2028 To Provide Rare Opportunity For Planet Hunting Around Alpha Centauri

In May 2028 Alpha Centauri A (left) will pass in front of a star bright enough to enable us to find planets orbiting the star through the distortion their gravity has on the more distant object's light. ESA/NASA

Little is known about S5, a previously disregarded star whose magnitude of 7.8 makes it visible in binoculars or small telescopes. It is thought to be a red giant at a distance of several thousand light-years.

As seen from Earth, Alpha Centauri A is predicted to pass just 0.015 arc seconds from S5, creating a lensing effect sharp enough that we should be able to detect any large planets near it at the same time. Kervella estimates a 45 percent chance of the approach being close enough to produce an Einstein Ring, the most dramatic form of lensing.

There will be four previous times when one of Alpha Centauri's stars pass in front of a background object, and many more before 2050. These are at least a thirty times fainter, greatly reducing the chance of detecting planets, although some may prove useful as test runs.

Trajectories of α Centauri A (orange curve) and B (red curve) superimposed on an image Alpha Centauri. Kervella et al/Astronomy and Astrophysics

The recent discovery of a planet orbiting Proxima Centauri has put the focus on our nearest stellar neighbor, but the twin stars of Alpha Centauri A and B are almost as close, and bear a much greater resemblance to the Sun.

Kervella's technique could be applied to other nearby stars. However, Alpha Centauri's location near the galactic plane means that it will pass in front of stars that are bright enough to be useful unusually often. For planet-hunting astronomers, 2028 could be a true once in a lifetime opportunity.


[H/T: The Register]

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