False alarm: Rogue star steers away, won’t hit us in 29,000 years

False alarm: Rogue star steers away, won’t hit us in 29,000 years
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A huge cosmic catastrophe has been averted! 

A massive rogue dead star was initially predicted to brush through our solar system roughly 29,000 years from now. 

Fortunately, updated calculations show that our planet will be spared from the damage wrought by this runaway star.

In 2022, researchers utilized data from the Gaia space telescope to project the trajectory of WD 0810-353, a rogue white dwarf star. A white dwarf is the hot and dense remnant left behind when a Sun-like star reaches the end of its life cycle.

Recent investigations have uncovered a surprising twist: it appears that this white dwarf may not be approaching our solar system at all.

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"We found that the approach speed measured by the Gaia project is incorrect, and the close encounter predicted between WD0810–353 and the sun is actually not going to happen," said astronomer Stefano Bagnulo in an official release of European Southern Observatory (ESO). 

Bagnulo further added: "In fact, WD0810–353 may not even be moving towards the sun at all. That's one less cosmic hazard we have to worry about!”

New calculations using VLT

??A rogue star is one that does not belong to any particular star system or galaxy and instead drifts aimlessly through interstellar space. 

Had this rogue star entered the solar system, it would have wreaked havoc. 

The gravitational influence of a rogue star passing through our solar system would disturb the orbits of planets and various celestial objects, causing major changes in their locations. 

It would also cause disruption in the Oort Cloud, a remote area of the solar system containing a large number of comets. The gravitational consequences of the rogue star's passage might cause some of these comets to be redirected toward the inner solar system, potentially presenting threats to Earth and other planets.

However, humanity may now breathe a sigh of relief because there is no longer a threat. 

The new calculations were generated from ESO's Very Large Telescope (VLT), which is located in northern Chile's Atacama Desert.

Objects in the Oort Cloud can be sometimes nudged towards the inner parts of the Solar System, like the comet marked here with a red line.

ESO/L. Calcada 

White dwarf's huge magnetic field

Astronomers used the VLT's high-tech FOcal Reducer and low dispersion Spectrograph 2 (FORS2) instrument to conduct a new observation of the rogue star. 

The primary objective of this observation was to obtain highly precise spectral data from the white dwarf. This data was collected in order to investigate whether the white dwarf's extremely strong magnetic field might be influencing the interpretation of the Gaia telescope's findings.

The initial Gaia observations did not take into account the large magnetic field of this rogue star.

 “Unusually, this old white dwarf also has a huge magnetic field. In astronomy, magnetic fields are crucial to understand many physical aspects of a star and not considering them can lead to misinterpretations of physical phenomena,” said Eva Villaver, an astronomer at the Astrobiology Center in Spain and co-author of the study.

Initially, researchers calculated the white dwarf's radial velocity and concluded that it was nearing our solar system. Typically, this computation is performed by examining the spectrum of light radiated by the star.

Astronomers may identify whether a star is moving away from or toward the observer by examining the degree of redshift or blueshift in the spectrum of its light, providing crucial information about its speed and direction in space.

In the fresh measurements, the team utilized the polarized spectrum of WD 0810-353 to create a model of this dead star’s magnetic field. The findings revealed that the approach velocity as measured by the Gaia is inaccurate, and the projected close encounter between WD 0810-353 and the Sun would not take place.

The results were published in The Astrophysical Journal.

Study abstract:

WD 0810-353 is a white dwarf within the 20 pc volume around the Sun. Using Gaia astrometric distance and proper motions, and a radial velocity derived from Gaia spectroscopy, it has been predicted that this star will pass within 1 pc of the solar system in about 30 kyr. However, WD 0810-353 has been also shown to host a magnetic field with a strength of the order of 30 MG. Its spectrum is therefore not like those of normal DA stars of similar effective temperature. We have obtained and analyzed new polarized spectra of the star around H?. Our analysis suggests that the visible surface of the star shows two regions of different field strength (?30 and ?45 MG, respectively), and opposite polarity. The spectra do not change over a 4 yr time span, meaning that either the stellar rotation period is no shorter than several decades, or that the field is symmetric about the rotation axis. Taking into account magnetic shift and splitting, we obtain an estimate of the radial velocity of the star (+83 ± 140 km s?1); we reject both the value and the claimed precision deduced from the Gaia DR3 spectroscopy (?373.7 ± 8.2 km s?1), and we conclude that there will probably be no close encounter between the solar system and WD 0810-353. We also reject the suggestion that the star is a hypervelocity runaway star, a survivor of a Type Ia supernova explosion. It is just a stellar remnant in the solar neighborhood with a very strong and complex magnetic field.

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