August
25, 2008
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Bryant 217
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Ramsey
Lundock (Tohoku University) |
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Observational Models for
Extrasolar Planets |
| Abstract |
Within the 10 years, next generation telescopes such as TPF
and will be capable of directly observation Extrasolar planets and
collecting spectrography data from them. The theoretical framework for
interpreting that data needs a strong foundation based on comparisons
to the solar system planets. In this presentation I discuss preliminary
observations performed at Hiroshima Observatory and plans for future
Antarctic observations, which together will create a planet observation
library for comparison with Extrasolar planet simulations and
observations.
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| September
1, 2008 |
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Labor Day
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| September
8, 2008 |
Physics 2165
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Nathan De
Lee (UF Astronomy)
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Tracing the Galactic Halo: RR
Lyrae Stars from SDSS-II
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| Abstract |
As we prepare to enter the era of large multi-epoch
photometric surveys,
LSST and PAN-STARRS to name a few, it is important to lay the ground
work
for many of the automatic detection and characterization techniques of
variable stars. This talk describes the creation of a large
catalog of RR
Lyrae stars, their lightcurves, and their associated photometric and
kinematic parameters. This catalog contains 421 RR Lyrae
lightcurves with
305 RRab and 116 RRc derived from the SDSS-II Supernova Survey.
Of these,
241 stars have stellar spectra taken with either the Blanco 4m RC
spectrograph or the SDSS/SEGUE survey, and in some cases taken by
both.
From these spectra, and photometric methods derived from them, an
analysis
is conducted of the RR Lyrae's distribution, metallicity, kinematics,
and
photometric properties within the galactic halo.
In particular, the idea of a dual halo is explored primarily in the
context of radial velocity distributions as a function of |Z| vertical
distance from the plane. Since there are no proper motions
available, the
radial velocity is used as a proxy for orbital velocity, and is
ultimately
compared and contrasted with a single halo galactic model. Also,
the
variation of the Oosterhoff dichotomy, an empirical distribution in RR
Lyrae star properties, is discussed.
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September
15, 2008
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Bryant 217
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| Abstract |
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September
22, 2008
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Physics 2165
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| Abstract |
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September
29, 2008
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Bryant 217
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| Abstract |
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October
6, 2008
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Bryant 217
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Jos Oomens (FOM-Institute
for Plasma Physics Rijnhuizen |
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IR Spectroscopy of Ionized Carbonaceous
Compounds of Astrophysical Internest
|
| Abstract |
Large carbonaceous molecules are now well-accepted to occur
abundantly in inter- and circumstellar environments. However, their
identification by microwave spectroscopy is often hindered by the large
rotational partition functions and sample heterogeneity. Moreover, in
the dilute environment of interstellar clouds, ionic and radical
systems may easily survive, making their spectroscopic study in the
laboratory difficult.
I will give an overview of our studies on the gas-phase IR spectroscopy
(5 - 20 m) of cationic polyaromatic molecules against the background
of the Unidentified Infrared emission bands (UIRs) that have been
observed toward many galactic sources. Other carbonaceous species of
interest include diamondoid molecules and fullerenes. Spectra are
obtained through infrared multiple photon dissociation (IRMPD)
spectroscopy using a free electron laser as source of intense and
widely tunable infrared radiation.
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October
13, 2008
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Bryant 217
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Nancy
Levenson (Kentucky) |
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US Access to Large Ground-Based Telescopes
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| Abstract |
NOAO established the ALTAIR (Access to Large Telescopes for
Astronomical Instruction and Research) committee to identify US
scientific needs at these facilities over the next ten years. Both
indpendent and federally-supported 6--10 meter telescopes are being
considered. The committee's conclusions will also contribute to
renegotiation of the international agreement for operation of Gemini,
which will be effective beginning in 2014. The committee
conducted an
on-line survey over the summer and is currently preparing its report.
I will share some of the initial findings. Most importantly, I
hope
to stimulate a discussion about needs and priorities of the UF
community.
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October
20, 2008
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Physics 2165
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Althea Moorhead
(UF Astronomy)
|
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The eccentricity evolution
of giant planets in the presence of
circumstellar disks |
| Abstract |
Most of the extrasolar planets discovered to date orbit
their host
stars with larger eccentricities and smaller semi-major axes than
similarly sized planets in our own solar system do. It is generally
agreed that the interaction between giant planets and circumstellar
disks (Type II migration) drives the planets inward to small radii,
but the effect of these same disks on orbital eccentricity is
controversial. I present my recent efforts to determine the
effect of a circumstellar disk on orbital eccentricity, comparing
analytic
approximations with the results of hydrodynamical simulations.
