Montañés-Rodríguez, P.; López, R.; Gutiérrez-Navarro, A. M.; Kiang, N. Y.; Parenteau, M. N.; Pallé, E.; Sanromá, E.
Referencia bibliográfica
The Astrophysical Journal, Volume 780, Issue 1, article id. 52, 11 pp. (2014).
Fecha de publicación:
1
2014
Revista
Número de citas
18
Número de citas referidas
16
Descripción
Ongoing searches for exoplanetary systems have revealed a wealth of
planets with diverse physical properties. Planets even smaller than the
Earth have already been detected and the efforts of future missions are
aimed at the discovery, and perhaps characterization, of small rocky
exoplanets within the habitable zone of their stars. Clearly, what we
know about our planet will be our guideline for the characterization of
such planets. However, the Earth has been inhabited for at least 3.8 Gyr
and its appearance has changed with time. Here, we have studied the
Earth during the Archean eon, 3.0 Gyr ago. At that time, one of the more
widespread life forms on the planet was purple bacteria. These bacteria
are photosynthetic microorganisms and can inhabit both aquatic and
terrestrial environments. Here, we use a radiative transfer model to
simulate the visible and near-infrared radiation reflected by our
planet, taking into account several scenarios regarding the possible
distribution of purple bacteria over continents and oceans. We find that
purple bacteria have a reflectance spectrum that has a strong
reflectivity increase, similar to the red edge of leafy plants, although
shifted redward. This feature produces a detectable signal in the
disk-averaged spectra of our planet, depending on cloud amount and
purple bacteria concentration/distribution. We conclude that by using
multi-color photometric observations, it is possible to distinguish
between an Archean Earth in which purple bacteria inhabit vast
extensions of the planet and a present-day Earth with continents covered
by deserts, vegetation, or microbial mats.
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