The delivery of organic compounds from stars to the solar system might have played an important role in the origin of life on Earth, an Academia Sinica researcher said yesterday.
In a review article published in British science journal Nature yesterday, author Kwok Sun (郭新), the director and distinguished research fellow of the Institute of Astronomy and Astrophysics, Academia Sinica, summarized the evidence collected from recent infrared astronomy satellites showing that old stars can form complex organic compounds.
"No one had expected that complex organic compounds could be created in stars. In fact, theoretically, we still do not understand how it is possible," Kwok told the Taipei Times.
"But from our observations we have no doubt that these compounds are being made [in stars], and made on very short time lines," he added.
Given the availability of complex organic compounds in early Earth, life on the planet could have an easier start than previously believed. Kwok said that these organic compounds were probably incorporated in Earth during the formation of the solar system 4.5 billion years ago.
Using the technique of infrared spectroscopy, Kwok found that a chemical synthesis can occur rapidly in stars. In the research paper, Kwok argued that over a period of only several thousand years, small organic molecules with aliphatic structures are shown to have evolved into large, complex aromatic molecules. Since only a few thousand years are needed, differing levels of infrared spectra give the most direct evidence of a chemical synthesis in stars. Kwok said that most of these results were obtained from observations using the European Space Agency's Infrared Space Observatory satellites.
In the 1950s, many scientists were tasked with finding the origin of life. Around the world, the scientific community was examining what kind of environment would be needed to allow life to begin. Since the Miller-Urey experiment in 1953, most scientists have held the view that life on Earth was created from simple inorganic molecules. With a suitable energy source, such as lightning, and a hospitable environment, such as oceans, complex organic molecules such as sugars and amino acids are thought to have originated from methane, hydrogen, and ammonia. These organic molecules then formed what is believed to be the basis of life as we know it today.
However, in the past couple years, there has been a shift in the opinion of the scientific community that external delivery (for example, a collision by a meteorite into the earth) played a larger role in the origin of life than previously thought, Kwok said.
"Instead of life being created spontaneously from simple inorganic compounds, it now seems that the Earth had the advantage of having more complex ingredients at the starting point," Kwok said.
Kwok's main research interests have been old stars and infrared spectroscopy. The conclusions were made possible by comparing astronomical infrared spectroscopy with the laboratory analysis of meteorites, performed by scientists at the Washington University at St. Louis in the US.
"Clearly this is not the whole solution to the problem of origin of life or the existence of extraterrestrial life, but it does represent one small step in our understanding of how life began on Earth and how unique life is in the Galaxy," Kwok said.
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