Meet the Scientists is an Armed with Science segment highlighting the men and women working in the government realms of science, technology, research and development. The greatest minds working on the greatest developments of our time. If you have someone you’d like AWS to highlight for this segment, email Jessica L. Tozer at science@dma.mil.
Dr. Jean Vettel. (Photo provided by the Army Research Lab/Released)
WHO: Dr. John Carr. Originally from the Los Angeles area, he’s a scientist with an eye on the far, far, far distant skies. We’re talking literal light years, people. Good thing, too, because his interest in the far-off final frontier has uncovered a first-of-its-kind, incredible space discovery.
TITLE: Astrophysicist for the U.S. Naval Research Laboratory. He’s worked in the lab, in the Remote Sensing Division, for the past 19 years. He has a PhD in astronomy from the University of Texas.
MISSION: Carr and the other research team members set out to study the protoplanetary disk around a star known as HD 100546. Basically, they were looking at a ring around a baby star. What they found, however, is something truly spectacular. He and his team discovered what they believe is rare evidence of a forming planet around a star. That, it seems, was the start of something scientifically spectacular.
You were recently a part of a team that discovered what they believe is evidence of a new planet forming, which is amazing! What was your role in that discovery?
“I’m part of a small core group of astronomers who have been studying this particular star closely for several years. A big effort like this requires all of us to put our heads together in order to reach our conclusions. Besides just trying to interpret what is going on, there’s a lot of work to write the proposals, plan the measurements, and make the trips to these remote observatories. By 2012 we had already developed our hypothesis of this forming planet orbiting around the star. We were still cautious about our conclusions, though.”
(In addition to Dr. Carr, the research team consists of Dr. Sean Brittain, Clemson University; Dr. Joan R. Najita, National Optical Astronomy Observatory in Tucson, Arizona; and Dr. Sascha P. Quanz and Dr. Michael R. Meyer, both of ETH Zurich, Institute for Astronomy.)
“Then we realized that, if the signal we had already detected was really moving around the star the way we thought it was, then we could predict where it would be in the future. So we wrote a new proposal and I went down to Chile and collected new data in 2013. Amazingly, the object was right at the position and moving at the right speed as we predicted, so that was really a nice and satisfying result.”
How long does it take a planet to form?
“It depends on what type of planet, actually. The type of planets we’re talking about are very large planets like Jupiter or bigger. About a million years? The star I’m talking about is around a million years old.”
That’s relatively young for a star, correct?
“Yes, that’s an infant.”
What is your goal or the overarching mission of this research and what do you hope it will achieve?
“The big picture goal of this research really fits into an understanding on how planets are formed, or how the solar system was made. We know there are many other planets or systems in our galaxy, yet, most of these are very different from our own solar system. So why is that?”
“Towards that big picture goal, my collaborators and I and a lot of other workers in this area have been examining these very young stars that have been identified as potential sites of current planet formation. Young in this case is about a million years old. These are infant stars, still surrounded by very large flattened disks of gas and solid particles which are rotating around the star and are a remnant of the formation of the star. This is the material which astronomers believe give birth to planetary systems. In particular we’ve been using techniques of infrared spectroscopy to study the gas in these young planet forming disks around these stars. Our aim is to determine things like the composition of the material, to measure its motions around the star, determine the temperature of the gas and things like that. We try to put all of this together to get an understanding of the conditions that give rise to planets, and this information can be used to help refine theories of planet formation and hopefully shed light on say, the formation of our solar system.”
So what you’re doing is one of the steps towards understanding life, the universe and everything?
“That’s right.”
In your own words, what is it about your research that makes it so significant?
“Let me put this into a larger context. One of the really exciting developments in astronomy over the last two decades has been the discovery of planets orbiting around other stars in the galaxy.”
“Now, this idea that there could be worlds around other stars actually goes back centuries. It’s in all our science-fiction, from Star Trek to Star Wars. It wasn’t until 1995 that the first convincing evidence for an extrasolar planet – that’s what we call planets outside our solar system – was put forward.”
“Since 1995, this field has really exploded, and to date, astronomers have found that something approaching two thousand planets which are known to exist around other stars. There’s a great diversity of these planets, the sizes, how far away from the stars, how many planets there are, and various properties. Most of these are very different from our solar system, which is the most amazing thing.”
