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BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Stars, Planets, and ISM Seminar
LOCATION:PMA 15.216B
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:
Title: TBA
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210825T120000
DTEND;TZID=America/Chicago:20210825T130000
SEQUENCE:0
RRULE:FREQ=WEEKLY;UNTIL=20211209T000000Z;INTERVAL=1;BYDAY=WE
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Organizational Meeting
LOCATION:PMA 15.216B
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Organizational Meeting
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210825T120000
DTEND;TZID=America/Chicago:20210825T130000
RECURRENCE-ID;TZID=America/Chicago:20210825T120000
SEQUENCE:0
TRANSP:OPAQUE
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BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:No talk scheduled
LOCATION:PMA 15.216B
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:No talk scheduled
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210901T120000
DTEND;TZID=America/Chicago:20210901T130000
RECURRENCE-ID;TZID=America/Chicago:20210901T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:No talk scheduled
LOCATION:Online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:No talk scheduled
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210908T120000
DTEND;TZID=America/Chicago:20210908T130000
RECURRENCE-ID;TZID=America/Chicago:20210908T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two Talks
LOCATION:Online and PMA 15.216B
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Madeline Lucey, The University of Texas at Austin
The Chemo-dynamical Origins of Metal-poor Bulge Stars (COMBS) Survey
Abstract
The characteristics of the stellar popul
ations in the Galactic Bulge inform and constrain the Milky Way's formation
and evolution. The metal-poor population is particularly important in ligh
t of cosmological simulations, which predict that some of the oldest stars
in the Galaxy now reside in its center. The metal-poor bulge appears to con
sist of multiple stellar populations that require dynamical analyses to dis
entangle. In this talk, I will discuss my detailed chemodynamical study of
the metal-poor stars in the inner Galaxy. Using VLT/GIRAFFE spectra of 319
metal-poor stars, we perform stellar parameter analysis and report 12 eleme
ntal abundances (C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Zn, Ba, and Ce). Ba
sed on kinematic and spatial properties, we categorize the stars into four
groups, associated with the following Galactic structures: the inner bulge,
the outer bulge, the halo, and the disk. We find evidence that the inner a
nd outer bulge population is more chemically complex (i.e., higher chemical
dimensionality and less correlated abundances) than the halo population. T
his result suggests that the older bulge population was enriched by a large
r diversity of nucleosynthetic events. We also find one inner bulge star wi
th a [Ca/Mg] ratio consistent with theoretical pair-instability supernova y
ields and two stars that have chemistry consistent with globular cluster st
ars.
Michael Gul
ly-Santiago, The University of Texas at Austin
Frontiers
in Forward Modeling Substellar Atmospheres, Part II & Growing an Ecosys
tem of Spectral Investigative Tools
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210915T120000
DTEND;TZID=America/Chicago:20210915T130000
RECURRENCE-ID;TZID=America/Chicago:20210915T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Neal Evans, The University of Texas at Austin
LOCATION:Online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:The Central Problem of Star Formation: Why So Slow?
