{"id":795811,"date":"2025-05-01T03:21:05","date_gmt":"2025-05-01T08:21:05","guid":{"rendered":"http:\/\/spaceweekly.com\/?p=795811"},"modified":"2025-05-01T03:21:05","modified_gmt":"2025-05-01T08:21:05","slug":"origins-of-gold-traced-to-extreme-explosions-of-collapsed-stars","status":"publish","type":"post","link":"https:\/\/spaceweekly.com\/?p=795811","title":{"rendered":"Origins of gold traced to extreme explosions of collapsed stars"},"content":{"rendered":"
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Gold may not come from where you think. According to new research, some of the gold found in objects like phones and laptops could have been forged in violent magnetar explosions billions of years ago.<\/p>\n
In December 2004, the magnetar SGR 1806-20, 28 400 light-years away, emitted a giant flare observed by NASA\u2019s RHESSI and ESA\u2019s INTEGRAL satellites. A delayed gamma-ray signal, peaking 10 minutes later, indicated rapid neutron capture (r-process) producing gold and other heavy elements. <\/p>\n
\u201cIt\u2019s answering one of the questions of the century,\u201d said Anirudh Patel, lead author and doctoral student at Columbia University.<\/p>\n
The study, published in The Astrophysical Journal Letters, used 20-year-old archival data from NASA and ESA telescopes to estimate that the flare ejected one-millionth of a solar mass of r-process material. This included gold, silver, and uranium, contributing 1% to 10% of the galaxy\u2019s heavy element inventory. The flare\u2019s energy reached 1046<\/sup> erg in less than a second.<\/p>\n
\nSchematic of the three high-energy emission phases from the 2004 SGR 1806\u201320 flare: a prompt \u22721\u202fs gamma-ray spike, a minutes-long spin-modulated X-ray tail, and a delayed MeV component peaking at ~600\u2013800\u202fs and fading over hours, possibly powered by r-process material from crustal ejection during magnetic reconnection. Image credit: Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806-20 Magnetar Giant Flare \u2013 Anirudh Patel et al.<\/figcaption><\/figure>\n<\/div>\n
Magnetars, neutron stars with magnetic fields trillions of times stronger than Earth\u2019s, trigger giant flares when their crust fractures. This ejects material at 10% the speed of light, enabling r-process synthesis of nuclei like gold, with atomic masses above 130. The process involves an alpha-rich freeze-out in the ejected material.<\/p>\n
The delayed gamma-ray emission, detected from 400 to 12 000 seconds, showed a power-law decay index of 1.2, matching r-process decay predictions. Its fluence, 9 \u00d7 10-4<\/sup> erg cm-2<\/sup>, supports models of gold and heavy element production.<\/p>\n
\u201cIt was noted at the time, but nobody had any conception of what it could be,\u201d said co-author Eric Burns on the signal\u2019s initial mystery.<\/p>\n
\nExample \u223cMeV gamma-ray light curve from r-process ejecta (Patel et al. 2025) compared to late-time emission from the 2004 SGR 1806\u201320 flare (INTEGRAL\/ACS), showing a decay \u221d t\u22121.2 t^{-1.2}t\u22121.2 and cumulative fluence consistent with ACS and RHESSI data for a source distance of 8.7 kpc.Image credit: Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806-20 Magnetar Giant Flare \u2013 Anirudh Patel et al.<\/figcaption><\/figure>\n<\/div>\n
Konus-WIND data measured a fluence of 2 \u00d7 10-4<\/sup> erg cm-2<\/sup> in the 80\u2013750 keV range, while RHESSI recorded thermal bremsstrahlung at 1.9 MeV. SkyNet simulations confirmed the gamma-ray signature as r-process decay. <\/p>\n
Magnetar flares, unlike delayed neutron star mergers, occur soon after star formation, potentially seeding early stars with gold and other elements. This could explain their presence in metal-poor stars. Only three such flares have been observed in our galaxy and the Large Magellanic Cloud.<\/p>\n
\nTop: Mass fractions and radioactive nuclei contributions to gamma-ray energy (10\u00b3\u201310\u2074\u202fs) from the fiducial model matching SGR 1806\u201320; bottom: synthetic spectra at 1000, 3000, and 12,000\u202fs with Doppler broadening, overlaid with the bremsstrahlung fit from Boggs et al. (2007) and its \u00b10.7\u202fMeV uncertainty. Image credit: Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806-20 Magnetar Giant Flare \u2013 Anirudh Patel et al.<\/figcaption><\/figure>\n<\/div>\n
The flare\u2019s ejecta may accelerate heavy nuclei, including gold, into cosmic rays, potentially surpassing other sources. Hydrodynamical simulations supported the ejection mechanism. <\/p>\n
\u201cIt\u2019s very cool to think about how some of the stuff in my phone or my laptop was forged in this extreme explosion,\u201d Patel said.<\/p>\n
NASA\u2019s COSI mission, launching in 2027, will aim to detect specific isotopes in future flares, enhancing gold production studies. A UV\/optical signal from these events may also be observable. <\/p>\n
References:<\/p>\n
1 <\/sup>Direct Evidence for r-process Nucleosynthesis in Delayed MeV Emission from the SGR 1806-20 Magnetar Giant Flare \u2013 Anirudh Patel et al. \u2013 The Astrophysical Journal Letters \u2013 April 29, 2025 \u2013 \u2013 OPEN ACCESS<\/p>\n
2 <\/sup>Where Does Gold Come From? NASA Data Has Clues \u2013 NASA \u2013 April 29, 2025<\/p>\n
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