What we know about Solar System formation might need a revision thanks to this latest image from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile. The new image — and it’s an image, not a model or a simulation — shows a very nascent solar system.
The star in this instance is HL Tau, an orange dwarf star that’s only about a million years old. That’s extremely young; our Sun, by comparison, is about 4.6 billion years old. It sits about 450 light years from the Earth, and it’s surrounded by a disk of gas and dust, an accretion disk we know spins around a star and eventually coalesces into planets.
And that’s exactly what we’re seeing in this image. The image isn’t just a disk, it’s a series of bright, concentric rings separated by gaps. Those gaps are left by very young planets just starting to come together. Over time, gravity binds the material in the disk to form larger bodies, bodies that amass more material as their gravity increases. Eventually, they will become full planets in their own right, shaping the solar system and clearing wider and wider gaps as they orbit their parent star. We’re seeing the very first stages of that process in this image.
That we can see this process happening at all is sort of amazing. Normally a gaseous cloud like this would obscure this protoplanetary process from view, but ALMA was able to see through it. That’s because ALMA’s telescopes see in the radio to infrared part of the electromagnetic spectrum, waves that are shorter than the visible light we can see. Warm dust glows in theses wavelengths, which means ALMA can look through the obscuring dust to bring us this stunning view of a solar system being born.
A composite image of the young star HL Tauri and its surroundings using data from ALMA (enlarged in box at upper right) and the NASA/ESA Hubble Space Telescope (rest of the picture). This is the first ALMA image where the image sharpness exceeds that normally attained with Hubble. Credit: ALMA (ESO/NAOJ/NRAO)/NASA/ESA
The image is the clearest one to date showing a solar system’s formation, and offers the best evidence that our theories about solar system formation are right. But it’s especially interesting because HL Tau is so young. Thanks to this image, astronomers can conclude that the process of planetary formation occurs much faster than previously thought.
But even if you’re not into all the incredible science in this baby photo, you can’t deny that something being born is a pretty amazing sight.
Feature image via Alma Observatory