Abstract
The Central Problem of star formation ha
s been clear for over 40 years: simple estimations predict star formation r
ates more than 100 times what is observed in the Milky Way and other galaxi
es. Much ingenious theoretical work has been expended to solve this problem
, enhancing our understanding of turbulence and feedback in molecular cloud
s, but the fundamental problem remains. This situation suggests a reconside
ration of the basic assumption that underlies the problem: that molecular c
louds are bound entities. In the most complete catalog of structures from C
O emission maps, most molecular clouds are unbound, ameliorating the proble
m. Preliminary work combining this information with theoretical models of h
ow the star formation rate depends on the initial virial parameter, along w
ith considerations of how metallicity affects the conversion of CO luminosi
ty into mass, suggests that a solution to the Central Problem may be at han
d for the Milky Way. The situation for other galaxies is less clear.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210922T120000
DTEND;TZID=America/Chicago:20210922T130000
RECURRENCE-ID;TZID=America/Chicago:20210922T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:David Guszejnov, The University of Texas at Austin
LOCATION:PMA 15.216B and online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:
The Effects of Feedback on Star Formation in the STARFORGE Simulation
s
Abstract
In this talk I will pre
sent results from the STARFORGE project that are the first ever cloud-scale
radiation-magnetohydrodynamic simulations that follow individual stars and
include detailed gas thermodynamics, as well as stellar feedback in the fo
rm of protostellar jets, stellar radiation, winds and supernovae. This suit
e includes a large number of runs with different combinations of physical p
rocesses as well as varied initial conditions, allowing us to disentangle t
he effects of different physical mechanisms and to describe them as a funct
ion of the initial condition. Our results show that radiative feedback is e
ssential in quenching star formation and disrupting the cloud, however the
mass scale of the IMF is still predominantly set by magnetic fields and pro
tostellar jet physics. We find the effects of stellar winds to be minor in
our simulations, similar to supernovae that happen too late to affect the I
MF or quench star formation. We find that the star formation history of a c
loud is strongly dependent on its initial condition, but the final, post-di
sruption stellar population (i.e., IMF) is insensitive to most cloud proper
ties (e.g., surface density, level of turbulence), providing an explanation
to the observed near-universality of the IMF in the Galaxy.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20210929T120000
DTEND;TZID=America/Chicago:20210929T130000
RECURRENCE-ID;TZID=America/Chicago:20210929T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Zack Maas, The University of Texas at Austin
LOCATION:PMA 15.216B and online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:
The Galactic Chemical Evolution of Phosphorus: A survey of 160 Stars
with the Habitable-zone Planet Finder Instrument
Abstract
Phosphorus is a key element for life and may be p
roduced in a variety of nucleosynthesis channels. However, phosphorus has f
ew accessible absorption lines making abundance measurements in stars diffi
cult. To better understand how this odd-Z element is created, my collaborat
ors and I have conducted a study of phosphorus in the Galaxy by measuring P
abundances using the Habitable-zone Planet Finder on the Hobby-Eberly tele
scope. We have found that phosphorus abundances are similar to the alpha el
ements, especially Mg. We also find a difference in [P/Fe] of ~0.1 dex betw
een thin and thick disk stars classified with kinematics. Finally, we have
preliminary [P/Fe] ratios in halo stars likely associated with the Gaia-Enc
eladus-Sausage system.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211006T120000
DTEND;TZID=America/Chicago:20211006T130000
RECURRENCE-ID;TZID=America/Chicago:20211006T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Keith Hawkins, The University of Texas at Austin
LOCATION:Online and PMA 15.216B
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:The Origins of Massive (Young) Alpha Enhanced Stars
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211013T120000
DTEND;TZID=America/Chicago:20211013T130000
RECURRENCE-ID;TZID=America/Chicago:20211013T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Erica Sawczynec, The University of Texas at Austin
LOCATION:Online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Asteroseismology of a Nearby Resolved Binary
Abstract
As stars age, they lose mass and
angular momentum resulting in a surface rotation spin-down over time. Gyrochronology is a promising tool for age dating where o
ther methods fail but requires calibration using stars with well-known age
and rotation periods to be successful. Due to the lim
ited amount of calibrators with precise ages, gyrochronology struggles to a
ccurately predict the rotation periods of low-mass-cool stars. In this work, we utilize the coevality of HIP 43232--a wide-binar
y system comprised of a solar-like star with an M dwarf companion--to add a
new calibrator in the cool-low-mass regime of gyrochronology. Using a combination of spectroscopic and asteroseismic constraint
