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List of colloquium talks given during the summer of 2011
Links to:
Program of the SAO Summer Intern Symposium, August 10, 2011
2011 Summer Program Calendars for June
, July
, and August
Abstracts for posters presented at the January, 2012 AAS Meeting
INTERN: Kate Alexander (Brown University)
ADVISOR: Prof. Alicia Soderberg (OIR Division CfA)
PROJECT TITLE: A Blind Search for Radio Transients in M51 and
Associated Radio Observations of SN1994I
Abstract:
CO-ADVISOR: Dr. Laura Chomiuk (OIR Division CfA)
The student will conduct a search for radio transients in M51 using
archival data from the Very Large Array collected over a period of
six months following the discovery of the Type I supernova 1994I on
May 2, 1994. The student will also construct light curves and
analyse spectra for the supernova 1994I for the three available epochs,
April 10, May 4, and August 8, 1994, and will use these data to study
the physical properties of the supernova explosion and model the
nature of the progenitor.
INTERN: Joanna Barnes (St. Andrews University)
ADVISOR: Dr. Rosanne DiStefano (TA Division CfA)
PROJECT TITLE: Gravitational Lensing Events
Abstract:
CO-ADVISOR: Dr. Joshua Carter (OIR Division CfA)
The study of nearby lenses is a relatively new endeavor and there are
a variety of projects, both theoretical and observational, that can be
productive on short time scales. The project I propose for this summer
would provide training on both the theoretical aspects and
observational aspects of searching for evidence of nearby lenses. The
student would learn to compute both the astrometric and photometric
shifts induced by gravitational lensing. She would then compare the
results with what is and/or can be observed by a variety of
telescopes, from those used by amateurs, to the Hubble Space
Telescope. Very likely, the student will co-author one or more papers
within the year after completing the summer program.
ADVISOR: Dr. Francesca Civano (HEA Division CfA)
PROJECT TITLE: Properties of X-ray Emitting Quasar Close Pairs from
the Chandra COSMOS Survey
Abstract:
We have reduced optical and X-ray data on ~15 such quasar pairs
from the COSMOS survey. The student will measure X-ray and optical
spectra of this sample of quasar pairs, extract SEDs, measure quasar
mass, luminosity, optical slope and NIR slopes, and put these pairs on
diagnostic diagrams such as Mass versus Luminosity or optical versus
near-IR slope. These results will then be compared with simulations to
estimate the significance of their numbers relative to what is
predicted from standard clustering models.
CO-ADVISOR: Dr. Tom Aldcroft (HEA Division CfA)
Pairs of X-ray emitting sources within a small range of
redshift and at a distance of 10-20kpc one to the other have
been found in the Chandra COSMOS survey.
Galaxy evolution theory says their host galaxies are likely
to merge, and that their activity may be stimulated by tidal
disruptions of their ISM. Questions we wish to address include:
Does being in a pair, on a 'death plunge' affect the quasars, or are
they unaware of the fate that is in store?
Do their optical spectra look any different from normal quasars?
Do their X-ray to radio spectral energy distributions look peculiar or
normal? Do these quasar pairs lie in an unusual place on any diagnostic
diagrams, i.e. the mass (M) versus luminosity (L) plane or
optical vs near-IR slope?
INTERN: Chelsea Harris (UC Santa Barbara)
ADVISOR: Dr. Stella Offner (TA Division CfA)
PROJECT TITLE: Dynamics of Dense Cores in Simulated and Observed
Molecular Clouds
Abstract:
Project:
[1] Ridge, N. et al., "The COMPLETE Survey of Star Forming Regions:
Phase 1 Data", 2006, AJ, 131, 2921
[2] Kirk, H., Pineda, J., Johnstone, D., & Goodman, A. "The Dynamics
of Dense Cores in the Perseus Molecular Cloud. II. The Relationship
Between Dense Cores and the Cloud," 2010, ApJ, 723, 457
[3] Offner, S., Klein, R., & McKee, C. "Driven and Decaying Turbulence
Simulations of Low-Mass Star Formation: From Clumps to Cores to
INTERN: John Hoffman (University of Illinois)
ADVISOR: Dr. Hans Moritz Guenter (HEA Division CfA)
PROJECT TITLE: Stellar Cycles
Abstract:
Project:
We will start with XMM-Newton observations of the spectroscopic cal
targets and look for the stars in the field of the MOS and PN fields,
because these fields have been visited a large number of times.
Depending on the progress the project makes we can easily extend it (we
have a list of sky regions XMM has looked at more then 10 times and we
also had a first look at some of the repreated Chandra observations,
e.g. the stars in the Deep Field South).
If we find stellar cycles, this will result in the publication, if not,
we will try to estimate and upper limit and the magnitude and length of
average stellar cycles.
