Twin Stars

Looking for Earth-like alien planets (or exoplanets) seems to be all the rage nowadays. Humanity has invested much in searching for planets that may harbor life, or civilizations that may be broadcasting their signals.

But searching just for planets that look like Earth isn't going to answer some of the questions we have about our Universe.

Luckily, there are a number of fellows who look for things that are decidedly unEarth-like. To that end, American scientists have located a unique binary system, and both stars are harboring remarkably large planets. Notably, these stars are locked in the tightest embrace ever discovered.

The scientists, who were using the Planet Finder Spectrograph mounted at Carnegie’s Las Campanas Observatory in Chile, were trying to find Jupiter-sized planets in order to better understand how they impact star systems. Actually, the broader goal of their study is to look at how unique our Solar System is by finding these Jupiter-sized planets and then comparing their orbits to those in our own system.

But what they found was is truly wild.

Uniqueness

This particular system is far more unique more than the usual binary system. One of the stars, HD 133131A , has two planets, and the other, HD 133131B, has one. For that class of system, these stars are the closest to each other: 360 Astronomical units, or 54 billion kilometres (33 billion miles).

Carnagie Science

And these planets are definitely huge: HD 133131A has one planet 1 and a half times Jupiter’s mass, and the other just half of Jupiter. HD 133131B's planet is 2.5 times Jupiter’s mass.

But the uniqueness doesn't stop there. These stars are "metal-poor", being made-up mostly of hydrogen and helium. In contrast, other stars with giant planets have heavier elements. They are also not exactly identical, having slightly different compositions. This suggests the stars have consumed smaller planets before.


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