A team of astronomers used three instruments from the Keck Observatory to study WR 104, a stellar system nicknamed the 'death star'. They discovered that the two massive stars composing it orbit each other with a period of eight months. Their interaction generates a dust spiral visible in infrared.
Artist's impression of WR 104, a binary system forming a dust spiral.
Credit: W. M. Keck Observatory/Adam Makarenko.
Contrary to initial hypotheses, the orbit of these stars is inclined at 30 to 40 degrees relative to our line of sight. This discovery eliminates the risk of a potential gamma-ray burst directed toward Earth. Previous models suggested a very different orientation.
The dust spiral, discovered in 1999, had led to speculation about a face-on orientation toward Earth. The new spectroscopic data reveal a different reality. The study, published in the
Monthly Notices of the Royal Astronomical Society, uses spectra to measure the stars' velocities.
This unexpected inclination raises new questions about dust spiral formation. Astronomers must now understand why the orbit and the spiral are not aligned. This discovery paves the way for new research on binary systems.
Grant Hill, the study's lead author, emphasizes the importance of such surprises in astronomy. They challenge our knowledge and push us to explore new avenues.
Future observations could reveal other unexpected aspects of this system. Astronomers hope to learn more about the mechanisms governing these cosmic phenomena. WR 104 remains a unique laboratory for studying massive stars and their interactions.
What is a Wolf-Rayet star?
Wolf-Rayet stars are massive stars at the end of their lives, characterized by extremely powerful stellar winds. These winds, rich in heavy elements like carbon, are ejected at speeds reaching several thousand kilometers per second.
These stars are rare, and studying them helps us understand the final phases of stellar evolution. Their intense luminosity and unique chemical composition make them major objects of interest for astronomers.
The collision of stellar winds in binary systems like WR 104 produces structures such as dust spirals. These phenomena provide valuable clues about the physical processes at work.
Why are gamma-ray bursts dangerous?
Gamma-ray bursts are the most energetic explosions in the Universe. In just seconds, they can release energy equivalent to what the Sun emits over its entire lifetime.
If such an event occurred near Earth, the consequences could be catastrophic. Intense radiation could damage the ozone layer, exposing the planet to dangerous levels of ultraviolet rays.
Fortunately, the probability of a gamma-ray burst affecting Earth is extremely low. Most of these events occur in distant galaxies, and their energy beams are usually very narrow. WR 104, though nearby, does not pose this risk according to the latest study, thanks to its orientation.