245 research outputs found
Exploring Strategy Planning and Execution Methods in Church Missions Programs
The aim of this thesis is to explore the extent to which church missions programs employ strategic planning and execution methods. In order to validate available literature on the topic of strategic planning (both biblical and secular), the author contributes a current survey dataset which validates the problem and highlights specific areas of potential improvement. This research successfully articulates the need for North American Southern Baptist Convention churches to focus on strategic planning. In analyzing the survey data, one is able to understand the cause-and-effect relationships between successful strategic planning and a church’s ability to optimize their ability to advance the kingdom of God
Spitzer Secondary Eclipses of Qatar-1b
Previous secondary eclipse observations of the hot Jupiter Qatar-1b in the Ks
band suggest that it may have an unusually high day side temperature,
indicative of minimal heat redistribution. There have also been indications
that the orbit may be slightly eccentric, possibly forced by another planet in
the system. We investigate the day side temperature and orbital eccentricity
using secondary eclipse observations with Spitzer. We observed the secondary
eclipse with Spitzer/IRAC in subarray mode, in both 3.6 and 4.5 micron
wavelengths. We used pixel-level decorrelation to correct for Spitzer's
intra-pixel sensitivity variations and thereby obtain accurate eclipse depths
and central phases. Our 3.6 micron eclipse depth is 0.149 +/- 0.051% and the
4.5 micron depth is 0.273 +/- 0.049%. Fitting a blackbody planet to our data
and two recent Ks band eclipse depths indicates a brightness temperature of
1506 +/- 71K. Comparison to model atmospheres for the planet indicates that its
degree of longitudinal heat redistribution is intermediate between fully
uniform and day side only. The day side temperature of the planet is unlikely
to be as high (1885K) as indicated by the ground-based eclipses in the Ks band,
unless the planet's emergent spectrum deviates strongly from model atmosphere
predictions. The average central phase for our Spitzer eclipses is 0.4984 +/-
0.0017, yielding e cos(omega) = -0.0028 +/- 0.0027. Our results are consistent
with a circular orbit, and we constrain e cos(omega) much more strongly than
has been possible with previous observations
Spitzer/MIPS 24 μm Observations of HD 209458b: Three Eclipses, Two and a Half Transits, and a Phase Curve Corrupted by Instrumental Sensitivity Variations
We report the results of an analysis of all Spitzer/MIPS 24 μm observations of HD 209458b, one of the touchstone objects in the study of irradiated giant planet atmospheres. Altogether, we analyze two and a half transits, three eclipses, and a 58 hr near-continuous observation designed to detect the planet's thermal phase curve. The results of our analysis are: (1) a mean transit depth of 1.484% ± 0.033%, consistent with previous measurements and showing no evidence of variability in transit depth at the 3% level. (2) A mean eclipse depth of 0.338% ± 0.026%, somewhat higher than that previously reported for this system; this new value brings observations into better agreement with models. From this eclipse depth we estimate an average dayside brightness temperature of 1320 ± 80 K; the dayside flux shows no evidence of variability at the 12% level. (3) Eclipses in the system occur 32 ± 129 s earlier than would be expected from a circular orbit, which constrains the orbital quantity ecos ω to be 0.00004 ± 0.00033. This result is fully consistent with a circular orbit and sets an upper limit of 140 m s^(–1) (3σ) on any eccentricity-induced velocity offset during transit. The phase curve observations (including one of the transits) exhibit an anomalous trend similar to the detector ramp seen in previous Spitzer/IRAC observations; by modeling this ramp we recover the system parameters for this transit. The long-duration photometry which follows the ramp and transit exhibits a gradual ~0.2% decrease in flux over ~30 hr. This effect is similar to that seen in pre-launch calibration data taken with the 24 μm array and is better fit by an instrumental model than a model invoking planetary emission. The large uncertainties associated with this poorly understood, likely instrumental effect prevent us from usefully constraining the planet's thermal phase curve. Our observations highlight the need for a thorough understanding of detector-related instrumental effects on long timescales when making the high-precision mid-infrared measurements planned for future missions such as EChO, SPICA, and the James Webb Space Telescope
Prediction of flight measurements of high enthalpy nonequilibrium flow from a cubesat-class atmospheric probe
Spectral radiation is sensitive to many physical chemical aspects of high-enthalpy, non-equilibrium flows affect radiation and heat transfer estimates at low-earth altitudes, which is important as a flow diagnostic. For diatomic molecules, high energy collisions in the bow shock region result in ro-vibrionic transitions and release of photons in different wavelength bands. In this work, the Direct Simulations Monte Carlo (DSMC) method is used for the SASSI2 mission to determine the external flow field around a 3U CubeSat. The Nonequilibrium Radiative Transport and Spectra Program (NEQAIR) code is used to determine ultraviolet radiation from nitric oxide and the tangent slab approximation is used to estimate spacecraft visible glow radiance from nitrogen dioxide. Additional calculations are performed to provide a sensitivity analysis of radiance estimates based on the DSMC code utilized, chemical reaction rates, and CubeSat orientation
Spitzer Secondary Eclipses of the Dense, Modestly-irradiated, Giant Exoplanet HAT-P-20b Using Pixel-Level Decorrelation
HAT-P-20b is a giant exoplanet that orbits a metal-rich star. The planet
itself has a high total density, suggesting that it may also have a high
metallicity in its atmosphere. We analyze two eclipses of the planet in each of
the 3.6- and 4.5 micron bands of Warm Spitzer. These data exhibit intra-pixel
detector sensitivity fluctuations that were resistant to traditional
decorrelation methods. We have developed a simple, powerful, and radically
different method to correct the intra-pixel effect for Warm Spitzer data, which
we call pixel-level decorrelation (PLD). PLD corrects the intra-pixel effect
very effectively, but without explicitly using - or even measuring - the
fluctuations in the apparent position of the stellar image. We illustrate and
validate PLD using synthetic and real data, and comparing the results to
previous analyses. PLD can significantly reduce or eliminate red noise in
Spitzer secondary eclipse photometry, even for eclipses that have proven to be
intractable using other methods. Our successful PLD analysis of four HAT-P-20b
eclipses shows a best-fit blackbody temperature of 1134 +/-29K, indicating
inefficient longitudinal transfer of heat, but lacking evidence for strong
molecular absorption. We find sufficient evidence for variability in the 4.5
micron band that the eclipses should be monitored at that wavelength by
Spitzer, and this planet should be a high priority for JWST spectroscopy. All
four eclipses occur about 35 minutes after orbital phase 0.5, indicating a
slightly eccentric orbit. A joint fit of the eclipse and transit times with
extant RV data yields e(cos{omega}) = 0.01352 (+0.00054, -0.00057), and
establishes the small eccentricity of the orbit to high statistical confidence.
