Scientists confirm the existence of a new class of galactic nebula

(ORDO NEWS) — For the first time, scientists, since the discovery of amateur scientists, have been able to confirm the existence of a fully developed common envelope in a binary star system.

The starting point for this unique discovery is a group of German-French amateur astronomers who painstakingly searched for unknown objects in historical images of stars in currently digitized archives, and finally found a fragment of the nebula on photographic plates of the 1980s.

For their find, the group turned to international scientific experts, including the Department of Astrophysics and Particle Physics of the University of Innsbruck, which has extensive experience in this field. By collecting and combining observations over the past 20 years from the public archives of various telescopes, as well as data from four space satellites, the Innsbruck researchers were able to rule out their first assumption, namely the discovery of a planetary nebula formed by the remnants of dying stars.

The enormous size of the nebula became apparent thanks to measurements made by telescopes in Chile. Scientists from the United States have finally supplemented these observations with spectrographs. “The diameter of the main cloud is 15.6 light years across, which is almost 1 million times the distance from Earth to the Sun and much more. than the distance from our Sun to the nearest neighboring star.

In addition, fragments were found 39 light-years apart. Since the object lies slightly above the Milky Way, the nebula could have evolved with little or no disturbance from other clouds in the surrounding gas, “says Kimeswenger of the discovery.

“Towards the end of their lives, ordinary stars swell into red giant stars. Since a very large part of stars are in binary systems, this affects evolution at the end of their life. In close binaries, the swelling outer part of a star merges into a common envelope around both stars.

However, within this shell of gas, the cores of the two stars are practically intact and follow their evolution as independent single stars, ”explains astrophysicist Stefan Kiemeswenger from the University of Innsbruck. The researchers published their findings in the journal Astronomy & Astrophysics.

It is known that many stellar systems are the remnants of such evolution. Their chemical and physical properties serve as fingerprints. In addition, stellar systems that are just about to form a common shell have already been discovered due to their specific and high brightness. However, a fully formed envelope and its ejection into interstellar space have not yet been observed in this form.

“These shells are of paramount importance to our understanding of the evolution of stars in their final stages. Moreover, they help us understand how they enrich interstellar space with heavy elements, which in turn are important for the evolution of planetary systems such as our own, ”explains Kimeswenger the importance of the newly discovered galactic nebulae.

He also explains why the likelihood of their discovery is low: “They are too large for the field of view of modern telescopes and at the same time very dim. In addition, their lifetimes are rather short, at least when viewed on a cosmic time scale. only a few hundred thousand years. ”

By combining all this information, the researchers were able to create a model of the object. It is a close binary system of 66,500-degree white dwarf stars and a normal star with a mass slightly less than the mass of the Sun. Both stars revolve around each other in just 8 hours 2 minutes at a distance of only 2.2 solar radii.

Another part of the mystery associated with the discovery of a new class of galactic nebulae has not yet been solved, says Stefan Kimeswenger: “It is even possible that this system is associated with the observation of a new star by Korean and Chinese astronomers in 1086. In any case, the positions of historical observation coincide very well with the positions of our object described here. ”


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