Sun - Astronomia - USP

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Sun - Astronomia - USP

Outline• Metallicity – giant planet connection• Lithium: is there a link to planets ?• Signatures of terrestrial planets• Signatures of giant planets• Solar twin planet survey with HARPS at ESOSunset in Paracas, Peru(c) www.flickr.com/photos/rodrigocampos/


Metallicity – giant planet connection


Metallicity – giant planet connectionComparisonsampleStars withgiant planets


Lithium: is there a planet connection?ʘIs the Sunpeculiar in Li?Sun vs. Stars withPlanets (SWP) andwithout PlanetsGonzalez et al (2010):Sun has a Liabundance 0.7 dexlower than 50comparison stars


Lithium: is there a planet connection?Open cluster with solar age (~ 4 Gyr) andslightly higher [Fe/H] = +0.03Solar twins in M67(Pasquini et al. 2008)Randich et al. 2006, Pace et al. 2008)Sun seemsnormal in Liwith respect tosolar twins inM67.


Using solar twins to learn more on thesolar Li abundance and Li-depletionHigh resolution(R=65,000) high S/N(200-450) spectraMcDonald 2.7mMagellan 6.5m- Meléndez et al. 2010, Ap&SS, 328, 193- Baumann, Ramirez, Melendez, Asplund& Lind 2010, A&A, 519, A87


Lithium insolartwins(Meléndez et al. 2010Ap&SS 328, 193)The solar Liis “normal” fora 1-solarmassof solarmetallicity at4.6 GyrYonsei-Yale isochrones


Solartwins inComa BenericesopenHyadesNGC762clusterand fieldstarsM67The solar Li isnormal for a1-solar-massstar at 4.6 Gyr(Meléndez et al. 2010 Ap&SS 328, 193)


Nonstandardsolarmodelsroughly fitdata(Meléndez et al. 2010 Ap&SS 328, 193)Montalban &Schatzmann:mixing by internal wavesXiong & Deng:Convective overshooting+ gravitational settlingDo Nascimento et al:Difussion + grav settling +rotation-induced mixing


Conclusion: the Sun hasa normal Li abundance(for a solar-metallicity solarageone-solar-mass star)What about lithium instars with giant planets ?


Planet hostsComparisonPlanet-hoststars aroundsolar T eff seemdepleted in Li


You cannot compare apples and oranges ...comparer des pommes avec des orangescomparer des pommes et des poirescomparar peras con manzanasYou cannot add pears and apples …No puedes sumar peras con manzanas


LuminosityComparingapples &apples


Li depletion is not enhanced in planet hosts !Comparing apples & apples(only stars with similar stellarparameters within 2-sigma)Planet hostsComparisonBaumann,Ramírez,Meléndez, &Asplund 2010,A&A, 519, A87


Li depletion is not enhanced in planet hosts !Apples &orangesIsraelian et al.2009, NaturePlanet hostsComparisonApples &applesBaumann,Ramírez,Meléndez, &Asplund 2010,A&A, 519, A87


The Sun has a normal Li abundance, butwhat about other chemical elements ?Are the solar abundances typical ofother Suns ?


Magellan ultra highprecision study ofsolar twins- Magellan 6.5m Clay Telescope& Mike spectrometer- R = 65,000- S/N = 450 per pixel- coverage 340 – 1000 nm- Solar spectrum: Vesta- 3 nights of observationsObservations of the solar twin 18 ScoBLUE frameRED frame


Example ofMagellanspectra(total spectralcoverage3400 A -1um)Small part(597-603nm)of solar twin &Sun’s spectraMeléndez et al. 2009, ApJ, 704, L66


Δ abundance:Sun - vs. atomicnumber ZSun typical :Δ = 0Sun weird :Δ ≠ 0Our solarsystem is nothost by atypical ‘Sun’Meléndez et al. 200


