Multiple supernovas may have implanted our solar system with the seeds of planets

rod

Oct 22, 2019
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This is a good report. Here are some others on this 26-Al find. Nearby star-forming region yields clues to the formation of our solar system, https://phys.org/news/2021-08-nearby-star-forming-region-yields-clues.html

Reference paper, A Solar System formation analogue in the Ophiuchus star-forming complex, https://www.nature.com/articles/s41550-021-01442-9, 16-August-2021.

[My observation. An important statement in this report on 26-Al and planet formation. “A key ingredient here is aluminum-26, an element built inside of stars and one that has a relatively short lifetime of roughly 100,000 years. Because the first planets likely took a billion years or so to form, this element's presence suggests a nearby source…The explanation of aluminum-26's arrival from multiple stellar deaths doesn't come without its challenges. In order to match observations from meteorites, scientists need to not only address the quantity of aluminum, but also to explain a so-called "global reset" of the aluminum in the stellar disk to synchronize their radiogenic clocks to give them the same apparent formation period. Such a reset would require a global heating event that would vaporize all of the solids in the solar system…According to Ciesla, the short period of CAI formation may be due to a combination of the small time frame that encompasses when the sun was both hot enough to form CAIs including aluminum-26 and distribute the CAIs in the disk through its evolution. Such a process has been explored by several researchers, including Ciesla.” My note. The report concerns Ophiuchus region. This is about 140 pc distance with stars that have some disks reported and young ages, some 2 to 6 million years old. How 26-Al with a lifetime ~ 100,000 years could be incorporated into the disks observed in Ophiuchus region and meteorites is not clear, especially when the source for the 26-Al reported is not in the Ophiuchus region, thus the time for 26-Al migration to that area is critical. The article says, “He also pointed out that the aluminum-26 his team observed is centered on the cluster of massive stars next door to Ophiuchus.” My note. Here is a NASA ADS Abstract on the ages found in the region and distance. A Survey for New Stars and Brown Dwarfs in the Ophiuchus Star-forming Complex, https://ui.adsabs.harvard.edu/abs/2020AJ....159..282E/abstract, June 2020. "We have performed a survey for new members of the Ophiuchus cloud complex using high-precision astrometry from the second data release of Gaia, proper motions measured with multi-epoch images from the Spitzer Space Telescope, and color-magnitude diagrams constructed with photometry from various sources. Through spectroscopy of candidates selected with those data, we have identified 155 new young stars. Based on available measurements of kinematics, we classify 102, 47, and 6 of those stars as members of Ophiuchus, Upper Sco, and other populations in Sco-Cen, respectively. We have also assessed the membership of all other stars in the vicinity of Ophiuchus that have spectroscopic evidence of youth from previous studies, arriving at a catalog of 373 adopted members of the cloud complex. For those adopted members, we have compiled mid-infrared photometry from Spitzer and the Wide-field Infrared Survey Explorer and have used mid-infrared colors to identify and classify circumstellar disks. We find that 210 of the members show evidence of disks, including 48 disks that are in advanced stages of evolution. Finally, we have estimated the relative median ages of the populations near the Ophiuchus clouds and the surrounding Upper Sco association using absolute K-band magnitudes (MK) based on Gaia parallaxes. If we adopt an age 10 Myr for Upper Sco, then the relative values of MK imply median ages of ∼2 Myr for L1689 and embedded stars in L1688, 3-4 Myr for low-extinction stars near L1688, and ∼6 Myr for the group containing ρ Oph." The arXiv paper link, https://arxiv.org/pdf/2005.10096.pdf, " Using the available parallaxes with σπ/π < 0.1 from Gaia DR2 for our adopted members, we measure median distances of 138, 145, 137, and 140 pc for the groups toward L1688, L1689, L1709, and ρ Oph, respectively." My note. I adopt 140 pc distance in this record. The arXiv paper has 32 references to disks. I did not see reported gas and dust disk masses.]
 
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