Finally, I demonstrate that if the disk can be assumed to damp
semi-major axis and eccentricity, the combination of Type II migration
and planet-planet interactions roughly reproduces the distribution of
orbital elements of the observed extrasolar planets. |
October
27, 2008
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| Abstract |
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November
3, 2008
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Sebastian Hidalgo (IAC)
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Recovering the Ages of Stars of a Complex Stellar
Population System: IAC-pop/MINNIAC and the LCID project
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| Abstract |
We present IAC-pop/MINNIAC, a code to recover the age of
stars of a complex stellar population system, like a galaxy. It uses a
genetic algorithm to minimize a $\chi^2$ merit function
comparing the star distributions in the observed color-magnitude
diagram (CMD) and the CMD of a synthetic stellar population. A
parametrization of the CMDs is used, which is the main input of the
code.
The computation of the synthetic CMD can be done using the code
IAC-star. Since this is a quite time consuming step, a method is
presented requiring computation of only a single synthetic CMD.
IAC-pop/MINNIAC has been run through several consistency test and has
been proved with deep ACS@HST photometry from the LCID project. We
present the first results for the star formation histories
of six galaxies using IAC-pop/MINNIAC code.
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November
10, 2008
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Bryant 217
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Matt Payne (Cambridge)
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| Abstract |
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November
17, 2008
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Alex Lobel (Royal
Observatory of Belgium)
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Radiative Transfer Modeling of
the Winds of Massive Stars |
| Abstract |
I will present results of research work on modeling the
winds
and circumstellar environments of a variety of prototypical hot and
cool
massive stars with multi-D radiative transfer calculations.
This research aims at unraveling the detailed physics of various
mass-loss mechanisms of luminous stars in the upper portion of the
HR-diagram. I focus in on the importance of mechanical wave propagation
for structuring the very extended winds of three key supergiant stars;
HD 64760 (B Ib), Rho Cas (F-G Ia0), and Alpha Ori (M Iab), based
on long-term monitoring programs over the past 15 years of their
ultraviolet and optical high-resolution spectroscopic variability. |
November
24, 2008
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Bryant 217
|
Klara Schure (Utrecht)
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Evolution of supernova
remnants |
| Abstract |
I will give an overview of my work aimed at understanding
more of the evolution of supernova remnants (SNRs). Using the
Cassiopeia A supernova remnant as an example, it will be shown that the
asymmetry in the form of jets can be a valuable diagnostic to probe the
progenitor history. Additionally, I will look at the evolution of
magnetic fields, and how the interplay between cosmic ray acceleration
and magnetic fields may influence the evolution of SNRs. |
December
1, 2008
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| Abstract |
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December
8, 2008
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Sivarani Thirupathi (UF Astronomy) |
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Stellar relics from the
early Galaxy: Elemental abundances in
Extreme Metal Poor (EMP) stars. |
| Abstract |
Modern spectroscopic surveys (HK, HES, SDSS and
SEGUE) with follow-up high resolution spectroscopy have
provided very accurate abundances for several hundreds of
metal poor (< [Fe/H] -2.5) stars in our Galaxy. These old
stars are expected to retain nucleosynthesis records of the
First stars. Here, we present the abundance patterns of EMP
stars observed during the ESO-VLT large programme(P.I. R. Cayrel),
and possible constraints on the nature of the First stars.
We will discuss the growing evidence of increase in carbon abundance
at low metallicities and its possible implications for the early
IMF of the Galaxy. |
December
15, 2008
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Rachel Mason
(Gemini)
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The origin of the silicate emission in NGC 2110
|
| Abstract |
The unified model of AGN predicts silicate emission features
at 10 and
18 microns in type 1 AGN, and such features have now been observed in
objects ranging from distant QSOs to nearby LINERS. More surprising,
though, is the detection of silicate emission in a few type 2 AGN. By
combining ground-based and Spitzer IR imaging and spectroscopy of
NGC2110, the closest known Seyfert 2 galaxy with silicate emission
features, we are able to constrain the location of the silicate
emitting region to the innner narrow-line region or the torus
itself. Furthermore, we are able to reproduce the silicate emission
features and SED of this object with emission from an edge-on clumpy
torus. In this talk I will discuss this first demonstration that
silicate emission features can plausibly arise in the torus even in
type 2 AGN.
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Spring
2009 Schedule
Spring
2008 Schedule