s, we precisely characterize the solar-like component HIP 43232A through ME
SA modeling. We also explore the effects on several s
tellar parameters by choosing different potential input physics combination
s when modeling with MESA. MESA estimates the age of
HIP 43232A to be ~3.7 Gyr, a regime that hosts an extremely limited populat
ion of M dwarfs with precisely measured ages. Pairing K2 with ZTF light curves, we estimate the ro
tation period of HIP 43232B, the M dwarf companion, to be 41.3 +— 4.1 days. P
eriod-age relationships from the literature overpredict the amount of angul
ar momentum loss and predict a slower period for HIP 43232B than we observe
. However, models that account for internal angular m
omentum transport include a period of spin-down stall and predict the rotat
ion period of HIP 43232B significantly better. HIP 43
232B is one of the first M dwarfs with a precisely measured age and rotatio
n period in this regime, making it a benchmark calibrator for future gyroch
ronology models.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211020T120000
DTEND;TZID=America/Chicago:20211020T130000
RECURRENCE-ID;TZID=America/Chicago:20211020T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two Talks
LOCATION:Online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Kendall Sullivan, The University of Texas at Austin
Exploring Correlations Between Optical and NIR Excess in T Tauri Star
s
Fritz Benedict, The University of Texas at Austin
The eta Aquilae System: Radial Velocities and Astrometry in S
earch of eta Aql B
Abstract
The c
lassic Cepheid eta Aql was not included in past Leavitt Law work (Bene
dict et al. 2007) because of a presumed complicating orbit due to a kn
own B9.8V companion. In an effort to determine an orbit and mass for eta Aq
l B, and obtain a parallax for eta Aql, we analyze a significant numbe
r of radial velocity measures (RV) from eight sources, including four
more recent. With these we establish the radial velocity variation due to C
epheid pulsation, using a twelve Fourier coefficient description of t
he Cepheid pulsation, while solving for velocity offsets required to
bring the eight RV data sets into coincidence. Residuals to the Cephe
id pulsation model provide no evidence of significant orbital motion,
suggesting a nearly face on A-B orbit orientation. Our astrometric re-
analysis of Hubble Space Telescope Fine Guidance Sensor data now inclu
des reference star parallax and proper motion priors from Gaia EDR3. A
model without EDR3 priors for eta Aql yields parallax and proper moti
on values inconsistent with EDR3, and the Benedict 2007 Leavitt Law. Large
residuals hint at unmodeled orbital motion. However, we h
ave an insufficient number of epochs with which to establish an orbit.
Introducing EDR3 parallax and proper motion priors reduces the residu
als and produces a parallax in agreement with EDR3.We hypothesize an e
ta Aql A-B orbit with a one year period. We use the parallax mismatch
to estimate a perturbation size, and find a mass for eta Aql B agreeing wit
h past estimates.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211027T120000
DTEND;TZID=America/Chicago:20211027T130000
RECURRENCE-ID;TZID=America/Chicago:20211027T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two Talks
LOCATION:PMA 15.216B and online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Boyuan Liu, The University of Texas at Austin
The First Star Clusters
Abstract
We use N-body simulations to study the dynamical evolution of Population II
I (Pop III) star clusters/groups and the resulting binary statistics. We de
sign a physically-motivated framework for the initial conditions of Pop III
star clusters, based on small-scale hydrodynamic simulations and the scale
-free nature of disk evolution during Pop III star formation. Our novel app
roach enables us to explore the dependence of binary statistics on initial
conditions and arrive at more robust predictions for the signals of Pop III
X-ray binaries (XRBs) and (compact object) remnant mergers, compared to si
mple extrapolations of Pop III protostar systems. We find that binary prope
rties are highly sensitive to the initial cluster size and distribution of
binary separation, while the effect of initial mass function is relatively
minor. Our simulations predict less close binaries, and thus, significantly
lower efficiencies (by a factor of 10-10,000) for the formation and accret
ion of Pop III XRBs, than found in previous studies, implying that the
contribution of Pop III XRBs to the cosmic X-ray background is negligible
and their feedback effects are unimportant. The efficiency of forming Pop I
II remnant mergers via the "classical".binary stellar evolution (BSE) chann
el is also reduced in the lack of close binaries. In light of this, we prop
ose an alternative channel of forming Pop III mergers by dynamical hardenin
g in nuclear star clusters, which is shown to be as efficient as the BSE ch
annel. We conclude that gravitational N-body dynamics is an important conte
xt of Pop III remnant mergers for both initial formation of binaries and su
bsequent evolution in dense star clusters. Therefore, deeper understanding
of the initial conditions of star clusters based on star formation theory i
s required to better model (high-z) star clusters and fully unleash the pow
er of GW astronomy.
