These summaries were taken from the
Program Reports
filed with the NSF. The NSF report include a more detailed discription of
the individual summer programs, including itineries, pictures, lectures,
and joint student projects.
1999 Summer Students |
Active galaxies (AGNs) are thought to be powered by accretion onto a
central, massive black hole. Seyfert galaxies are the nearest AGNs that
show all of the classic signs of activity, including radio jets, broad
optical line emission, hard X-ray emission, and rapid variability. They
are indistinguishable from quasars except that they are nearer and less
luminous. Recent VLBA observations have demonstrated that the radio
emission from a Seyfert nucleus is, however, peculiar. The nuclear radio
properties may owe to thermal processes in gas located very near the
massive black hole (i.e., a few light years from the AGN).
I have several projects investigating peculiar radio sources in Seyfert
nuclei, two of which are naturally suited for summer student research. One
is a VLA survey of high frequency (22 and 43~GHz) emission from Seyfert
nuclei. The goal is to locate potential flat-spectrum sources and address
the effects of thermal free-free absorption (or possibly emission). There
are currently data for 13 sources in hand, and we anticipate having an
additional 15 sources this summer (TAC-willing). The other is a VLBI
survey of nearby Seyfert galaxies. The main goal of the VLBI project is to
investigate the Seyfert radio jets at a spatial resolution of ~ 1 light
year. We will be receiving snapshot VLBI data for 8 sources this spring.
Both programs are technically challenging, and the summer student can
expect to come away with an advanced understanding of aperture synthesis
techniques. The student might choose either to concentrate on complete
reduction of the survey data, in which case he or she will receive
co-authorship on the survey paper, or to focus on the analysis
and interpretation of a specific source and assume lead authorship.
My summer with NRAO in Charlottesville began as smoothly as one could
hope, even though I was completely unfamiliar with our subject, flocculent
galaxies. I had just finished school a week earlier, allowing little
preparation time. Michele began the summer with a discussion of our project,
data, goals, and motivation. In short, galaxies with large-scale spiral
structure are thought to contain spiral density waves. A spiral density
wave is a compression wave that is able to organize a galaxys' constituents,
forming spiral arms. However, not all galaxies have a large scale spiral
design. Another galaxy type, flocculent galaxies, has a disc like the
grand-design spirals, but no arms are visible in optical light. Due to
their lack of organization, flocculent galaxies have been assumed by some of
the astronomical community to not contain spiral density waves. In
addition, the topic draws very little attention, and little data is
available to those who wish to investigate the matter. So, Michele made
this her doctoral thesis topic, investigated several flocculents, including
the prototypical flocculent galaxy, NGC 5055, and found conclusive evidence
for density wave presence in a few of them. She wished to continue this
work, and turned the telescopes toward another flocculent, NGC 7331.
Michele was granted 15 hours of observing time with NRAOs Very Large Array,
and the data was safe in hand well before the summer. She soon turned her
efforts toward new topics, with the NGC 7331 data set unreduced.
I immediately began my background readings, consisting mostly of
astrophysical and astronomical journals, spanning the spiral galaxy
formation process, spiral form maintenance, galactic surveys, galactic
kinematics, galactic interactions and mergers, and of course an introduction
to radio astronomy. In addition, the other summer students and I attended a
few lectures each week concerning other astronomical topics, each about an hour
long, and each by a different NRAO scientist. This introductory time was
focused yet unhurried, and perhaps the most learningful period of my life.
After only a few weeks, my view of the universe had changed considerably.
Suddenly galaxies were dynamical, evolving systems, and the cosmos was much
more exciting.
Soon, however, it was back to earth and into the world of AIPS and
LINUX. UNIX is an operating system. Prior to NRAO, I may have thought the
whole world was either Windows or Mac. However, my eyes were shown
additional operating systems, UNIX/LINUX and SUN OS, and my digital
adventure was underway. But, not before I was shown AIPS, and opened to
what real radio astronomy consists of. AIPS is the data reduction program
used for reduction of data collected by NRAO telescopes. Data from
observations is stored onto DAT tape, and AIPS enters when you're ready to
read and/or edit the data. AIPS consists of tasks and verbs used to
configure your data, and with AIPS, bytes are turned into actual images of
your object. Initially, I was very intimidated by both AIPS and LINUX, but
as my stay at NRAO advanced, I became much more confident in my
understanding of both, or at least the parts of each we used.
