In the last several years, I have worked intensively on the supermassive star
Eta Carina, which in its great eruption 160 years ago, ejected an enormous mass
(10-20 times that of our sun) into space. In a short period of time,
astronomically speaking, the star itself may finally die in a supernova explosion.
The Hubble Space Telescope (HST) has designated our study of Eta Carina as one of
its Treasury Projects, devoting large amounts of time to studying its variations.
I'm enthralled by dirt -- at least the astronomical kind. The dust out of which
our planet formed, originally came from the stars. For many years, I have
been studying the conditions under which this dust condenses out of hotter gases.
Novae, for example, are stars that undergo non-fatal explosions that expel enormous
amounts of dust into space. I have played major roles in the decades-long
planning and development of the Spitzer Infrared Telescope, now bringing us
spectacular images of our dusty space environment. I am looking forward to using
the infrared-optimized LBT to study dust in interesting systems such as the RY
Scuti binary system, with two stars orbiting each other so closely that they touch.
My research spans the structure of our Milky Way to the study of the populations
of massive stars here and in nearby galaxies. I use our own in-house database
of a 100 million objects to map the structure of our galaxy and observations with
the Steward telescopes to study the "supernova imposters," which are very massive
stars expelling large amounts of matter into space.
I am an infrared astronomer who specializes in measuring the polarization of
light. This type of observation can reveal the structure of dust in comets,
the magnetic field geometry in galaxies and pinpoint the location of hidden
stars. Specialized observing procedures are required, but a few major
facilities such as the NASA IRTF and the Hubble Space Telescope have a
polarimetric capability I am able to use. We are building a precision infrared
imaging polarimeter for use on the MMT in combination with the AO secondary.
I do research in theoretical and computational astrophysics, mainly
addressing problems associated with very energetic phenomena and their
impact on the universe. My students and I carry out large fluid dynamical
simulations including specially developed routines to follow the microphysics
responsible for the emission we observe from such astronomical objects as
supernova remnants, active galaxies and clusters of galaxies.
Our calculations can be compared directly with observational data
to test basic theories about the origins of these objects.
I'm interested in the extremely high energy particles generated in shock waves,
both in giant clusters of galaxies on scales up to millions of light years, and
in the smaller explosions of dying stars, as they create supernova remnants. I
study these systems using radio, optical, X-ray and infrared images and spectra
from both ground- and space-based telescopes.
My research focuses on galaxy formation and evolution, using observations from both ground and space based facilities. My work covers all evolutionary stages of galaxies, from their infancy at the end of the dark ages, to their maturity in the local universe. This approach allows us to directly constrain what mechanisms are important in the galaxy formation process, and understand if their role changes with time.
Understanding how galaxies are formed and evolve presents arguably the biggest
challenge for astrophysics in the next decade. As new observing facilities
come on-line, we can look back to the earliest ages of our universe and
learn more about galaxies in their infancy. I am currently conducting a parallel
approach by studying the nearest dwarf galaxies which are the most numerous
galaxies in the Universe and the likely building blocks of all galaxies. Like
an archaeologist, I reconstruct their lives by exploring the
fossil records by measuring the ages, metallicities, and distributions of their
I am interested in the distribution of "dark matter" in the Universe, on scales
ranging from sub-galactic to those larger than clusters of galaxies. Dark matter
is the dominant matter component in the Universe, yet its nature has eluded us
so far. I study gravitational lensing of high redshift sources, and dynamics
of individual galaxies and clusters, to gain detailed knowledge of the clustering
properties of dark matter.
One focus of my current research is the study of solar system comets, which are
frozen reservoirs of primitive solar dust grains and ices. I analyze the
composition and size distribution of cometary dust grains from infrared imaging
and polarimetry techniques using the LBT and Steward Observatory telescopes which
support my Spitzer Infrared Telescope activities. In this way, I can determine the
physical characteristics of the solid materials that constituted the primitive solar
nebula, out of which planetesimals, then planets, and eventually we, ourselves,
Deep inside a star, the churning and the transfer of massive amounts of energy
are not open to direct observation. However, through the use of sophisticated
physical models and numerical simulations on supercomputers, we can investigate
how these invisible processes work. Recently, we have been concentrating on the
convection processes in stars near the end of their red giant phases.
Our observational colleagues can search for the subtle signatures of these processes,
and improve our understanding of the hidden interiors of stars.
