The Physics Nobel Prize 2020 was all about the most compact and massive objects in the universe, namely black holes. Roger Penrose (University of Oxford) received half of this year’s award for his work on the robust prediction of general relativity in the formation of black holes.
It was the Briton who documented the formation of black holes ten years after Albert Einstein’s death and described it in detail: as a singularity in which the well-known laws of nature are suspended. Einstein himself was not convinced of this during his lifetime, but as Penrose pointed out, these complex objects can be derived from general relativity.
the authors
Anneliese Haika is AHS teacher and member of the Vienna Working Group for Astronomy. Stefan Wallner is an astronomer at the University of Vienna.
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The other half of the prize is shared by Reinhard Genzel (Max Planck Institute for Extraterrestrial Physics, Garching) and Andrea Ghez (University of California, Los Angeles) for the discovery of a supermassive compact object in the center of our galaxy.
Through the precise observation of star movements in Sagittarius A *, the name of the region in the center of the Milky Way, it became clear that this can only be explained by the existence of an extremely massive, invisible object. This is a supermassive black hole with about four million solar masses and an extent no larger than our solar system, as Genzel and Ghez found through their observations.
Exoplanets in focus
Well over 4,000 planets around stars other than our sun, so-called exoplanets, have already been identified and the number is increasing continuously. The task now is to get to know this multitude of distant objects better and to categorize them. To get one step closer to this goal, the space telescope CHEOPS (“Characterizing Exoplanet Satellite”) of the European Space Agency ESA started operations this year and delivered the first scientific data.
WASP-189 b was measured, a giant gas planet that is 20 times closer to its star than the sun and whose temperature reaches up to 3,200 degrees. In addition, the orbit of this exoplanet is strongly inclined – it leads almost over the poles of the star. It is one of the most extreme planets found so far.
Two further European missions for the discovery and classification of exoplanets are in preparation. PLATO (“Planetary Transits and Oscillations of Stars”) is already under construction and is supposed to find mainly smaller rock planets around bright, sun-like stars. The mission ARIEL (“Atmospheric Remote-sensing Infrared Exoplanet Large-Survey”) got the green light for construction in November. This space telescope will primarily focus on the chemical composition and temperature of exoplanets. The planned start dates are 2026 for PLATO and 2029 for ARIEL.
Austrian institutes are involved in all three missions in important areas. The Institute for Astrophysics of the University of Vienna and that Institute for Space Research of the Austrian Academy of Sciences in Graz develop software and hardware for the space telescopes. In addition, both institutes are involved in the scientific evaluation of the data.
Visit to asteroids
The Japanese Mission Hayabusa 2 had the ambitious goal of bringing material from the near-Earth asteroid 162173 Ryugu to Earth. Launched in 2014, the spacecraft reached the small body in summer 2018. The following year, soil samples were taken from Ryugu.
The small capsule with this valuable material landed safely in the Australian desert at the beginning of December 2020. The space probe itself flew past Earth and is expected to perform new tasks in the planetary system over the next decade.
Another asteroid is currently visiting from Earth. The NASA mission OSIRIS-REx currently accompanies the asteroid 101955 Bennu and was able to take a soil sample in October of this year. This should be returned to Earth in 2023.
Asteroids of these types presumably contain primordial material from the early days of the solar system. It is hoped that the investigation of these soil samples will provide new insights into the formation of the inner planets and the origin of water on earth.
Both missions fulfill another important task: the precise investigation of the composition of near-Earth asteroids. The more details are known about it, the sooner a defense can succeed if one of these space chunks is on a collision course with the earth. But don’t worry: there is currently no known threat to our home planet.
The view of the sun
A further space probe was added to the fleet of satellites for solar observation at the beginning of the year. The Solar Orbiter, a mission of the European Space Agency ESA, observes the sun and its surroundings with 10 instruments, whereby the orbit around the sun becomes ever narrower. In two years’ time, the probe will fly past our star at a distance of only 48 million kilometers, comparable to the closest distance to the planet Mercury, the closest to the sun.
A key goal of the research is to predict space weather. Big eruptions on the sun throw billions of tons of charged particles into space. If such a “storm” hits the earth, satellites in orbit, among other things, can be damaged or fail completely. Solar Orbiter will therefore, together with 5 other space probes from NASA and ESA, closely monitor these events and investigate the causes of the eruptions. The first promising results have already been achieved.
The University of Graz and the Institute for Space Research of the Austrian Academy of Sciences are with Software and hardware components significantly involved in this international mission.
A star causes a stir …
Betelgeuse, a red supergiant with a radius 750 times that of our sun, is a popular destination for astronomical research. As a bright corner point in the conspicuous constellation Orion, it can also be easily observed with the naked eye. The star at a distance of about 725 light years is likely to be in the final stage of its life and thus on the verge of a supernova. At the beginning of this year, signs of the impending star explosion were believed to have been found.
Beginning in October 2019, the star’s luminosity apparently began to decrease, in February 2020 it was only a third of its brightness. But it didn’t stop there, just two months later, in April 2020, it reached its original brightness again. Such a variability of a red giant, insofar as it originates directly from it, may well be an indication of a subsequent supernova. So there was also great hope that the sky spectacle, which could also be seen in the sky during the day, could still be seen during the lifetime of current generations.
Observations by the Hubble Space Telescope (NASA / ESA) and the STELLA telescope from the Leibniz Institute for Astrophysics Potsdam (AIP) dashed these hopes. Velocity measurements of the outer layers of the stars showed that hot, ejected star material caused the Stimulated formation of dust.
It was this dust that saw the star from the earth darkened. So this “stellar sneeze” was responsible for the phenomenon and the wait for the visibility of Betelgeuse’s spectacular end of life as a supernova continues. How long? Opinions differ greatly here, the estimates speak of thousands to hundreds of thousands of years, astronomically therefore “shortly” before that, if we consider a whole star’s life.
Water on the moon
The moon’s surface is a dusty desert with extreme temperature fluctuations between day and night. All the more surprising was the discovery that traces of water can be found in sunlit craters. The infrared telescope SOFIA, a joint project of the German Aerospace Center and NASA, was able to Water molecules in the bottom of the Clavius crater prove. So far, water ice has been discovered in the ground of some craters near the south pole of the moon. However, these areas are permanently in shadow. It is puzzling how the water molecules that have now been discovered can survive at temperatures of up to +120 degrees Celsius.
Even if only about 0.3 l of water are assumed to be distributed in one cubic meter of lunar material on the surface, the discovery is important for future projects. Several space agencies and private initiatives are planning inhabited lunar stations in the not too distant future. Having water locally on the moon would be invaluable in this regard.
Probably no life on Venus
Phosphine – a well-known molecule, colorless, malodorous and highly explosive. On earth we know it from sewage, rice fields or through industrial production. Although we humans tend to avoid this inglorious molecule, it can serve as a label for biological organisms in oxygen-free environments of space.
So it was a big surprise when an international research team made observations with the James Clerk Maxwell telescope and the ALMA radio telescope of the European Southern Observatory significantly higher traces of this molecule on our neighboring planet Venus, as could be explained by non-biological processes. Is this a first indication of microbiological life in the Venusian atmosphere? In any case, this discovery in the higher cloud layers of the planet was considered very significant in this regard.
However, the disillusionment came only a few months later, because as the new processing of the originally obtained data showed, there were probably problems in the ALMA software that falsified the data – and so also the value for the amount of phosphine. In fact, the newly calculated value should only be a seventh of the primary results. Further analysis of the data is now necessary to finally answer the question about microbes in the clouds of Venus.
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