Astronomers have discovered that a planet may have been destroyed by a white dwarf at the center of a planetary nebula, marking the first time this phenomenon has been observed. The finding explains a mysterious X-ray signal detected from the Helix Nebula for over 40 years.
The Helix Nebula is a planetary nebula, a late-stage star like our Sun that has shed its outer layers leaving a small dim star at its center called a white dwarf. Data from NASA’s Chandra X-ray Observatory indicates that this white dwarf has destroyed a very closely orbiting planet. The debris from the planet will eventually form a disk around the white dwarf and fall onto its surface, creating the mysterious signal in X-rays.
The discovery was made using data from Chandra and the XMM-Newton telescope, which analyzed X-ray signals from the Helix Nebula since 1980. Initially, scientists detected highly energetic X-rays coming from the white dwarf WD 2226-210, located 650 light-years from Earth. However, a new study suggests that this X-ray signal could be caused by debris from a destroyed planet being pulled onto the white dwarf.
According to observations between 1992 and 2002, the X-ray signal has remained approximately constant in brightness during that time. The data also suggest a subtle, regular change in the X-ray signal every 2.9 hours, indicating the remains of a planet exceptionally close to the white dwarf.
The researchers propose that there could have been a planet like Jupiter even closer to the star than initially thought. The besieged planet would have been torn apart by tidal forces from the star once it approached close enough. WD 2226-210 has similarities in X-ray behavior to two other white dwarfs, suggesting they may constitute a new class of variable objects.
The discovery appears in The Monthly Notices of the Royal Astronomical Society and is available online.
Source: https://www.nasa.gov/image-article/x-ray-signal-points-to-destroyed-planet-chandra-finds