#radio_astronomy

Scientists have observed long-term emission of radio waves arising above sunspots and reminiscent of the “northern lights” on Earth A sunspot is not just an area on the Sun's surface with a relatively cool temperature. This is an area where the magnetic field is especially strong. A recent study by a team of astronomers at the New Jersey Institute of Technology's Center for Solar-Terrestrial Research (NJIT-CSTR) found that long-lasting polarized radio bursts occur over such sunspots, lasting for several weeks. These radio wave bursts are reminiscent of the phenomena we can see as the “northern lights,” or aurora, on Earth and other planets in the solar system, including Jupiter and Saturn. On Earth, “auroras” arise under the influence of solar activity, which is accompanied by emissions of charged particles interacting with atoms in the atmosphere. These particles, especially accelerated electrons, produce intense radio emissions at certain frequencies. [caption id="attachment_83281" align="aligncenter" width="650"] Radio sunspot[/caption] Radio sunspot aurora offers new insight into the interaction of energetic particles and magnetic fields However, the observed radio wave bursts over sunspots have their own characteristics. First, they are long-lasting, lasting several weeks, which is different from regular solar radio bursts, which last for a few minutes or hours. Secondly, their spectrum differs from previously known radio disturbances. The team believes that the reason for these phenomena lies in the capture of high-energy electrons by the magnetic fields of the sunspot, which interact with the cooler and more intense magnetic regions of the sunspot, creating a favorable environment for the occurrence of magnetic resonance electron cyclotron maser emissions (the process of generating electromagnetic waves in the vicinity of sunspots). ). Magnetic resonance emissions occur when energetic electrons, in the presence of a strong magnetic field, experience a resonant interaction with the magnetic fields of a sunspot. Magnetic resonance occurs as a result of the fact that the frequency of an electron's revolution around a magnetic line corresponds to the frequency of electromagnetic waves generated by this process. A cyclotron maser is a phenomenon of amplification of electromagnetic waves in the presence of a strong magnetic field. In the context of sunspots, this means that electrons, under the influence of the sunspot's magnetic field, are accelerated and emit electromagnetic waves in certain frequency ranges. This phenomenon plays a significant role in the formation of observed radio wave bursts over sunspots. The discovery is of great importance for understanding the processes occurring in the magnetic fields of stars. It can contribute to the development of new models and theories because it offers new evidence for the interaction of energetic particles and magnetic fields in the vicinity of sunspots. New observations may help link magnetic phenomena on the Sun with similar phenomena in the atmospheres of other stars. Such a comparison may lead to a revision of existing models of stellar magnetism and the study of its physical nature.

The world's largest radio telescope observed Barnard's Star in search of signals from alien civilizations Barnard's Star is a small red dwarf star located just six light years from Earth. Despite its proximity, it was discovered only in 1916, when E.E. Barnard discovered a particularly high intrinsic velocity of this star. It was seen on Harvard Observatory photographic plates taken in the late 1800s, but as a small and faint star, it received little attention. But since then, Barnard's star has become one of the most studied red dwarfs. Barnard's Star was one of the first stars to have planets discovered. Already in the 1970s, it was announced that there were giant planets in the orbit of this star, but further observations refuted these results. Then in 2018, astronomers measured the star's radial motion, indicating the presence of an exoplanet around 3 Earths in mass around the star. However, subsequent observations refuted this discovery, indicating that the radial fluctuations seen earlier were caused by starbursts. Recent studies have confirmed that Barnard's star does not have nearby planets that could be larger than 70% of the size of Earth and potentially habitable. [caption id="attachment_62723" align="aligncenter" width="780"] FAST radio telescope[/caption] The FAST radio telescope scanned Barnard's Star in search of extraterrestrial signals This makes Barnard's star somewhat unusual since most red dwarfs have planets. For example, the star Kepler-42, similar in size and age to Barnard's star, has at least three exoplanets. So while Barnard's Star isn't a strong candidate for extraterrestrial life, a recent study has made detailed observations of the star looking for signs of an alien signal. The study used the 500-meter spherical radio telescope FAST. The Chinese telescope has an antenna design similar to the Arecibo Observatory but is significantly larger. FAST operates in the frequency range from 70 MHz to 3 GHz, making it a good tool for searching for alien life. During the study of Barnard's Star, the astronomer looked for emissions that might be noticeable if an alien civilization were sending radio messages in our direction. The team focused its search on signals coming from Barnard's hypothetical super-Earth b and took into account the Doppler effect caused by the relative motion between it and Earth. As might be expected, the study found no evidence of an alien signal. However, this study was mainly a test of the capabilities of the FAST telescope. Future studies, especially those aimed at nearby stars with confirmed planets in the habitable zone, will have a higher chance of detecting signals.