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[Music]

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howdy my name is Ben Hayworth

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I'm a graduate student at Penn State and

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thank you to the conveners for giving me

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the opportunity to talk about this

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project that I quite literally just

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started so if you like some of the

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predictions about this that I'm making

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you should come to age you to see the

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final results alright so in general the

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project I'm looking at is whether or not

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space weather can impact an exoplanets

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atmospheric chemistry on such a level

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that you then can affect its

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habitability and perhaps future

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observations of that planet so I am

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currently in everyone's favorite part of

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a project model development so I'm kind

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of stuck right now up in those first two

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boxes but that's not what's driving the

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appreciative that's that's much better

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okay all right so I'm right now stuck in

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those first two boxes but what's driving

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it are the potential implications of

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this so the first one which has been

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explored by another group is that space

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weather can potentially build up a

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biotic lees nitrous oxide on your planet

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which is a potent greenhouse gas so it

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can radiatively force it and then I put

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plus haze there because nitrous oxide we

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find that our preliminary results has a

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very interesting relationship with

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organic haze that you build up on your

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planet and both of those impacts the

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habitability of the planets we want to

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explore that relationship further over a

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wide sweep of parameter space now I also

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put observations because one like secret

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said n2o is a potential bio signature on

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modern-day earth the only two processes

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that really build up n2o is lightning

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and life and if we are able to abiotic

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we build it up with another process we

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should look at whether or not that is a

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good bio signature and also what

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environments can it build up it turns

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out space weather may not be able to

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build up into Oh in certain environments

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but it can and others and that's

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something we want to explore and finally

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this one's more speculative but this is

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what actually got me thinking about this

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problem was right now we talk a lot

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about whether a magnetic field is

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necessary or impacts the habitability of

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an exoplanet but at least for us triol

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ones we have no way of detecting them

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it's well below any detection threshold

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we can think of but if we know a process

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that impacts the atmospheric chemistry

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of a planet and can potentially be

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buffered by that planet's magnetic field

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we could use that as a proxy for

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inferring whether or not these planets

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may have magnetic field all right so I

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keep saying space weather what am I

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talking about I'm talking about

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solar proton events those that follow

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coronal mass ejections so this is one

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for our own Sun in 2012 what these are

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they're very magnetically active events

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where the star will shed some of its

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coronal mass in the form of a plasma

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stream these streams are going to be

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very high number density high-energy

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charged particles and they

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preferentially occur in the axis of

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rotation of your star so for systems

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that aren't that misaligned this will

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also hit your planets it depends on how

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active the star is our star right now is

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pretty quiet but we know a lot of em

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dwarves that are very active now it's

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also been proposed that potentially

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magnetic fields can shield you from this

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that's actually one of their arguments

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why they might be good for habitability

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this right here from the other group

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I'll mention in a second this was a

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Carrington like event modeled against

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modern day Earth's magnetic field the

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white lines are our magnetic field lines

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and you'll see that it's actually able

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to shear the Earth's magnetic field open

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enough that more of these particles can

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make it n so I'm not gonna be talking

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about solar wind the reason for that is

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that's constantly buffeting the Earth's

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magnetic or atmosphere and it's not

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really driving any chemistry mainly

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because those particles are typically

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slow enough energy that they're

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deflected by our magnetic field and even

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those that are able to make it in lose

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their energy well above 100 kilometers

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in most cases all right so what kind of

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chemistry are these high-energy

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particles able to drive it's relatively

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simple it's just splitting n2 which is a

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very difficult thing to do in the modern

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atmosphere so like I said lightning down

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in the troposphere is able to split n2

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it's a really difficult triple bond and

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we don't readily photolyze and - in the

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lower atmosphere the reason for that is

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the wavelengths that are able to make it

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into our mid altitudes

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the absorption cross-section for

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ionization and dissociation friend two

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are relatively similar so we end up is

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amend two but not really dissociating it

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so what occurs is these high-energy

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protons are able to make it into the

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atmosphere

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they will ionize the neutral gas around

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them and then the subsequent secondary

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electrons then have the correct

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cross-sections and energies the split

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end to and once you split end to it can

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stick the other things like hydrogen

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it's very reactive and you end up

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getting n 2o or h ZN usually not both of

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them and that depends on your your

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background atmosphere so this process

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had previously been explored by aaron at

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all in 2016 it's a very exciting idea

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the space weather can drive atmospheric

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chemistry so they used a very

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sophisticated magneto hydrodynamic model

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to calculate these particle fluxes at

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the top of the planet's atmosphere how

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many are able to make it through the

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magnetic field and then down into it and

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then they used a sort of a box chemical

