2nd brazilian corot workshop - ubatuba, nov 6 2005 why being earth-centered when searching for life...
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2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
WHY BEING EARTH-CENTERED WHEN SEARCHING FOR LIFE IN THE COSMIC NEIGHBORHOOD?
1Divisão de Astrofísica, - INPE2Instituto de Biofísica Carlos Chagas Filho - UFRJ3Instituto Astronômico e Geofísico - IAG/USP4Instituto de Química - UFRJ5Observatório do Valongo - UFRJ
Carlos Alexandre Wuensche1
Claudia Lage2
Amâncio Friaça3
Sérgio Pilling4
Heloísa Boechat-Roberty5
Contato: [email protected]
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
A cosmological perspective to
search of life in the Universe...
Life building blocks come
from these components...
Ωb = 0.04 ΩT
LET´S GIVE IT UP, THEN...
Bennett et al., ApJ Suppl Series 2003
NOT!
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
How can we define life?
• It is quite a subjective concept, but we can list some common characteristics (J. Schneider, astro-ph/9604131, 1996; Szostak et al., Nature, 2001, Bains,
Astrobiology 2005)– Complex and diversified interactions with the
environment– System out of thermodynamical equilibrium– Memory + reading/recovering mechanism– Self-replication capability
Life is a self-sustained chemical system, capable of evolution in a Darwinian sense (Joyce 1994).
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
For a practical search, restrictive hipothesis...
• What kind of complex systems?– Liquid crystals, plasmas...
• Conservative hipothesis – a chemical system.– C, Si?
• Presence of a liquid millieu?– H2O: excelent solvant and abundant in the Universe
• Existence of a solid/liquid interface?– Favours molecular interactions...
Questions
1) Does life need, necessarily, such atoms and physical-chemical conditions?
2) Can life develop, in another planet, under totally different conditions?
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Most definitions tend to be EMost definitions tend to be EARTH-ARTH-CENTEREDCENTERED
So, let´s understand “Earth model”So, let´s understand “Earth model”
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
HABITABLE ZONE (68% e 95%)
Lineweaver et al., Science, 303, 59 (2004)
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
•[X/H]=log(X/H)-log(X/H)Sun.
•Components: halo, thick and
thin disks.•Universe age: 13 Gyr. •Solar age: 4.6 Gyr
Minimum abundance to form terrestrial
planets: [X/H]=-1.0 +/- 0.3.
(Lineweaver, Icarus, 151, 307, 2001)
Biologically interesting elements abundance in the Galaxy
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Stellar habitable zone
R
Main assumptions: Surface H2O for ~ Gyear, geological activity, CO2-H2O-N2 atmosphere, B-field, climate stability, resistance to catastrophes for ~ Gyear
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
In the early Earth:
Miller & Urey, 1961
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Saladino et al., Chem. Biochem, 2004
Images´ source: http://www.whfreeman.com/life/update/
Pre-cellular life... Where does it come from?• Nucleic acids required!
• But NO NUCLEIC ACIDS were found in Miller & Urey experiment.
• How could they be formed? Polymerisation of cyanide, which can be readily formed in a primitive atmosphere!
• So what? This still doesn't look much like a nucleic acid! However, the tetramer can be rearranged as follows:
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Pathways for biomolecule formation in space:the glycine case - Environment
1 Ori C
ORION M42
TRAPEZIUM - HST 2003
Young starsT ~ 30000K X-rays
Lx ~ 2 x1032 erg s-1 (Chandra)ne ~ 5000 neMI
Excitation of rotational-vibrational levels
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Pathways for biomolecule formation in space:the glycine case - Model
Tielens & Hollenbach (1985) ApJ 291, 747
Schulz etal 2001 ApJ, 549, 4441Schulz etal 2001 ApJ, 549, 4441
FUV ~ 10-100 erg cm-2 s-1 ngas ~ 104-105 cm-3 (107-103 cm-3)T ~ 50-200 K (10 - 1000 K)
PDRs Typical Features
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Measurements in spaceAcetic acid
Formic acid
NH2CH2COOH
++(-H(-H22O)O)
methanolamine
++
Methylenimine
Ammonia
++(-H(-H22))
Formic acid ice/gas ratio ~ Formic acid ice/gas ratio ~ 10000!10000!
Low resistence to radiation field?
Which pathway is more probable?
Formation via ice or gas phase? ++ (-H(-H22O; -H)O; -H)
Protonated
methanolamine
++(-H2O; -H)
Protonated
Hidroxilamine
Ehrenfreund et al 2001 JGR , 106, E12, 33291; Whittet et al 1996 Ehrenfreund et al 2001 JGR , 106, E12, 33291; Whittet et al 1996 A&A 315, L357A&A 315, L357
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Results from space
Liu etal 2002 Apj 576, 255
(~2 x 1015 cm2)
Remijan etal 2002 ApJ 576, 264
Kuan etal 2004 ASR, 33, 31
(~6x 1015 cm2)
Through acetic
acid
Through
formic acid
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Results from collisions at LNLS
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
H
C
N
Recent detection of a PANH in the IRHudgins et al. ApJ, 2005
• Spitzer detected PANHs in various galaxies, besides our own. • First direct evidence for the presence of a prebiotic interesting compound in
space.• Presence of N is essential in biologically interesting compounds (clorophyle).• The presence of a planet is no longer necessary for the formation of a PANH.
Caffeine
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Porto de Mello et al., Astrobiology, 2005
Astrobiologically interesting stars and planets
Explore the star/planet contrast in the thermal IR(Des Marais et al 2002, Segura et al 2003)
Thermal IRCO2 15 mO3 9.6 mH2O: 6.3 m + 12 m band to microwaves CH4 7.7 mWindow at 8-12 m: surface temperatureColor temperature + flux = radius (problems with clouds)
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Any alternatives at this point???
• Other liquids may define other biochemistries
• Ammonia (Jupiter satellites), methane/ethane
(Titan), nitrogen (silicon-oriented)
• Light (mostly IR) on the surface of Titan may
allow photosynthesis-like processes, even at
low temperatures.
• Chemolitotrophy possibly available in any
liquid environment (Galilean satellites).
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Water-based oceans
Other liquid
possibilities
OUR SOLAR SYSTEM´S LIQUID POSSIBILITIES
water/ammonia (surface lakes)
water/ammonia (subsurface)
methane/ethane
(surface lakes)
nitrogen (su
rface)
nitrogen (su
bsurface)
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
Criptoendoliths
Thermophile bacteria
Hidrotermal vents
Hot geisers and volcans
Extremophiles survival chart
Antarctica• Temperature: -15° C < T < 230° C• 0 < pH < 12• 0 < Pressure < 1200 atm• No mandatory oxygen-based metabolism• 20-40 Myears of dormancy• 2 ½ years in space, at 20 K, with no
nutrients, water and exposed to radiation
(Strep. Mitis)
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
What do we suggest?• Carbon based, DNA-like search, in planetary
systems
– Targeting small constituints of organic compounds – IR/X
(Pilling et al., A&A 2005)
– Targeting PANHs – IR (Hodges et al., ApJ 2005)
• Other alternatives (chemical/physical)
– Other liquids/fluids demand a different chemistry (not
CHON based) due to thermodynamical requirements
(Bains, Astrobiology 2005).
– Self-sustained ability to disturb a local environment
(Bains, Astrobiology 2005).
2nd Brazilian COROT Workshop - Ubatuba, Nov 6 2005
WHERE IS DNA OR ANY OF ITS RELATIVES?
The end…
… or the beginning?????