Apresentação em tema: "Habitabilidade. Eixos de pesquisa astrobiológica História da complexidade cósmica Universo molecular Habitabilidade Sistema Solar Exoplanetas Extremófilos."— Transcrição da apresentação:
Eixos de pesquisa astrobiológica História da complexidade cósmica Universo molecular Habitabilidade Sistema Solar Exoplanetas Extremófilos Origens da vida Bioassinaturas Evolução das biosferas Ação humana na Terra e além
Habitability Homes for Life Conditions for the rising of life (conditions for the development of complexity – complex chemistry, long time spans, critical prebiotic mass) Conditions for the life to survive (against catastrophes of geological or astronomical origin)
Three Levels of Habitability Biophilic Cosmos Galactic Habitable Zone Stellar Habitable Zone
On the most basic level The Goldilocks zone in planetary systems The Stellar Habitable Zone
A Biophilic Universe Martin Rees Our Cosmic Habitat A universe hospitable to life – what we may call a biophilic universe – has to be very special in many ways. The prerequisites for any life – long-lived stars, a period table of elements with complex chemistry, and so on – are sensitive to physical laws and could not have emerged from a Big Bang with a recipe that was even slightly different.
APENAS SEIS NÚMEROS N = 10 36, a razão da força eletromagnética para a força gravitacional entre dois prótons. = 0.007, medida da intensidade da energia de ligação entre os neutrons e prótons dentro do núcleo atômico. = 0.3, quantidade de matéria no Universo = 0.7, quantidade de energia em vácuo no Universo Q = 1/100 000, medida da profundidade média das flutuações de densidade do Universo D = 3, número de dimensões do espaço
Qual a Origem dos Elementos Quimicos? Nucleossíntese primordial é insuficiente Não ultrapassa o numero de massa 8 Produz apenas Hélio, Deutério e Lítio Do Carbono em diante, e necessaria a nucleossíntese estelar! O nascimento das estrelas é essencial para o surgimento do C e da química necessária à vida!!!
Supernovas Morte Violenta! Mais de um tipo: –Ia: sistemas binários –II: estrelas de alta massa SNII: queima nuclear até Fe Colapso gravitacional Núcleo estrela de neutrons Camadas exteriores supernova O, elementos, C, (Fe), (N) Tempos: Manos (ou anos para as hipernovas primevas) SN1987A (David Malin and the Anglo Australian Observatory)
Nebulosas Planetárias O Sol vai morrer assim! Estrelas com massas menores que 8 vezes a massa do Sol Núcleo anã branca Camadas exteriores nebulosa planetária C, N Tempos: até varios Ganos Promovem as condições pré-bióticas.
Connecting Galaxy Formation to Biophilic Environments The galaxies are natural blocks (cells) from which the Universe is composed The stars occur in galaxies, and they are the responsible for the chemical evolution The galaxies have optimal levels of chemical abundances and radiation fields needed for the rise of the life The early evolution of galaxies are characterized by starbursts, in which dust and molecules are formed, leading to complex chemistry. The first, massive stars, harbored in protogalaxies, synthetize mainly CNO, thus organic chemistry is present in a Universe as young as z=30 at least
Galaxies and Habitability Intensive view Galaxies as laboratories of complex chemistry
Example: dusty early spheroids (elliptical galaxies and bulges of spirals) complex chemistry as revealed by PAH lines Spheroids in formation resemble dusty starburts Large amounts of dust produced in 0.1-0.3 Gyr Reprocessing of UV starlight into local FIR Rest-frame FIR redshifted to submm/mm Lines of PAHs (rest-frame MIR) –Features at 3.3, 6.2, 7,7, 8.6 and 11.3 m due to C-H and C-C bounds –Intensity of the features sets ages for the starburst in the 0.03-1 Gyr range
H C N Recent detection of a PANH in the IR Hudgins 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
Galaxies and Habitability Extensive view Galactic Habitable Zone
Defined by P GHZ proportional to the star formation rate conditions for forming rock planets typical long evolutive biological times survival to violent galactic events (e.g. SNe)
HABITABLE ZONE (68% e 95%) Lineweaver et al., Science, 303, 59 (2004)
Probability of Forming Rock Planets Probability of destroying Earths (parameter Z DE ) Probability of producing Earths (parameter Z PE ) Probability of harboring Earths (P HE =P metals ) Highly Sensitive to the Metallicity* Z *Metals= for astrophysics every element heavier than He Defined by P metals
Probability of Evolution over Biological Timescales Defined by P evol Darwins Theory requires long timescales P evol depends on t evol For Earth t evol = 4 Gyr t evol could be shorter than 4 Gyr?
Probability of Survival to Galactic Violent Events Defined by P SN Normalization to Earth? P evol depends on past evens through t SN For Earth, t SN = t evol = 4 Gyr Again, t SN could be shorter than 4 Gyr Other Killers: GRBs, GMCs, AGNi
How frequent are biophilic environments in galaxies? Estimating through P GHZ comparing several galaxy types Spirals (disks) and Ellipticals (spheroids) Evaluated at several radii. Influence of AGNi ?
Spheroid (Elliptical Galaxy) The Chemodynamical Model Multi-zone chemical evolution solver + hydrodynamical code Chemodynamical approach chemical evolution of the gas + dynamical state of the gas (inflow/outflow) star formation history even after galactic winds spatial variations in age and metallicity Bright Ellipical Galaxy 2 10 11 M sun
Perspectives for Life in an Extragalactic Setting Disks seem to be biophilic environments In spheroids, conditions are too harsh or too barren In elliptical galaxies, the central regions could be biophilic Care should be taken against to be too earth- centered The inner regions of the Galaxy (between the solar radius and 2 kpc) are biophilic
Reasons for habitability on Earth 1)Liquid water allowed microbes to originate and evolve 2)Moon prevents against chaos in Earth´s rotation axis 3)Plate tectonics replenishes CO 2 for life to persist 4)A magnetic field protects from solar wind 5) Evolution of the Atmosphere Microbes made O 2, CH 4 CH 4 then O 2 dominated Ozone layer formed at ~ 2.3 Gy Simple algae, fungi developed More O 2 and animals at 0.6 Gy Modern humans at 2 My (1/3 of the O 2 goes to the brain) Mankind returns CO 2 and increases the greenhouse effect