice?
Our discoveries raise new questions. Is the chemistry of the water in the south polar subglacial lakes suitable for life? How does this modify our definitions of habitable environments? Was there ever life on Mars?
To address these questions new experiments and new missions must be planned. In the meantime, we are gearing up to continue acquiring MARSIS data to collect as much evidence as possible from the Martian subsurface.
Each new piece of evidence brings us one step closer to answering some of the most fundamental scientific questions about Mars, the solar system and the universe.
Read more: Mars: mounting evidence for subglacial lakes, but could they really host life?
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Scientists find evidence of multiple underground lakes on Mars – Yahoo News Canada
The team used data from a radar instrument on the European Space Agency’s (ESA) Mars Express spacecraft to investigate the planet’s southern polar region. Mars Advanced Radar for Subsurface and Ionosphere Sounding or MARSIS, as the instrument is called, is capable of sending out radio waves that bounce off materials on the planet’s surface. Different materials reflect those signals differently, and the same technique is used to find subsurface glacial lakes here on Earth.
Upon observing an area that’s around 75,000 square kilometers in size, they found locations that reflected those signals back in a way that indicates the presence of water trapped underneath a kilometer of ice. The main lake, the one discovered back in 2018, measures 30 kilometers or 19 miles across, while each of the three smaller lakes surrounding it are a few kilometers across.
<p class="canvas-atom canvas-text Mb(1.0em) Mb(0)–sm Mt(0.8em)–sm" type="text" content="While the scientists’ findings are promising, some experts still believe we won’t find lakes on the red planet at all. Jack Holt, a planetary scientist part of NASA’s Mars Reconnaissance Orbiter program, doesn’t believe there’s enough heat flow under the surface of the planet for water to remain liquid. And even if we do find liquid water under Martian ice, that won’t automatically mean we’ll also find life. See, the lakes have to be very salty to remain liquid, but their salt content must not exceed five times that of seawater to be able to support life. As John Priscu, an environmental scientist at Montana State University, told Nature:” data-reactid=”27″>While the scientists’ findings are promising, some experts still believe we won’t find lakes on the red planet at all. Jack Holt, a planetary scientist part of NASA’s Mars Reconnaissance Orbiter program, doesn’t believe there’s enough heat flow under the surface of the planet for water to remain liquid. And even if we do find liquid water under Martian ice, that won’t automatically mean we’ll also find life. See, the lakes have to be very salty to remain liquid, but their salt content must not exceed five times that of seawater to be able to support life. As John Priscu, an environmental scientist at Montana State University, told Nature:
“There’s not much active life in… briny pools in Antarctica. They’re just pickled. And that might be the case [on Mars].”
'Most extreme planet discovered': Scientists find blistering exoplanet with temperatures near 3,200C – National Post
As the study of planets outside our solar system continues, astronomers have discovered what they have described as the ‘most extreme planet’ ever observed, with surface temperatures more blistering than those of some stars.
Researchers at the University of Bern say that the exoplanet, dubbed WASP-189b, is a gaseous giant 1.6 times larger than Jupiter and can record temperatures of up to 3,200 degrees Celsius, hot enough enough to met all rocks and metal and turn them into gaseous form.
The planet, they said, orbits the star HD 133112, known to be one of the hottest stars with a planetary system 2,000 degrees Celsius hotter than our Sun.
Despite being an enormous gaseous giant, WASP-189b is situated much closer to its star than Jupiter is to the sun, and so only take 2.7 days to orbit its star, with one side experiencing a permanent ‘night’ and the other a permanent ‘day’.
“WASP-189b is especially interesting because it is a gas giant that orbits very close to its host star,” astrophysicist Monika Lendl said, according to the university’s press release. “It takes less than three days for it to circle its star, and it is 20 times closer to it than Earth is to the Sun.”
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