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White dwarfs hold key to life in the universe, suggests study
A new study shows white dwarf stars create an essential component of life.
- White dwarf stars create carbon atoms in the Milky Way galaxy, shows new study.
- Carbon is an essential component of life.
- White dwarfs make carbon in their hot insides before the stars die.
New analysis adds another wrinkle to the notion that we are all made of stars. Researchers found that white dwarfs, remains of stars, are a key source of carbon, an element essential to life.
90 percent of all stars end their celestial existence as white dwarfs that keep getting cooler and dimmer over billions of years. When they are at the point of final collapse, their ashes get picked up by stellar winds and are spread throughout the universe. These ashes are chock-full of chemical elements like carbon, created deep inside the star just prior to its death.
While every carbon atom in the universe was made by stars through the fusion of three helium nuclei, astrophysicists have argued over which ones were the primary source of carbon in our Milky Way galaxy – white dwarfs or massive stars that exploded, going supernova.
Now an international team of astronomers found that white dwarfs in open star clusters of the Milky Way carry the clues to the source of the galactic carbon. Open stars clusters can have up to a few thousand stars, as explains the press release from UC Santa Cruz, whose Enrico Ramirez-Ruiz, professor of astronomy and astrophysics, led the study.
Ramirez-Ruiz and his team based their work on astronomical observations conducted in 2018 at the W. M. Keck Observatory in Hawaii.
"From the analysis of the observed Keck spectra, it was possible to measure the masses of the white dwarfs, explained Ramirez-Ruiz. "Using the theory of stellar evolution, we were able to trace back to the progenitor stars and derive their masses at birth."
What Are White Dwarf Stars?
By analyzing the connection between the starting and final masses of the stars, the scientists found that the initial masses of the white dwarfs were much larger than they predicted. The explanation for this "kink"? The creation of carbon.
"Our study interprets this kink in the initial-final mass relationship as the signature of the synthesis of carbon made by low-mass stars in the Milky Way," shared lead author Paola Marigo from the University of Padua in Italy.
The research shows that before they died, the central cores of massive stars, twice the size of our Sun, grew even larger and fused carbon atoms in their melting insides. These were subsequently moved over to the surface and spread far and wide on stellar winds.
This artist's concept shows an exoplanet and debris disk orbiting a polluted white dwarf.
Interestingly, the scientists concluded that a star had to be large enough, weighing 1.5 solar masses to be able to diffuse its ashes full of carbon. A progenitor of this kind had to be responsible for the carbon on our own planet, crucial to life that came to inhabit it.
"Now we know that the carbon came from stars with a birth mass of not less than roughly 1.5 solar masses," said Marigo.
The researchers also propose that a large amount of the light emitted by very distant galaxies actually comes from bright carbon-rich stars near death.
Other scientists involved in the study came from Johns Hopkins University, American Museum of Natural History in New York, Columbia University, Space Telescope Science Institute, University of Warwick, University of Montreal, University of Uppsala, International School for Advanced Studies in Trieste, Italian National Institute for Astrophysics, and the University of Geneva.
Read their new study published in Nature Astronomy.
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Scientists used CT scanning and 3D-printing technology to re-create the voice of Nesyamun, an ancient Egyptian priest.
- Scientists printed a 3D replica of the vocal tract of Nesyamun, an Egyptian priest whose mummified corpse has been on display in the UK for two centuries.
- With the help of an electronic device, the reproduced voice is able to "speak" a vowel noise.
- The team behind the "Voices of the Past" project suggest reproducing ancient voices could make museum experiences more dynamic.
Howard et al.<p style="margin-left: 20px;">"While this approach has wide implications for heritage management/museum display, its relevance conforms exactly to the ancient Egyptians' fundamental belief that 'to speak the name of the dead is to make them live again'," they wrote in a <a href="https://www.nature.com/articles/s41598-019-56316-y#Fig3" target="_blank">paper</a> published in Nature Scientific Reports. "Given Nesyamun's stated desire to have his voice heard in the afterlife in order to live forever, the fulfilment of his beliefs through the synthesis of his vocal function allows us to make direct contact with ancient Egypt by listening to a sound from a vocal tract that has not been heard for over 3000 years, preserved through mummification and now restored through this new technique."</p>
Connecting modern people with history<p>It's not the first time scientists have "re-created" an ancient human's voice. In 2016, for example, Italian researchers used software to <a href="https://www.smithsonianmag.com/smart-news/hear-recreated-voice-otzi-iceman-180960570/" target="_blank">reconstruct the voice of Ötzi,</a> an iceman who was discovered in 1991 and is thought to have died more than 5,000 years ago. But the "Voices of the Past" project is different, the researchers note, because Nesyamun's mummified corpse is especially well preserved.</p><p style="margin-left: 20px;">"It was particularly suited, given its age and preservation [of its soft tissues], which is unusual," Howard told <em><a href="https://www.livescience.com/amp/ancient-egypt-mummy-voice-reconstructed.html" target="_blank">Live Science</a>.</em></p><p>As to whether Nesyamun's reconstructed voice will ever be able to speak complete sentences, Howard told <em><a href="https://abcnews.go.com/Weird/wireStory/ancient-voice-scientists-recreate-sound-egyptian-mummy-68482015" target="_blank">The Associated Press</a>, </em>that it's "something that is being worked on, so it will be possible one day."</p><p>John Schofield, an archaeologist at the University of York, said that reproducing voices from history can make museum experiences "more multidimensional."</p><p style="margin-left: 20px;">"There is nothing more personal than someone's voice," he told <em>The Associated Press.</em> "So we think that hearing a voice from so long ago will be an unforgettable experience, making heritage places like Karnak, Nesyamun's temple, come alive."</p>
Inequality in wealth, gender, and race grew to unprecedented levels across the world, according to OxFam report.
- A new report by global poverty nonprofit OxFam finds inequality has increased in every country in the world.
- The alarming trend is made worse by the coronavirus pandemic, which strained most systems and governments.
- The gap in wealth, race and gender treatment will increase until governments step in with changes.
People wait in line to receive food at a food bank on April 28, 2020 in Brooklyn.
Photo by Spencer Platt/Getty Images
Credit: Oxfam International
A supernova exploded near Earth about 2.5 million years ago, possibly causing an extinction event.
- Researchers from the University of Munich find evidence of a supernova near Earth.
- A star exploded close to our planet about 2.5 million years ago.
- The scientists deduced this by finding unusual concentrations of isotopes, created by a supernova.
This Manganese crust started to form about 20 million years ago. Growing layer by layer, it resulted in minerals precipitated out of seawater. The presence of elevated concentrations of 60 Fe and 56 Mn in layers from 2.5 million years ago hints at a nearby supernova explosion around that time.
Credit: Dominik Koll/ TUM