Constrainingtheaccretionregionsofmeteoritesviaastrochemicalmodellingofprotoplanetarydisks

JonRamsey,SørenFrimann,ElishevahvanKooten,TommasoGrassi

SusanneWampfler,JesK.Jørgensen,MartinBizzarroCentreforStarandPlanetFormation,

NaturalHistoryMuseumofDenmarkandtheNielsBohrInsitute,

UniversityofCopenhagen

November9,2017

TheBeginning

Thisprojectspringsfrom"AdivergentheritageforcomplexorganicsinIsheyevolithicclasts"synergy

project(vanKootenetal.,2017,GCA,205,119).

IsheyevoisaCH/CBcarbonaceouschondritewithtwonoticeably

differentlithologiesbutacontinuoustransitionbetweenthetwo.

Itcontainspristinelithicclaststhatcanbecategorisedaseitherhydrated(H)or

weaklyhydrated(A).

TheA-clastsare -enriched( )relativetotheH-

clasts( ).

Thereare hotspotsreaching .

fortheA-clastsand

fortheH-clasts.

15N 15N/N = 0.004 − 0.00615N/N = 0.0039 − 0.0043

15N/N ∼ 0.022

D/H = (1.1 − 1.3) × 10−4 D/H = (1.2 − 1.6) × 10−4

Imagecredit:D.Weir'smeteoritestudies.com

Imagecredit:ElishevahvanKooten

IsotopicTrendsinIsheyevo

vanKootenetal.(2017)

increasinghydration←−−−−−−−−

A-clasts:orange;H-clasts:blue.

δ15N = ( − 1) × 100015N/Nmeas15N/Nair

Canweconstraintheaccretionregionsofmeteoriteparentbodies?

TounderstandIsheyevo,onecaninvoke

heterogeneousaccretion.

Perhapstheaccretionofthedifferentlithologies

occurredatdifferentspace-timesintheSolar

System.

Howcanweplaceconstraints?

Let'suseChemistry!

Isotopicratiosarecommonlymeasuredinmeteorites.

Wewillassumethatvolatilesendupinmeteoriteparent

bodiesviafreeze-out.

Approach

HowcanwelearnaboutthechemicalstructureofthePPD?1. Radiativetransfer:Hyperion(http://www.hyperion-rt.org)

Dustradiativetransferincl.isotropicscatteringandinternalviscousheating(singlegrainsize;nosettling).

Temperature-dependentmeanopacitiesfromSemenovetal.(2003),Fergusonetal.(2005).

Dustsublimationisaccountedforintheopacities.

HardworkcourtesyofSørenFrimann.

2. Non-equilibriumchemisitry:KROME(http://kromepackage.org)

TheKIDAdatabasenetworkisused(http://kida.obs.u-bordeaux1.fr/),modifiedfor , ,isotopefractionation(Roueffetal.,

2015),iceaccretion/thermaldesorption(Charnley,Rodgers&Ehrenfreund2001;Rodgers&Charnley,2003)andsimplified

photochemistry.

Thenetworkis"isotopologised"( ,butnot );isotopologizedreactionratesdeterminedby

"statisticalapproach"(Millaretal.,1989).

Bindingenergiesforthermaldesorption"scraped"fromtheliterature.

Thereare1341chemicalspecies(including56icespecies)andmorethan53400reactions.

TheDOCMAKEtoolisusedtoexplorethenetwork,examinereactionratesandproduceintegratedphotochemicalrates(with

cross-sectionsfromtheLeidendatabase).

15N D

D,D2, D3, 15N 15N2, D4

3.Theglue:SLiPPD(SnowLinesinProtoplanetaryDisks)Pythonpackage.

https://bitbucket.org/perrybothron/slippd

SetsupandinvokesHyperionandKROMEinsuccessionorindividuallyinserialorinparallel(MPI).

Visualisationandanalysisscriptsareprovided.

Foragivennetwork,youcancalculatethechemicalfluxesofreactionsoverarangeofdensitiesandtemperatures.

BetweenRTiterations,hydrostaticequilibriumisre-calculatedandthedensityadjusted.

Itwillbecomepubliconceapaperissubmitted(alsothechemicalnetwork).

ParameterisedDiskStructure

Internalviscousheatingisincluded:

Constantgas-to-dustratioof100.

Dustsublimationaccountedforvia

temperature-dependentopacities.

ρ(R, z) = ρ0 ( )−2.3exp(− )

exp[− ( )2]

R0

RRR0

12

zh(R)

Γvisc = αPΩKep94

α = 10−3

Mdisk = 0.01M⊙,M∗ = 1.0M⊙

Teff = 4339K, R∗ = 1.78R⊙

TheMiddle:PreliminaryResults

After2.5Myrofchemicalevolution

InitialconditionsarefromBrudereretal.(2009).

Nowwithisotopologisedinitialabundances

Freeze-outtimescale

Desorptiontimescale

∝ n−1T −1/2

∝ exp(−Eb/T)

D-bearingmolecules

-bearingmolecules15N

More!

Inthemidplane

TheEnd(fornow)

Thevariationof and ratiosindifferenticespeciesasafunctionofradiusisnotsimple.

RecallthevaluesinIsheyevo:

A-clasts: ; .

H-clasts: ; ;

Hotspots: .

Overall,theresultsareinreasonableagreementwiththerangeofSolarSystemmeasurements,including

theIsheyevoclasts,butwedonotreachthehotspotvalues.

WishListWhatwoulddustsurfacechemistrydo?

ViaLIME,generatesyntheticobservationsfordifferentdisks.

Addheatingandcoolingtotemperaturecalculation(CRheating,photoelectricheating,etc.).

D/H 15N/N

15N/N = 0.004 − 0.006 D/H = (1.1 − 1.3) × 10−4

15N/N = 0.0039 − 0.0043 D/H = (1.2 − 1.6) × 10−4

15N/N ∼ 0.022

Thankyouforyourattention!

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