Sun’sanomalies arestronglycorrelated todustcondensationtemperature ofthe elements!Correlation ishighly significantprobability ~10 -9 tohappen by chanceIt’s most likely to winthe lottery~ 0.08 dex ~ 20%Dust condensation temperature (K)Meléndez et al. 20


CondensationCondensation in the solar nebulaMercuryVenus


Meléndez et al. 2009The missingrefractories wereused to form dust,planetesimals &terrestrial planetsThe late accretedgas in theconvection zonewas deficient inrefractories


Relation with terrestrialplanet formation:T cond trend in meteoritesAlexanderet al. (2001)The abundancepattern seen inmeteorites is amirror-image of theSun’s chemicalcomposition


Relation with terrestrial planet formation:Amount of dust removed from the Sun isenough to form terrestrial planetsHow much dust-cleansed gas is required to affectthe Sun in this way?Assume gas accretion untilsolar convection zone reached~ present size (~0.02 M sun ):Refractories depleted in theSun: ~2*10 28 g ≈ 4 M Refractories locked-up interrestrial planets:~8*10 27 g ≈ 1.3 M


Earth-likematerialSUN


SUNMeteorite-like material


SUNEarth-likematerialMeteorite-like material


Are there other solutions besides rocky planets?Could it be a problem in the abundance analysis ?Is the effect confirmed by other samples ?Can you really get this unprecedented precision ?Any problems with the asteroids used ?Could it be just pollution by a supernova or AGB ?Perhaps it is just galactic chemical evolution ?What about random line-of-sight effects ?Could it be an age effect?No matter what, I don’t believe it


Results are almost independent ofadopted model atmospheresAs the stars aresolar twins, theresults do notdepend muchon the adoptedmodels.Effect of usingdifferent sets ofmodels is only~0,001 dexMeléndez et al. 2012, A&A, 543, A29


Yes, the abundance trend is realThe abundancesignature is alsoseen in othersamples andusing differentinstruments anddifferent asteroidsOur Sun isindeedanomalous inits chemicalmakeupMeléndez et al. 2012, A&A, 543, A29


High precision (0,005 dex) is possible !Analysis of solarspectra using twodifferent asteroidsshows that it ispossible to achievea precision ofabout 0,005 dex !Meléndez et al. 2012, A&A, 543, A29


Asteroids are suitable for high precisionhigh resolution spectroscopyComparison of asteroids ofdifferent spectral types showsno meaningful trend withcondensation temperatureJunoCeresChapman, Morrison & Zellner (1975)Meléndez et al. 2012, A&A, 543, A29


There is no line-of-sight (inclination) effectThere are no changes inthe abundances obtainedat different latitudes in theSun for both volatile (towithin 0.005 dex) andrefractory (to within 0.002dex) elements.


Pollution by AGB stars,supernova type II,supernova type Ia, orhypernova, are notresponsible for theabundance signatureMeléndez et al. 2012, A&A, 543, A29


Also, the abundance signature cannotbe explained by age by galactic chemicalevolution effectsThe most likely explanation for theabundance signature seems to bethe formation of terrestrial planets


HIP 56948 : the mostlikely candidate forScienceNews, 30/8/2012, Star'smissing elements could signal lurkingsmall planets: solar chemistrysuggests best places to hunt.hosting other Earths ? Meléndez et al. 2012Rádio USP - Revista FAPESP,6/7/2012, Um outro Sol.Revista FAPESP, 6/2012, Umsegundo sol.Veja, 4/5/2012, Astrônomo da USPrevela estrela 'gêmea' do Sol.Object: the star HIP 56948Size: same as the SunTemperature: same as the SunComposition: same as the SunPlanets: same as the Sun?Meléndez et al. 2012, A&A, 543, A29Discovery News, 26/4/2012, Sun'stwin discovered ? the perfect setitarget ?New Scientist, 20/4/2012, Astrophile:an alien sunrise just like Earth's.