Profile: Kristy McQuinn
I am a post-doc working with Dr. Evan Skillman to
determine the duration of starbursts in nearby dwarf galaxies. A starburst
is an episode of intense star formation in a galaxy that affects not only
the structure and evolution of the host galaxy but also the chemical
composition of the galaxy's external environment (the intergalacitc
medium). Understanding how long a starburst lasts requires a
reconstruction of the galaxy's recent star formation history. The duration
is an important and fundamental parameter in the study of starbursts
because it affects much of the subsequent analysis and study of a
starburst galaxy's evolution. Our work uses optical images from the Hubble
Space Telescope of more than a dozen nearby dwarf systems and stellar
evolution models to determine the rate of star formation over the past 1
Profile: Danielle Berg
I am a graduate student working with Dr. Evan Skillman to
investigate the formation and evolution of galaxies. I am particularly
interested in measuring the metallicities and ages of galaxies through
various spectroscopic methods. This research not only provides me with
many opportunities to use world-class observing facilities to obtain
spectra, but also to learn and apply new reduction and analytical
techniques to these data. Recently I have been reanalyzing galaxies previously believed to be low-mass, high-metallicity outliers, and soon will begin to work with Local Volume Legacy (LVL) objects.
Awards: Penrose Endowment Fellowship, 2010–2011
I am a graduate student currently working with Dr. Claudia Scarlata to analyze the emission of Lyman-α photons from galaxies at varying redshifts. Ly-α photons are important for probing the star-forming regions of distant galaxies because it is the only emission line we can detect from them at very high redshift (z>6). At present, I am extracting flux data from images of Ly-α emitting galaxies at redshift z<0.5, taken by the Spitzer Infrared Space Telescope. The goal of this project is to determine the Ly-α escape fraction for these galaxies, and learn how it relates to the galaxies' other properties, such as luminosity, mass, and dust extinction. With this knowledge, we can learn more about galaxies at more distant redshifts, using their Ly-α emissions to trace their formation and evolution over time.
Profile: Damon Farnsworth
I am a research assistant working under Professor Larry Rudnick, currently investigating galaxy cluster radio relics and their role as tracers of the large scale filamentary structure of the Universe. I also investigate the inside of my eyelids sometimes, and the role food (or lack thereof) plays in my level of grumpiness.
Young, massive stars play a major role in the evolution of galaxies through stellar winds and supernova explosions, which heats and enriches the interstellar medium. By studying resolved, luminous stars, their formation rate and history can be studied. However, unlike the sun, the majority of the light budget of massive stars resides in the ultraviolet and so the identification of star forming regions requires UV observations. Using GALEX and HST to identify regions of intense star formation, I study the detailed properties of the star forming regions and their effects on the global properties in M101.
Awards: Edward P. Ney Fellowship, 2010–2011
In August 2011 I graduated with a Master's degree from Leiden University and am now working towards a Ph.D. here at the University of Minnesota. I am working with Dr. Scarlata on the relative escape fraction of ionizing photons from high redshift galaxies.
I am a graduate student studying dwarf galaxies under the direction of Dr.
Evan Skillman. By studying resolved stellar populations with both
ground-based and space-based observations, we hope to construct
quantitative star formation histories of the dwarf galaxies in the Local
Group. Those histories can teach us a great deal about how galaxies are
constructed and evolve over time.
Awards: Penrose Endowment Fellowship, 2011–2012
My undergraduate years at Wesleyan University were spent on hunting for and studying AGN in nearby, low-luminosity galaxies with the help of the SDSS and our own spectroscopic data obtained from a number of major observatories. Recently, I've started working with Dr. Lucy Fortson on a sub-sample of blue elliptical and red spiral galaxies from the Galaxy Zoo project, with the purpose of characterizing nuclear activity, environment and star formation history.
I am a graduate student working with Bob Gehrz and Terry Jones in the Infrared Astronomy Group, where I assist in the department's ongoing programs on the enrichment of the interstellar medium by classical novae as well as the study of regions of massive star formation. I am particularly interested in learning the techniques of observational astronomy and developing instrumentation for use in the infrared.
Resolving the stellar populations of local galaxies using the Hubble Space Telescope has been invaluable for obtaining detailed histories of star formation and understanding how these galaxies have evolved over time. I am interested in applying this resolved-stars technique to the star-forming regions in galaxies—namely locations of high ultraviolet and/or high H-alpha emission—for an in-depth analysis of the stellar populations associated with such regions. As a member of the Panchromatic Hubble Andromeda Treasury, my work is mainly focused on M31/the Andromeda galaxy, though I have been studying the more distant irregular galaxy Holmberg II as well. My goal is to learn about the massive stars producing the UV and H-alpha flux from which star formation rates can be estimated, and possibly to help characterize the high-mass end of the initial mass function.