Observations of a Disturbed Circumstellar Disk

Planets are thought to form in the circumstellar disks around young stars. Astronomers have simulated this with computer model, and have been able to replicate (to a pretty good extent) the formation of our solar system via the circumstellar disk around our sun when it was very young. Planet formation is evident around nearby young stars as well. The caveat is that we can not directly see the planet forming inside the disk. Instead, astronomers use infrared and radio data to infer the a gap in the disk, probably due to the formation of a planet. Recently, astronomers were able to catch a rare glimpse or what appear to be a circumstellar disk around a star that's been distorted due to the presence of a planet.

 

Now we can't see the planet directly, but the fact that the disk has a spiral shape and not a circular shape suggests that a planet has been gravitationally disturbing the disk material. The image was taken with the Subaru telescope, an optical and infrared 8.2m scope in Mauna Kea, HI. The light from the star has been intentionally blocked out in the image, so that we can see the disk glowing in infrared. The disk is bright in the infrared because it is colder than the star it surrounds. How are we able to see such a disk? It's a combination of the fact that the telescope is very large, it uses very high tech adaptive optics to remove atmospheric affects, and the star is relatively close to us (~450 ly away). Astronomers are not certain that these arms are due to planets, but modeling shows that planets do have the capability of causing such structure. More modeling observations will need to be done to confirm these ideas.

Image credit: NASA's Goddard Space Flight Center/NCSA

Living in the Local Bubble

3D view of the local bubble (white) and pieces of adjacent parts of the interstellar medium (purple and blue)

Did you know that we live inside a bubble? Believe it or not, the solar system, along with many other stars, sits inside what astronomers call the Local Bubble. It's a region of space that is less dense than the surrounding area of space, and contain very hot gas ( greater than 1,000,000 degrees!) that emit soft x-rays. Inside the bubble, space has about 0.01 hydrogen atoms per cubic inch (compare this to the ~10^20 atoms per cubic inch here on earth!). The bubble is shaped like an egg or a cylinder that is about 10x as tall as it is wide (30x200 parsecs), and sits upright with the plane of our galaxy crossing through the bottom third of the bubble. The solar system itself sits inside a thin sheet of cloud called the Local Fluff (no joke!), that is slightly more dense than the surrounding bubble. So where did this bubble come from? Astronomers are not a hundred percent sure, but the leading theory says that a supernova must have went off somewhere near the sun and essentially "blew" the bubble and heated up the gas inside. This probably happened around 10 million years ago, way after the sun and planets had already formed! So in a sense we survived a supernova explosion! Now the big question is this: are we living inside a supernova remnant that is still actively heating and removing material from the area? Or has the remnant material disappeared and left behind an "empty" bubble. Astronomers are actively trying to answer this question. But for now we are living happily in a sheet of fluff inside our own little galactic bubble!