This is an Across the Bench piece! Check out Laura's interview of Amanda here!
You may imagine the depths of space as a silent scene, filled with stars but mostly inert. But in fact, there's quite a bit of action: comets, asteroids, and baby planets smash into each other, shattering into pieces, and grinding into bits of space dust and debris. Within this mess lies the potential to discover whether planets exist near stars many light years away - and that's why Laura Haney is studying debris disks.
Haney is a 5th year PhD student in the department of Physics and Astronomy at UCLA, working with Professor Ben Zuckerman to examine circumstellar debris disks. These large, disk-shaped collections of gas and dust surround some stars (circum- 'around', stellar- 'star'), and are formed when solid objects such as comets, asteroids, and planets collide and break pieces of each other off. Debris disk creation is a normal part of planet formation around a star. While planet hunters search for the planets that orbit other stars, Haney and other debris disk researchers search for the debris disks that result from planet formation. The advantage is that dust is easier for astronomers to observe due to the way it absorbs and re-emits light - much easier, in fact, than even a large body like a planet. By identifying debris disks, astronomers can guess whether a planet might be present near a star.
What's a day in the life of an observational astronomer like? Much of Haney's work involves analyzing images from world-class telescopes. First, she has to reserve time on the telescopes, such as the Keck telescope on Mauna Kea, Hawaii, one of the largest visible light telescopes in the world. Conveniently but perhaps unfortunately for Los Angeles-based Haney, the telescopes can be controlled remotely, so there is no need to travel to Hawaii. During control of the instrument Haney points it at a star in the sky she is interested in observing, takes pictures in the visible light spectrum (light that all humans can see), and also acquires spectroscopic data about the presence of various elements in the star.
Once an image of the star is acquired, the age of the star can be determined by examining its elemental components. Young stars, defined as less than 100 million years old, tend to have more lithium than older stars, which have burned their lithium away. If the star is young and therefore more likely to have planets near it, Haney captures an image with a different telescope which can see into the infrared spectrum. The dust in a debris disk tends to absorb visible light from the star and re-radiate it in the infrared spectrum. By subtracting out the signal of the actual star from the infrared image, the observer is left with a glowing disk of gas and dust.
These images are the highlight of Haney's work. Not every debris disk can be resolved in an image. "When you can and you get these beautiful images, it's crazy to stop and think about what you're seeing," says Haney. "I'm looking at the remnants of a planetary collision around another star, hundreds of light years away."
Not only are the images awe-inspiring, they're also informative. "The amount of information you can glean from a point of light is astounding," explains Haney. For instance, astronomers can differentiate between debris disks that are made from comets and/or asteroids smashing into each other - our solar system's own asteroid belt is one example - and disks created by more catastrophic collisions between small planets. These chaotic events are more likely to have bigger objects form as a result, such as moons and new planets. Astronomers are very interested in the presence of moons, because moons affect their planets in a variety of ways (creating tides, regulating the planet's spin speed, etc) to make them more likely to support life.
The most frustrating part? "80% of what I do is just staring at tables, numbers, and figures. You have to slog through a lot of that to get to the really cool stuff. But the payoff is totally worth it." Haney will be graduating with her PhD in June 2016 and inspiring a new generation of astronomers at her next position as a high school physics instructor.
- Amanda Freise (@AmandaFreise)
Signal to Noise co-founder and Editor-in-Chief
PhD Candidate, Molecular and Medical Pharmacology