Webb

The Webb Telescope observed the black hole in the center of the Milky Way. Has discovered a chaotic light show

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Three years ago we saw for the first time The Supermassive Black Hole that inhabits the center of our galaxy. Now the James Webb space telescope has opened a window to study its surroundings. And it has turned out to be a chaotic show of lights that never stops. Context. In the center of the Milky Way inhabits A gigantic black hole called Sagittarius a*. Astronomers have managed to unravel the extreme dynamics of their accretion disk, the spiral of gas and dust that turns around it. To do this, they observed it for 48 hours (distributed in several periods of 2023 and 2024) using the Nircam instrument of the Webb Telescope. A disco ball. The observations revealed that sgr a* emits A continuous game of lights and flashes which is characterized by constant blinking interspersed with a series of intense eruptions. These emissions have a weak and continuous component, probably originated in the internal turbulence of the disc, and a bright and short -term component, eruptions associated with magnetic reconnection, in which magnetic fields collide and release huge amounts of energy. Fluctuations can occur in seconds or as changes that extend for days, weeks and months. The explanation. The study of these variable emissions, published in The Astrophysical Journal Letterssuggests that fluctuations intensify at major scales. According to researchers, the small internal disturbances of the disk, associated with fluctuations in density and magnetic field, generate the faint flashes, while large eruptions are related to specific events of magnetic reconnection, comparable to the solar flares, but at levels much older energy. “In our data we observe a constantly changing luminosity,” Farhad Yusef-Zadeh explainsmain author of the study. “Suddenly, Boom! A great explosion of brightness appears suddenly and then calms down, without following a fixed pattern.” This nature, apparently random, demonstrates that the accretion disc is regenerated all the time, causing between five and six and six Great daily rashes, in addition to multiple intermittent outbreaks. The lags. An advantage of the NIRCAM instrument of the Webb Telescope is its ability to observe two infrared wavelengths simultaneously (2.1 and 4.8 micrometers). This allowed researchers to compare how the brightness of eruptions with each wavelength changed. Surprisingly, they discovered that the events observed in the shortest wavelength changed shine a little before the events of the longest. “It is the first time that we see a delay in the measurements of these wavelengths,” said Yusef-Zadeh. “We notice that the longest wavelength is delayed between three and 40 seconds.” This finding is a key clue that energy particles lose energy as they cool, a process known as syncrotron cooling. New observations. Researchers now plan to make a continuous observation of up to 24 hours from SGR A* using the Webb Telescope, which will help them determine if eruptions follow repetitive patterns or if they are truly random. Each flash and every flicker on the accretion disk of the supermassive hole offers us a deeper understanding of physics on the events horizon, one of the most extreme environments in the universe. In other words, it helps us discover how space-time and matter behave under the influence of overwhelming gravity. Image | NASA, ESA, CSA, RALF CRAWFORD (STSCI) In Xataka | The Webb Telescope has managed to penetrate the nucleus of a neighboring galaxy, home to a furiously active black hole In Xataka | Telescopes from all over the world worked together in this image: the black hole of the Milky Way and its magnetic fields

There is a 2% probability that the asteroid impact the earth, but we will not know how much it measures until the webb observes it

