New simulation shows disk anomalies around stars may not be planets after all

July 11, 2013 by Bob Yirka, report
Linear analysis of the axisymmetric modes of the photoelectric instability. Credit: Nature 499, 184–187 (11 July 2013) doi:10.1038/nature12281

( —Two researchers affiliated with several research centers in the U.S. have built a computer simulation that casts doubt on the claim of many recent exoplanet discoveries. In their paper published in the journal Nature, Wladimir Lyra and Marc Kuchner describe how they added gas to debris disks in their simulations and found irregularities similar to those found around real stars. This means, the researchers explain, that not all disk cluster irregularities are caused by planets.

For the past several years, researchers have been attributing the presence of planets to found in the disk pattern surrounding some stars. The thinking was that dust in the disk was being impacted by the gravity of a planet. But, Lyar and Kuchner write, that doesn't take into account the impact that in the disk may be having on its structure. Together they created a computer simulation similar to others used to study solar systems in the universe, but with the addition of gas and its interaction with dust.

In their simulation, gas heated by the star is transferred to nearby dust in the disk. That, the simulation showed, caused the dust to clump in some parts of the disk, causing irregularities that resemble those observed in real solar systems. This, the researchers write, suggests that claims of planet discoveries in the absence of other observable phenomena might have to be reviewed.

This chart compares the gas mass for several debris disk systems and shows where the photoelectric instability is most important. Systems like TW Hydrae contain so much gas that the instability is suppressed, but it could arise in relatively gas-free regions near the center of the disk. Credit: NASA's Goddard Space Flight Center

In star systems observable from Earth, researchers have seen dust clusters that have formed into disks. But rather then natural smooth ovals, several have sharp edges or orbits that are lopsided. Until now, researchers have discounted the possible impact of on such disks concluding that they were caused by the presence of planets—most of which, unfortunately, are too dim to be seen because of the overbearing light emitted from the star. Lyar and Kuchner postulate that gas amounts in disks surrounding stars may fall below the limits of detection, but not so much that they have no impact on the disk. Their simulation, they write, suggests that stargazers should not be so quick to label odd shaped disks around stars as proof of the existence of a planet.

Watch the changing dust density and the growth of structure in this simulated debris disk, which extends about 100 times farther from its star than Earth's orbit around the sun. At left, the disk is seen from a 24-degree angle; at right, it's face-on. Lighter colors show higher dust density. Credit: NASA Goddard/W. Lyra (JPL-Caltech), M. Kuchner (Goddard)

Explore further: Modeling Jupiter and Saturn's possible origins

More information: Formation of sharp eccentric rings in debris disks with gas but without planets, Nature 499, 184–187 (11 July 2013) doi:10.1038/nature12281

'Debris disks' around young stars (analogues of the Kuiper Belt in our Solar System) show a variety of non-trivial structures attributed to planetary perturbations and used to constrain the properties of those planets. However, these analyses have largely ignored the fact that some debris disks are found to contain small quantities of gas, 9, a component that all such disks should contain at some level. Several debris disks have been measured with a dust-to-gas ratio of about unity, at which the effect of hydrodynamics on the structure of the disk cannot be ignored. Here we report linear and nonlinear modelling that shows that dust–gas interactions can produce some of the key patterns attributed to planets. We find a robust clumping instability that organizes the dust into narrow, eccentric rings, similar to the Fomalhaut debris disk. The conclusion that such disks might contain planets is not necessarily required to explain these systems.

Press release

Related Stories

Modeling Jupiter and Saturn's possible origins

March 5, 2013

New theoretical modeling by Carnegie's Alan Boss provides clues to how the gas giant planets in our solar system—Jupiter and Saturn—might have formed and evolved. His work was published recently by the Astrophysical Journal.

Fragments falling onto the Sun

July 1, 2013

( —Stars form as gravity coalesces the gas and dust in an interstellar cloud until the material develops clumps dense enough to become stars. Even after a star begins to burn its nuclear fuel it continues to grow ...

Spiral arms hint at the presence of planets

October 19, 2011

A new image of the disk of gas and dust around a sun-like star has spiral-arm-like structures. These features may provide clues to the presence of embedded but as-yet-unseen planets.

Recommended for you

First to red planet will become Martians: Canada astronaut

September 22, 2018

Astronauts traveling through space on the long trip to Mars will not have the usual backup from mission control on Earth and will need to think of themselves as Martians to survive, Canada's most famous spaceman half-jokingly ...

Three NASA missions return first-light data

September 21, 2018

NASA's continued quest to explore our solar system and beyond received a boost of new information this week with three key missions proving not only that they are up and running, but that their science potential is exceptional. ...

Dwarf companion to EPIC 206011496 detected by astronomers

September 20, 2018

Using ESO's Very Large Telescope (VLT), European astronomers have uncovered the presence of an M-dwarf around the star EPIC 206011496. The newly found object is more than 60 percent less massive than our sun and is bounded ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

1 / 5 (1) Jul 11, 2013
Flat Earthers and other pseudo-scientific luddites will rejoice.......a straw to use to try to defeat the accomplished fact of exoplanets and substitute religious dogma in its place. Ancient Greeks and earlier societies knew Earth was a sphere; but after thousands of reasonable folks were burned at stakes or tortured to death in the inquisitions, a centuries long dark age ensued during the Medieval period. That dark age was broken only by war! A war brought about by the enabling technology of the printing press and the vagaries of Clausewitzian and Machiavellian politics that gave birth to the Reformation. Tragically, the dogmatics had to be killed in the mass death of the Thirty Years War along with millions of innocents.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.