INTERN: Mackenzie Jones (Butler University)
ADVISOR: Dr. Elisabeth Adams (OIR Division CfA)
PROJECT TITLE: The Complete Life-Cycle of an Exoplanet Transit Light Curve
Abstract:
INTERN: Ali Ahmad Khostovan (UC Irvine)
ADVISOR: Dr. Jan Forbrich (HEA Division CfA)
PROJECT TITLE: Initial Conditions of Star Formation in the Pipe Nebula
Abstract:
The Pipe Nebula is a nearby molecular cloud complex with an unusually
low star formation rate. The region contains hundreds of starless
cores and only a single cluster of young stars. The starless cores
have been identified by observations of how the Pipe Nebula affects
background starlight (extinction mapping). We have
surveyed the entire region extensively with various observational
techniques, and we have obtained observations of ten different
molecular transition lines toward the sample of starless cores using
single-dish radio telescopes in North America and Australia. Early
results suggest that cores with similar properties
(e.g. mass, radius, density, stability, etc.) show very different
molecular line emission, and the underlying chemical differences are
likely related to their relative evolutionary stages. While most of
the chemistry in dense cores occurs in the gas phase, the surfaces of
dust grains are involved as well. The millimeter radio observations
will thus allow us to study chemical differences across the sample
that will shed new light on the question why the Pipe Nebula
region has but one region of active star formation. In addition to the
pointed observations of starless cores, we also have data to a analyze
the spatial structure of selected cores, for example from molecular
line mapping observations. This project will start with a survey of
the literature concerning the chemistry of starless cores. In a second
step the results will be applied to the Pipe Nebula
observations, beginning with a cross-correlation of the molecular line
detections and other properties of the cores.
INTERN: Sajjan Mehta (Drexel University)
ADVISOR: Dr. Scott W. Randall (HEA Division CfA)
PROJECT TITLE: X-ray Properties of the Intra-Cluster Medium in
Optically Selected Galaxy Groups
Abstract:
One concern when dealing with X-ray selected samples of galaxy
clusters or groups is the inherent selection bias in such samples.
X-ray brighter objects will be preferentially detected over fainter
ones, leading to an over-representation of such objects in samples.
Thus, X-ray selected samples may not be a fair representation of the
full population of groups and clusters. With this project, we will
examine the X-ray properties of an optically selected sample of galaxy
groups. Although optically selected samples will have their own
selection biases, these biases are expected to be different from, and
largely independent of, X-ray selection biases. A difference between
the X-ray properties of X-ray selected and optically selected group
samples would indicate significant selection biases, which would need
to be fully understood to properly interpret our samples. In
particular, we will search for a bimodal distribution in the central
entropy of optically selected groups, which is observed cluster
samples. Groups with higher central entropy may be overlooked in
X-ray selected group samples, since they are expected to be less X-ray
bright than low central entropy groups (as is observed with clusters).
The student will learn the fundamentals of high energy astrophysics in
the context of the study of galaxy groups and clusters, and the basics
of analyzing X-ray data from working with archival Chandra
observations. The work will involve understanding, running, and
possibly modifying some "homemade" code to carry out the
analysis. Some coding experience, particularly a familiarity with
Perl, is a plus (although not required).
INTERN: Alex Spatzier (Oberlin College)
ADVISOR: Dr. Catherine Espaillat (RG Division CfA)
PROJECT TITLE: A Multi-Wavelength View at a Stellar Nursery
Abstract:
INTERN: Jordan Wheeler (University of Missouri - Columbia)
ADVISOR: Dr. Huiqun Wang (AMP Division CfA)
PROJECT TITLE: Martian Weather Observations Using Mars REconnaissance
Orbiter (MRO) Data
Abstract:
CO-ADVISOR:Dr. Helen Kirk (RG Division CfA)
Background:
Within our close galactic neighborhood (a few hundred parsecs
or lightyears), many molecular clouds have been detected where
star formation is ongoing. Many puzzles remain in understanding
star formation, including the influence of the large-scale
cloud properties on the formation and evolution of the embedded
forming stars. To better understand these processes, large surveys
are underway at several telescopes focussing on nearby
molecular clouds, and an unprecedented amount of data is becoming available.
One of the precursors to these multi-telescope, multi-cloud surveys
was COMPLETE (led by Dr. Goodman, [1]), which focussed on star
formation in several molecular clouds, particularly the Perseus
molecular cloud. Most stars appear to form in clusters,
where interactions between dense star-forming cores may play an
important role in subsequent evolution. Observations from the COMPLETE
survey have shown that dense cores in Perseus tend to have very small motions
relative to their immediate surroundings, and that the
motions between cores within a clustered region are a factor
of two smaller then the large-scale gas motions [2].
Interpretation of these results is challenging without knowledge of
the 3D structure and dynamics of the cloud. The most promising avenue
to improving understanding is through comparisons with numerical
simulations of star-formation, where the intial environmental
conditions and the 3D cloud structure is known.
In this project, the student will create and analyze
synthetic observations of simulated high-resolution turbulent
molecular clouds [3]. The student will use existing code to derive
the observed velocity distribution of various molecules, like N2H+
and 13CO, and obtain measurements in a manner that mimics real
observing modes. Comparisons between the `observed'
and real 3D dynamical properties will provide insight into how the
actual observational data can be interpreted. Comparisons can also
help to constrain the important physics and initial conditions used
CO-ADVISOR: Dr. Nick Wright (HEA Division CfA)
Background:
Our sun has a well-known activity cycle of 11 years. Activity can be
traced in cromospheric signatures like Ca H and K and traditionally this
has been the way to search for cycles on other stars as well (the famous
Mount Wilson S index), however on our sun the difference between minimum
and maximum activity is much stronger in X-rays than in the
Chromosphere. Only very few stars have observed cyclic variability in
X-rays and only in one case (our sun) actually more than one cycle is
observed. Individual stars, which are monitored on a long-term basis are
e.g. alpha Cen and 61 Cyg.