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He Asteroid 2024 YR4 He has aroused unusual interest since his discovery on December 27. Although the probability of impact with the earth remains very low, has risen from 1 to 2% As new observations are obtained. However, astronomers are having difficulty measuring their size and have decided to resort to the most powerful space telescope in history to get out of doubt. There is a problem in how an asteroid is measured. Until now, the size estimates of 2024 YR4 have oscillated between 40 and 90 meters in diameter, a too wide range to assess the danger that would represent an eventual impact with our planet. This lack of precision has a reason and is that The size of the asteroid is calculated from the reflected visible lighta method that depends on the reflectivity of its surface. 2024 YR4 could be an object of 40 meters very reflective or an object of 90 meters very dark. As well as any intermediate option. The James Webb space telescope to the rescue. Unlike other observatories, The 10,000 million dollar telescopeoperated by NASA, ESA and the Canadian space agency, does not observe the visible spectrum, but the infrared spectrum, and with an unprecedented sensitivity. Astronomers will allocate hours of webb use to analyze the infrared light emitted by the asteroid to obtain a more precise measurement of its size and temperature. With luck, it will allow them to discern whether 2024 YR4 is at the lower or upper end of the estimated range, crucial information to better evaluate the consequences of their unlikely but possible impact. Two rounds of observation are planned. Space agencies have foreseen Two rounds of crucial observations With the Webb Telescope. The first will take place in early March, when the asteroid is at its point of greatest brightness and visibility for the telescope. The second round, scheduled for May, will allow scientists to study how the object temperature varies as it moves away from the sun, in addition to continuing to obtain data on its trajectory when the object has ceased to be visible by terrestrial telescopes. Why fluctuate the probability of impact. The 2% estimate is the most up -to -date ES has provided so far (NASA publishes a 2.1% estimate). The figure varies constantly because the calculations have been incorporating new observations that reduce the uncertainty of their trajectory. These fluctuations are, in fact, typical behavior in the estimation of the impact risk of newly discovered objects. NASA planetary defense equipment and ESA are based on orbital dynamic systems (such as Scout, Sentry, Meerkat and Aegis) that generate multiple possible trajectories for the asteroid. As less likely orbits are discarded, targeting on Earth may increase the fraction of possible impacts, although, over time, additional observations allow the threat to definitively discard. If this were not the case with 2024 YR4, we would be talking about a meteorite that could fall in countries as populated as Colombia, Nigeria or India on January 22, 2032. Then we would start talking about a mission to divert it, a task in the that We already have some practice. Image | Two of the 18 mirrors of the Webb Telescope (NASA/C. GUNN) In Xataka | The impact probability of asteroid 2024 YR4 has risen to 1.6%. The UN has already activated a special protocol

The probability that the asteroid falls on Earth has risen to 2.3%. Even the Webb Telescope is monitoring it

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The last NASA calculations They place the probability that the asteroid 2024 YR4 impact with the land by 2.3%, a figure that the European Space Agency (ESA) has confirmed with Its own 2.27% estimate. For those who have lost their account, in just one week of observations We have gone from 1 between 83 possibilities that the asteroid crosses the planet Earth to 1 between 43. The options are still low, but they are high enough for the offices of NASA planetary defense and that They have intensified their monitoring efforts. To the James Webb space telescope, 10,000 million dollars, will be monitoring The little asteroid. 2024 YR4 is not much, but with A diameter of between 40 and 90 meterscould destroy an entire city if it survived the reentry and impact an urban area. When? On January 22, 2032. Where? At some point in the strip that extends from the East of the Pacific Ocean to northern South America, the Atlantic Ocean, Africa, the Arabian Sea and the south of Asia. It should be noted that These impact estimates They are calculated taking as reference the quotient between the diameter of the earth and the width of the area of ​​uncertainty of the asteroid, generated from simulations. The problem: 2024 YR4 is moving away from Earth In an elliptical trajectorywhich hinders its detection with conventional instruments. In a few weeks it will have become so faint that even professional four -meter telescopes have trouble capturing it. As of April, it will be necessary to resort to the Webb or the Vary Large Telescope of the Austral European Observatory to continue watching it until the object reappears In June 2028. The monitoring of the trajectory of an asteroid is a dynamic process that surely gives us a roller coaster of emotions. As more observations from the asteroid and its trajectory have, the probability of impact could increase again and then progressively reduce until reaching zeroconfirming the main hypothesis: that the asteroid will pass by instead of colliding with the earth. If not, the good news is that humanity has experience in asteroid diversion. In 2022, NASA’s dart mission He showed that it is possible to alter the trajectory of a spatial object through a kinetic impact. This historical achievement is the empirical test that we have the technology and knowledge necessary to at least try to protect our planet. Meanwhile, the UN has put on alert the Space Missions Advisory Group (SMPAG), which agreed to meet again at the end of April or early May to study possible mitigation measures in case the probability of impact is maintained or increased . Image | Daniel Bamberger In Xataka | The impact probability of asteroid 2024 YR4 has risen to 1.6%. The UN has already activated a special protocol

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