By Thomas Guengerich
SOCORRO, N.M., Jan. 7, 2009 – Seven New Mexico Tech physics students presented their research at the annual conference of the American Astronomical Society from January 4 to 8.
Fred Davies, Danielle Lucero, Josh Marvil, Krista McCord, Stephanie Moats, Delia Mocano and Kristina Nyland traveled to Long Beach, Calif., to present their interstellar work. Lucero, Marvil and Nyland are graduate students. The others are undergraduates.
“We think attending national conferences is an essential learning experience,” physics chairman Dr. Dave Westpfahl said. “Students do better if we can start them early on going to conferences.”
The AAS conference is the largest in the field of astronomy. Westpfahl said the event included nearly 3,000 researchers. He said only a handful of the presenters were undergraduate students – including four Tech students.
“These students will have an opportunity to meet some of the most famous people in the profession,” Westpfahl said. “And many of these people are very gracious and very generous with their time with students.”
Nyland said she’s excited to return to another AAS conference. As an undergraduate student at the University of Michigan, she presented research about galaxy clusters.
“I got to hear a lot of lectures and talk with very famous astronomers,” she said. “It was great. There are all sorts of booths, plenty of giveaways and so much to learn. It felt like an astronomy carnival.”
Four of the students – Marvil, Davies, Moats and Mocanu – completed NRAO internships last summer and presented their research posters at the conference.
Mocanu spent the summer at the NRAO headquarters in Charlottesville, Va. Moats completed her internship at the NRAO facilities in Greenbank, W.Va. Marvil and Davies worked at the NRAO in Socorro.
“It’s a real feather in the cap to get an NRAO internship,” Westpfahl said.
McCord, Nyland and Lucero presented their research done at New Mexico Tech.
Right: Delia Mocanu and Josh Marvil, New Mexico Tech students who made presentations at AAS. Mocanu wrote software to help analyze spectral lines. Marvil is studying radio spectra of star-forming galaxies.
Marvil, a doctoral student from San Diego, said he’s looking forward to interacting with other astrophysicists working on similar research.
“I think it’s a good opportunity to show others in the community what I’m working on and get feedback,” he said.
Mocanu, who is a native of Romania, worked with Dr. Bob Garwood to write prototype software that will analyze large calibrated spectral-line data sets generated by the Greenbank telescope. Current software examines individual spectral lines separately. Mocanu wrote code that lets the user view, and interact with, any number of spectra simultaneously.
“It would be easier now to detect sources of interference,” she said.
Marvil is studying the radio continuum spectra of star-forming galaxies and trying to improve the existing models that describe this phenomenon.
“We have models, but there’s some discrepancies,” he said. “So I’m taking the physics from earlier simple models and trying to elaborate.”
Marvil is examining very low frequency emission data collected from almost 100 galaxies to see if these emissions persist below what is expected from thermal absorption models. He is looking at data from the formation of a variety of different types of galaxies – from normal spiral galaxies to ultra-luminous infrared galaxies, which are thought to form stars at a much higher rate.
“We think the spectra should all fit a self-consistent model,” he said. “There should be a model that can predict what these things look like based on their physical properties.”
Right: Danielle Lucero
Lucero's doctoral work focuses on the interstellar medium (gas and dust) in elliptical galaxies.
â€œThe distribution and amount of the atomic and molecular gas in these galaxies can tell us a lot about the formation histories of ellipticals and how they evolve,â€ she said. â€œIn spiral galaxies, the amount of gas in each phase (molecular and atomic) is known to be a linear function of external pressure. Spiral galaxies have very different stellar populations, evolution histories, and gas contents, so it is not clear whether the same relationship will exist in ellipticals.â€
Her presentation at the conference explored this question by comparing high resolution maps of the atomic gas and images of molecular gas in a large sample of elliptical galaxies.
The comparison shows that the relationship between the gas content and the hydrostatic mid-plane pressure indeed does exist in ellipticals. Apart from the lack of spiral arms, the gas systems in ellipticals fundamentally resemble that of spiral galaxies, she said.
Left: Stephanie Moats and Fred Davies, New Mexico Tech students who presented research at AAS. Moats is studying the molecular composition of the Taurus Molecular Cloud. Davies is studying the galaxies M84 and M87.
Moats, a junior who graduated from Cibola High School in Albuquerque, spent the summer studying new molecules found in the interstellar medium.
Using radio astronomy, she looked at the Taurus Molecular Cloud, which is known for its high concentration of molecules, compared to normal interstellar space.
Molecules emit photons when electrons change levels. Each photon has a frequency that is unique to the molecule. The Greenbank telescope detects the frequency of the photons, thus giving scientists a glimpse of the composition of the Taurus Molecular Cloud.
