TY - JOUR
T1 - Storms or Systematics? The changing secondary eclipse depth of WASP-12b
AU - Hooton, Matthew J.
AU - de Mooij, Ernst J. W.
AU - Watson, Christopher A.
AU - Gibson, Neale P.
AU - Galindo-Guil, Francisco J.
AU - Clavero, Rosa
AU - Merritt, Stephanie R.
PY - 2019/4/5
Y1 - 2019/4/5
N2 - WASP-12b is one of the most well-studied transiting exoplanets, as its
highly-inflated radius and its 1.1 day orbit around a G0-type star make
it an excellent target for atmospheric categorisation through
observation during its secondary eclipse. We present two new secondary
eclipse observations of WASP-12b, acquired a year apart with the Wide
Field Camera on the Isaac Newton Telescope (INT) and the IO:O instrument
on the Liverpool Telescope (LT). These observations were conducted in
the $i^\prime$-band, a window expected to be dominated by TiO features
if present in appreciable quantities in the upper atmosphere. We
measured eclipse depths that disagree with each other by $\sim$3$\sigma$
(0.97 $\pm$ 0.14 mmag on the INT and 0.44 $\pm$ 0.21 mmag on the LT), a
result that is mirrored in previous $z^\prime$-band secondary eclipse
measurements for WASP-12b. We explore explanations for these
disagreements, including systematic errors and variable thermal emission
in the dayside atmosphere of WASP-12b caused by temperature changes of a
few hundred Kelvin: a possibility we cannot rule out from our analysis.
Full-phase curves observed with TESS and CHEOPS have the potential to
detect similar atmospheric variability for WASP-12b and other optimal
targets, and a strategic, multi-telescope approach to future
ground-based secondary eclipse observations is required to discriminate
between explanations involving storms and systematics.
AB - WASP-12b is one of the most well-studied transiting exoplanets, as its
highly-inflated radius and its 1.1 day orbit around a G0-type star make
it an excellent target for atmospheric categorisation through
observation during its secondary eclipse. We present two new secondary
eclipse observations of WASP-12b, acquired a year apart with the Wide
Field Camera on the Isaac Newton Telescope (INT) and the IO:O instrument
on the Liverpool Telescope (LT). These observations were conducted in
the $i^\prime$-band, a window expected to be dominated by TiO features
if present in appreciable quantities in the upper atmosphere. We
measured eclipse depths that disagree with each other by $\sim$3$\sigma$
(0.97 $\pm$ 0.14 mmag on the INT and 0.44 $\pm$ 0.21 mmag on the LT), a
result that is mirrored in previous $z^\prime$-band secondary eclipse
measurements for WASP-12b. We explore explanations for these
disagreements, including systematic errors and variable thermal emission
in the dayside atmosphere of WASP-12b caused by temperature changes of a
few hundred Kelvin: a possibility we cannot rule out from our analysis.
Full-phase curves observed with TESS and CHEOPS have the potential to
detect similar atmospheric variability for WASP-12b and other optimal
targets, and a strategic, multi-telescope approach to future
ground-based secondary eclipse observations is required to discriminate
between explanations involving storms and systematics.
KW - Astrophysics - Earth and Planetary Astrophysics
U2 - 10.1093/mnras/stz966
DO - 10.1093/mnras/stz966
M3 - Article
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
ER -