Bibcode
Yan, F.; Fosbury, R. A. E.; Petr-Gotzens, M. G.; Zhao, G.; Wang, W.; Wang, L.; Liu, Y.; Pallé, E.
Referencia bibliográfica
International Journal of Astrobiology, Volume 14, Issue 2, pp. 255-266
Fecha de publicación:
4
2015
Número de citas
28
Número de citas referidas
25
Descripción
With the rapid developments in the exoplanet field, more and more
terrestrial exoplanets are being detected. Characterizing their
atmospheres using transit observations will become a key datum in the
quest for detecting an Earth-like exoplanet. The atmospheric
transmission spectrum of our Earth will be an ideal template for
comparison with future exo-Earth candidates. By observing a lunar
eclipse, which offers a similar configuration to that of an exoplanet
transit, we have obtained a high-resolution and high signal-to-noise
ratio (SNR) transmission spectrum of the Earth's atmosphere. This
observation was performed with the High Resolution Spectrograph at
Xinglong Station, China during the total lunar eclipse in December 2011.
We compare the observed transmission spectrum with our atmospheric
model, and determine the characteristics of the various atmospheric
species in detail. In the transmission spectrum, O2,
O3, O2 . O2, NO2 and
H2O are detected, and their column densities are measured and
compared with the satellites data. The visible Chappuis band of ozone
produces the most prominent absorption feature, which suggests that
ozone is a promising molecule for the future exo-Earth characterization.
Due to the high resolution and high SNR of our spectrum, several novel
details of the Earth atmosphere's transmission spectrum are presented.
The individual O2 lines are resolved and O2
isotopes are clearly detected. Our new observations do not confirm the
absorption features of Ca II or Na I which have been reported in
previous lunar eclipse observations. However, features in these and some
other strong Fraunhofer line positions do occur in the observed
spectrum. We propose that these are due to a Raman-scattered component
in the forward-scattered sunlight appearing in the lunar umbral
spectrum. Water vapour absorption is found to be rather weak in our
spectrum because the atmosphere we probed is relatively dry, which
prompts us to discuss the detectability of water vapour in Earth-like
exoplanet atmospheres.
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Enric
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