skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


  • NSF Public Access
  • Search Results
  • Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53 Mn, 60 Fe, 182 Hf, and 244 Pu into Deep-sea Archives. Surfing the Wave?
Title: Inhomogeneous Enrichment of Radioactive Nuclei in the Galaxy: Deposition of Live 53 Mn, 60 Fe, 182 Hf, and 244 Pu into Deep-sea Archives. Surfing the Wave?
Abstract While modeling the galactic chemical evolution (GCE) of stable elements provides insights to the formation history of the Galaxy and the relative contributions of nucleosynthesis sites, modeling the evolution of short-lived radioisotopes (SLRs) can provide supplementary timing information on recent nucleosynthesis. To study the evolution of SLRs, we need to understand their spatial distribution. Using a three-dimensional GCE model, we investigated the evolution of four SLRs:53Mn,60Fe,182Hf, and244Pu with the aim of explaining detections of recent (within the last ≈1–20 Myr) deposition of live53Mn,60Fe, and244Pu of extrasolar origin into deep-sea reservoirs. We find that core-collapse supernovae are the dominant propagation mechanism of SLRs in the Galaxy. This results in the simultaneous arrival of these four SLRs on Earth, although they could have been produced in different astrophysical sites, which can explain why live extrasolar53Mn,60Fe, and244Pu are found within the same, or similar, layers of deep-sea sediments. We predict that182Hf should also be found in such sediments at similar depths.  more » « less
Award ID(s):
1927130
PAR ID:
10397482
Author(s) / Creator(s):
; ; ; ; ;
Publisher / Repository:
DOI PREFIX: 10.3847
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
944
Issue:
2
ISSN:
0004-637X
Format(s):
Medium: X Size: Article No. 121
Size(s):
Article No. 121
Sponsoring Org:
National Science Foundation
More Like this
  1. ; ; ; ; ; (, Astronomische Nachrichten)
    ABSTRACT We run a three‐dimensional Galactic chemical evolution (GCE) model to follow the propagation of53Mn (exclusively produced from type Ia supernovae, SNIa),60Fe (exclusively produced from core‐collapse supernovae, CCSNe),182Hf (exclusively produced from intermediate mass stars, IMSs), and244Pu (exclusively produced from neutron star mergers, NSMs). By comparing the predictions from our three‐dimensional GCE model to recent detections of53Mn,60Fe, and244Pu on the deep‐sea floor, we draw conclusions about their propagation in the interstellar medium. 
    more » « less
  2. ; ; ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract 244Pu has recently been discovered in deep-sea deposits spanning the past 10 Myr, a period that includes two60Fe pulses from nearby supernovae.244Pu is among the heaviestr-process products, and we consider whether it was created in supernovae, which is disfavored by nucleosynthesis simulations, or in an earlier kilonova event that seeded the nearby interstellar medium with244Pu that was subsequently swept up by the supernova debris. We discuss how these possibilities can be probed by measuring244Pu and otherr-process radioisotopes such as129I and182Hf, both in lunar regolith samples returned to Earth by missions such as Chang’e and Artemis, and in deep-sea deposits. 
    more » « less
  3. ; ; ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract The astrophysical sites where r -process elements are synthesized remain mysterious: it is clear that neutron star mergers (kilonovae (KNe)) contribute, and some classes of core-collapse supernovae (SNe) are also possible sources of at least the lighter r -process species. The discovery of 60 Fe on the Earth and Moon implies that one or more astrophysical explosions have occurred near the Earth within the last few million years, probably SNe. Intriguingly, 244 Pu has now been detected, mostly overlapping with 60 Fe pulses. However, the 244 Pu flux may extend to before 12 Myr ago, pointing to a different origin. Motivated by these observations and difficulties for r -process nucleosynthesis in SN models, we propose that ejecta from a KN enriched the giant molecular cloud that gave rise to the Local Bubble, where the Sun resides. Accelerator mass spectrometry (AMS) measurements of 244 Pu and searches for other live isotopes could probe the origins of the r -process and the history of the solar neighborhood, including triggers for mass extinctions, e.g., that at the end of the Devonian epoch, motivating the calculations of the abundances of live r -process radioisotopes produced in SNe and KNe that we present here. Given the presence of 244 Pu, other r -process species such as 93 Zr, 107 Pd, 129 I, 135 Cs, 182 Hf, 236 U, 237 Np, and 247 Cm should be present. Their abundances and well-resolved time histories could distinguish between the SN and KN scenarios, and we discuss prospects for their detection in deep-ocean deposits and the lunar regolith. We show that AMS 129 I measurements in Fe–Mn crusts already constrain a possible nearby KN scenario. 
    more » « less
  4. ; ; ; ; ; ; ; (, The Astrophysical Journal)
    Abstract Analysis of inclusions in primitive meteorites reveals that several short-lived radionuclides (SLRs) with half-lives of 0.1–100 Myr existed in the early solar system (ESS). We investigate the ESS origin of107Pd,135Cs, and182Hf, which are produced byslowneutron captures (thes-process) in asymptotic giant branch (AGB) stars. We modeled the Galactic abundances of these SLRs using theOMEGA+galactic chemical evolution (GCE) code and two sets of mass- and metallicity-dependent AGB nucleosynthesis yields (Monash and FRUITY). Depending on the ratio of the mean-lifeτof the SLR to the average length of time between the formations of AGB progenitorsγ, we calculate timescales relevant for the birth of the Sun. Ifτ/γ≳ 2, we predict self-consistent isolation times between 9 and 26 Myr by decaying the GCE predicted107Pd/108Pd,135Cs/133Cs, and182Hf/180Hf ratios to their respective ESS ratios. The predicted107Pd/182Hf ratio indicates that our GCE models are missing 9%–73% of107Pd and108Pd in the ESS. This missing component may have come from AGB stars of higher metallicity than those that contributed to the ESS in our GCE code. Ifτ/γ≲ 0.3, we calculate instead the time (TLE) from the last nucleosynthesis event that added the SLRs into the presolar matter to the formation of the oldest solids in the ESS. For the 2M⊙,Z= 0.01 Monash model we find a self-consistent solution ofTLE= 25.5 Myr. 
    more » « less
  5. ; (, Annual Review of Nuclear and Particle Science)
    Live (not decayed) radioisotopes on the Earth and Moon are messengers from recent nearby astrophysical explosions. Measurements of60Fe in deep-sea samples, Antarctic snow, and lunar regolith reveal two pulses about 3 Myr and 7 Myr ago. Detection of244Pu in a deep-sea crust indicates a recent r-process event. We review the ultrasensitive accelerator mass spectrometry techniques that enable these findings. We then explore the implications for astrophysics, including supernova nucleosynthesis, particularly the r-process, as well as supernova dust production and the formation of the Local Bubble that envelops the Solar System. The implications go beyond nuclear physics and astrophysics to include studies of heliophysics, astrobiology, geology, and evolutionary biology. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email