Scientists using NASA's Hubble Space Telescope have confirmed the presence of electrically charged molecules in football-shaped spaces that shed light on the mysterious content of the interstellar medium (ISM) – the gas and dust that fill the interstellar space ,
As stars and planets form collapsing gas and dust clouds in space, "the diffuse ISM can be viewed as the starting point for the chemical processes that ultimately create planets and life," said Martin Cordiner of the Catholic University of America , Washington. "Full identification of the content provides information about the ingredients available for generating stars and planets." Cordiner, who is based at NASA's Goddard Space Flight Center in Greenbelt, Maryland, is the lead author of a paper on this research published on April 22 in the Astrophysical Journal Letters (19459014). The molecules team identified by Cordiner and his colleague are a form of carbon called buckminsterfullerene, also known as buckyballs, consisting of 60 carbon atoms (C 60 ) arranged in a hollow sphere. C 60 has been found on Earth in rocks and minerals in some rare cases and may also occur in high temperature burned soot.
C 60 was seen in space ago. However, this is the first time that it has been confirmed that an electrically charged (ionized) version exists in the diffuse ISM. The C 60 is ionized when ultraviolet light from stars demolishes an electron from the molecule, giving the C 60 a positive charge (C 60 + ). "The diffuse ISM has historically been considered too rough and too thin for a significant amount of large molecules to occur," Cordiner said. "Before the detection of C 60 the largest known molecules in space were only 12 atoms in size, and our confirmation of C 60 + shows how complex astrochemistry can become"  Life, as we know it, is based on carbonaceous molecules, and this discovery shows that complex carbon molecules can form and survive in the harsh environment of interstellar space. "In some ways, life can be considered the ultimate measure of chemical complexity," said Cordiner. "The presence of C 60 clearly demonstrates a high degree of chemical complexity that is important for space environments, and suggests a strong likelihood of other extremely complex carbon-containing molecules being spontaneously formed in space."
Most of the ISM is hydrogen and helium, but it is spiked with many compounds that have not been identified. With the interstellar space so remote, the scientists study how it affects the light of distant stars to identify its contents. As starlight passes through space, elements and compounds in ISM absorb and block certain colors (wavelengths) of light. When scientists analyze starlight by dividing it into its component colors (spectrum), the absorbed colors appear weak or absent. Each element or compound has a unique absorption pattern that acts as a fingerprint and allows identification. However, some absorption patterns of the ISM cover a wider range of colors that are different from any known atoms or molecules on earth. These absorption patterns are called diffuse interstellar bands (DIBs). Their identity has remained a mystery ever since they were discovered by Mary Lea Heger, who published observations of the first two DIBs in 1922.
A DIB can be assigned by finding an exact match with the absorption fingerprint of a substance in the laboratory. However, there are millions of different molecular structures that need to be tested.
"Today, more than 400 DIBs are known, but (apart from the few that were re-attributed to C 60) + ), none has been clearly identified," said Cordiner. "Taken together, the appearance of DIBs indicates the presence of a large amount of high-carbon molecules in space, some of which may be involved in the chemistry that gives rise to life, but the composition and properties of this material remain unknown until the remaining DIBs have been assigned. "
Decades of laboratory investigations have not found exact agreement with any DIBs until work on C 60 + . In the new work, the team was able to adapt the absorption pattern of C60 + in the laboratory to that of Hubble observations of the ISM, confirming the recently claimed assignment by a team from the University of Basel, Switzerland, whose laboratory studies yielded the required results C 60 + comparative data. The major problem in detecting C 60 + using conventional ground-based telescopes is that the atmospheric water vapor blocks the view of the absorption pattern C 60 + . However, the Hubble telescope circles most of the atmosphere in space and has a clear, unobstructed view. Still, they still had to push Hubble far beyond his usual sensitivity limits to recognize the faint fingerprints of C 60 + .
The observed stars were all blue supergiants from the plane of our galaxy, the Milky Way. The interstellar material of the Milky Way is located primarily in a relatively flat disk, so that lines of sight to stars in the galactic plane traverse the largest amounts of interstellar matter and therefore have the strongest absorption characteristics due to interstellar molecules.
C 60 + in the diffuse ISM supports the team's expectations that very large, carbon-containing molecules are likely candidates for explaining many of the remaining, unidentified DIBs. This suggests that future laboratory tests will measure the absorption pattern of C60 + related compounds to identify some of the remaining DIBs. See how widespread buckyballs are in the Universe. According to Cordiner, C 60 + seems to be very widespread in the galaxy according to her previous observations.
Mysterious absorption lines of the stars could light up a 90-year puzzle
M.A. Cordiner et al., Confirming Interstellar C 60 + Using the Hubble Space Telescope, The Astrophysical Journal (2019). DOI: 10.3847 / 2041-8213 / ab14e5
Hubble finds tiny "electric footballs" in space and helps solve interstellar puzzles (2019, June 25)
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