Unprecedented Indian Ocean level rise

This is an “unprecedented rise” in the level of the central Indian Ocean, a very worrying rise identified by scientist Paul Kench of Simon Fraser University. The researcher, who published a study on Nature Geoscience, reveals, in a press release published on the website of the same Canadian university, that sea levels in the central Indian Ocean have increased by about one meter over the last two centuries.

The researcher came to this disconcerting conclusion by analyzing certain types of fossil corals which can be considered “recorders of past sea levels”, the researcher reports. By measuring in particular the age and depth at which these fossils are found, it is possible to identify the various periods when the sea level may have been lower or higher and this for hundreds of years.

In particular, the researcher found that the sea level in this area was much lower in the past than ever calculated. The researcher identified in particular two periods during which the sea level off the Maldives was among the lowest, namely between 234 and 605 AD and 1481 and 1807.

According to the researcher, these reductions in sea level were due to reductions in the temperature of the sea surface itself associated with the late ice age of antiquity and the small ice age. Moreover, the data he acquired confirm, as reported in the abstract of the study, also the acceleration of sea level rise in the last two centuries at unprecedented rates.

Naturally, such news is a source of concern not only for marine eco-environments, in particular coral reefs, but also for all cities and coastal communities in general in the area, not a few considering, for example, regions such as those of southern India, Sri Lanka and the African coast.

There could be two black holes in the center of the Milky Way

There could be a second black hole gravitating around the main one at the center of the galaxy even though we haven’t found any evidence yet. That’s what a new article in The Conversation written by astrophysicist Smadar Naoz, Professor of Physics and Astronomy at the University of California at Los Angeles, who has made a new study that has appeared on arXiv for the time being.

According to Naoz and colleagues the black hole that lies at the center of our galaxy (its presence is now accepted by the vast majority of astronomers and astrophysicists), called Sagittarius A* and having a mass of about 4 million times that of our Sun, may in fact have a companion, another black hole, smaller, that orbits around it.

Naoz and colleagues have found no direct evidence of the presence of a second black hole, but they are confident that it may actually exist because they rest on the idea that galaxies evolve mostly by merging with each other, a phenomenon that we are also increasingly finding through the observations of other galaxies and that is becoming increasingly common in our eyes.

And since it is believed that each galaxy has a black hole at its centre that guides its entire gravitational process, this means that pairs of black holes must exist at the centre of many galaxies (in those cases where they have not merged). And among these galaxies there could also be the Milky Way since at the same time we have not even found real evidence that a second black hole cannot exist.

If at the center of a galaxy there are two black holes and not just one, the gravitational attraction that the two bodies generate is different because the two supermassive black holes orbit around each other and at the same time exert an attraction on the stars and matter around them.

To understand this complex gravitational movement, the researchers first analyzed S0-2, the one that can be considered as the most studied star that is located in the whirling central region of our galaxy and that completes an orbit around the supermassive central black hole every 16 years.

Examining the orbit of this star, the researchers found no evidence that there could be another supermassive black hole with at least 100,000 times the mass of the Sun (100,000 solar masses is usually considered the minimum threshold for a black hole to be considered “supermassive”). However, there could be one with a smaller mass, so small that it does not alter the orbit of SO-2 in a way that is detectable with the tools we have today.

The astronomers themselves are waiting for the next minimum distance approach that the star S0-2 will have to Sagittarius A* in 16 years’ time. At that time it will be possible to test several of Einstein’s predictions on general relativity and among these is the one about the change in the orientation of the elongated orbit of the stars. If there really is a second black hole, it could alter this result.

Also, the gravitational waves of the two black holes orbiting each other could be detected. Currently, it is not possible to detect them with the LIGO and Virgo detectors because they are waves with too low a frequency, however it might be possible to detect them with the new space detector called LISA of the European Space Agency that should be launched around the mid 2030s.

Ketogenic diet protects gnats’ brains from concussions

According to a team of researchers the fruit fly version of the ketogenic diet of humans, a diet regimen that can also be used to lose weight, can be very useful for this animal to reduce aggression after concussions. It is of this opinion a research group of the University of Connecticut that published a study on Frontiers in Neuroscience.

Concussion studies are becoming more and more numerous since a kind of scandal has erupted regarding the impact of American football on professional athletes, impacts that for many of these athletes seem to have caused permanent brain damage. And since the concussion treatments themselves are quite scarce, as Derek Lee, a researcher involved in the study, admits, research like this may prove to be very useful and not as useful to themselves as it might seem.

According to Lee himself, who worked with neurobiologist Geoff Tanner, concussions can kill brain cells through so-called excitotoxicity. The latter is a phenomenon that sees cells become excessively excited precisely because of injuries to the skull and consume all the glucose, a substance that they need to produce energy. This leads them to death.

However, glucose itself is not the only source of energy for brain cells: they can also function thanks to the so-called ketone bodies produced by fats. They can metabolise them instead of glucose and can remain “calmer”, preventing convulsions and, in the case of concussions, excitotoxicity.

In order to prove this theory, researchers have carried out experiments on fruit flies. They took several male specimens and inserted them in a particular device that simulated the traumatic impact on the head that a human being who is diagnosed with a concussion may have.

After these repeated brain injuries the researchers divided the gnats into two groups: one fed a normal carbohydrate diet and the other fed a diet supplemented with beta-hydroxybutyrate, a ketone body, therefore a diet very close to what can be considered the ketogenic diet for humans.

The gnats of the first group, those of the traditional diet, were more aggressive among themselves when confronted with a female specimen than the males of the second group fed on a ketogenic diet. According to the researchers, such a diet may work as a treatment to protect injured brain cells and help them recover, at least in fruit flies. The researchers now want to find out whether such effects could also occur with regard to concussions in humans.