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model to see what happened

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so these are some profiles from their

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chemical model and they found that in

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the mid altitudes like say 30 to 40

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kilometers they could get parts per

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million of nitrous oxide which is enough

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for it to be radiatively effective now

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what we want to do is go back and look

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at this process but there were some

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physics missing in the original chemical

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model so we want to explore that because

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a lot of this is very important for n2

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the first one is fatalis so originally

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was used and optimistic and a

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pessimistic photo destruction rate turns

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out when you look at n 2o wavelength by

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wavelength then it very very readily

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wants to photo dissociate at almost any

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UV wavelength so that's something you

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have to consider also convection so a

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lot of these high-energy particles again

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they will fall off with pressure as they

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enter the atmosphere so you'll be doing

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a lot of this chemistry high up and then

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less and less as you work your way down

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so mixing processes are important to

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consider when you're doing this

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chemistry third is organic haze so I

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just said n2o likes to fertilize very

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easily and you need something to shield

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it so we're thinking what could shield

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it out to those wavelengths and organic

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haze if it's thick enough is very

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capable of shielding in the UV

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I put fractal up here just because

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people that typically model Hayes know

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that it's not nice little spheres that

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you model when it's scattering it

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typically aggregates into gross

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geometries which will pretend are

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fractals and that makes it a very

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effective scatterer in the UV so it

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allows it to shield out further

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wavelengths and then finally ion

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chemistry

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so I just said these protons as they

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come through the atmosphere they'll be

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producing secondary electrons that

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ionizes the background neutral

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atmosphere and while it's short-lived

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it's on the similar time skills as these

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chemical reactions and the reactive

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cross-sections for those ions are

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considerably different than their

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neutral counterparts so these are you

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know the physics that we're gonna be

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throwing in the model that I'm currently

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working on okay

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so I'll run through this real quick so

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this is the boring part but I can't get

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a thesis doing this on the back of a

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cocktail laughing I have to show that I

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did some science so we'll be looking at

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how efficiently these particles are able

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to propagate through the atmosphere once

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we know their fluxes by altitude we can

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then run them through our chemical model

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to know how much of this chemistry is

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actually going to be driven do we end up

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with m2o hcn haze and then we also do

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care about the habitability so we can

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then take those profiles mixing ratio

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profiles and run them through a 1d

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radiative convective model to see if

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they have any effect on the surface

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temperature and finally I did mention

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that in the future we want to think of

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what these signals would mean

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observational II so we can use smart or

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PSG which we've currently been looking

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at to generate spectra using those

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pressure temperature in the exterior

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profiles okay so I said n2l readily

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photolyze --is the left plot right here

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that red line is the absorption

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cross-section for nitrous oxide and

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these black lines right here are the

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fraction of its catalysis per wavelength

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then and just right up front I'll tell

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you both of those curves integrates to

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about one so almost all the Anto you

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build up immediately photolyze it's in

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UV the black solid lines at the top of

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the atmosphere so it's photolyze anova

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its entire range that's because there's

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nothing shielding it and and down in the

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troposphere I believe this was 15

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kilometers none of its fertilizing outs

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of 2009 strums that's because co2 is

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ineffective she

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and then immediately after it everything

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fertilizes we tried to think what can we

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put that can shield it out to at least

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2500 angstroms

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so we tried methane like the previous

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authors had proposed methane though

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while it dissociates under UV it is not

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effective

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past like 1700 angstroms so this plot

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right here is we were just taking upper

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fluxes from the previous air peach

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nettles group plugging them in and

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seeing can we get any of this to connect

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down and then be shielded by methane

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this was an unrealistically methane

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heavy case I was like a 20% mixing ratio

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of methane on the planet all right but

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can hey shield it the answer is yes

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so after stare suck I feel like I should

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talk about different kinds of Hayes's

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than the one in this model but it is

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just a hydrocarbon haze that's what we

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currently have optical properties for

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but I'd be excited don't get nitrogen

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very Hayes's okay so in our model what

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we do is we build up a hydrocarbon haze

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by adjusting the methane to co2 ratio

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under a UV environment and so this is

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very relatively thick haze you'll see at

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the top of the atmosphere and at 75

276
00:10:12,050 --> 00:10:09,690
kilometers almost none of our UV energy

277
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is lost once you get to 50 kilometers

278
00:10:16,250 --> 00:10:13,769
you start to just dip below that haze

279
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deck and then down at 25 in the surface

280
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almost none of the UV makes it down