The data set came in three main sets, each corresponding to a different
antenna configuration used to obtain the data. Different configurations
provide information on different size scales. However, the reduction
process is basically the same for each. Michele and I went through the first
data set together, taking notes the entire time so that I could repeat the
process by myself. However, it was not thoughtless replication. Each data
set is different, almost taking on a character. Each had its own problems,
requiring data interpretation and troubleshooting until the final image was
satisfactory. The first eight of my twelve week stay at NRAO consisted of
this reduction process, until three final images were obtained, one from
each configuration.
These three images served as the base of all our further
investigations. The three images were combined to create one "mother
image." From this image, we were able to create velocity maps, density
maps, major and minor axis velocity slices, and zooms of each, corresponding
to different regions of NGC 7331. Again, we used each to look for density
wave signatures in NGC 7331. We were not the first to look at NGC 7331 with
density wave detection in mind. A previous group had used optical means to
search for density waves, and claimed to detect density wave perturbations
along the western side of the galaxy. We investigated the same region, and
the rest of the galaxy. Interestingly, we could not confirm the wave
detection along the western side of NGC 7331, but found more significant
perturbations along the southeastern side of the galaxy. This final
analysis process, along with my preparation for the final presentation of
our research to the NRAO staff, occupied the last four weeks of my stay in
Charlottesville, and before I knew it, the summer was over.
My summer at NRAO was as pleasing an experience as I could have
imagined. I formed great friendships during my stay. I experienced the
reality of astronomical research. I saw what astronomers do all day, what
they eat, what they talk about, and even how they drive. My plans before
NRAO included attending an astronomical graduate program. After my summer
at NRAO, these plans have solidified. In fact, I plan to pursue astronomy
more than ever. Perhaps I'll have a summer student working under me some
day.
Mr. Mason worked on preparing Turner's 2mm survey for presentation
on the WWW. The input to the problem is (i) the observed spectra in
tabular form (the form to be determined); (ii) and catalog of computed
spectral lines including Lovas, JPL, and my own calculations; (iii)
tables of spectral line parameters measured by me from the spectra.
The problem will be to provide a WEB setup that allows the user to
click on a given spectrum, and obtain several features including (i) a
plot which with cursor control may be scaled in both axes, over a
chosen frequency range; (ii) may be linked to the atlas of computed
lines with which any selected line on the plot may be searched and
labelled if a match is found; (iii) contain most of the elementary
features of Unipops or AIOS++ such as rms (requiring designation of
baseline parameters); perhaps gaussian fitting; 0th moment measures,
etc. The result may be viewed
here.
Mr. Durbin helped to design wideband balanced amplifiers
for operation in the 1-6 GHz band. Specifically, we need to develop
multi-octave hybrid couplers. The student will learn about the
operation of such components and then use computer-aided design tools
to simulate their performance. Test structures will be fabricated and
evaluated.
Collisions between galaxies can be dealt with analytically only in
very specific cases. Unfortunately, the conditions that are prevalent
in the bulk of galaxy interactions rarely satisfy these idealisations
and so, when considering such situations, the researcher must make use
of N-Body simulations to model the encounters. In general, pictorial
representations of the time evolution of such encounters is desired.
In this report, I will discuss my work in this area; in particular I
will concentrate on how I developed a means to convert observational
and simulation data into a form that is readable by the interactive 3
dimensional visualization tool, Geomview. I will also describe my work
on the matching of simulation and observational data for the case of
NGC 4038/9, the "Antennae", as well as the motivation for such model
matching and the characteristic features of a system that are
particularly suited to such fitting.
As an interesting aside, I indulged myself and present brief
discussions on The History of Mergers and previous attempts to model
the "Antennae" in Numerical Models of NGC 4038/9. My work may be
reviewed
here.
Using the existing deep VLA radio images for 6 clusters of galaxies
with z between 0.25 and 0.41 and existing optical imaging
(ground-based and HST),the student would make the optical
identifications. The student would use these data, along with
existing optical spectroscopy to estimate size of the radio
populations in each of these clusters and whether the radio galaxies
were likely star-formation driven or AGN's. These data would then be
compared with lower redshift results to evaluate the evolution of
these populations with redshift and other cluster properties.
