One of the interesting facets of Venus is that we haven’t found anything like it elsewhere in the galaxy. To be fair, we haven’t found anything that’s really like Earth, either. We’re just not to that point in our observations, yet, as much as we would like to be. Let’s face it — we’re still trying to sort out the whole planetary formation issue.
This week, that issue got a bit more complicated as researchers presented observations of a planetary debris disk to the 240th meeting of the American Astronomical Society (AAS). And the observations were not what was expected or predicted.
The parent star involved is HD 53143. Scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to image the star’s debris disk, which was discovered in Hubble observations back in 2006. The debris disk was thought to be similar to our own Kuiper Belt — smaller bodies and comets engaged in a game of cosmic billiards, grinding each other down. And based on the Hubble observations, the debris disk was thought to be basically face-on from our view on Earth. That all seemed simple enough.
Until ALMA came along.
Now it appears that this system has not only a highly eccentric debris disk but possibly a second disk and even a planet. Lead researcher Meredith MacGregor explains: Until now, scientists had never seen a debris disk with such a complicated structure. In addition to being an ellipse with a star at one focus, it also likely has a second inner disk that is misaligned or tilted relative to the outer disk. In order to produce this structure, there must be a planet or planets in the system that are gravitationally perturbing the material in the disk.
These new observations mean that HD 53143 is the most eccentric debris disk found to date. This result is unexpected, definitely unusual, and means something must be perturbing the disk – something like a planet, perhaps.
Understanding how this particular system got its shape is another piece of the planetary formation process, which seems to be more like a tree with lots of branches than a “one solution fits all” kind of theory. As Dr. Joe Pesce from the NSF notes: This research demonstrates how astronomy works and how progress is made, informing not only what we know about the field but also about ourselves.
NRAO press release
“ALMA Images the Eccentric HD 53143 Debris Disk,” Meredith A. MacGregor et al., to be published in The Astrophysical Journal Letters (preprint)