281
00:10:24,050 --> 00:10:21,029
there so organic haze can be an

282
00:10:25,610 --> 00:10:24,060
effective shield for this now what does

283
00:10:27,410 --> 00:10:25,620
this mean for habitability we know that

284
00:10:30,110 --> 00:10:27,420
we need a is to shield n2o and we know

285
00:10:32,840 --> 00:10:30,120
that n2o can radiatively force the

286
00:10:34,340 --> 00:10:32,850
climate so the previous work was done

287
00:10:36,170 --> 00:10:34,350
for the early Earth here peach natal

288
00:10:38,059 --> 00:10:36,180
group wanted to answer the fam Sun

289
00:10:39,740 --> 00:10:38,069
paradox if we had a more active young

290
00:10:42,019 --> 00:10:39,750
star could we potentially warm it with

291
00:10:43,639 --> 00:10:42,029
this n2o and that seems like a natural

292
00:10:45,379 --> 00:10:43,649
place to start since we have a different

293
00:10:47,600 --> 00:10:45,389
suite of models and it's always good to

294
00:10:49,579 --> 00:10:47,610
retest hypotheses I throw up an orange

295
00:10:51,949 --> 00:10:49,589
earth because I'm gonna pretend early

296
00:10:54,800 --> 00:10:51,959
Earth was hazy if you disagree don't

297
00:10:56,389 --> 00:10:54,810
know I need it for this all right and

298
00:10:57,769 --> 00:10:56,399
then also early Mars we have problem

299
00:10:59,600 --> 00:10:57,779
warming that so it's a natural next step

300
00:11:01,069 --> 00:10:59,610
but this is EXO climb so we care about

301
00:11:02,509 --> 00:11:01,079
exoplanets and this is where it's going

302
00:11:04,939 --> 00:11:02,519
to be really interesting to explore the

303
00:11:06,259 --> 00:11:04,949
relationship between haze and n2l so I

304
00:11:08,199 --> 00:11:06,269
put the trap is system up here on

305
00:11:10,670 --> 00:11:08,209
purpose because it's orbiting an M dwarf

306
00:11:12,800 --> 00:11:10,680
very active stars they'll have very

307
00:11:14,750 --> 00:11:12,810
frequent coronal mass ejections

308
00:11:16,930 --> 00:11:14,760
and also they are all orbiting very

309
00:11:19,010 --> 00:11:16,940
close to the star not only will you

310
00:11:21,350 --> 00:11:19,020
experience more of these high-energy

311
00:11:23,540 --> 00:11:21,360
particles but more than will interact

312
00:11:24,920 --> 00:11:23,550
with the atmosphere and they potentially

313
00:11:26,630 --> 00:11:24,930
don't have magnetic fields at least

314
00:11:28,160 --> 00:11:26,640
that's what most people think right now

315
00:11:31,040 --> 00:11:28,170
so you shouldn't have any mitigation

316
00:11:33,110 --> 00:11:31,050
from that all right so let's say we have

317
00:11:34,910 --> 00:11:33,120
a very active star and we want to see

318
00:11:36,769 --> 00:11:34,920
how this plays out you've a very active

319
00:11:38,570 --> 00:11:36,779
star you're gonna have more coronal mass

320
00:11:41,150 --> 00:11:38,580
ejections more of these particles in the

321
00:11:45,470 --> 00:11:41,160
atmosphere true you're also gonna have a

322
00:11:47,570 --> 00:11:45,480
higher XUV flux from flares now this

323
00:11:48,769 --> 00:11:47,580
step is very compositionally dependent

324
00:11:50,390 --> 00:11:48,779
and this is where a large sweep over

325
00:11:52,460 --> 00:11:50,400
parameter space is necessary for

326
00:11:54,530 --> 00:11:52,470
exoplanets on the right here I said

327
00:11:56,660 --> 00:11:54,540
having a higher xev flux means you'll

328
00:11:58,579 --> 00:11:56,670
have more organic haze that is heavily

329
00:12:01,130 --> 00:11:58,589
dependent on you having those precursor

330
00:12:02,990 --> 00:12:01,140
molecules in your atmosphere at least in

331
00:12:04,730 --> 00:12:03,000
our model that would be a methane to co2

332
00:12:06,380 --> 00:12:04,740
ratio so if you have a lot of methane

333
00:12:08,840 --> 00:12:06,390
you have enough of that to break apart

334
00:12:12,170 --> 00:12:08,850
into CH very reactive you'll start to

335
00:12:14,510 --> 00:12:12,180
form those haze aggregates now on the

336
00:12:17,030 --> 00:12:14,520
Left more n2o is produced that is also

337