Space VLBI missions have unique imaging requirements relative
to ground VLBI. For the highest resolutions, there typically
are large holes in the (u,v) plane, both due to the high spacecraft
orbit and to intermittent tracking. Also, high sensitivity is
required, but the space telescope cannot nod back and forth
between sources due to a limited slewing capability, making
phase referencing impossible for the space element. These
two issues should be addressed in order to provide better imaging
for the future ARISE mission. Either problem is reasonably
well-defined, and could be completed in a summer term, assuming
a well-prepared student with some AIPS and radio interferometry
background. The proposed approaches are outlined below, with the
final selection to be made based on the student's and advisor's
negotiation. Item (1) is probably a more tractable problem for
a summer, although item (2) might also be possible.
(1) Explore techniques in AIPS and/or DIFMAP for imaging of ARISE
data having large holes in the (u,v) plane. The approach would be to
take on-hand VSOP data from my projects or other observations, then
create (u,v) holes of varying sizes by deleting antennas giving long
ground spacings (e.g., use the southwestern VLBA stations plus HALCA).
The data would be used to examine techniques for fringe-fitting,
self-calibration, and data weighting in order to find the best range
of parameters, the limitations to dynamic range, and the inflection
points at which the images begin to degrade rapidly. Simulated data
might also be used.
(2) Investigate the possibility of phase-referencing the ground
telescopes at high frequencies, while keeping ARISE pointed at the
program source, in order to increase the coherent integration time
and the detection threshold. There are two possible approaches,
either through the acquisition of VLBA test data with most (but not
all) of the antennas phase referencing, or by generation of simulated
data with such an observing strategy. Currently, the latter strategy
is favored, because real test data would still have an atmosphere
above the VLBA antenna that is not phase referencing; the whole point
of the project would be to test phase referencing for an antenna
that cannot slew, but also has NO atmosphere.
Evidence is accumulating that jets in FR I radio galaxies are
relativistic from pc to kpc scales. The strongest evidence is based
on measurement of apparent superluminal motions of features about
100~pc along the jet in the FR~I radio galaxy M87. As convincing as
these important M87 results are, it would be reassuring to find direct
evidence for relativistic speeds in other, more traditional FR~I radio
galaxies. We therefore began a search for moving features less than
7 arcsec (550pc) along the northern jet of the FR I radio galaxy M84.
Our preliminary results for M84, based on two VLA A-configuration runs
8 years apart, offer some evidence for relativistic motions. We
conducted a cross-correlation analysis of features a-d in the
northern jet. We were unable to obtain reliable results
for features a and c, probably because those features
lack maxima with steep brightness gradients, but we did obtain
credible results for the other features. Feature b, located
3.8 arcsec (300 pc) from the core, moved 11+/-2 mas East and
15+/-2 mas South, for a net motion of 19 mas in 8 years or
0.58+/-0.06c toward PA 144 degrees. Feature d, located
6.1 arcsec (480 pc) from the core, moved 2+/-3~mas East and
25+/-4 mas North, for a net speed of 0.80+/-0.14c toward PA 5
degrees. The formal errors from the cross-correlation fits do not
reflect systematic uncertainties. These measurements are being
refined with a third A-configuration run that extends the time
baseline for this proper motion study from 8 to 20 years.
Multi-object spectroscopy of objects in this z=0.4 cluster was
undertaken to determine how important dust extinction is in moderate
redshift clusters, and to clarify galaxy type in clusters at redshifts
between 0.3 and 0.5. The data were from the HYDRA imstrument of NOAO reduced
with IRAF. The optical data suggested that significant extinction
was, in fact, present. Comparison to reddening-free radio images
should prove useful. A complete written report is available.
Niruj will work mainly on VLA spectral line data from two proposals
AN81 and AM614. This will form the basis of his Ph.D. thesis. If time
permits, he will also work on VLBA continuum data on PKS 1830-211 (at
90 and 50 cm) from the project BA031.
AN81 is a VLA proposal to study Recombination line emission near 8.5
GHz from a variety of starburst galaxies: a Wolf-Rayet Galaxy (He
2-10), a blue compact Dwarf (NGC 5253), an interacting system (NGC
1808) and two merging systems (NGC 4038 and VV 114). This proposal
was awarded a total of 38 hours of VLA time (14 hrs in CnB, 4 hrs in
C, 16 hrs in DnC and 4 hrs in D configurations). The CnB and C array
observations were made in Nov/Dec 98 and is awaiting data reduction.