David Wilson, The University of Texas at Austin
Measu
rements of the Ultraviolet Spectral Characteristics of Low-mass Exoplanetar
y Systems (Mega-MUSCLES)
Abstract
The Measurements of the Ultraviolet Spectral Characteristics of Low-mass E
xoplanetary Systems (Mega-MUSCLES) Treasury project, together with the prec
ursor MUSCLES project, is producing full spectral energy distributions of a
representative sample of M dwarfs, covering a wide range of stellar mass,
age, and planetary system architecture. We have obtained x-ray and ultravio
let data for 12 stars using the Hubble, Chandra and XMM space telescopes, a
long with state-of-the-art DEM modelling to fill in the unobservable extrem
e ultraviolet regions. Our completed SEDs will be available as a community
resource, with the aim that a close MUSCLES analogue should exist for most
M dwarfs of interest. In this presentation I will overview the Mega-MUSCLES
project, describing our choice of targets, observation strategy and SED pr
oduction methodology. I will also discuss notable targets such as the TRAPP
IST-1 host star and the discovery of high-energy flares on Barnard's Star.<
/p>
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211103T120000
DTEND;TZID=America/Chicago:20211103T130000
RECURRENCE-ID;TZID=America/Chicago:20211103T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Harriet Dinerstein, The University of Texas at Austin
LOCATION:TBD
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Excitation of Molecular Hydrogen in Strong UV Radiation Fields<
/p>
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211110T120000
DTEND;TZID=America/Chicago:20211110T130000
RECURRENCE-ID;TZID=America/Chicago:20211110T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two Talks
LOCATION:PMA 15.216B and online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:
Tyler Nelson, The University of Texas at Austin
Distant Cousins - The chemistry of comoving pairs
Borj
a Anguiano, The University of Texas at Austin
WD binaries
in APOGEE
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211117T120000
DTEND;TZID=America/Chicago:20211117T130000
RECURRENCE-ID;TZID=America/Chicago:20211117T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:No talk scheduled
LOCATION:TBD
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:No talk scheduled
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211124T120000
DTEND;TZID=America/Chicago:20211124T130000
RECURRENCE-ID;TZID=America/Chicago:20211124T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two Talks
LOCATION:PMA 15.216B and online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Melanie Rowland, The University of Texas at Austin
Towards Robust Atmospheric Retrievals for Cloudy L dwarfs: Tests on So
nora Spectra
Abstract
Retrieving
atmospheric properties from spectra is the only method through which proper
ties of brown dwarf atmospheres can be determined since in situ measurement
s are impossible at astronomical distances. However, our ability to charact
erize these atmospheres is complicated by the degeneracies produced between
the thermal structure, chemical abundances, and the presences of clouds in
cooling brown dwarf atmospheres. Incorporating the complex physics that go
vern cloudy brown dwarf and planetary atmospheres into retrieval frameworks
necessitates making assumptions, many of which are not yet robustly verifi
ed for accuracy. We test two key assumptions regarding the thermal profile
and abundances using state-of-the-art cloud-free models (the Sonora model g
rid) to create mock data sets. We use the CHIMERA retrieval framework to te
st these assumptions on a wide temperature range of cloud-free Sonora spect
ra for which ground truth values are known. These tests reveal under what c
onditions these assumptions break down, and which assumptions are valid in
the warm brown dwarf temperature regime.
