- 3493 - YTTERBIUM - discovered in galaxies? A research team led by Lund University in Sweden has provided an important clue to the origin of the element Ytterbium in the Milky Way The element largely originates from supernova explosions
--------------------- 3493 - YTTERBIUM - discovered in galaxies?
- Ytterbium (Yb) is one of four elements in the periodic table named after the Ytterby mine in the Stockholm archipelago. The element was first discovered in the black mineral gadolinite, which was first identified in the Ytterby mine in 1787.
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- Ytterbium may have two different cosmic origins. Researchers believe that one half comes from heavy stars with short lives, while the other half comes from more regular stars, much like the sun, and that they create Ytterbium in the final stages of their relatively long lives.
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- By studying stars formed at different times in the Milky Way, we have been able to investigate how fast the Ytterbium content increased in the galaxy. What we have succeeded in doing is adding relatively young stars to the study.
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- It has been speculated that Ytterbium was thrown into space by supernova explosions, stellar winds and planetary nebulae. There, it accumulated in large space clouds from which new stars formed.
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- By examining high-quality spectra of about 30 stars in the sun's vicinity, the researchers were able to provide important experimental support for the theory of the cosmic origin of Ytterbium. It seems that Ytterbium largely originates from supernova explosions.
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- The instrument we used is a super-sensitive spectrometer that can detect infrared light in high resolution. It was used with two telescopes in the southern United States, one in Arizona and one in Texas.
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- Since the Ytterbium analysis was done using infrared light, it will now be possible to study large areas of the Milky Way that lie behind impenetrable dust. Infrared light can get through the dust in the same way that red light from a sunset can get through the Earth's atmosphere.
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- This study opens up the possibility of mapping extensive parts of the Milky Way that have previously been unexplored. This means that we will be able to compare the evolutionary history in different parts of the galaxy.
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- Measuring the abundances of neutron-capture elements in Galactic disk stars is an important part of understanding key stellar and galactic processes. In the optical wavelength regime a number of different neutron-capture elements have been measured, however from the infrared H-band only the “s-process’ dominated element cerium has been accurately measured for a large sample of disk stars.
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- The more ‘r-process’ dominated element ytterbium has only been measured in a small subset of stars so far. The aim is to measure the ytterbium (Yb) abundance of local disk giants using the
- “Yb II’ line at λair = 16,498Å, angstroms
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- Then compare the resulting abundance trend with “Ce” and “Eu’ abundances for the same stars to analyze the s- and r-process contributions. They analyze 30 K-giants with high-resolution H-band spectra using spectral synthesis.
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- The very same stars have already been analyzed using high-resolution optical spectra using the same method, but the abundance of Yb was not possible to determine from those spectra due to blending issues for stars with [Fe/H] > -1.
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- This analysis utilizes the stellar parameters determined from the optical analysis. They determined the Yb abundances with an estimated uncertainty for [Yb/Fe] of 0.1 dex.
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- From comparison, the trend of [Yb/Fe] follows closely the [Eu/Fe] trend and has clear s-process enrichment in identified s-rich stars. From the comparison, both the validity of the Yb abundances are ensured, and the theoretical prediction of a roughly 40/60 s-/r-process contribution to Yb's origin is supported.
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- These results show that with a careful and detailed analysis of infrared spectra, reliable Yb abundances can be derived for a wider sample of cooler giants in the range
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----------------------------- -1.1 < [Fe/H] < 0.3.
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- This is promising for further studies of the production of Yb and for the r-process channel, key for Galacto-chemical evolution, in the infrared.
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March 5, 2022 YTTERBIUM - discovered in galaxies? 3493
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