The remaining obsevations will be made sometime during during Mar-Jun
99. These proposals were prepared by Niruj and the observe files were
also made by him.
AM614 is a VLA proposal that Niruj wrote to followup our earlier
detection of RRLs from two well known starburst systems, IC694 and NGC
3628. Models for line emission that were made based on the detections
at 8.5 GHz, predicted a strong variation of line strength with
frequency. It is crucial to study higher frequency RRLs to constrain
the models. This proposal is for observations of RRLs at 2 cm and has
been awarded a total of 16 hours of VLA time in the D-configuration.
I expect that these observations will be made when Niruj is visiting
Socorro and thus he will take care of all aspects of these observations.
Another project that Niruj is involved in, and which is only
peripherally related to the main theme of his thesis, is search for
RRLs at 20cm from the gravitational lens system PKS1830-211 (VLA
proposal AA220). To study the effect of intervening ionized gas (due
to free-free absorption and scattering) on the continuum structure of
PKS 1830-211, we have obtained a 10 hr VLBA observation (Program
BA031) at 90 cm and 50 cm. If time permits, I will ask Niruj to work
on this data as well while he is here. This will provide him (and me)
valuable experience with low-frequency VLBA data.
Ms Brogan will be working with Drs D. A. Frail and W. M. Goss on an
effort to perform 1720 MHz Zeeman observations of OH masers toward
galactic supernova remnants. The 1720 MHz transition has proven to be
a powerful probe of supernova remnant interactions with molecular
clouds. The 1720 MHz line also exhibits the Zeeman effect, allowing
for the magnetic field strength to be measured in these regions for
the first time. The goal of this project will be to increase
significantly the small number of such measurements in order to
accurately model the role of magnetic fields in molecular shocks.
The goal is the detection of long-lived afterglows from gamma-ray
bursters at radio wavelengths. The study of these afterglows in the
radio yields unique diagnostics not obtainable by any other means. In
particular radio observations give the size and allow one to infer the
expansion of the relativistic fireball that is produced in the burst.
A student might be expected to work on several things including
(1) the monitoring of known radio afterglows (2) searching for radio
emission from new bursts, (3) modeling the flux evolution of the
synchrotron-emitting fireball, (4) developing observing/reduction code
to simplify the process of obtaining radio data on GRBs. Depending on
the student's talents I can see this as a pure observing project, a
theory project or a partial software project. The detection of an
afterglow would almost certainly involve the publication of paper.
The Compact Symmetric Object 1946+708 was the first extragalactic
source in which bi-directional motions were directly observed (Taylor
& Vermeulen 1997, ApJL, 485, L9). This offers a unique chance to
measure H$_0$. Along with Rene Vermeulen, I have obtained multi-epoch
VLBA observations of 1946+708 at 8 and 15 GHz. Our program will also
measure the advance speeds of the hot spots, from which we will obtain
the age of the source. The past year has seen the first such direct
measurements of the hotspot advance speed in extragalactic radio
sources (Owsianik, Conway & Polatidis 1998, A&A, 336, L37; Owsianik &
Conway 1998, A&A, 337, 69). The high reported velocities (0.25 c) in
the Compact Symmetric Objects 0108+388 and 0710+439, give ages of
order 1000 years, reinforcing the idea that these objects are compact
by virtue of their youth and are not confined ("frustrated") by a
dense environment. A velocity of 0.25 c (0.06 mas/yr) will be readily
detectable by our monitoring observations. The basic work for a
summer student would be to calibrate and image four VLBA epochs at 8
and 15 GHz on 1946+708 and to determine the motions of the jet
components and especially the hot spots. A summer student working on
this project would learn about the physics of Compact Symmetric
Objects, and about the reduction and analysis of phase-referenced VLBI
data. The goal for the student would be the publication of a paper in
the ApJ and presentation of the results at a AAS meeting or other
suitable conference.
Miller Goss:
Chris De Pree and I have started a program to determine the relative
positions of H2O and continuum components in the giant HII regions Sgr
B2 and W49. The observing technique is to do simultaneous continuum
and H2O observations ( both IF's ). We self cal on the strong H2O
masers and then can detect the weak 1.3 cm continuum components at
high resolution ( 0.2 arc sec or so in the B array). The data
reduction is complete for Sgr B2 and just started for W49. The
relative positions can be determined at the level of 0.001 arc sec or
so due to the favorable signal to noise. An REU student can bring
this program to completion.
