Binary planetary systems caught in the act of forming!

# Binary planetary systems caught in the act of forming!

The entire universe in blog form
July 2 2009 7:00 AM

# Binary planetary systems caught in the act of forming!

Astronomers have discovered a young binary system where both stars are surrounded by thick disks of material that are in the process of forming planets! And it's a near thing, too -- this system almost didn't exist at all.

Phil Plait

Phil Plait writes Slate’s Bad Astronomy blog and is an astronomer, public speaker, science evangelizer, and author of Death From the Skies!

First, the cool image:

On the right is a Hubble Space Telescope image of the two stars (collectively called, weirdly, 253-1536). In the optical, the disk enveloping the star on the left (called 253-53 a, so I'll just call it Star A) is obvious. It's dark because it blocks most of the light from the star, which is deeply embedded in the disk and can barely be seen. The star on the right (Star B) has a disk as well, but it's far smaller than the other star's disk, and swamped by the light of the star. So the components of this binary are like Jekyll and Hyde: one star is blocked by the dark disk, and in the other the disk is outglared by the bright star.

The image on the left was made using the Submillimeter Array, or SMA. At this wavelength (almost out in the radio part of the spectrum) the warm dust in the disks is bright, and the stars are almost completely dark. The disk on the right becomes obvious. Using some relatively simple math, the mass of the disks can be calculated (basically by measuring the size and brightness of the disks): Star A's disk on the left has a mass of about 70 times that of Jupiter, and Star B's disk is about 20 times Jupiter's mass.

Our entire solar system of planets (that is, everything except the Sun) has roughly twice the mass of Jupiter. So what we're seeing here is easily enough material to make a fully-fledged system of planets! In fact, this is the very first time a binary star, where both stars are detected in visible light, has been seen where each has a disk capable of making planets.