J/ApJ/790/53 Photometric data of HD 209458b (Zellem+, 2014)
The 4.5 µm full-orbit phase curve of the hot Jupiter HD 209458b.
Zellem R.T., Lewis N.K., Knutson H.A., Griffith C.A., Showman A.P.,
Fortney J.J., Cowan N.B., Agol E., Burrows A., Charbonneau D., Deming D.,
Laughlin G., Langton J.
<Astrophys. J., 790, 53 (2014)>
=2014ApJ...790...53Z 2014ApJ...790...53Z (SIMBAD/NED BibCode)
ADC_Keywords: Photometry ; Stars, double and multiple ; Planets
Keywords: atmospheric effects - methods: numerical -
planets and satellites: general -
planets and satellites: individual: HD 209458b -
techniques: photometric
Abstract:
The hot Jupiter HD 209458b is particularly amenable to detailed study
as it is among the brightest transiting exoplanet systems currently
known (V-mag = 7.65; K-mag = 6.308) and has a large planet-to-star
contrast ratio. HD 209458b is predicted to be in synchronous rotation
about its host star with a hot spot that is shifted eastward of the
substellar point by superrotating equatorial winds. Here we present
the first full-orbit observations of HD 209458b, in which its 4.5
µm emission was recorded with Spitzer/IRAC. Our study revises the
previous 4.5 µm measurement of HD 209458b's secondary eclipse
emission downward by ∼35% to 0.1391%-0.0069%+0.0072%, changing our
interpretation of the properties of its dayside atmosphere. We find
that the hot spot on the planet's dayside is shifted eastward of the
substellar point by 40.°9±6.°0, in agreement with
circulation models predicting equatorial superrotation. HD 209458b's
dayside (Tbright= 1499±15 K) and nightside (Tbright= 972±44 K)
emission indicate a day-to-night brightness temperature contrast
smaller than that observed for more highly irradiated exoplanets,
suggesting that the day-to-night temperature contrast may be partially
a function of the incident stellar radiation. The observed phase curve
shape deviates modestly from global circulation model predictions
potentially due to disequilibrium chemistry or deficiencies in the
current hot CH4 line lists used in these models. Observations of the
phase curve at additional wavelengths are needed in order to determine
the possible presence and spatial extent of a dayside temperature
inversion, as well as to improve our overall understanding of this
planet's atmospheric circulation.
Description:
The observations were taken between 2010 January 17 20:55:24.4 UT and
2010 January 21 21:28:42.0 UT, resulting in 96.55 hr of data. They
begin shortly before secondary eclipse, continue through primary
transit, and end shortly after secondary eclipse. To minimize readout
time and thereby maximize image cadence, the subarray mode was used in
which 32 x 32 pixel images were stored as sets of 64 in a single FITS
datacube with a single image header. By assuming uniform spacing in
time, the mid-exposure time for each image is calculated from the
header keywords MBJD_OBS (start of the first image in each cube),
AINTBEG (integration begin), and ATIMEEND (integration end).
Effectively, the image spacing is 0.4 s. We report our timing
measurements using BJD_UTC. For this analysis, the orbital period
(P = 3.5247455 days) and eccentricity (e = 0) are fixed.
Objects:
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RA (ICRS) DE Designation(s)
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22 03 10.8 +18 53 04 HD 209458b = NAME Osiris
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 96 754282 Photometric data
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See also:
J/A+A/508/1509 : Sky maps for hot Jupiters (Heller+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 20 F20.16 d BJD Barycentric Julian Date (UTC) - BJD-2455000
22- 39 F18.16 --- RFlux Raw, filtered relative flux
41- 58 F18.16 --- e_RFlux Uncertainty in RFlux
60- 77 F18.16 --- FFlux Final, corrected relative flux
79- 96 F18.16 --- e_FFlux Uncertainty in FFlux
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History:
From electronic version of the journal
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 17-Mar-2017