I think I have a cool project for an REU student -- working with our
brand new dual frequency GPS unit. It looks as though the software
support promised by the software group will be a little late in
showing up. We could probably use a student to help us learn how to
use the device. It is run from a PC running Windows NT, and does lots
of cool things. Once we
get the receiver up, and the software loaded, more experiments with
polarized pulsars will be needed to finish the project.
OVLBI and NRAO is to complete the design of our
new Peltier controller. This is a 90% hardware and 10% software project,
so it would be good to have an EE as opposed to a CE. I think it could be
finished in a summer and would help all on the site. There are a few other
small things as well, one would be capturing schematics, updating our
documentation.
A project in the cryogenics lab. An automated system
for characterizing and logging the cooling capacity of the various
refrigerator needs to be designed built and tested. This would be a nice
summer long project which could be carried through form design to
completion during the summer months. What I have in mind is a test
dewar(s) with variable loads on the first and second stages of the
refrigerators. A computer controls the energy applied to each load and
graphs a load diagram for the particular refrigerator. This project
entails thermodynamics, electrical engineering and writing code for the PC.
The project will involve programming in C or C++ for the
Green Bank Interferometer project. It can involve either
My project was a study of star formation and molecular clouds using
data from the Five College Radio Astronomy Observatory's CO Outer
Galaxy Survey (Heyer et al. 1998, ApJ Suppl,115,241) and the IRAS
point source catalog. The CO survey contains more than 2 million
spectra and is the most detailed millimeter spectral line map ever
made. It covers approximately 300 square degrees of sky in the outer
Perseus arm of the Galaxy.
The beginning of the project consisted of a general overview of the
properties of molecular clouds in the outer Galaxy, including analysis
of their masses, volume densities, sizes, dynamics, and temperatures.
As a familiarity with these characteristics was developed, the project
shifted into an examination of star formation within the clouds of the
survey.
Using the IRAS point source catalog, I created images of the clouds
and embedded stars using IDL. After thorough analysis of the IRAS
sources' spectra, two samples of clouds were compiled: one of clouds
with embedded stars and the other of clouds without embedded stars.
Many comparisons between these two samples were made to bring out any
characteristics that are indicative of star formation. Specifically, I
found a relationship between the samples that suggests that most of the
integrated mass of clouds with embedded stars is in a much higher mass
range than that of the clouds without embedded stars. Additionally,
comparing the column densities of the two samples revealed signs that
clouds with embedded stars are more compact than those clouds without
stars. These results affirm that molecular clouds that are more massive
and compact are likely to have greater star formation efficiencies.
Historically, the inversion transition of ammonia (NH3) has
been used as the primary temperature indicator in dense molecular
clouds. However, the physical approximation typically used for this
method assumes that only three energy levels are populated. This
model breaks down when the temperature becomes high enough, about 50K.
Recent investigations designed to determine the temperatures of the
cores of molecular clouds have found that many of them to be at about
70-150K. As these temperatures are beyond the range of accuracy of
the NH3 inversion transition method, these numbers have significant
inaccuracies. We propose a different temperature probe which retains
its accuracy at higher temperatures than the probes previously used.
This probe uses the rotational transitions of methyl cyanide (CH3CN),
a symmetric rotor. Using measurements of the J=6-5, 8-7, and 12-11
rotational transitions of CH3CN obtained with the IRAM 30m Telescope,
we have derived the kinetic temperature within a sample of molecular
cloud cores. The analysis of these data used two separate analysis
methods; a statistical equilibrium technique which compared the
intensities of the different K-transitions within a given J-ladder,
and a rotational temperature diagram analysis. The results of this
analysis has yielded good temperature and column density figures for
some 24 molecular cloud cores within our galaxy. The results of this
work will be presented at the AAS meeting in Atlanta, Georga in
January 2000.