XMM-Newton and Chandra have been launched more than a decade ago and
there are plenty of fields in the archive, which have been observed for
several times for varying reasons. Nick has looked at the stellar
content of the COSMOS field and in this project the student would
analyse archival data. It it a well-defined and self-contained project,
which leads the student through the analysis of X-ray data from
selecting the data in the archive, downloading it, reduce it, detect
point sources, measure count rates (and compare his/her results with
pipeline products), extract and fit spectra (to confirm it is a star -
this goes beyond pipeline products), generate long-term lightcurves and
search for periodicities.
CO-ADVISOR: Dr. Joshua Carter (OIR Division CfA)
I have a stockpile of a dozen or more good-quality transit light
curves from several exoplanets, which I would really like to fully
reduce and fit (and, ideally, publish). The student would get to see the
entire life cycle of a transit light curve: photometry to get the best
light curve, literature search for other light curves of the same
planet, joint fits of all the light curves to get a consistent set of
orbital parameters, examining the timing and other parameters, and
then writing up the results. Most of the transits were observed with a
new PI instrument on the IRTF, and I have five transits scheduled to
be remotely observed with the same instrument between early June and
late July; it would be great if the intern could help me with those
observations.
CO-ADVISOR: Drs. Charlie Lada, Karin Oberg (RG Division CfA)
Stars in the mass range of our own Sun form in molecular cloud cores.
Starless cores thus are ideal laboratories for the initial conditions
of low-mass star formation. The best tool to study these cold cloud
cores (with temperatures of ~10 K) are observations in molecular
transition lines that occur in the millimeter wavelength (microwave)
radio range.
CO-ADVISOR: Dr. Paul Nulsen (HEA Division CfA)
As the largest virialized structures in the Universe, clusters of
galaxies are extremely useful probes of cosmology. Since galaxy
clusters are filled with diffuse, high temperature gas that shines
brightly at X-ray wavelengths (the intracluster medium, or ICM), X-ray
observations are particularly well suited to the detection and study
of clusters. If one is to use X-ray observations to catalog the
properties of galaxy clusters, it is important to understand the
physics of the ICM. Galaxy groups, the lower-mass cousins of galaxy
clusters, are ideal for the study of physical processes in the ICM
since there are more of them nearby, and since such processes will
have a larger relative impact on the ICM in groups due to their
shallower gravitational potentials. Furthermore, although groups are
less massive than clusters, they are more numerous, and contain a
significantly larger fraction of the total mass in the Universe as
compared to clusters. They are therefore interesting objects to study
CO-ADVISOR: Dr. Scott Wolk (HEA Division CfA)
Stars similar to our Sun form deeply embedded in molecular clouds. As
they evolve, they become less and less embedded, and they form
circumstellar disks, the birthplace of planets. The processes of low-
mass star formation can be best studied by observations of nearby young
clusters. IC 348 is such a nearby cluster of young stars that lies at
a distance of only about 300 pc (1000 light years) from the Sun.
To characterize the population of this cluster, astronomers use
observations at very different wavelengths. It has become a common
tool to use both infrared and X-ray data to assemble a census of young
stars in different evolutionary stages. We have recently
obtained new X-ray images of this cluster with the Chandra X-ray
Observatory, improving both on the sensitivity and the spatial
coverage of previous datasets. These images will allow us to find
previously undetected X-ray sources and better characterize the
population of this cluster. The new X-ray sources that we will find can
then be characterized by existing infrared, centimeter radio, and
submillimeter observations. The infrared data, both from ground-based
telescopes and the Spitzer Space Telescope, will tell us about
the evolutionary stage of the sources by providing information on the
existence of circumstellar disks. We will use the submillimeter data,
obtained at longer wavelengths than the far infrared, to characterize
the youngest sources that are still deeply embedded in their natal cloud
cores. Finally, radio data at centimeter wavelengths can help us to
further constrain the high-energy processes that are related to the
X-ray emission.
CO-ADVISOR: Dr. Sarah Stewart (EPS Department, Harvard University)
This project consists of making Mars Daily Global Maps from images
taken by the MRO Spacecraft and using them to study the pattern of
Martian weather. MRO Mars Color Imager takes 13 sets of multispectral
global map swaths each day. These images will be radiometrically and
photometrically corrected, projected and merged into a global weather
map each day. Dust storms and clouds will be identified, recorded and
classified. Patterns of dust storms and clouds of various types will
be summarized. If there is still time left, then the results above can
be compared to atmospheric eddies derived from the concurrent
temperature data and modeled by a Mars General Circulation
Model. Student working on this project will practice IDL image
processing of spacecraft data, gain expert knowledge of Martian
weather, and apply atmospheric science principles to another planet.