Bibcode
Pallé, E.; Zapatero Osorio, M. R.; Miles-Páez, P. A.
Bibliographical reference
Astronomy and Astrophysics, Volume 562, id.L5, 4 pp.
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2
2014
Journal
Citations
20
Refereed citations
16
Description
Aims: We aim to extend our current observational understanding of
the integrated planet Earth spectropolarimetry from the optical to the
near-infrared wavelengths. Major biomarkers like O2 and water
vapor are strong flux absorbents in the Earth's atmosphere, and some
linear polarization of the reflected stellar light is expected to occur
at these wavelengths. Methods: Simultaneous optical (0.4-0.9
μm) and near-infrared (0.9-2.3 μm) linear spectropolarimetric data
of the earthshine were acquired by observing the nightside of the waxing
Moon. The data have sufficient spectral resolution (2.51 nm in the
optical, and 1.83 and 2.91 nm in the near-infrared) to resolve major
molecular species present in the Earth's atmosphere. Results: We
find the highest values of linear polarization (≥10%) at the bluest
wavelengths, which agrees with other studies. Linear polarization
intensity steadily decreases toward red wavelengths reaching a nearly
flat value beyond ~0.8 μm. In the near-infrared, we measured a
polarization degree of ~4.5 % for the continuum. We report the detection
of molecular features due to O2 at 0.760,1.25 μm, and
H2O at 0.653-0.725 μm, 0.780-0.825 μm, 0.93, and 1.12
μm in the spectropolarimetric data, and most of them show high linear
polarimetry degrees above the continuum. In particular, the broad
H2O 1.12 μm band displays a polarimetric intensity as high
as that of the blue optical. These features may become a powerful tool
for characterizing Earth-like planets in polarized light.
Reduced spectra (FITS Files) are only available at the CDS via anonymous
ftp to http://cdsarc.u-strasbg.fr
(ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/562/L5
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