News

Comet C/2020 F3 (Neowise) above the Hans Haffner Observatory

For a comet of this size - the diameter is estimated by NASA to be about 5000 meters - this celestial object was discovered unusually late, only in spring this year. On March 27th, 2020, NASA's Wide-Field Infrared Survey Explorer (WISE) detected the comet as part of the NEOWISE project, which scans the southern sky. Already on July 3rd, comet C/2020 F3, as it has been correctly named since then, reached its perihelion, the point closest to the sun on its elliptical orbit. Comets consist mainly of ice, which is made of water, carbon monoxide and carbon dioxide, and dust - which is why astronomers call them dirty snowballs. When such an ice ball approaches the sun, the volatile part of the matter begins to evaporate and forms the coma (shell) around the comet's core. By the solar wind a part of the coma is pushed away, which can be seen as a tail. From the beginning of July, NEOWISE, as its colloquial name is known, could be observed very well in the morning sky above the Hans Haffner Observatory. As he now moved away from the sun again, he became darker with each passing day. At the same time, visibility shifted further forward during the course of the day, so that from mid-July onwards it could also be seen in the evening sky. On 23rd July it had reached the smallest distance to the earth with 103.5 million km. In the following nights the brightness of this tail star decreased more and more and since the beginning of August it is no longer visible with the naked eye. If it survives its journey through space undamaged, C/2020 F3 will not pass earth again for another 6700 years.

New cell disruption process established

Bacteria can be genetically modified to produce specific proteins. In the pharmaceutical industry, for example, human insulin is produced in this way. In the student laboratory, transgenic Escherichia coli bacteria are used to synthesize fluorescent proteins. Originally, the gene for the green fluorescent protein (GFP) comes from the jellyfish Aequorea victoria. This protein can be excited to green fluorescence with ultraviolet light. The GFP was first described in 1962 by the Japanese biochemist Osamu Shimomura. In modern research, GFP and the variants emanating from it are an important tool for studying the spatial and temporal distribution of proteins in a cell. For this purpose, the GFP gene is coupled with the protein gene under investigation. If this gene is now expressed, the GFP is also synthesized. By irradiation with UV light, the GFP starts to glow and thus the time and place of occurrence of the protein under investigation can be determined. In the meantime, there are numerous proteins that fluoresce in all colors. In the student laboratory we produce bacteria that produce either a green (GFP) or a red (RFP) fluorescent protein. After the transgenic bacteria were incubated overnight, they produced the protein. This protein is then extracted from the bacteria by "cracking" the bacteria. In the absence of other alternatives, cell disruption in the school lab has so far been done by enzymatic digestion with lysozyme. This procedure was very lengthy and not very successful. Now, an ultrasound disintegrator for mechanical cell disruption with ultrasound could be purchased and the new procedure implemented in the student laboratory. The ultrasound disintegrator transmits high-energy ultrasound waves into the bacterial suspension with a sonotrode tip. The resulting cavitation forces (cavitation: formation and dissolution of gas bubbles) cause the bacterial cells to collide violently with each other and thus break up. This releases the cell contents including the proteins. The proteins can now be purified accordingly and obtained in pure form. This process was established by the former FKG students Jannik Kania and Julius Klamt, who study chemistry and biology at the University of Würzburg.

Brightness maximum of AGN OJ 287 discovered

The brightness of the blazar OJ 287 has been regularly determined by us since the beginning of the research project "AGN-Monitoring". From the end of March 2020 we could observe an increase in brightness of this object, which peaked on April 26th of 2020. During these almost six weeks the brightness of this Active Galaxy Nucleus (AGN) increased by 1.25 magnitudes and decreased again afterwards. This discovery was published in an ad-hoc announcement in Astronomer's Telegram worldwide. The Astronomer's Telegram is an Internet platform where significant astronomical events are quickly spread around the world so that they are documented and can be verified all over the globe. The students' measurements and evaluations matched very well with the observations of other working groups. The monitoring of AGN at the Hans Haffner Observatory is carried out in coordination with the MAGIC collaboration, which operates a telescope system for gamma radiation on the Canary Island of La Palma. Unfortunately, parallel measurements could not be performed there due to the corona shut-down. OJ 287 is located in the constellation of Cancer, is 3.5 billion light years away from earth and contains one of the largest known black holes, with 18 billion solar masses. This supermassive black hole is orbited by a smaller second black hole, which weighs about 100 million solar masses and takes about 12 years to orbit. During this orbit, it passes twice through the accretion disk of the central black hole, which leads to strong disturbances of the jet emanating from it. This is also reflected in brightness fluctuations observed from earth. Due to the brightness outbursts it was possible to determine the masses of this binary system of black holes very precisely. The orbit of the small black hole could also be determined very precisely. It was also found that the two black holes converge and merge in 10 000 years. Therefore, OJ 287 is also an interesting object for measuring gravitational waves with the planned space interferometer LISA. The project "AGN-Monitoring" in cooperation with the Chair of Astronomy of the University of Würzburg and the Chair of Experimental Particle Physics 5b of the Technical University Dortmund exists since 2012.