EarthSky
Not long ago, we couldn’t see planets orbiting distant stars at all. Now astronomers have captured the passage of exoplanet Beta Pictoris b into the glare of its star … then its re-emergence 2 years later.
ESO's Very Large Telescope (VLT) has captured an unprecedented series of images showing the passage of the exoplanet Beta Pictoris b around its parent star. This young massive exoplanet was initially discovered in 2008 using the NACO instrument at the VLT. The same science team since tracked the exoplanet from late 2014 until late 2016, using the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument (SPHERE) — another instrument on the VLT. Beta Pictoris b then passed so close to the halo of the star that no instrument could resolve them from one another. Almost two years later, after seeming to merge into the image of the star, Beta Pictoris b has now emerged from the halo. This reappearance was captured again by SPHERE. The complete series of images, with the bright glow of the star Beta Pictoris blocked out, have been compiled to create a stunning and unique time-lapse of the long-period orbit of Beta Pictoris b. SPHERE caught sight of Beta Pictoris b by looking at it directly — not by inferring its existence. Most known exoplanets have been discovered using indirect methods — observing how they affect a star's position or brightness. ESO's SPHERE specialises in a method called direct imaging, hunting for exoplanets by taking their photographs. This extraordinarily challenging endeavour provides us with clear images of distant worlds such as Beta Pictoris b, 63 light-years away. Beta Pictoris b orbits its star at a distance similar to that between the Sun and Saturn, approximately 1.3 billion kilometres, meaning it’s the most closely orbiting exoplanet ever to have been directly imaged. The surface of this young planet is still hot, around 1 500 °C, and the light it emits enabled SPHERE to discover it and track its orbit, seeing it emerge from its passage in front of its parent star. Whilst a glance at these images might suggest that the planet transits the star, eclipsing a little of its light, Beta Pictoris b does not in fact quite transit. These images are a remarkable achievement, heralding a new era in one of the most exciting and challenging areas of astronomy — discovering and characterising exoplanets.