How did all the planets and systems come into being?
We think we know when this happens, we know where it’s happening, and we have a lot of detailed theories as to how this process can take place. However, to find a planet that’s in the act of formation has been a major challenge. The real significance of the results we published recently is we’ve found a rare example of a forming planet.”
An artist’s conception of the young massive star HD100546 and its surrounding disk. A planet forming in the disk has cleared the disk within 13AU of the star, a distance comparable to that of Saturn from the sun. As gas and dust flows from the circumstellar disk to the planet, this material surrounds the planet as a circumplanetary disk (inset). (Image provided by P. Marenfeld & NOAO/AURA/NSF/Released)
“We’ve been able to show that this is an object that’s orbiting around the star while this primordial disk of gas and dust is still in place, within the material from which it was born. I should add that the type of planet we’re talking about is a very massive one, not anything like the Earth. This is something that is at least a few times larger in mass than Jupiter. It would be a big thing. The distance the planet is from the star is about the same distance that Saturn is from our Sun.”
In your own words, why is this research so important for humanity?
“So we’re being a bit philosophical, eh? I think our quest to understand how stars form, how planets form, is really a part of the quest for our origins. What is the origin of our solar system? How did the Earth form? How did life originate on the Earth? This question of where we came from, from the larger cosmic to the smaller biotic scale is a fundamental question of human intellect. I think that in my own research, this quest forms the basis of my interest in this field.”
What got you interested in this field of study?
“I’ve a long interest in understanding how planets and stars form since my days in graduate school. It stemmed from that. It’s been an ongoing endeavor. It’s hard to say how I got into that particular field of research, but astronomy is a long time interest. A lot of people grow up with an interest in astronomy and I was lucky enough to end up pursuing that as a career.”
Are you working on any other projects right now?
“I’m working on several projects in this research area. A lot of these are making use of data from infrared space observatories. I think the one I am most interested in is the evolution of water, and the origin of simple organic compounds in space. We’re using infrared spectral techniques to study the water content in planet-forming disks, for example, trying to understand how the water evolves as these disks are forming. And eventually, how does the water get incorporated into planets.”
“One of the biggest questions is: how did the water get incorporated into the Earth? There’s no consensus among astronomers as to how the Earth acquired its water.”
“The research I’m interested in, and the projects I’m working on, do tie into this question, even though we’re not studying the Earth itself, but objects that are many, many light years away that are yet to form planets. By studying the water content in these systems, and studying the basic organic material that we observe in this gas – the same material that forms the basis for more complicated molecules required for life – it all ties into this very important question.”
If you could go anywhere in time and space, where would you go and why?
“That’s quite a question! The first thing that jumped into my mind is that I would like to go back to the age of the dinosaurs. Not only would it be amazing to see these creatures walking around the Earth, but everything would be so different – the plants, the animal life, the oceans, the climate. It would be really amazing to experience that. From a scientific and an intellectual point of view, you learn something about a very, very different time in Earth’s evolution.”
Do you have anything else you’d like to add?
“What I think is important about this particular paper is that it’s given us a rare opportunity to study planet formation as it happens. We give evidence for the detection of hot gas that is swirling around and falling onto this giant body – a giant planet – as it continues to form. It’s actually in the process of collecting material and growing. What I find really important and interesting about this is not only that ‘there’s a forming planet’ but that we find evidence for a process which has been predicted theoretically. It’s been predicted by models that, as these large planets form, there are disks that form around them that mediate the growth of the planet. This is really the first observational evidence that these disks actually exist.”
Thanks to Dr. John Carr for contributing to this article, and for his contributions to the science and technological communities.
Publications:
Organic Molecules and Water in the Inner Disks of T Tauri
Gas at the Inner Disk Edge
High-Resolution Infrared Spectroscopy of Protoplanetary Disks
Hot H2O Emission and Evidence for Turbulence in the Disk of a Young Star
Evidence for Residual Material in Accretion Disk Gaps: CO Fundamental Emission from the T Tauri Spectroscopic Binary DQ Tauri
The First Stellar Abundance Measurements in the Galactic Center: The M Supergiant IRS 7
Jessica L. Tozer is the editor and blogger for Armed with Science. She is an Army veteran and an avid science fiction fan, both of which contribute to her enthusiasm for science and technology in the military.
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