Astronomers have finally solved the mystery of highly energetic X-rays emanating from WD 2226-210, a white dwarf star at the center of the Helix Nebula. This enigmatic signal has puzzled scientists for over four decades.
Located just 650 light-years away, white dwarfs like WD 2226-210 typically don’t emit strong X-rays. However, previous observations by NASA’s Einstein X-ray Observatory and ROSAT telescopes revealed a significant X-ray signal coming from the star.
Researchers now believe that this X-ray signal might be caused by debris pulled onto the white dwarf due to the gravitational interaction with other planets in the system. A Neptune-sized planet was initially thought to orbit WD 2226-210, completing one revolution in less than three days. However, scientists have discovered a possible explanation for the X-rays.
The study suggests that a Jupiter-like planet could have been even closer to the star, but its gravity was strong enough to tear it apart. The debris from this destroyed planet would then be heated by the white dwarf’s surface and emit X-rays.
Observations show that the X-ray signal has remained relatively constant in brightness over the past two decades. However, data indicate a subtle change every 2.9 hours, hinting at the remains of an exceptionally close planet to the white dwarf.
The researchers also explored alternative explanations, including the possibility of a low-mass star being torn apart by the white dwarf. While such stars are possible, they are unlikely to have been destroyed in this way.
WD 2226-210’s X-ray behavior shares similarities with other white dwarfs outside planetary nebulas. These similarities may indicate a new class of variable objects that can provide insights into planet survival around older stars like the Sun.
The team’s findings will be published in the Monthly Notices of the Royal Astronomical Society, offering scientists a new understanding of this enigmatic star and its place in the universe.
Source: https://www.sci.news/astronomy/helix-nebula-x-ray-emission-13722.html