The last few decades of astronomical surveys have revealed several thousand exoplanets in the cosmos, but very few have ever been seen directly. We can only infer the presence of most exoplanets from their gravity or ability to block starlight. However, researchers using the Very Large Telescope (VLT) in Chile recently turned it toward a star 63 light-years away called Beta Pictoris to hunt for a gas giant (Beta Pictoris c), and they snapped an image of it.
Our current level of technology makes it almost impossible to image exoplanets directly. Compared with stars, planets are so dim that we usually can’t resolve them in the halo of light. Beta Pictoris c joins a list of less than two-dozen extrasolar worlds (including Pictoris b) that scientists have spied directly, and some of those are still highly contentious.
Scientists were able to get this new image thanks to all the interest in the Beta Pictoris system over the years. Beta Pictoris c and its sibling world Beta Pictoris b are less than two million years old. Pictoris b was discovered via direct imaging, which again, is quite rare. However, anomalies in its radial velocity prompted astronomers to look closer. Radial velocity analysis is a less common way of detecting exoplanets that relies on using telescopes to detect small wobbles in stars caused by the gravity of their planets. Just last year, a team discovered Beta Pictoris c while attempting to explain those anomalous radial velocity readings.
As a result of this planet-hunting endeavor in Beta Pictoris, scientists had an excellent data set describing the motion of these exoplanets. That’s exactly what the ExoGRAVITY team, led by astronomer Mathias Nowak of the University of Cambridge, needed to get started. Nowak’s effort uses the GRAVITY interferometer on the VLT to study exoplanets, and the wealth of data on Beta Pictoris helped the team know just where to look for Beta Pictoris c. All four VLT telescopes scanned the alien solar system, feeding data into a “virtual telescope” that combines them for a sharper image. And that’s how we ended up with an image of Beta Pictoris c, one of the first exoplanets studied via both direct imaging and radial velocity.
There are still some mysteries to unravel in Beta Pictoris, though. The light from Beta Pictoris c is six times fainter than Pictoris b. However, Pictoris c is eight times the mass of Jupiter, so how big is Pictoris b? We thought it was just a little larger than Pictoris c, but it’s going to take more research to figure out exactly what’s going on here. That won’t be a problem — with two visible exoplanets, Beta Pictoris will be a target for plenty of astronomers.
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Exoplanet, Star, Light-year, Observation, Beta Pictoris b, Gravity, Astronomy
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