Abstract
The hot Jupiter HD 189733b is probably the best studied of the known
extrasolar planets, with published transit and eclipse spectra covering
the near UV to mid-IR range. Recent work on the transmission spectrum
has shown clear evidence for the presence of clouds in its atmosphere,
which significantly increases the model atmosphere parameter space that
must be explored in order to fully characterize this planet. In this
work, we apply the NEMESIS atmospheric retrieval code to the recently
published HST/STIS reflection spectrum, and also to the dayside thermal
emission spectrum in light of new Spitzer/IRAC measurements, as well as
our own re-analysis of the HST/NICMOS data. We first use the STIS data
to place some constraints on the nature of clouds on HD 189733b and
explore solution degeneracy between different cloud properties and the
abundance of Na in the atmosphere; as already noted in previous work,
absorption due to Na plays a significant role in determining the shape
of the reflection spectrum. We then perform a new retrieval of the
temperature profile and abundances of H2O, CO2,
CO, and CH4 from the dayside thermal emission spectrum.
Finally, we investigate the effect of including cloud in the model on
this retrieval process. We find that the current quality of data does
not warrant the extra complexity introduced by including cloud in the
model; however, future data are likely to be of sufficient resolution
and signal-to-noise that a more complete model, including scattering
particles, will be required.
Original language | English |
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Number of pages | 12 |
Journal | The Astrophysical Journal |
Volume | 786 |
Issue number | 2 |
DOIs | |
Publication status | Published - 01 May 2014 |
Externally published | Yes |
Keywords
- methods: data analysis
- planets and satellites: atmospheres
- radiative transfer