Ladies and gentlemen—
And now, for something entirely unrelated!
In the summer of 2005 I engaged in astronomy research at the University of Rochester through a “Research Experience for Undergraduates” program, funded by the National Science Foundation.
Some of the research seemed mundane, some was incredibly exciting, and some was just plain incomprehensible to me at the time (and some still is!).
But to make a two-year-long story very short, I got extremely lucky, and I’m now listed as the third author on two journal articles, one in the Astrophysical Journal (ApJ) and one in Nature.
To have an article published in ApJ as an undergraduate is fantastic, and requires some luck. To be published in Nature requires way more than luck (many university professors don’t have papers published in Nature). But to be published in both over the span of two months—again, as an undergraduate, or at least recent alum—is too glorious for words!
Needless to say, I’m ecstatic, and chances are I’ll use those two publications to my advantage in the near future when I begin the grad school application process. But that’s a story for another entry.
Anyway, onto the content.
Due to rules from the two journals, I’m not allowed to upload PDF’s of the articles to any website until six months from the date of publication, so if you all want to see the real thing, just shoot me an email.
Or, if you want to purchase and download the articles online, here’s the information for each one:
[http://www.nature.com/nature/podcast/index.html] – this is Nature’s weekly “Podcast,” or radio-show-esque recording outlining the most exciting of that week’s developments. Make sure to look for the 30 August recording; our portion ranges from 15:14 – 18:58.
Citation: Watson, D. M., Bohac, C. J., Hull, C., Forrest, W. J., Furlan, E., Najita, J., Calvet, N., d’Alessio, P., Hartmann, L., Sargent, B., Green, J. D., Kim, K. H., & Houck, J. R., “The development of a protoplanetary disk from its natal envelope,” 2007, Nature, 448, 1026.
Astrophysical Journal article:
Citation: Dubus, G., Taam, R. E., Hull, C., Watson, D. M., Mauerhan, J. C., “Spitzer Space Telescope Observations of the Magnetic Cataclysmic Variable AE Aquarii,” 2007, Astrophysical Journal, 663, 516.
Also, if you want to see the flurry of articles written about our Nature paper, go to Google and type in the following:
“Journal Nature” “Dan Watson”
(You can even get a few hits if you replace “Dan Watson” with “Chat Hull” – Google knows who I am now…!)
They’re all pretty much the same story, and there are lots of them…but they’re all interesting! (And as is to be expected, some are better written than others.)
And finally, I present to you my own for-the-general-public version of our Nature research, with a short sidebar about the more confusing ApJ article. My article puts more of a focus on the “missing link” in star formation than on the “rain” that you’ll see highlighted in the online articles…feel free to compare, contrast, and comment!
This article should be published within the next few days in Penn Yan’s highly regarded Chronicle Express, for those of you who are within its circulation radius…
Chronicle Express article:
[Here are two cartoons that go with the article]
ROCHESTER – Penn Yan native Chat Hull, University of Rochester physics and astronomy professor Dan Watson, and their colleagues from UR and other North American universities may have found the missing link in the formation of solar systems like our own.
In their paper, published in the August 30, 2007 issue of Nature, a leading international science journal, they describe how they used the Spitzer Space Telescope to peer into the cold, dark regions of a young, developing star, known as a protostar, called NGC 1333-IRAS 4B, located about 1,000 light-years from Earth.
What they saw was a stormy scene: a protostar surrounded by enough water to fill the Earth’s oceans five times, and a forecasted precipitation rate of approximately 23 Earth-masses of water per year.
“Raining” down at speeds faster than a mile per second, supersonic chunks of ice pelt the surface of a dense, dusty disk surrounding the infant star and vaporize on impact, creating what astronomers call an “accretion shock.”
The astronomers detected this supersonic hailstorm by analyzing the infrared light emitted by the star. Much of this light was emitted by the “shocked” water as it cooled down after falling from a cloud surrounding the natal star and slamming into the protostellar disk.
“The news here…is this missing link of how the disks assemble themselves within these envelopes,” says Watson in Nature’s August 30 podcast, referring to how the spherical envelope—the cloud of dust, gas, and ice that surrounds a very young protostar—collapses to form the pancake-shaped disk. “This is the first time we’ve ever seen the process by which the surrounding envelope’s material arrives at the disk,” he adds.
Astronomers think that stars begin as cold blobs of dust and gas, which then begin to contract and form a hotter, protostellar core in the blob’s center. As time goes on, the spherical cloud surrounding the protostar collapses onto a flat, dense disk. And finally, the material in the disk either falls inward onto the forming star, or condenses to form planets, sometimes resulting in solar systems similar to our own.
The discovery in IRAS 4B of an accretion shock, which, according to Watson, “has been searched for and theorized about for decades,” fills a gap in the long-accepted theory of stellar and planetary formation: while astronomers have long been able to study the later stages of star formation, they had never seen evidence of the earlier stage when the envelope falls onto the disk.
One of the reasons astronomers haven’t been able to solve this puzzle until now is that the clouds that surround the youngest, “Class 0” protostars such as IRAS 4B are simply too thick and dusty. “What’s special about the Spitzer Space Telescope,” says Watson, “is that it lets us see through dense dust and gas clouds. In fact, we’re now able to see what used to be invisible material at the cores of protostellar condensations.”
Class 0 protostars are stars in their earliest stages of formation, and may be anywhere from a few thousand to ten or twenty thousand years old. “We think that what we’re seeing in [IRAS 4B] now is quite a lot like what our solar system was like at the same age,” Watson says.
This research also sheds light on how our own, rocky, watery Earth may have come to be. “For the first time,” Watson says, “we’re witnessing the arrival of some future solar system’s supply of water.”
However, although the water vaporizes after crashing into the disk, it isn’t ready to fill any Finger Lakes yet. According to Watson, afterward the water must refreeze to form “asteroids and comets before it will be the stuff that will decorate the surfaces of the rocky planets someday and form oceans.”
Chat Hull is currently living in Guatemala and teaching high-school math and physics in the rural, Mayan town of San Mateo Ixtatán. He and Jessica Butler, a fellow teacher and Penn Yan resident, will return to their homeland in early November after the end of the Guatemalan school year.
Chronicle Express sidebar:
Chat Hull also contributed research to another paper that was published in the July 1 issue of the Astrophysical Journal.
In the paper, Hull, Dan Watson (see associated article), and other astronomers used the Spitzer Space Telescope to observe a star known as AE Aquarii, located in the constellation Aquarius.
AE Aquarii is a binary (two-star) system known as a cataclysmic variable, which consists of a bloated, aging star that is sloughing off much of its material onto a quickly rotating white dwarf, an extremely dense, ancient star remnant.
The white dwarf is thought to expel most of the material streaming onto it from the aging donor star (see image). However, the exact conditions near the star are not known, as the spectrum of light emitted from the binary system includes several features that have yet to be explained. Research is ongoing.