Ian J. M. Crossfield, Brad M. S. Hansen, Travis Barman
We report the tentative detection of the near-infrared emission of the Hot
Jupiter WASP-12b with the low-resolution prism on IRTF/SpeX. We find a K-H
contrast color of 0.137% +/- 0.054%, corresponding to a blackbody of
temperature 2400 (+1500/-500) K and consistent with previous, photometric
observations. We also revisit WASP-12b's energy budget on the basis of
secondary eclipse observations: the dayside luminosity is a relatively poorly
constrained (2.0-4.3) x 10^30 erg/s, but this still allows us to predict a
day/night effective temperature contrast of 200-1,000 K (assuming A_B=0). Thus
we conclude that WASP-12b probably does not have both a low albedo and low
recirculation efficiency. Our results show the promise and pitfalls of using
single-slit spectrographs for characterization of extrasolar planet
atmospheres, and we suggest future observing techniques and instruments which
could lead to further progress. Limiting systematic effects include the use of
a too-narrow slit on one night -- which observers could avoid in the future --
and chromatic slit losses (resulting from the variable size of the seeing disk)
and variations in telluric transparency -- which observers cannot control.
Single-slit observations of the type we present remain the best option for
obtaining lambda > 1.7 micron spectra of transiting exoplanets in the brightest
systems. Further and more precise spectroscopy is needed to better understand
the atmospheric chemistry, structure, and energetics of this, and other,
intensely irradiated planet.
View original:
http://arxiv.org/abs/1201.1023
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