Meteorites and Distant Forming Solar Systems
SciWorks Radio is a production of 88.5 WFDD and SciWorks, the Science Center and Environmental Park of Forsyth County, located in Winston-Salem.
One benefit of living in a galaxy, as we do, is that there are stars in our sky at different stages of their lives. The frustrating thing is that we can’t get up close for a visit, but we have gotten good at exploring them from here.
We can understand the formation of planetary systems that also tell us about our own solar system.
That’s Dr. Rachel Smith, Director of the Astronomy & Astrophysics Research Lab, and - get this - Curator of Meteorites at the North Carolina Museum of Natural Sciences in Raleigh. She's also Assistant Professor in the Department of Physics and Astronomy at Appalachian State University. Her research involves studying newly-forming solar systems and comparing them to the formation of our own.
Solar systems form from a spinning disk of gas and dust, and what happens is that in a molecular cloud, something triggers a collapse which starts a star forming. Just by the basic laws of physics, you get a disk of gas and dust forming around it. Material is going to stick to the star as it's forming, and the material that doesn’t stick to the star eventually forms planets.
What doesn’t become part of a planet is left floating in space, with the chemistry of the primordial solar system locked in, like a time capsule. Sometimes a bit of this material falls to Earth as a meteorite.
Cosmo chemists who study meteorites look at the formation of the solar system by exploring that chemistry because meteorites are the oldest material we have from the early solar system.
Meteorites show us a 4.6 billion year old baby picture of our solar system. But we study the chemistry of distant solar systems using spectroscopy. A spectrograph breaks starlight into a spectrum of colors; like a rainbow, only science-ier. The absence of specific colors is a code, telling us about the chemistry of the star and its system.
Astronomers can observe the gas and dust around stars forming today, and these protostars that are analogous to our solar system when it was forming, in the gas and dust swirling around a forming star, you can make these connections with the meteorites and with the chemistry of our sun to try to better understand the physics and chemistry of planetary system formation. What I’ve been working on is looking at the chemistry in the gas surrounding these protostars, and using powerful telescopes on the ground, and these are the largest optical infrared telescopes in the world, and have very powerful spectrographs that can look at the precise abundance of certain types of molecules that we’re interested in.
A molecule is a group of two or more types of atoms bonded together. For example, a molecule of water, H2O, is an oxygen atom bonded to two hydrogen atoms. An isotope is a heavier version of an element’s atom.
There are lots of molecules we can look at, and we can look at the abundances of the isotopes and compare that to what we see in meteorites.
Astronomers can infer planets by the effects they have on their parent star. (We learn about their atmospheres using spectroscopy.)
We have the Kepler space mission, and other big ground-based telescopes that observe exoplanets and try to understand how these planets form and how to connect them to our solar system. What we’re finding is that there are many different kinds of planetary systems out there. Planets can be stable around not just one star, but two stars, three stars. If you remember in Star Wars, there was Luke Skywalker looking at a duel sunset. Then, that was science fiction, but now we know that if there was a planet that was habitable in a system like that, then that’s what they would see. The molecules needed for life are already in space, and carbon tells the story about how the chemical pathways lead to organic compounds, and we know that organic compounds lead to life eventually. We’re not looking for life or looking for evidence of life, but we are trying to understand the mechanisms that eventually will lead to life. So if we trace the carbon before life happened, we eventually get a bigger picture of how life could evolve. We can compare these to meteorites and try to understand what happened in our early solar system to create this chemical signature in the meteorites.