1ASTR 1040 ASTR 1040 AccelAccelAstroAstro::Stars & GalaxiesStars & GalaxiesProf. Prof. JuriJuriToomreToomreTA: Nicholas NelsonTA: Nicholas NelsonLecture 30 Lecture 30 ThurThur28 Apr 201128 Apr 2011zeus.colorado.edu/astr1040zeus.colorado.edu/astr1040--toomretoomreAllenAllenTelescopeTelescopeArrayArrayUltimate EventsUltimate Events••Review current big Review current big outstanding questionsoutstanding questionsor or issues in astronomyissues in astronomy••Look briefly atLook briefly atPossibilities of Life ElsewherePossibilities of Life Elsewhere––and Extraand Extra--Solar PlanetsSolar Planets••Final Exam ReviewFinal Exam Reviewtonighttonightby Nick, here, 7by Nick, here, 7--9pm. 9pm. Final review sheetFinal review sheetavailable available ••Graded Graded Observing Projects BObserving Projects Breturnedreturned••Homework 12Homework 12returned + answers returned + answers ••Overview read Overview read Chap 24: Life beyond EarthChap 24: Life beyond EarthSmall temperature fluctuationsSmall temperature fluctuationsused to used to test models of universetest models of universeone degree scale in sky one degree scale in sky ----> > flat flat universe with early inflationuniverse with early inflationWMAPWMAPINFLATION needed to explain uniformity of CMBINFLATION needed to explain uniformity of CMB0.3 degree resolution0.3 degree resolutionREVIEWREVIEWCLOSEDCLOSEDCRITICALCRITICAL(FLAT)(FLAT)OPENOPENTIMETIMESIZESIZENOWNOWModels of universe Models of universe ––and its fatesand its fatesGalaxy clustering in ever deeper surveysGalaxy clustering in ever deeper surveysGalaxies are always moving:Galaxies are always moving:““Hubble flowHubble flow””+ respond to local clustering+ respond to local clusteringMilky Way at centerMilky Way at centeris moving toward is moving toward Virgo cluster, thenVirgo cluster, thenComa Coma superclustersupercluster600 M 600 M lylyacrossacross2The Big MysteriesThe Big Mysteries••What will be the fate of the universe ?What will be the fate of the universe ?••What is the universe made of ?What is the universe made of ?••What is the dark matter ?What is the dark matter ?••Is the theory of inflation correct ?Is the theory of inflation correct ?••What is the dark energy ?What is the dark energy ?••Which of this, if any, should we believe?Which of this, if any, should we believe?Science is not about belief, itScience is not about belief, it’’s about explorations about exploration……Discussion Clicker QDiscussion Clicker QIs ExtraIs Extra--Sensory Perception (ESP), or Sensory Perception (ESP), or telepathy, possible telepathy, possible ……or is it nutty?or is it nutty?A.A.Pretty unlikely (No)Pretty unlikely (No)B.B.Sure, I believe it (Yes)Sure, I believe it (Yes)C.C.Darned if I know (and why ask this in Darned if I know (and why ask this in astronomy)astronomy)D.D.How could such How could such ““communicationcommunication””be be carried out? (Interested)carried out? (Interested)E.E.I prefer to sleep, wake me when its overI prefer to sleep, wake me when its overLife in the Milky Way galaxyLife in the Milky Way galaxyA.A.life of any kind is present only on Earthlife of any kind is present only on EarthB. B. primitive life exists elsewhere (Mars, otherprimitive life exists elsewhere (Mars, otherplanetary systems), intelligent life isplanetary systems), intelligent life isunique to Earthunique to EarthC.C.intelligent life developed elsewhere,intelligent life developed elsewhere,but has since died outbut has since died outD.D.other civilizations exist, but are rareother civilizations exist, but are rareE.E.other civilizations are very commonother civilizations are very commonWhich do you think is most likely?Which do you think is most likely?What is What is LIFE ?LIFE ?Complex ,Complex ,complicated,complicated,delicate delicate Building blocksBuilding blocksfor life formsfor life formsHow doesHow doeslife life startstart??ThreeThreepropositionspropositionsStanley MillerStanley Miller3Life on EarthLife on Earth::4 ingredients4 ingredientsProteinsProteins::complex DNA RNAcomplex DNA RNAencodingencodingSimple life formSimple life form::nanobacteriananobacteriaThermal pools in Yellowstone host life, despite very Thermal pools in Yellowstone host life, despite very harsh conditions (high temperatures, acid water)harsh conditions (high temperatures, acid water)Life in many forms Life in many forms ……some surprisingsome surprisingZones of habitabilityZones of habitability::requirements forrequirements forcarboncarbon--based life based life (ecospheres) (ecospheres) Requirement for Requirement for liquid waterliquid waterdefines a defines a habitablehabitablezonezone: : range of distances from a star where the range of distances from a star where the surface temperature is between freezing and boilingsurface temperature is between freezing and boilingNot known observationallyNot known observationallyhow often a rocky planet how often a rocky planet occupies the habitable zoneoccupies the habitable zoneThought on theoretical Thought on theoretical grounds that habitable grounds that habitable planets should be commonplanets should be commonEcospheresEcospheresto nurture andto nurture andsustain lifesustain life(on planets)(on planets)4Varying zonesVarying zonesof of habitabiltyhabitabiltyaround starsaround starsAA--type starstype starsfavorable, butfavorable, butlifetime on MS ?lifetime on MS ?Our ECOSPHEREOur ECOSPHEREBut maybe life on Titan?But maybe life on Titan?How many stars host planetary systems?How many stars host planetary systems?Extremely hard to form Extremely hard to form imagesimagesof extraof extra--solar solar planets: faint, very close planets: faint, very close to bright host starto bright host starJupiter is ~10Jupiter is ~1099times times fainter than Sun as seen fainter than Sun as seen by distant observerby distant observerMost extraMost extra--solar planets detected by solar planets detected by radial velocity radial velocity methodmethod, many now by looking for transits (, many now by looking for transits (KeplerKepler))Searches by several teams show that ~10%Searches by several teams show that ~10%of stars similar to Sun host of stars similar to Sun host giant gas planetsgiant gas planetsSmallerSmallerextraextra--solar Earths solar Earths are not yet detectableare not yet detectableDebra FischerDebra FischerGeoffrey MarcyGeoffrey MarcyFirst 77