TechBurnt-out star puzzles astronomers: It's not approaching the Sun

Burnt-out star puzzles astronomers: It's not approaching the Sun

Observations of the white dwarf confused astronomers. The burnt-out star is not getting closer to the Sun.
Observations of the white dwarf confused astronomers. The burnt-out star is not getting closer to the Sun.
Images source: © Wikimedia

3:40 PM EDT, November 4, 2023

White dwarfs are the hot, dense remains of a star, and the object WD 0810-353 falls into this category. What sets it apart is its perceived potential to disrupt the tranquility of our solar system. However, as recent revelations suggest, it's not going to do that.

The white dwarf WD 0810-353 has garnered attention in recent years for its perceived threat. Astronomers Vadim Bobylev and Anisa Bajkova discovered it while analyzing data from the Gaia project. It was inferred from the data that the star would be about 31,000 astronomical units (AU) away from the sun, almost reaching the Oort Cloud.

Interloping stars considered a threat to the Solar System

The Oort Cloud marks the boundary of our solar system, abounding in cosmic debris. The celestial objects within it move under the tenuous gravitational influence of the sun. The emergence of a foreign star in the vicinity potentially disrupts this equilibrium.

This is not an uncommon occurrence. Estimations suggest that over 400 stars have traversed through the Oort Cloud during the sun's lifetime. The most recent of these cosmic travelers was Scholz's Star, which brushed by this region approximately 70,000 years ago. WD 0810-353 was predicted to arrive in 29,000 years, a visit that could have serious repercussions.

The white dwarf could incite the debris in the Oort Cloud's belt into motion. Some space rocks would drift further from the solar system, but others could set on a collision course with its celestial bodies. Their potential impact on Earth could present a real danger.

The white dwarf WD 0810-353 is not on a collision course with the Solar System

As it turns out, there's no cause for alarm. The European Southern Observatory (ESO) reports an error in interpreting the observational data.

The mistake arose from determining the speed of WD 0810-353 based on its spectrum. Depending on whether the object is moving towards or away from the observer, its spectrum shifts towards shorter or longer waves—an effect known as redshift or blue shift, respectively.

However, an extremely old white dwarf like WD 0810-353 possesses a significant magnetic field. In such cases, spectral lines can be misinterpreted as multiple lines, shifting to other wavelengths. If the object is scrutinized without considering its magnetic field, it is impossible to accurately determine its motion direction.

The prospect of a drastic disruption in our orderly solar system prompted astronomers to discount this error. The Very Large Telescope (VLT) of the ESO was trained on the white dwarf. With access to precise spectral data and magnetic field modeling of WD 0810-353, it emerged that the previously recorded direction of the star's movement was a misinterpretation.

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