The final moments of planetary debris

IT House reported on February 10 that astronomers have for the first time observed the moment when debris from a destroyed planet hit the surface of a white dwarf.

The paper, published today (9th local time) in the journal Nature, is the first direct measurement of the rocky material accretized by white dwarfs and confirms indirect evidence of accretion by more than a thousand stars to date. It is worth mentioning that the event we observed this time occurred billions of years after the formation of the planetary system.

Astronomers at the University of Warwick in the United Kingdom have used X-rays to detect the rock and gaseous material left behind by a planetary system after its host star collides and is swallowed up on the surface of the star, opening up the book for mankind.

Most stars, including stars like the Sun, have the fate of eventually becoming white dwarfs. We've found more than 300,000 white dwarfs in the Milky Way, and many are thought to be accruing the remnants of planets and other objects that once orbited them.

For decades, astronomers have been experimenting with spectroscopy and ultraviolet wavelengths to measure the abundance of elements on a star's surface and derive the composition of its contents.

Indirect evidence suggests that these objects are actively acclimating, and spectroscopic observations show that 25-50% of white dwarf atmospheres have heavy elements such as iron, calcium, and magnesium.

Until now, though, astronomers haven't seen the process by which this material is pulled into the star.

Dr Tim Cunningham, from the University of Warwick's Department of Physics, said: "We have finally observed the fact that there is matter entering the atmosphere of a star. This is the first time we have been able to derive an accretion rate that does not depend on a detailed model of the atmosphere of a white dwarf. Notably, it doesvetails very well with previous studies.

"Previously, the measurement of accretion rate used spectroscopy and relied on a model of white dwarfs. These are just numerical models, just used to calculate how quickly elements sink from the atmosphere into stars. It tells you how many elements fall into the atmosphere in the form of accretion rates, and then you can calculate in reverse to calculate how many elements a single element is in the matrix, whether it's a planet, a moon, or an asteroid. ”

IT House learned that a white dwarf is a star that has burned out its fuel and shed its outer layers, potentially destroying or disrupting any celestial body in orbit in the process. When material from these objects is pulled into the star at a high enough speed, it crashes into the star's surface, forming a plasma with temperatures between 100,000 and 1 million Kelvin. Once plasma settles on the surface of a star and cools down, it emits X-rays that can be detected.

In fact, detecting these X-rays is very challenging, because the small amount of X-rays that reach Earth can be lost in other bright X-ray sources in the sky.

So the scientists analyzed the white dwarf G29-38 by detecting X-rays and then confirmed that the white dwarf was currently accruing remnants of the old planetary system. Detecting accretion in this way gives us a glimpse into the possible fates of thousands of known exoplanet systems, including our own solar system.

With the chandra telescope's improved angular resolution than other telescopes, they could isolate the target star from other X-ray sources and observe X-rays from isolated white dwarfs for the first time. It confirms decades of observations of material coalescing into white dwarfs that rely on spectroscopic evidence.

Dr Cunningham added: "The really exciting thing about this result is that we are looking at a different wavelength of X-rays, which means that we are able to detect a completely different type of physics."

"This discovery provides the first direct evidence that white dwarfs are currently gathering remnants of old planetary systems." Detecting accretion in this way provides a new technology through which we can study these systems, giving us a glimpse into the possible fates of thousands of known exoplanet systems, including our own solar system. ”