Cristina M. Murray
of University of New Mexico
worked with Jack Gallimore
on Black Holes in Active Galaxies
Dustin Bambic, of
Western Kentucky University
worked with
Michele Thornley
on NGC 7331: Characterizing the contribution of spiral density waves in
flocculent galaxies
Porter Mason , of
Duke University
worked with Barry Turner
on The 2mm Spectral Survey
Jonathan Durbin , of
Valdosta State University
worked with Richard Bradley
on Wideband Balanced Amplifiers
Chris Power, of
Trinity College, Dublin
worked with John Hibbard
on N-body Simulation of "The Antennae"
Darrell Osgood
of New Mexico Institute of Mining and Technology
worked with Frazer Owen
on Evolution of Populations of Radio Galaxies in Clusters
Teddy Cheung
of Brandeis
worked with Jim Ulvestad
on ARISE Imaging
Colleen Schwartz
of Colby College
worked with Joan Wrobel
on PROPER MOTIONS IN THE FR~I RADIO GALAXY M84
Andreea Petric, of
Columbia University and NMIMT
worked with Frazer Owen
on Multi-object Spectroscopy of the Cluster CL0939+47
Niruj Mohan , of
Raman Research Institute, Bangalore
worked with K. Anantharamiah
on Recombination Line Emission from Starbursts
Crystal Brogan ,
of The University of Kentucky
worked with Dale Frail
on 1720 MHz Zeeman Observations of OH Masers Toward SNRs
Chad Young of
Mississippi State University,
worked with Dale Frail
on Afterglows from Gamma-ray Bursters
Hanna Smith , of
Smith College,
worked with Greg Taylor
on Compact Symmetric Object 1946+708
Elizabeth McGrath of
Vassar
worked with Miller Goss
on Water and HII in the Giant HII Region W49
Makenzie Lystrup of
Portland State University
worked with Craig Walker
on Phase Referencing with the VLBA: Structure and Motion of 3C120
The compact radio source 3C120 was one of the first in which
superluminal motions were observed. VLBI monitoring observations at 5
GHz were made three times per year between 1979 and 1988 with the
Global VLBI Network to study the superluminal motions on parsec
scales. Other VLBI monitoring were made at 1.7 GHz using large global
arrays between 1982 and 1997 (and are being continued) to study the
motions out to about 100 parsecs. The summer student project is to
help produce the final images from the monitoring observations and to
begin writing the paper that presents the observations.
Bryan Jones, of
Northern Arizona University
worked with Rick Perley
on Ionospheric Correction Using A Dual Frequency GPS Unit
Scott Zmerick, of
West Virginia University
worked with Ron Maddalena
and Sue Ann Heatherly
on A 40 Foot Upgrade
We are currently updating the control interface and receiver system for the
40-ft educational telescope. A programming student is needed to complete
the graphical user interface to the telescope system.
Steve Hicks, of
University of Memphis
worked with Dan Pedtke
on An OVLBI Controller
Christopher S Deyoung , of
University of Houston
worked with Steve White
on Test Dewars for Radioastronomy Instrumentation
Jill C. Kamienski , of
University of Colorado, Boulder
worked with Frank Ghigo
on Green Bank Interferometer Upgrades
1. Developing software for control of two 85-foot telescopes,
in a vxWorks environment. The software would generate commands
for moving the telescope to desired positions, would monitor
the positions and other status information, and would write
the status data in a log file.
or
2. Developing a system for on-line editing and analysis of
data from the Interferometer. Perhaps this will include
an automated way of identifying radio sources that are flaring
or exhibiting unusual behavior, and of identifying hardware
problems.
David Sand, of
UCLA,
worked with Jim Braatz
on Distant Megamasers
The student and I will address the question of whether water megamaser
sources are preferentially detected in AGNs with highly inclined galactic
disks. Such a trend was detected at early stages of the maser surveys,
and it can now be updated with survey results from the past two years, and
the question addressed more confidently. The project will involve
collecting,
cataloguing, and analyzing properties of galaxies which have been observed
for water. Statistical comparisons of the detected and undetected
populations
will then be pursued.
Jeanine Wilson , of
The University of Washington,
worked with Dana Balser and Toney Minter
on Diffuse Ionized Gas in Galaxies
The summer student will work on modelling the diffuse ionized gas of
galaxies. Models of ionization levels of different atoms will be
computed using the program CLOUDY for many different types of stars
and differing ISM characteristics around these stars. The results
from the CLOUDY models will then be used to model a galactic disk.
These models will then be compared to the galactic disk of the Milky
Way and other galaxies with extended emission from diffuse ionized gas
such as NGC 891.
Sean Andrews,
of Northwestern University
worked with Jonathan Williams
on Molecular Clouds and Star Formation in the Outer Galaxy
Andria Schwortz , of
Alfred University
worked with Jeff Mangum
on Methyl Cyanide as a Probe of Kinetic Temperature in Dense
Molecular Clouds
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