[ad_1]
In 1670, two observers of the sky independently noticed the appearance of a new star, or nova, in the constellation Cygnus. He first appeared as a point of light that faded, reappeared and disappeared into view. Now known as CK Vulpeculae, relics of the first reliably documented nova appear as two fans of debris moving away from a compact, hourglass-shaped central body.
Researchers who studied CK Vulpeculae initially thought that apparent nova resulted from the collision of two stars in the main sequence. But new observations with the Atacama Large Millimeter / submillimeter array, or ALMA, indicate that this was the result of a collision between a white dwarf, the cooling core of an extinct star and a brown dwarf, a star without enough mass to support nuclear fusion.
"It now seems that what has been observed centuries ago is not what we would describe today as a" nova, "said Sumner Starrfield, astronomer of the University of California. Arizona and co-author of an article published in the Monthly Notices of the Royal Astronomical Society.
"Instead, it was the fusion of two stellar objects, a white dwarf and a brown dwarf. When these two objects met, they created a cocktail of unusual molecules and isotopes, which allowed us to better understand the nature of this object. "
The white dwarf, much smaller, was probably 10 times more massive than the brown dwarf. As the brown dwarf spiraled under the gravity of the white dwarf, it was torn apart by extreme tidal forces. By studying the light of the stars passing through the clouds of gas left by the collision, the researchers detected lithium, which is easily destroyed by the stars of the main sequence.
"The presence of lithium, as well as the unusual isotopic ratios of carbon, nitrogen and oxygen elements suggest the rejection of a brown dwarf star on the surface of a white dwarf," said Stewart Eyres, lead author at the University of South Wales. "The thermonuclear 'burning' and the eruption of this material gave the hourglass we see today."
Formaldehyde and other organic compounds are also present in hourglass-shaped clouds, molecules that would not be present in a nuclear fusion star.
[ad_2]
Source link
