Hubble observes weird star system with three off-kilter, planet-forming disks

By Georgina Torbet Published May 4, 2023

Planets form from large disks of dust and gas that collect around their host stars. Billions of years ago, our solar system would have looked like a single point of bright light coming from the sun, with a disk of matter swirling around it that eventually clumped into planets. To learn about how our solar system formed, it’s helpful to look at other systems that are currently going through this process — such as TW Hydrae, a system located 200 light-years away and turned face-on toward us, making it the perfect place to observe planetary formation.

But there’s something odd about the TW Hydrae system. In 2017, astronomers first noticed a strange shadow that was visible on the disk of dust and gas surrounding the star. While such shadows are typically from a planet formed within the disk, in this case the shadow’s shape and movement suggested it was actually from a second disk, located within the first disk and tilted at a different angle. Now, astronomers think they have spotted evidence of a third disk, with all three stacked up and creating a complex pattern of shadows.

This illustration is based on Hubble Space Telescope images of gas and dust discs encircling the young star TW Hydrae. We have an oblique view of three concentric rings of dust and gas. At the centre is the bright white glow of the central star. The reddish-coloured rings are inclined to each other and are therefore casting dark shadows across the outermost ring. — This illustration is based on NASA/ESA Hubble Space Telescope images of a gas and dust discs encircling the young star TW Hydrae. Hubble photos show shadows sweeping across the discs encircling the system. The interpretation is that these shadows are from slightly inclined inner discs that block starlight from reaching the outer disc, and therefore cast a shadow. The discs are slightly inclined to each other because of the gravitational pull of unseen planets warping the disc structure. NASA. ESA, L. Hustak (STScI)

Researchers used data from the Hubble Space Telescope collected in 2021 to observe the system, finding that the shadow was different from what they expected based on the theory of one disk casting a shadow on a second disk.

Recommended Videos

“We found out that the shadow had done something completely different,” said lead research John Debes of the Space Telescope Science Institute in a statement. “When I first looked at the data, I thought something had gone wrong with the observation because it wasn’t what I was expecting. I was flummoxed at first, and all my collaborators were like: What is going on? We really had to scratch our heads and it took us a while to actually figure out an explanation.”

They figured out that the most likely explanation for the observations is two misaligned disks within a third, larger disk. That’s a very odd setup for a planetary system. “We’ve never really seen this before on a protoplanetary disc,” said Debes. “It makes the system much more complex than we originally thought.”

It could be that there are already planets formed within each of the disks, which is what is causing the shadows. To learn more, one possibility is to use the powerful infrared vision of the James Webb Space Telescope to observe the shadows in more detail.

The research is published in The Astrophysical Journal.

Georgina Torbet

Space Writer

Georgina has been the space writer at Digital Trends space writer for six years, covering human space exploration, planetary…

Topics

Tech News

Space

Astronomers spot rare star system with six planets in geometric formation

Orbital geometry of HD110067: Tracing a link between two neighbour planets at regular time intervals along their orbits, creates a pattern unique to each couple. The six planets of the HD110067 system together create a mesmerising geometric pattern due to their resonance-chain.

Astronomers have discovered a rare star system in which six planets orbit around one star in an elaborate geometrical pattern due to a phenomenon called orbital resonance. Using both NASA's Transiting Exoplanet Survey Satellite (TESS) and the European Space Agency's (ESA) CHaracterising ExOPlanet Satellite (CHEOPS), the researchers have built up a picture of the beautiful, but complex HD110067 system, located 100 light-years away.

The six planets of the system orbit in a pattern whereby one planet completes three orbits while another does two, and one completes six orbits while another does one, and another does four orbits while another does three, and so one. The six planets form what is called a "resonant chain" where each is in resonance with the planets next to it.

Space

Hubble spots an Earth-sized exoplanet just 22 light-years away

An artist’s concept of the nearby exoplanet, LTT 1445Ac, which is the size of Earth. The planet orbits a red dwarf star.

Although astronomers have now discovered more than 5,000 exoplanets, or planets outside of the solar system, the large majority of these planets are considerably larger than Earth. That's partly because it's easier to spot larger planets from tremendous distances across space. So it's exciting when an Earth-sized planet is discovered -- and the Hubble Space Telescope has recently confirmed that a nearby planet, which is diminutive by exoplanet standards, is 1.07 times the size of Earth.

The planet LTT 1445Ac was first discovered by NASA's Transiting Exoplanet Survey Satellite (TESS) in 2022, but it was hard to determine its exact size due to the plane of its orbit around its star as seen from Earth. “There was a chance that this system has an unlucky geometry and if that’s the case, we wouldn’t measure the right size. But with Hubble’s capabilities we nailed its diameter,” said lead researcher Emily Pass of the Harvard-Smithsonian Center for Astrophysics in a statement.

Space

Hubble observes mysterious bright explosion in the middle of nowhere

An artist’s concept of one of the brightest explosions ever seen in space.

The Hubble Space Telescope recently observed something strange: an extremely bright, extremely fast flash of light that popped up in the middle of nowhere. Technically known as a Luminous Fast Blue Optical Transient (LFBOT), the odd thing about this rare event was that it occurred outside of a galaxy.

These flashes have been observed only a few times since they were discovered in 2018, and this particular event was named The Finch. Hubble was used to track the flash's origin point, which was in between two galaxies: 50,000 light-years away from a larger spiral galaxy and around 15,000 light-years away from a smaller galaxy. This has astronomers puzzled, as these events were thought to issue from inside galaxies where stars are forming -- but this event happened far away from any star-forming region.