Given the existence of a bound stellar companion, HAT-P-20b is another
excellent candidate for orbital evolution via Kozai migration or other
three-body mechanism.Comment: version published in ApJ, minor text and figure revision
Constraints on the Atmospheric Circulation and Variability of the Eccentric Hot Jupiter XO-3b
We report secondary eclipse photometry of the hot Jupiter XO-3b in the
4.5~m band taken with the Infrared Array Camera (IRAC) on the Spitzer
Space Telescope. We measure individual eclipse depths and center of eclipse
times for a total of twelve secondary eclipses. We fit these data
simultaneously with two transits observed in the same band in order to obtain a
global best-fit secondary eclipse depth of and a center of
eclipse phase of . We assess the relative magnitude of
variations in the dayside brightness of the planet by measuring the size of the
residuals during ingress and egress from fitting the combined eclipse light
curve with a uniform disk model and place an upper limit of 0.05. The new
secondary eclipse observations extend the total baseline from one and a half
years to nearly three years, allowing us to place an upper limit on the
periastron precession rate of degrees/day the tightest
constraint to date on the periastron precession rate of a hot Jupiter. We use
the new transit observations to calculate improved estimates for the system
properties, including an updated orbital ephemeris. We also use the large
number of secondary eclipses to obtain the most stringent limits to date on the
orbit-to-orbit variability of an eccentric hot Jupiter and demonstrate the
consistency of multiple-epoch Spitzer observations.Comment: 14 pages, 11 figures, published by Ap
Spitzer IRAC Secondary Eclipse Photometry of the Transiting Extrasolar Planet HAT-P-1b
We report Spitzer/IRAC photometry of the transiting giant exoplanet HAT-P-1b
during its secondary eclipse. This planet lies near the postulated boundary
between the pM and pL-class of hot Jupiters, and is important as a test of
models for temperature inversions in hot Jupiter atmospheres. We derive eclipse
depths for HAT-P-1b, in units of the stellar flux, that are: 0.080% +/-
0.008%,[3.6um], 0.135% +/- 0.022%,[4.5um],0.203% +/- 0.031%,[5.8um], and
$0.238% +/- 0.040%,[8.0um]. These values are best fit using an atmosphere with
a modest temperature inversion, intermediate between the archetype inverted
atmosphere (HD209458b) and a model without an inversion. The observations also
suggest that this planet is radiating a large fraction of the available stellar
irradiance on its dayside, with little available for redistribution by
circulation. This planet has sometimes been speculated to be inflated by tidal
dissipation, based on its large radius in discovery observations, and on a
non-zero orbital eccentricity allowed by the radial velocity data. The timing
of the secondary eclipse is very sensitive to orbital eccentricity, and we find
that the central phase of the eclipse is 0.4999 +/- 0.0005. The difference
between the expected and observed phase indicates that the orbit is close to
circular, with a 3-sigma limit of |e cosw| < 0.002.Comment: 5 pages, 6 figures, 1 table. Accepted by The Astrophysical Journal,
10 Nov 200
Direct Measure of Radiative and Dynamical Properties of an Exoplanet Atmosphere
Two decades after the discovery of 51 Peg b, the formation processes and atmospheres of short-period gas giants remain poorly understood. Observations of eccentric systems provide key insights on those topics as they can illuminate how a planet's atmosphere responds to changes in incident flux. We report here the analysis of multi-day multi-channel photometry of the eccentric (e ~ 0.93) hot Jupiter HD 80606 b obtained with the Spitzer Space Telescope. The planet's extreme eccentricity combined with the long coverage and exquisite precision of new periastron-passage observations allow us to break the degeneracy between the radiative and dynamical timescales of HD 80606 b's atmosphere and constrain its global thermal response. Our analysis reveals that the atmospheric layers probed heat rapidly (~4 hr radiative timescale) from <500 to 1400 K as they absorb ~ 20% of the incoming stellar flux during the periastron passage, while the planet's rotation period is 93_(-35)^(+85) hr, which exceeds the predicted pseudo-synchronous period (40 hr)
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