00:12:19,550 --> 00:12:17,040
generally true if this original

338
00:12:21,200 --> 00:12:19,560
hypothesis is correct however it's going

339
00:12:23,030 --> 00:12:21,210
to depend on the seed Oh ratio of your

340
00:12:26,240 --> 00:12:23,040
atmosphere so there's a critical point

341
00:12:29,270 --> 00:12:26,250
where if you have too much carbon to

342
00:12:32,030 --> 00:12:29,280
oxygen you're gonna be forming HCM

343
00:12:34,430 --> 00:12:32,040
rather than nitrous oxide so there is a

344
00:12:36,050 --> 00:12:34,440
minimum threshold amount of methane we

345
00:12:37,910 --> 00:12:36,060
need to start building a haze but there

346
00:12:40,130 --> 00:12:37,920
might also be a maximum threshold for

347
00:12:41,840 --> 00:12:40,140
you'll be creating a gas that's not

348
00:12:43,220 --> 00:12:41,850
radiatively important still an

349
00:12:44,780 --> 00:12:43,230
interesting gas especially if you like

350
00:12:48,200 --> 00:12:44,790
prebiotic chemistry but not for

351
00:12:49,970 --> 00:12:48,210
habitability and we know hazel have a

352
00:12:52,310 --> 00:12:49,980
positive relationship with n 12 you need

353
00:12:54,020 --> 00:12:52,320
something to shield it now in general

354
00:12:55,280 --> 00:12:54,030
both of those will have opposing impacts

355
00:12:57,320 --> 00:12:55,290
on the planet if we're forming these

356
00:13:00,110 --> 00:12:57,330
really thick Hayes's that are necessary

357
00:13:01,520 --> 00:13:00,120
to form nitrous oxide they're also going

358
00:13:04,280 --> 00:13:01,530
to effectively raise the planetary

359
00:13:06,260 --> 00:13:04,290
albedo which cools the surface while n

360
00:13:07,400 --> 00:13:06,270
2o is a greenhouse gas it'll act to warm

361
00:13:09,290 --> 00:13:07,410
it and I have no idea what the

362
00:13:10,550 --> 00:13:09,300
magnitudes of those two are competing

363
00:13:12,079 --> 00:13:10,560
against one another and that's something

364
00:13:14,660 --> 00:13:12,089
that we definitely want to explore in

365
00:13:17,720 --> 00:13:14,670
this all right now I talked about

366
00:13:19,880 --> 00:13:17,730
observations n2o is a potential bio

367
00:13:22,670 --> 00:13:19,890
signature I'm not a biologist but notice

368
00:13:25,400 --> 00:13:22,680
through nitrate reduction and n2 it does

369
00:13:26,630 --> 00:13:25,410
have a nice absorption feature 4.5

370
00:13:30,920 --> 00:13:26,640
microns which is

371
00:13:33,380 --> 00:13:30,930
eventually observable potentially now

372
00:13:34,580 --> 00:13:33,390
this on the surface makes it seem like

373
00:13:36,410 --> 00:13:34,590
oh and tulle might be a bad bio

374
00:13:38,030 --> 00:13:36,420
signature but like we just said that

375
00:13:39,860 --> 00:13:38,040
might depend on the atmosphere so if we

376
00:13:42,590 --> 00:13:39,870
have a very you see an atmosphere that's

377
00:13:44,210 --> 00:13:42,600
very hazy and you like very hazy and you

378
00:13:45,620 --> 00:13:44,220
see nitrous oxide and I say that

379
00:13:48,320 --> 00:13:45,630
tongue-in-cheek saying you can see a

380
00:13:49,610 --> 00:13:48,330
signature and it's very hazy you know

381
00:13:52,100 --> 00:13:49,620
that maybe space weather would be

382
00:13:54,290 --> 00:13:52,110
producing HCN abiotic li non nitrous

383
00:13:56,630 --> 00:13:54,300
oxide so maybe it's still a good bio

384
00:13:58,760 --> 00:13:56,640
signature on that kind of atmosphere so

385
00:13:59,750 --> 00:13:58,770
it really depends on that's and we want

386
00:14:01,340 --> 00:13:59,760
to explore the difference between the

387
00:14:03,350 --> 00:14:01,350
background oxidized atoms for your

388
00:14:07,250 --> 00:14:03,360
bursts reduced because that'll also give

389
00:14:08,600 --> 00:14:07,260
you different phases alright and finally

390
00:14:10,910 --> 00:14:08,610
this was the more speculative one

391
00:14:13,250 --> 00:14:10,920
whether or not you could use this as a

392
00:14:14,150 --> 00:14:13,260
proxy for a magnetic field and to do

393
00:14:15,980 --> 00:14:14,160
that we would really have to know how

