First Author’s Institution: Centre for Exoplanets and Habitability & Department of Physics, University of Warwick, Coventry CV4 7AL, UK After using

What happens to planets when their host star dies?

submited by
Style Pass
2021-05-23 23:00:05

First Author’s Institution: Centre for Exoplanets and Habitability & Department of Physics, University of Warwick, Coventry CV4 7AL, UK

After using up the hydrogen in their cores, stars with masses below roughly 8 times that of the sun will expand into red giants , blow off their outer layers, and become white dwarfs . This can be a very destructive process for surrounding planets , as they may, for example, be engulfed by the expanding red giant or ejected from the system.

Signatures of heavy metals have been detected in the atmospheres of many white dwarfs, indicating the accretion of planetary material. Such objects are often referred to as polluted white dwarfs. Major planets (like the 8 in our solar system), minor planets (e.g. dwarf planets, asteroids), dust, gas, and metallic debris (from astronomers’ “metals” like carbon to real metals like iron) have all been detected surrounding white dwarfs, so we know that these objects can, at least under certain circumstances, survive a star’s red giant phase. The authors of today’s paper explore how HR 8799 could become one of these polluted white dwarfs, simulating possible futures for the star and its surrounding planets and debris.

HR 8799 is an A-type main sequence star, roughly 30 million years old and 1.5 times the mass of the Sun. It is surrounded by an inner debris disk , an outer debris disk, and four known giant planets in the gap between them (shown in Figure 1). The system is dynamically very interesting, as the four massive planets (2-10 times the mass of Jupiter) are on orbits that are wide around their star (15-70 the size of Earth’s orbit around the Sun) but are relatively close to one another in a way that would typically not be stable. HR 8799 is considered the perfect candidate to become a white dwarf planetary system for a few reasons: 

Leave a Comment