Featured Research

from universities, journals, and other organizations

First biological evidence of a supernova

Date:
May 8, 2013
Source:
Technische Universitaet Muenchen
Summary:
In fossil remnants of bacteria, researchers have found a radioactive iron isotope that they trace back to a supernova in our cosmic neighborhood. This is the first proven biological signature of a starburst. An age determination showed that the supernova must have occurred about 2.2 million years ago, roughly around the time when the modern human developed.

Remnants of a supernova in the constellation Cassiopeia, about 11,000 light-years away. The stellar explosion took place about 330 years ago.
Credit: Composite Image: X-ray: NASA/CXC/SAO; Optical: NASA/STScI; Infrared: NASA/JPL-Caltech/Steward/O.Krause et al.

In fossil remnants of iron-loving bacteria, researchers of the Cluster of Excellence Origin and Structure of the Universe at the Technische Universitaet Muenchen (TUM), found a radioactive iron isotope that they trace back to a supernova in our cosmic neighborhood. This is the first proven biological signature of a starburst on our Earth. The age determination of the deep-drill core from the Pacific Ocean showed that the supernova must have occurred about 2.2 million years ago, roughly around the time when the modern human developed.

Most of the chemical elements have their origin in core collapse supernovae. When a star ends its life in a gigantic starburst, it throws most of its mass into space. The radioactive iron isotope Fe-60 is produced almost exclusively in such supernovae. Because its half-life of 2.62 million years is short compared to the age of our solar system, no supernova iron should be present on Earth. Therefore, any discovery of Fe-60 on Earth would indicate a supernova in our cosmic neighborhood. In the year 2004, Fe-60 was discovered on Earth for the first time in a ferromanganese crust obtained from the floor of the equatorial Pacific Ocean. Its geological dating puts the event around 2.2 million years ago.

So-called magnetotactic bacteria live within the sediments of Earth's oceans, close to the water-sediment interface. They make within their cells hundreds of tiny crystals of magnetite (Fe3O4), each approximately 80 nanometers in diameter. The magnetotactic bacteria obtain the iron from atmospheric dust that enters the ocean. Nuclear astrophysicist Shawn Bishop from the Technische Universitaet Muenchen conjectured, therefore, that Fe-60 should also reside within those magnetite crystals produced by magnetotactic bacteria extant at the time of the supernova interaction with our planet. These bacterially produced crystals, when found in sediments long after their host bacteria have died, are called "magnetofossils."

Shawn Bishop and his colleagues analyzed parts of a Pacific Ocean sediment core obtained from the Ocean Drilling Program, dating between about 1.7 million and 3.3 million years ago. They took sediment samples corresponding to intervals of about 100,000 years and treated them chemically to selectively dissolve the magnetofossils -- thereby extracting any Fe-60 they might contain.

Finally, using the ultra sensitive accelerator mass spectrometry system at the Maier Leibnitz Laboratory in Garching, Munich, they found a tantalizing hint of Iron-60 atoms occurring around 2.2 million years ago, which matches the expected time from the ferromanganese study. "It seems reasonable to suppose that the apparent signal of Fe-60 could be remains of magnetite chains formed by bacteria on the sea floor as a starburst showered on them from the atmosphere," Shawn Bishop says. He and his team are now preparing to analyze a second sediment drill core, containing upwards of 10 times the amount of material as the first drill core, to see if it also holds the Fe-60 signal and, if it does, to map out the shape of the signal as a function of time.

Abstract: http://meetings.aps.org/Meeting/APR13/Event/192798


Story Source:

The above story is based on materials provided by Technische Universitaet Muenchen. Note: Materials may be edited for content and length.


Cite This Page:

Technische Universitaet Muenchen. "First biological evidence of a supernova." ScienceDaily. ScienceDaily, 8 May 2013. <www.sciencedaily.com/releases/2013/05/130508123022.htm>.
Technische Universitaet Muenchen. (2013, May 8). First biological evidence of a supernova. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2013/05/130508123022.htm
Technische Universitaet Muenchen. "First biological evidence of a supernova." ScienceDaily. www.sciencedaily.com/releases/2013/05/130508123022.htm (accessed July 22, 2014).

Share This




More Fossils & Ruins News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Neil Armstrong's Post-Apollo 11 Life

Neil Armstrong's Post-Apollo 11 Life

Newsy (July 19, 2014) — Neil Armstrong gained international fame after becoming the first man to walk on the moon in 1969. But what was his life like after the historic trip? Video provided by Newsy
Powered by NewsLook.com
A Centuries' Old British Tradition Is Far from a Swan Song

A Centuries' Old British Tradition Is Far from a Swan Song

AFP (July 19, 2014) — As if it weren't enough that the Queen is the Sovereign of the UK and 15 other Commonwealth realms, she is also the owner of all Britain's unmarked swans. Duration: 02:18 Video provided by AFP
Powered by NewsLook.com
Tooth Plaque Provides Insight Into Diets Of Ancient People

Tooth Plaque Provides Insight Into Diets Of Ancient People

Newsy (July 19, 2014) — Research on plaque from ancient teeth shows that our prehistoric ancestor's had a detailed understanding of plants long before developing agriculture. Video provided by Newsy
Powered by NewsLook.com
45 Years Later, Buzz Aldrin on Walking on Moon

45 Years Later, Buzz Aldrin on Walking on Moon

AP (July 18, 2014) — Forty-five years ago Sunday, Apollo 11's Neil Armstrong and Buzz Aldrin became the first humans to set foot on the moon. Speaking at the Intrepid Sea, Air & Space Museum, Aldrin described what he was thinking right before the historic walk. (July 18) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins