Research

Space isn't really "empty": in the space between stars, there is gas and what astronomers call "dust" (larger particles) throughout galaxies, called the interstellar medium (ISM). In order to collapse under gravity to form stars, gas must cool until molecules are able to form and survive. The subsequently formed stars release radiation, stellar winds, and eventually upon their death, huge amounts of energy via supernova explosions. They therefore influence the gas around them, from which future stars will form. This means that gas heating/cooling and star formation are intricately connected processes in galaxy evolution over the history of the universe. Molecular gas, being cool and forming the densest "clouds" in space, is the closest the interstellar medium and star formation connect to one another.

• CO as a Tracer of Warm Molecular Gas in Galaxies

Most molecular gas in the interstellar medium is in the form of hydrogen, but it is difficult to observe, so we rely on bright CO rotational lines to trace that gas.  With radiative transfer and likelihood analysis, I study the physical conditions of the gas as traced by CO.  

The Herschel Space Observatory, launched in 2009, allowed us to view a portion of the electromagnetic spectrum that is blocked by the atmosphere.  The higher-excitation CO lines available in this region were much brighter than expected, indicating emission from gas that is much hotter than the cool molecular gas typically traced by the lowest excitation CO J=1-0 line.  I am working on the best characterization of the line emission from these spectra and deriving physical conditions from the lines to study feedback mechanisms among star formation, gas, and AGN.

• High Spatial and Spectral Resolution Maps of CO with ALMA

Herschel was revolutionary in allowing us to reach above the atmosphere to view CO lines generally blocked by water vapor. In a few very high and dry places on Earth, we have some windows allowing us to peer through the atmosphere. The Atacama Large Millimeter Array, in northern Chile, is the largest astronomical project in the world. With this interferometer (a set of telescopes that all work together as one), we can study a small number of galaxies at a time than with Herschel, but with much more detail. 

• Comparing Herschel High-J CO Observations to Models

I worked with computational modelers to investigate the diagnostic power of high-J CO Herschel observations compared to galaxy evolution simulations. We determined "that while common CO SLED modeling techniques cannot reveal the underlying complexities of the molecular gas, they can distinguish bulk luminosity-weighted properties that vary with star formation surface densities and galaxy evolution, if a sufficient number of lines are detected and modeled." (Kamenetzky, Privon, and Narayanan 2018)

• Molecules in the Debris of SN1987A

Supernovae, the violent death of massive stars, are responsible for enriching the universe with heavy elements like carbon and oxygen.  SN1987A happened in February of 1987, and has been an incredibly important "laboratory" for studying the evolution of a supernova and its remnant over time.  

We used ALMA to observe the CO J=2-1 line of SN1987A and found that there must be at least 10 times as much CO present in the inner debris from the star than previously measured with vibrationally excited CO in the first ~ 900 days after the supernova.  ALMA's high spatial resolution also showed that this emission is in fact coming from the inner debris, not the shocked ring of gas (see figure, below).

I am a member of the Consortium for Dark Sky Studies, an academic center for interdisciplinary dark skies research. Light pollution has significant consequences for wildlife, human health, and culture, yet according to Falchi et al. 2016, "more than 80% of the world and more than 99% of the U.S. and European populations live under light-polluted skies. The Milky Way is hidden from more than one-third of humanity, including 60% of Europeans and nearly 80% of North Americans." My students and I have worked to characterize light pollution here in the Salt Lake Valley in two ways:

• First, by setting up Sky Quality Meters at the University of Utah and at Kodachrome Basin State Park, to monitor and record sky brightness levels over time.

• Second, by reproducing the procedures of Duriscoe, Luginbuhl, and Moore 2007 at the National Park Service to measure sky brightness using a wide-field CCD camera. We completed this procedure with all free software and low-cost equipment. 

Coming Soon

I have mentored summer research students in projects involving CCD monitoring of variable stars, using the South Physics Observatory at the University of Utah and submitting our final measurements to the American Association of Variable Star Observers. I have also participated in a guided research course hosted by Our Solar Siblings; my students and I used the remote telescopes of Las Cumbres Observatory to test theoretical period-luminosity relationships for RR Lyrae stars. 

I have studied questions related to student usage of textbook readings in introductory physics. I found that introductory physics students are more likely to come to class prepared if they are assigned to submit one question about the reading, but they are not necessarily more likely to see the value of the textbook for their learning.

See my Teaching page for some of the resources I use for active-learning in the physics and astronomy classroom.

Our scientific training often does not include the study of the social and political institutions that govern science.  I am particularly interested in understanding the larger context of my chosen career, so as part of a graduate course in science policy, I completed and published an analysis of the National Science Foundation's Broader Impacts criterion.*  I found that awarded grants satisfy this criterion in a wide variety of ways, and that the distributions vary with the culture of different fields (comparing Biological Sciences, Engineering, and Mathematical and Physical Sciences). Click this link to read the paper; if not accessible, feel free to email me to request a PDF copy.

See some of the sample syllabi on my Teaching page for how I incorporate science policy into undergraduate courses.