Transcript Document

Evolution of the universe:
FROM Astrophysics
CHEMICAL EVOLUTION
ON EARTH TO
From
to Astrobiology
INSTRUMENTATION ISSUES FOR TESTING
The
Abdus Salam ICTP,
Trieste, Italia
SYSTEMS
ASTROBIOLOGY
ON EXO-WORLDS
Julian Chela-Flores
and
Instituto de Estudios Avanzados, Caracas,
Republica Bolivariana de Venezuela
International Workshop on
The Origins: how, when and where it allChemical
started, Evolution and Origin of Life.
ITT Roorkee, 21 – 23 March 2013.
Accademia Nazionale dei Lincei. Centro Linceo Interdisciplinare “Beniamino Segre”,
Roma, 22 May 2006
A. B. Bhattacherjee 1, J. Chela-Flores 2 and S. Dudeja 3
1. Department of Physics, ARSD College, University of Delhi, New Delhi, India
2. ICTP, Trieste and IDEA, Caracas, Bolivarian Republic of Venezuela
3. Department of Chemistry, ARSD College, University of Delhi, New Delhi, India
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Life on exoworlds
The Earth-like worlds (ELWs: planets and exomoons)
2
Relative sizes of dwarf stars
MV3:
Gliese 581
GV5:
Kepler 22
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Red dwarfs
Planets within their HZ
Stellar class
Luminosity (f)
l/l0
Examples
M0Ve
7.2%
Lacaille 8760
An exoplanet
in a red dwarf HZ
—
M1V
3.5 %
Groombridge 34
—
M2V
2.3%
Lalande 21185
—
M3V
1.5%
Gliese 581
Gliese 581 c (5ME)
V: luminosity class of a mainsequence star
e: with emission line present
Gliese 581 d (6ME)
M4V
0.55%
V374 Pegasi
—
M5.5Ve
0.22%
Proxima Centauri
—
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Orbital period
The habitability zone of red
dwarfs is indeed
closer to the star
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Kepler-22b:
An ELW (a planet) around a yellow dwarf
G5V
G2V
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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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Preliminary parameters of ELWs
Kepler:
ELW
from
Transits
from the
Keplertransits
Mission
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or their Habitable Exomoons
(or exomoon)
Probing exoatmospheres will be possible with the Kepler successors:
(a) future missions and
(b) future instrumentation
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Future Missions:
ESA’s Exoplanet Characterisation
Observatory (EChO)
NASA’s Fast INfrared Exoplanet Spectroscopy
Survey Explorer (FINESSE)
NASA’s Transiting Exoplanet
Survey Satellite (TESS)
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Future instrumentation
James Webb Space Telescope
The Giant Magellan Telescope
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Distribution of life in the universe
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Systems (astro)biology
 Systems biology is used in biomedical research, but in our
case of systems of ELWs, we single out perturbations to
exoatmospheres, due to autochthonous biological
processes producing anomalous abundances of oxygen.
 With sufficient data from Kepler successors models of
systems (astro)biology will describe the structure of the
systems (ELWs) and their response to perturbations.
 The expected perturbations would be due to biologic
communities that shift the primary non-biogenic mixture of
CO2, N, a small fraction of O2, water into oxygenic
atmospheres.
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The Great Oxidation Event (GOE)
in the habitability zone of the solar system
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An analytic model
Assumptions:
 We assume the universality of biology.
 In particular, we assume evolutionary convergence.
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The 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 ELW, the luminosity of the Sun, t the
current time, and t0 is the time at which biogenic gas started
forming in substantial amount on Earth.
 In the expression for CO2 we have an additional parameter
taking into account that not all of it will be converted into O2
(other processes such as photorespiration will generate some
additional CO2).
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The 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.
 It suggests resetting the origin of time at the big bang.
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Preliminary results
ELWs orbiting a red dwarf
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Fraction of non-biogenic gas
ELWs orbiting a red dwarf
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Worlds around red dwarfs
Much older than the Earth?
Credit:
Dressing& Charbonneau
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Setting the time origin
Stars
Stellar
classification
Estimated mainsequence
lifetimes (Gyrs)
Presence of exoplanets
The Sun
G2
10
Earth (in HZ)
Kepler 22
G5
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Kepler 22b (super-Earth in HZ)
93 Her
K0
18.4
No
Upsilon Boötis
K5.5
45.7
No
VB 10,
van Biesbroeck
1944
M8V
104
VB 10b
(not in HZ,
a cold Jupiter)
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An exoplanet older than Earth
Orbits around red dwarfs
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Habitability could have preceded
terrestrial life
 Our own tiny Kepler environment
is less than 300 light years.
 With SETI the cosmic
environment accessible by 2020
should be about three times the
Kepler range, about 1000 light
years.
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Additional instrumentation issues
(further insights from the neighbouring moons)
Not incorporated
in the JUICE
payload
JUICE
Chela-Flores, 2010, Int. J. Astrobiol.
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Summary
 Most stars are red dwarfs and some host Earth-like
planets.
 Oxygen and carbon dioxide are the exo-bioindicators
considered in this work.
 Model predictions for exo-atmospheres have assumed:
Universal biology (evolutionary convergence)
 Testing the predictions for the exoatmospheres of
ELWs is possible with forthcoming new missions and
with future Earth-bound instrumentation.
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