Six new exoplanets very close to their star have been discovered with a new technique

Through three studies published in Nature Astronomy, a team of astronomers announced the discovery of six exoplanets using a new method. These planets are so close to their stars that they are evaporating and this phenomenon in turn leads to the creation of a ring of debris and gas. Precisely the detection of this ring, which then interferes in a particular way with the light from the same star, has allowed researchers to identify the same planets and this method could also prove useful in the future to detect further exoplanets that are at a similar stage.

The idea came in 2009 when astronomer Carole Haswell, from the Open University, England, examined Wasp-12b, a gaseous exoplanet that orbited very close to the star so that a year lasted only 26 hours. This close proximity caused the outer layers of this planet’s atmosphere to get lost in space and form a gas trail that interfered with the star’s light itself.

It was then that the same group of astronomers jumped at the idea of finding debris and trails like these to discover the exoplanets. That’s why Haswell herself, together with her colleagues, set up a new project, called the Dispersed Matter Planet Project, and checked 2700 Sun-like stars and discovered the same effect in relation to the disturbance of the light they emitted.

They then used more powerful telescopes to understand in greater detail what was happening around the stars showing this phenomenon and discovered in particular four exoplanets orbiting the star DMPP-1 and two others, one orbiting the star DMPP-2 and another around the star DMPP-3.

All six planets orbit around their stars much closer than Mercury is to the Sun. And all six were discovered using the above technique (confirmation of their existence was then obtained by the radial velocity method that examines the gravitational oscillations of the star induced by the planets themselves).

On the other hand, if this particular technique had not been used, these planets would probably have been imperceptible (at least with the techniques we have now) precisely because they were too close to their star. Haswell herself is enthusiastic about this new technique for the discovery of extrasolar planets, “a success beyond my wildest dreams”, as she says in Scientific American.

By the way, Venus herself may have gone through a similar phase in her past. Several models of the evolution of this planet, in fact, suggest that it has lost much of its water and atmosphere in the distant past precisely because of its proximity to the Sun and this dispersion of material has perhaps produced a similar trail.

Pioneer probes 10 and 11 and Voyager 1 and 2: here’s what they’ll do in the future

What about the NASA Pioneer 10 and 11 and Voyager 1 and 2 probes launched during the 1970s? It is to answer this question as precisely as possible that two researchers, Coryn Bailer-Jones and Davide Farnocchia, have published a study in Research Notes of the AAS.

Through complex calculations and also using data from the Gaia space telescope on the precise position of millions of stars, the two researchers have in fact traced the precise trajectories that the four spacecraft will undertake over the next thousands and millions of years and their approaches to star systems outside the solar system.

All four surveys are in the process of exiting our solar system and will approach about 60 stars over the next million years. The first real approaches (flyby) will see three of these spacecrafts (all except Pioneer 10) arrive near Proxima Centauri at distances ranging from 0.87 parsec to 1.07 parsec. This star is a red dwarf that is part of the triple star system of Alpha Centauri considered the closest star to the Sun.

Voyager 1 will flyby the nearest flyby near the star TYC 3135-52-1. The other two closest flybys will be to the stars Gaia DR2 2091429484365218432 and HD 28343. As for Voyager 2, the closest match will be the one near the star Ross 248 (0.5 parsec) while the second will be with the star Gaia DR2 4370380741264455296 (0.5 parsec).

Pioneer 10 will produce its closest encounter with the star HIP 117795 when, in about 90,000 years, it will pass to about 0.231 parsec from the star.

Pioneer 11 will make its closest flyby with the star TYC 992-192-1 (0.24 parsec) and its second closest flyby with the star Gaia DR2 454473057495679385 (0.43 parsec). In 1.2 million years, Pioneer 11 will also move to 0.8 parsec (2.6 light years) from the Delta Scuti star. This star, 202 light years away from us at the moment, just during the time of Pioneer 11’s close passage, will approach at a distance of only 11.6 light years becoming the brightest star that will appear in the Earth’s sky at that time, brighter even than Sirius today.

And as for the danger that these probes will have to face of being “captured” by any star system and therefore start an almost perennial orbit around one of these stars you can be more or less calm: researchers have calculated that such an eventuality should not happen, statistically speaking, before 1020 years (1 followed by 20 zero years or 100 billion billion years).

Whales use stealth to catch fish

Whales can be very stealthy, despite their size, when they have to catch fish to feed. This was discovered by a team of researchers led by David Cade, author of the study published in Proceedings of the National Academy of Sciences.

The researchers at Stanford ensure that whales know how to use stealth and deception, an apparently paradoxical feat, to catch fish during their “sinking” actions. The sinking is a predatory technique used by whales when they throw themselves underwater to catch as many fish as possible in the middle of a shoal, opening their mouths as much as possible and then filtering the excess water and swallowing only the animals.

Initially the scientists, as Cade himself states in the article presenting the study, wanted to understand why the fish, grouped in large schools, could not escape when this huge animal was approaching, so big that it was really very difficult not to see it.

By also conducting laboratory experiments that simulated the escape reaction of anchovies to a virtual whale and using the behaviour of real whales near the bay of Monterey, California, monitored by tags mounted on their bodies, the researchers came to the conclusion that the whale manages to avoid triggering the escape response of the fish with a precise timing when it opens its mouth in the middle of the shoal.

They manage to make up for their lack of speed and manoeuvrability, being quite large animals, opening their mouths only at the right time and sneaking relatively close to their prey. “This made sense when we realized that the fish have evolved to avoid being eaten by small predators for at least 100 million years, but feeding with lunges is a relatively new feeding strategy, in evolutionary terms”, reports Cade himself.