Kedron Silsbee, Max Planck Institute for Extraterr
estrial Physics
Core Accretion in Tight Binary Systems: v
iable despite destructive planetesimal collisions?
Abstract
The observed presence of planets in ti
ght binary systems places significant constraints on the planet formation p
rocess. A close-by companion star is expected to stir up planetesimal
s in the protoplanetary disk, leading to high-speed destructive collisions.
Simple estimates based on the parameters of known planet-hostin
g binary systems suggest that kilometer per second collision velocities are
not unreasonable. These are sufficient to destroy planetesimals
100’s of km in size. This raises questions about the viability of th
e standard core accretion model of planet formation, in which planetesimals
stick together in mutual collisions to form rocky planets or the cores of
giant planets. I will give an overview of the special challenges that
tight binaries pose for planet formation theories. I will
then discuss the dynamical evolution of planetesimals in binary systems.&nb
sp; I describe work in which we accurately calculated planetesimal collisio
n speeds and rates, and then used these to run a coagulation-fragmentation
simulation to model their growth or destruction. We find that fo
r reasonable disk parameters, planetesimal coagulation is possible starting
from bodies of a few to a few tens of km. This necessary starti
ng planetesimal size is smaller than that found in previous work, suggestin
g that core accretion is a viable scenario even in these challenging e
nvironments.
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211201T120000
DTEND;TZID=America/Chicago:20211201T130000
RECURRENCE-ID;TZID=America/Chicago:20211201T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
BEGIN:VEVENT
UID:09361828cf893191a51f618608a4488e
CATEGORIES:Stars, Planets, and ISM Seminar
SUMMARY:Two talks
LOCATION:Online
DESCRIPTION;ENCODING=QUOTED-PRINTABLE:Jake Clark, University of Southern Queensland
The Astronomical Throuple: Unveiling exoplanetary sci
ence through stellar surveys and galactic archaeology
Abstract
Pioneering photometric, astrometric
, and spectroscopic surveys are helping exoplanetary scientists better cons
train the fundamental properties of stars within our galaxy, and the planet
s these stars host. In this talk, I'll be highlighting the work done in my
dissertation in utilising the galactic archaeology survey GALAH, along with
GAIA and other surveys to to better understand the explanets and the stars
that host them across our galaxy. This includes; forward predicting what t
ypes of rocky worlds TESS is likely to uncover, determining differences in
planetary populations through stellar abundances, refining the fundamental
properties of exoplanets, using chemo-kinematics to determine stellar popul
ations of exoplanet hosts and more!
Alexis Heitzmann, University of Southern Queenslan
d
Are These Planets Revealing their Formation History?
Abstract
The evolution of exoplanet characteristics might be the key to understan
d the formation and evolution of gas giant exoplanets found to orbit very c
lose to their host stars. Orbit obliquity (i.e. the angle betwe
en the stellar rotation axis and the orbital normal of the planet) is one s
uch parameter. For very young systems, it can help disentangling the t
rue primordial orbits of orbiting planets and deliver crucial insights on t
heir formation and evolution pathways. HIP 67522 is a 17-Million-year-old Solar analogue that hosts a
close-in Jupiter-sized exoplanet with an orbital period of 6.95 days.
In this talk, I
will show how we measured, despite the stellar activity of the very young
host star, HIP 67522 b’s o
bliquity and discuss the implications of this finding. I will also present
an upcoming discovery of an exoplanet that might be giving away its fo
rmation history.
<
/p>
DTSTAMP:20240329T035550Z
DTSTART;TZID=America/Chicago:20211208T120000
DTEND;TZID=America/Chicago:20211208T130000
RECURRENCE-ID;TZID=America/Chicago:20211208T120000
SEQUENCE:0
TRANSP:OPAQUE
END:VEVENT
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