Transcript Document

Evolution of the universe:
From Astrophysics to Astrobiology
Julian Chela-Flores
Systems astrobiology
The Abdus Salam ICTP, Trieste, Italia
and
Instituto de Estudios Avanzados, Caracas,
Republica Bolivariana de Venezuela
for a reliable biomarker on exo-worlds
The Origins: how, when and where it all started,
Accademia Nazionale dei Lincei. Centro Linceo Interdisciplinare “Beniamino Segre”,
Roma, 22 May 2006
EGU
General Assembly
9 April 2013
EGU2013-1327-1
Julián Chela-Flores
The Abdus Salam ICTP, Trieste, Italia and
Instituto de Estudios Avanzados, Caracas,
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Bolivarian Republic of Venezuela
Life on exoworlds
The earth-like worlds (ELWs: planets and exomoons)
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Co-workers and
collaborations
Aranya B. BHATTACHERJEE
Department of Physics, ARSD College,
University of Delhi, New Delhi, India,
Moises SANTILLAN
Computational Systems Biology
Laboratory, Centro de Investigación y
Estudios Avanzados
del IPN, Unidad Monterrey, Mexico
Suman DUDEJA
Department of Chemistry, ARSD College,
University of Delhi, New Delhi, India.
UK Penetrator Consortium
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Census of Kepler mission planet candidates
(2013)
Credit: Kepler, NASA
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Orbital period
The habitability zone of red
dwarfs is indeed
closer to the star
M3V,
Constellation of
Libra
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Orbital period
1 year
less transits
contrast less favorable
10-25 days more transits, contrast
more favorable for the present
observations (Kepler),
as the habitability zone
is closer to the star
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or Their Habitable Exomoons
Credit: based on
Dressing& Charbonneau
HD 209458
Constellation Pegasus.
yellow dwarf, G0V
HD 209458 b
hot Jupiter/Na
atmosphere
To understand biogenic exoatmospheres we wait for the Kepler’s successors:
(a) Future missions,
(b) Present and future instrumentation, and
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(c) Additional instrumentation issues for ELWs that are exomoons
Future Missions
ESA’s
Exoplanet Characterisation
Observatory
NASA’s Fast INfrared Exoplanet
Spectroscopy Survey Explorer
(FINESSE)
NASA’s Transiting Exoplanet
Survey Satellite (TESS)
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Present and future instrumentation
High Accuracy Radial Velocity
Planet Searcher (HARPS, ESO, La
Silla)
The Giant Magellan Telescope,
with the G-CLEF Spectrometer
The 40-metre class E-ELT
James Webb Space Telescope
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Instrumentation issues for ELWs
when the venue for life is an
exomoon
Not incorporated
in the JUICE
payload
Biogeochemistry
is a useful science
Chela-Flores, 2010, Int. J. Astrobiol.
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Distribution of life in the universe
(
)
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The Great Oxidation Event (GOE)
in the habitability zone of our solar system
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Systems (astro)biology
 Systems biology is used in biomedical research, systems
are, for instance, cells and perturbations are drugs.
In our special case of systems astrobiology,
 Instead of systems of cells, we have systems of ELWs.
 Perturbations are not drugs perturbing cells, but rather
autochthonous biological perturbations of the primary
planetary atmosphere.
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Systems (astro)biology
 Models of systems of ELWs will be possible with responses to
biogenic perturbations that are under two constraints:
 1. The perturbation is due to communities of prokaryotic
photosynthetic aerobes, and anaerobes that are constrained to
remain microbial waiting for an evolving magnetic core that will
preserve planetary atmospheres and hydrospheres from stellar
wind erosion (Tarduno et al).
 2. The perturbation, while evolving, shifts the primary
atmosphere into anomalous oxygenic atmospheres after the
oxidation of the planetary surface is completed (Catling et al).
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An analytic model
Assumptions:
 We assume the universality of biology.
 In particular, we assume evolutionary convergence.
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An analytic model
Parameters:
 The current and starting abundance of biogenic gas (oxygen) and
non-biogenic gas (carbon-dioxide) in an ELW of the red dwarf.
 The luminosity of the red dwarf hosting an ELW and the luminosity
of the Sun.
The current time, and the time at which biogenic gas started
forming in substantial amount on Earth.
 A parameter taking into account photorespiration that will
generate some additional CO2. (In a process of photosynthesis, not
all the CO2 will be converted into O2.)
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An analytic model
Allows a prediction for:
 A GOE in an ELW orbiting a red dwarf.
 The abundance of the non-biogenic gas in an ELW orbiting
a red dwarf.
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ELWs orbiting a K star
(Fraction of non-biogenic gas)
Exoplanet of a
K star (40% L☉)
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ELWs orbiting an M dwarf
(Fraction of non-biogenic gas)
Fraction of biogenic gas
1.0
Earth
0.8
0.6
0.4
0.2
0.0
Exoplanet of red dwarf
(8% luminosity of our
sun)
0.0
0.5
1.0
1.5
Age of the exoplanet dimensionless units
2.0
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ELWs orbiting a K star
(Fraction of non-biogenic gas)
Exoplanet in the HZ of
a K star (40% L☉)
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ELWs orbiting a red dwarf
Fraction of nonbiogenic gas
(Fraction of non-biogenic gas)
1.0
0.8
0.6
Exoplanet in the
HZ of the red
dwarf
0.4
Earth
0.2
0.0
0.0
0.5
1.0
1.5
2.0
Age of the exoplanet dimensionless units
2.5
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Systems (astro)biology
 After the GOE event in an ELW in the HZ of a red dwarf,
further steps in evolution are possible:
 The microbial communities can evolve into eukaryotes that
are able to turn into complex life (multicellular).
 With sufficient time after the GOE has elapsed (> 2-3 Gyrs),
there will be strong selection advantage for the evolution of
intelligence.
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ELWs around red dwarfs are potential hosts
to organisms older than terrestrial ones
Credit: based on
Dressing& Charbonneau
This suggests resetting the origin of
time for the ELW at the big bang
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Setting the origin of time at the Big Bang for ELWs
older than Earth (orbiting around red dwarfs)
Exoplanet in the HZ of
a K star (40% L☉)
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Setting the origin of time at the Big Bang for ELWs
older than Earth (orbiting around red dwarfs)
Fraction of biogenic gas
1.0
Earth
0.8
0.6
0.4
Exoplanet in the HZ of
red dwarf
0.2
0.0
0
2
4
6
8
10
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Age as measured from the big bang Gyrs
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SKA
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Habitability could have preceded
terrestrial life
 Our so far tiny Kepler environment is less than 300 light years
across (estimated to be ≈ 0.003 of the whole celestial sphere).
 With SETI the cosmic environment accessible by 2020 should
be about three times the Kepler range, about 1000 light years.
 If the evolution of intelligent life is a possibility, ELWs in the HZ
of ancient red dwarfs become additional observable targets that
radio astronomers with their ever more sensitive instruments
have been following up for over half a century.
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Summary

Our attention is restricted to red dwarfs of which about 6% are expected to
have Earth-like planets (Dressing and Charbonneau, 2013).
 Oxygen and carbon dioxide are the only exo-bioindicators that we
considered at this stage.
 Our predictions are biology-dependent:
Universal biology (evolutionary convergence).

Testing the predictions for biogenic perturbations of ELWs is possible
with forthcoming new missions and with future Earth-bound
instrumentation, not excluding radio telescopes, such as the SKA.
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