A team of astronomers have found what could be one of the universe’s oldest stars, almost entirely made of materials formed by the Big Bang.
Residing in the same part of the Milky Way galaxy as our own solar system, the star is believed to be up to 13.5 billion years old which is evidenced by its extremely low metal content, or metallicity, Xinhua news agency reported.
According to co-author Andrew Casey, it was previously believed that the first stars that formed in the universe could not possibly still exist today.
“The findings are significant because for the first time we have been able to show direct evidence that very ancient, low mass stars do exist, and could survive until the present day without destroying themselves,” Casey said.
The metallicity of stars increases as they are born and die, in a cycle which results in the creation of more and more heavy metals, with the Earth’s sun being around 100,000 generations down that line and holding a metal content roughly equal to 14 Jupiters.
Stars created at the beginning of the universe, however, would have consisted entirely of elements like hydrogen, helium and small amounts of lithium – meaning the extremely low metallicity of the newly discovered star, about the same as the planet Mercury.
This suggests that it could be as little as one generation removed from the beginning of the universe, the researchers noted.
Up until around 1990, scientists believed that only massive stars could have formed in the early stages of the universe, and could never be observed because they burn through their fuel so quickly and die.
However, the new study has shown that it is possible for low mass stars to last as long as the 13 billion years since the Big Bang — Red Dwarf stars for instance, which have a fraction of the mass of the sun, are thought to live for trillions of years. (IANS)
Astronomers in Canada have detected a mysterious volley of radio waves from far outside our galaxy, according to two studies published Wednesday in Nature.
What corner of the universe these powerful waves come from and the forces that produced them remain unknown.
The so-called repeating fast radio bursts were identified during the trial run last summer of a built-for-purpose telescope running at only a fraction of its capacity.
Known by its acronym CHIME, the world’s most powerful radio telescope, spread across an area as big as a football pitch, is poised to detect many more of the enigmatic pulses now that it is fully operational.
“At the end of the year, we may have found 1,000 bursts,” said Deborah Good, a PhD student at the University of British Columbia and one of 50 scientists from five institutions involved in the research.
High energy bursts
Fast radio bursts (FRBs) flash only for a micro-instant, but can emit as much energy as the sun does in 10,000 years.
Exactly what causes these high-energy surges of long waves at the far end of the electromagnetic spectrum remains the subject of intense debate.
More than 60 bursts have been cataloged since 2007, but only one other, observed in 2012 at the Arecibo Observatory in Puerto Rico, was a repeater.
“FRBs, it seems, are likely generated in dense, turbulent regions of host galaxies,” Shriharsh Tendulkar, a corresponding author for both studies and an astronomer at McGill University, told AFP.
Cosmic convulsions created by the turbulent gas clouds that give rise to stars, or stellar explosions such a supernovae, are both possible incubators.
But consecutive radio bursts are a special case.
No little green men
“The fact that the bursts are repeated rules out any cataclysmic models in which the source is destroyed while generating the burst,” Tendulkar added.
“An FRB emitted from a merger of two neutron stars, or a neutron star and a black hole, for example, cannot repeat.”
It is not yet clear whether the breeding grounds of repeating bursts are different from those that produce only a single radio pulse.
Significantly, the 2012 and 2018 “repeaters” have strikingly similar properties.
CHIME (Canadian Hydrogen Intensity Mapping Experiment) also spotted a dozen single burst radio waves, but with an unusual profile.
Most FRBs spotted so far have wavelengths of a few centimeters, but these had intervals of nearly a meter, opening up a whole new line of inquiry for astronomers.
Could these enigmatic radio pulses point to intelligence elsewhere in the Universe? Might they be messages in a bottle?
“It is extremely, extremely unlikely,” Tendulkar said.
“As a scientist I can’t rule it out 100 percent. But intelligent life is not on the minds of any astronomer as a source of these FRBs.”
Constructed in British Columbia, CHIME is composed of four, 100-meter long half-pipe cylinders of metal mesh, which reconstruct images of the sky by processing the radio signals recorded by more than a thousand antennas.