Every month, the universe reveals its new, never-seen-before colors to us. And the same has been the case with September 2021. Last month, some spectacular astronomical discoveries knocked at our doors, and here, we have compiled a list of some of them!

Hycean worlds: A new class of habitable planets

In one of the most striking discoveries of the month, astronomers found a new class of exoplanets that could host life beyond Earth. Known as Hycean worlds, they are hot, have large oceans, thick hydrogen atmospheres, and are nearly 2.5 times the size of our planet. Because of their size, they fall somewhere between super-Earths and mini-Neptunes and enjoy the properties of both worlds.

However, not all the Hycean worlds are the same. Some orbit so close to their stars that they’re tidally locked. This gives them one scorching hot dayside and one eternally dark night side. On the other hand, some orbit so far away from their host star that they encounter very little stellar radiation. Despite these extreme conditions, Hyceans are expected to be habitable for microbial life. Their oceanic conditions are probably similar to those driving microbial life in Earth’s oceans. 

Hycean worlds are good places to search for biosignature gases: oxygen and methane. In the coming years, the James Webb Space Telescope is expected to detect some biomolecules on one of the most promising targets, K2-18b. A biosignature detection can bring a revolution in our understanding of life in the Universe. 

A premature supernova triggered by a dead star

In 2017, astronomers observed a particularly luminous and unusual source of radio waves. The observation was made as a part of the Very Large Array (VLA) Sky Survey, and since its observation in 2017, the bright radio flare has amused astronomers. Efforts have been made to identify the source of the flare. And now, a team of astronomers has figured out the reason that led to a bright radio flare. A new study has revealed that it resulted from a catastrophic crash between a black hole or neutron star and the companion star. 

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An illustration showing a massive star that is about to explode | Image: Chuck Carter / Caltech

Massive stars usually explode as supernovae when they run out of nuclear fuel. But this explosion was different from all the supernovae known to date. Here, an invading black hole or neutron star prematurely triggered its companion star to explode. While going through the data, researchers found an extremely luminous radio source. It appeared that the radio transient occurred when a star exploded in a supernova. However, the timescale of the explosion was a bit unusual.  Later, another team analyzed a different catalog of X-ray transients. Analysis showed that the X-rays and the radio waves were likely coming from the same event. 

The X-ray transient signaled that a relativistic jet was launched at the time of the explosion. While the radio transient indicated that the material from the explosion later crashed into a massive torus of dense gas ejected from the star centuries earlier. It’s believed that a leftover remnant of a star, either a black hole or a neutron star, was orbiting an active star. Further, the gravitational pull brought the dead star and the active star together and the black hole and the companion star crashed into each other, which prematurely caused the companion star to collapse in on itself and explode into a supernova. This collision created distinct X-ray and radio wave bursts, which had been predicted earlier.

This marks the first-ever confirmation of a merger-triggered supernova.

Astronauts to use their blood, urine, and tears to make concrete on Mars

Colonizing Mars has been on mankind’s wish list for a long time. However, building structures on Mars requires raw materials like concrete, bricks, and others. But, transporting raw materials from Earth to Mars is not a viable option. This means that we need technology to develop raw materials on Mars itself, and a new study has shown that it might be possible to do so. Mars consists of a layer of dirt and rubble on its surface, known as regolith. Experiments have shown that these regoliths can act as viable building materials, and the human body can help in gluing them together.

Earlier studies have found that urea in human urine helps in plasticizing concrete, making it less brittle, more flexible, and eventually harder to better withstand mechanical stresses. Moreover, a material called AstroCrete uses albumin, which is a protein found in human blood plasma, to bind the concrete together. The team used albumin to fabricate extra-terrestrial regolith biocomposites, which had compressive strengths as high as 25 megapascals. Moreover, the addition of urea increased the strength of AstroCrete to up to 39.7 megapascals, in comparison to the ordinary concrete on Earth that has strengths between 20 and 32 megapascals.

The team also tested synthetic spider silk and bovine serum albumin for the same and found that over two years, six humans could donate enough albumin to build 500 kilograms of AstroCrete. However, the long-term health effects of continuous plasma donation in a low-gravity, high-radiation environment are not known so far, and it is not clear that how much plasma can be taken from a single person sustainably.

Although the idea seems to be a short-term solution, with the advancements taking place, it will eventually be superseded by versatile bioreactors and other technologies.

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Perseverance finds signs of past life on Mars

In a breakthrough concerning the Red Planet, Perseverance has hinted that alien life might have flourished on Mars in the past. Perseverance reached Mars on 18 February 2021, at 20:55 UTC, and since then, it has been exploring the planet by collecting rock and soil samples. And the recent samples of rock that the rover has collected point to alien life.

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Structure of Perseverance rover | Image: NASA

When the salts from the rock samples were analyzed, these rocks were formed when water ran through the minerals. Alternatively, the evaporation of liquid water could have facilitated the creation of these salts. The two samples analyzed so far came from a single rock from the Jezero crater. And the samples have revealed that Mars once had an environment that would have allowed life to exist. 

Researchers are now hoping to establish some historical sequence of water’s existence on Mars. But, unfortunately, the equipment required to assess the rock samples in detail cannot be sent to Mars, and it will probably take at least 10 years from now for another rover to collect the samples. So it will take much longer to arrive at some conclusion regarding the past life on Mars. 

A huge cavity in the Milky Way!

While we look for secrets in the far-away cosmos, our own galaxy never fails to amaze us. Following this, astronomers have discovered an enormous cavity in the Milky Way galaxy that is believed to have formed after a stellar explosion millions of years ago. Researchers used data from the European Space Agency’s star-mapping Gaia spacecraft to map the Perseus and Taurus molecular clouds in 3D for the first time. Eventually, the map revealed a massive void that remained elusive in previous 2D maps of the region. 

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The green point shows the location of the cavity, while zoomed-in view of the cavity shows the Perseus and Taurus molecular clouds in blue and red, respectively. | Image: Alyssa Goodman/Center for Astrophysics | Harvard & Smithsonian

The Perseus and Taurus molecular clouds have been known for a long, but it’s the first that a link has been found between them. Theories suggest that either one supernova went off at the core of this bubble and pushed gas outward, forming the Perseus-Taurus supershell. Alternatively, a series of supernovae occurring over millions of years created it over time.

The cavity is 490 light-years wide and has suggested that the Perseus and Taurus molecular clouds are not independent structures in space,  rather, they formed together from the very same supernova shockwave.

Traversable wormholes are possible!

The concept of wormholes has never failed to arouse curiosity among us. However, wormholes described by Einstein’s general relativity suffer a significant setback. They’re not traversable, which means that they are one-way barriers in space. If you somehow enter a wormhole, you would never be able to leave it. Moreover, the theoretical wormholes are quite unstable. The moment even a single photon enters a wormhole, the entire wormhole collapses before that photon can even escape. 

Wormhole
Wormhole’s illustration

Earlier, it was proposed that for wormholes to exist in our universe, they must comprise exotic matter having negative energy or negative mass. But now, a new study has shown that exotic matter is not necessary for a traversable wormhole. However, for this to happen, the existing theory of gravity needs to be modified. 

Scientists employed a tweaked form of gravity called generalized hybrid metric-Palatini gravity. Although this theory is built on Einstein’s general theory of relativity, it allows more flexibility in relationships between matter and energy and space and time. Scientists found that layering the entrances to the wormholes with double thin shells of regular matter would make the wormhole traversable without any negative energy. The researchers are now aiming to test this theory experimentally. 

September was truly amazing as far as the developments in astronomy and astrophysics are concerned. So let’s see what October has in store for us!

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