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 dwarfs hold key to life in the universe, suggests study

White dwarfs.

NASA and H. Richer (University of British Columbia)
  • 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.

white dwarf artist rendering

This artist's concept shows an exoplanet and debris disk orbiting a polluted white dwarf.

NASA/JPL-Caltech

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.

A brief history of human dignity

What is human dignity? Here's a primer, told through 200 years of great essays, lectures, and novels.

Credit: Benjavisa Ruangvaree / AdobeStock
Sponsored by the Institute for Humane Studies
  • Human dignity means that each of our lives have an unimpeachable value simply because we are human, and therefore we are deserving of a baseline level of respect.
  • That baseline requires more than the absence of violence, discrimination, and authoritarianism. It means giving individuals the freedom to pursue their own happiness and purpose.
  • We look at incredible writings from the last 200 years that illustrate the push for human dignity in regards to slavery, equality, communism, free speech and education.
Keep reading Show less

Astrophysicists: Gamma-ray jets exceed the speed of light

Scientists find that bursts of gamma rays may exceed the speed of light and cause time-reversibility.

An artist's drawing of a particle jet emanating from a black hole at the center of a blazar.

Credit: DESY, Science Communication Lab (used with permission by Astronomy Picture of the Day, which is co-managed by Robert Nemiroff at Michigan Tech).
Surprising Science
  • Astrophysicists propose that gamma-ray bursts may exceed the speed of light.
  • The superluminal jets may also be responsible for time-reversibility.
  • The finding doesn't go against Einstein's theory because this effect happens in the jet medium not a vacuum.
Keep reading Show less

​'The time is now' for cryptocurrencies, PayPal CEO says

Is Bitcoin akin to 'digital gold'?

Technology & Innovation
  • In October, PayPal announced that it would begin allowing users to buy, sell, and hold cryptocurrencies.
  • Other major fintech companies—Square, Fidelity, SoFi—have also recently begun investing heavily in cryptocurrencies.
  • While prices are volatile, many investors believe cryptocurrencies are a relatively safe bet because blockchain technology will prove itself over the long term.
Keep reading Show less

"Clean meat" approved for sale in Singapore

Singapore has approved the sale of a lab-grown meat product in an effort to secure its food supplies against disease and climate change.

Credit: Adobe Stock / Big Think
Politics & Current Affairs
  • Singapore has become the first country to approve the sale of a lab-grown meat product.
  • Eat Just, the company behind the product, will have a small-scale commercial launch of its chicken bites.
  • So-called "clean meats" may reduce our reliance on livestock farming, which kills billions of animals worldwide every year.
  • Keep reading Show less
    Scroll down to load more…
    Quantcast