HIP 56948:best solartwinComparisonof HIP56948(red circles)and the Sun(solid line)HIRES spectraR ~ 95,000, S/N=600Meléndez et al. 2012, A&A, 543, A29


HIP 56948 isvery similarto the Sun inphysicalparametersand chemicalabundancesMeléndez et al. 2012, A&A, 543, A29


Abundancepattern of HIP56948 iscompatiblewith 1,5 Earthmasses ofEarth-likematerial(using Earth’scomposition fromChambers 2010)Meléndez et al. 2012, A&A, 543, A29


Planet search for HIP 56948No giant planets inthe terrestrial planetregion aroundHIP 56948 !Looks promising forhosting Earth-likeplanets in thehabitable zoneMeléndez et al. 2012, A&A, 543, A29


What about the effect of giant planet formation?16 Cyg: pair of solar analogs16 Cyg A : no planets16 Cyg B : giant planet


16 Cyg B (planet-host) is 0,04 dex more metal-poorin all elements (photospheric abundances)!Was the missing material used toform the giant planet around thesolar analog 16 Cyg B ?


Large Programme: 88 nights at La Silla3.6m telescope + HARPS spectrographBrasil no ESO: primeiros resultados3af, 14:30 (Salão Pentágono)Planets around solar twinsPI: Jorge Meléndez (IAG/USP)Collaborators:T. Monroe (IAG/USP)Australia: Alan Alves Brito,M. Asplund, L. CasagrandeUSA: I. Ramírez, J. BeanGermany: P. Baumann, S. Dreizler, K. Lind© Ana M. Molina at La Silla


Our Large Programme explores the planet – starconnection using precise chemical abundances (0,01dex) and precise radial velocities (1m/s) obtainedwith HARPS @ 3,6m telescope.88 nights from Oct 2011 – Oct 2015


© Jorge Meléndez at La SillaLarge Programme: 88 nights at La Silla3.6m telescope + HARPS spectrographCurrent Status- Whole sample observed with VLT and Magellanfor high precision (0,01 dex) abundance analysis- About 70 solar twins being observed for planetsusing HARPS at 1m/s precision- Visitor observing runs in Oct 2011, Feb 2012,April 2012, August 2012, January 2013, …, 2015


First results from our HARPS planet searcharound solar twins: Jupiter candidate


Pesquisa sobre procura de planetas com oHARPS é destaque na mídia nacionalHelpmostwelcomeO estudo se viabilizou graças ao acessorecém-obtido pelo Brasil às instalaçõesdo ESO (Observatório Europeu do Sul).O governo assinou no fim do anopassado o acordo que torna o país omais novo membro do consórcio.Embora o acerto ainda careça deaprovação do Congresso para entrarem vigor, o ESO já trata o Brasil comoparceiro, concedendo o direito desolicitar tempo de observação nostelescópios da organização.Foi por conta disso que a equipe deJorge Meléndez, peruano que trabalhano IAG (Instituto de Astronomia,Geofísica e Ciências Atmosféricas) daUSP, conseguiu aprovação num projetoque pode finalmente revelar algunsdos segredos mais bem guardadossobre os exoplanetas.


Pesquisa sobre procura de planetas com oHARPS é destaque na mídia internacionalMelendez and his colleagues arecurrently looking for smallplanets around roughly 75 solartwins, using the super-sensitiveHARPS instrument at the La SillaObservatory in Chile.


Treinamento de estudantes dadisciplina de AstrofísicaObservacional no ESO (La Silla)Palestra da Andressa Ferreira3af, 16:45 (Salão Turquesa)


Conclusions• Metallicity is related to frequency of giant planets• Lithium is not related to planets• Trend with condensation temperature may be relatedto the formation of terrestrial planets• Abundances at the 0,01 dex level can give us importantinformation on planets• Ongoing solar twin planet survey at ESO should allowbetter studies of the planet-stellar chemicalcomposition connection

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