Moats spent the summer examining data collected from the molecular cloud, in order to further the understanding of the sorts of material being formed. What she found was relatively novel.
“We’ve started to see a lot of spectra that indicate what molecules are being formed in the cloud,” she said. “We think we found a couple new molecules, never seen before in the interstellar medium. It’s hard to tell because the signal-to-noise ratio is somewhat weaker than we’d like, but we think we’ve found that large molecules are being created.”
Molecular clouds are often called “stellar nurseries,” because physicists believe that stars form only in the conditions found in molecular clouds, which are characterized by low temperature and high density.
“We want to find these large hydrocarbon chains,” Moats said. “It’s hard to find organic molecules, but if we can find that large molecules are formed with the Taurus Molecular Cloud, it may mean that organic molecules can also form. This means that the prehistoric Earth may have been seeded with organic molecules when it was initially formed.”
The Greenbank Telescope is among the most sensitive instruments on the planet, yet Moats said that to detect the existence of amino acids – the building blocks of life – the telescope would need much more time to detect them.
One startling piece of Moats’ research is not what she did find – but what she did not find. Previous studies claimed to detect some molecules that Moats did not detect.
“Our findings seem to refute previous research,” she said. “Perhaps the formation of organic molecules is more common than we had previously thought. So, this warrants more research, especially if we are to understand the formation processes of our solar system as well as our sun.”
Davies, a native of the Phoenix area, studied a cosmic jet coming out of the supermassive black hole at the center of the M87 Galaxy.
“A lot of what I did was process data to make images,” Davies said. “My advisor is trying to make a movie of the stuff shooting out of the jet.”
He also looked at the M84 Galaxy to study the relative motion of both galaxies.
“All we could do before is see their radial velocity – how fast they are moving away from us,” he said. “Now, we can get an idea of how these clusters are interacting.”
Davies used data collected from the Very Large Baseline Array, which combines information from telescopes across the hemisphere to create coherent data from super-distant galaxies. The galaxy clusters of M84 and M87 are around 51 million light years from Earth.
Right: Kristina Nyland, a doctoral student in physics at New Mexico Tech, is studying elliptical galaxies.
Nyland will present her research about elliptical galaxies and how neutral hydrogen, or HI, is distributed in and around them.
“There’s been a lot of study of HI in spiral galaxies, which have much more of this cold gas,” she said. “HI is the raw material from which stars are formed. Elliptical galaxies generally have older stars and less gas. However, in order to better understand the star formation history and evolution of elliptical galaxies, we need to study what little cold gas they do have.”
Nyland, along with her advisor Dr. Lisa Young, is re-examining data collected from the HI Parks All Sky Survey, known as HIPASS, at the Parks Radio Telescope in Australia. She is studying data from 37 elliptical galaxies observed during the HIPASS project.
Nyland's research is the first unbiased sample of elliptical galaxies. Similar projects have examined collections of “favorite” elliptical galaxies, while Nyland is looking at all of the observable ellipticals from the HIPASS project.
Nyland and Young observed their sample of HIPASS-selected ellipticals with the Very Large Array.
“We’re learning from the VLA data that only about half of the galaxies that the Parks Telescope predicted to have HI actually have it,” she said. “More interestingly, the results demonstrate that the HI morphologies of elliptical galaxies are varied; there are some regular, quiescent systems as well as disturbed, interacting systems with prominent features like HI tidal tails.”
Nyland’s project is, however, a work in progress. “We still need to do statistical analysis, study the mass of cold, neutral hydrogen and increase the size of our sample.”
Left: Krista McCord's research helped to determine which optical coatings should be used on mirrors for Magdalena Ridge Observatory.
McCord, a senior from Texas will, offer a presentation about her tests of the coatings that will be applied to the telescope mirrors at the MRO.
McCord received mirrors with several different test coatings from Optical Surface Technologies, the Albuquerque-based builder of the mirrors. She tested the samples to determine which performed the best under given weather conditions on Magdalena Ridge. Her presentation at AAS focused on the methods and materials that functioned the best.
McCord is another returning presenter. The senior from Texas attended last year’s conference and offered her research about the Magdalena Ridge Observatory’s fringe-tracker modulator.
“It was a new experience,” McCord said. “There are only a handful of undergraduates, so that’s pretty rare. I got to meet with people from NASA who asked me about my poster. Most people thought I was a graduate student.”
McCord will graduate in May 2009 and is applying at several graduate schools.
“It’s a good to meet people in the physics community,” she said. “Some of the professors reviewing my application will be at this conference. That’s got to help.”
– NMT –