Humanity has identified thousands of exoplanets, so you think we got a great handle on seeing them. And yet, the universe surprises us. A new study led by Andrew Vanderberg of the University of Wisconsin-Madison reveals a possible exoplanet about 80 light-years away. The solar system is very strange, however. The planet is orbiting a stellar remnant, a dead star known as the white dwarf. If confirmed, this first-of-its-kind discovery could change our understanding of the stellar life cycle.
The star under consideration is known as WD 1856, and it was probably somewhat sun-like in the past. When it exhausted its fuel about 6 billion years ago, WD 1856 destroyed much of its mass, leaving an exposed core of super-dense “electron-degenerate matter” that we would call a white dwarf Huh. On its way to becoming a white dwarf, WD 1856 would have expanded to become a red giant. Until now, scientists believed that any star would meet its end of life in such a way and could destroy any large planet in orbit. Nevertheless, astronomers examining data from the Transiting Exoplanet Survey Satellite (TESS) and ground-based telescopes believe that the WD 1856 orbiting gas is a giant.
The team tentatively dubbed the mysterious planet WD 1856 b. As with many “normal” solar systems, scientists identified the WD 1856B through the transit method. It involves looking at a distant star for a long time which hopes to plunge into the light. When these dip, it may be evidence that an exoplanet is passing through the star. This is the way the Kepler mission has used thousands of candidate planets – TES does the same thing but with a focus on objects within a few hundred light years.
The large exoplanet with quick orbital span is easy to detect, and the WD1856B certainly fits that description. Thanks to data from the now-offline Spitzer Telescope, the team is confident that the planet is about 14 times more massive than Jupiter, a much larger planet in an already grand plan. It revolves around WW1,557 every 1.4 Earth days, blocking about half the light from the dead stellar core.
This raises the question, how could WD 1856B survive the red giant phase of the star? The study offered two possible explanations. One, it may have originally orbited far away, but the star’s death disturbed its orbit, causing it to migrate inward. Alternatively, the planet was always close to the star and the expansion pierced many layers of its atmosphere. According to the authors this is a less likely scenario.
To study this bizarre solar system in more detail, we will need new equipment such as the chronological delayed James Webb Space Telescope (JWST). This telescope can make the planets orbiting this dead star more intact. If we get to know what happened to WD 1856, it can preview what our solar system will look like in a few billion years.