394
00:14:18,440 --> 00:14:15,990
many of these energy solar energetic

395
00:14:20,660 --> 00:14:18,450
particles are buffered by the planet

396
00:14:23,120 --> 00:14:20,670
having a magnetic field versus not so if

397
00:14:25,970 --> 00:14:23,130
you see a planet that you think I'd have

398
00:14:29,060 --> 00:14:25,980
a Geo Dynamo around a very active star

399
00:14:30,560 --> 00:14:29,070
and it has a haze but no HCN maybe that

400
00:14:32,180 --> 00:14:30,570
means none of those particles are making

401
00:14:34,490 --> 00:14:32,190
it down into the lower atmosphere and

402
00:14:36,260 --> 00:14:34,500
can drive that chemistry that's very

403
00:14:39,190 --> 00:14:36,270
speculative but that's at least why I

404
00:14:42,230 --> 00:14:39,200
found it exciting to begin with and

405
00:15:01,450 --> 00:14:42,240
those are my conclusions and I'll take

406
00:15:08,260 --> 00:15:04,550
what are what the photochemical lifetime

407
00:15:12,710 --> 00:15:08,270
of nitrous with and without a haze out

408
00:15:14,120 --> 00:15:12,720
haze it is I know it's about three to

409
00:15:18,050 --> 00:15:14,130
four orders of magnitude difference but

410
00:15:26,210 --> 00:15:18,060
I don't remember the actual numbers okay

411
00:15:32,900 --> 00:15:26,220
thank you so okay thank you over on the

412
00:15:34,550 --> 00:15:32,910
side how just sort of thinking about

413
00:15:35,960 --> 00:15:34,560
most of place you're looking at in the

414
00:15:39,950 --> 00:15:35,970
next a plain sense it's all tightly

415
00:15:41,750 --> 00:15:39,960
locked so you've got one side where the

416
00:15:43,700 --> 00:15:41,760
NGO is going to be fertilized but if it

417
00:15:45,800 --> 00:15:43,710
can make it over to the night side will

418
00:15:47,810 --> 00:15:45,810
its lifetime be sort of increased

419
00:15:51,410 --> 00:15:47,820
significantly on one of the implications

420
00:15:53,360 --> 00:15:51,420
of at idea dog system I'm not sure I

421
00:15:55,880 --> 00:15:53,370
actually have no idea how Hayes's would

422
00:15:57,440 --> 00:15:55,890
work in 3d if you would be able to

423
00:15:59,470 --> 00:15:57,450
transport the necessary totalized

424
00:16:02,570 --> 00:15:59,480
components to the night side and then

425
00:16:04,070 --> 00:16:02,580
continually shield it so I don't that

426
00:16:06,200 --> 00:16:04,080
would be a 3d problem and everything

427
00:16:07,550 --> 00:16:06,210
I've thought about some in 1d that's an

428
00:16:22,010 --> 00:16:07,560
interesting question

429
00:16:23,960 --> 00:16:22,020
thank you RJ from Oxford um does after

430
00:16:25,880 --> 00:16:23,970
you if you make a lot of into if you

431
00:16:27,440 --> 00:16:25,890
have a high end to plug into a flux does

432
00:16:31,220 --> 00:16:27,450
it eventually get converted back to n2

433
00:16:33,140 --> 00:16:31,230
or as does the into oh end up like in

434
00:16:35,060 --> 00:16:33,150
the ground or something like could you

435
00:16:36,650 --> 00:16:35,070
imagine this being like a sink on on

436
00:16:38,540 --> 00:16:36,660
into and like decreasing the surface

437
00:16:42,740 --> 00:16:38,550
pressure of your planet over time or

438
00:16:44,630 --> 00:16:42,750
would it just equilibrated some value ya

439
00:16:46,550 --> 00:16:44,640
know the particle flux for these

440
00:16:47,870 --> 00:16:46,560
energetic particles are not enough to at

441
00:16:49,370 --> 00:16:47,880
least for like the modern earth you're

442
00:16:51,410 --> 00:16:49,380
not changing the background pressure and

443
00:16:52,250 --> 00:16:51,420
to by doing this it's it's relatively

444
00:17:01,990 --> 00:16:52,260
small scales

445
00:17:08,720 --> 00:17:05,960
Shami Oxford very interesting talk just

446
00:17:13,840 --> 00:17:08,730
a quick question is there also a minimum

447
00:17:17,780 --> 00:17:13,850
threshold for producing NGO with the

448
00:17:20,900 --> 00:17:17,790
nitrogen like you have to have a

449
00:17:22,520 --> 00:17:20,910
nitrogen dominating sphere right now

450
00:17:23,449 --> 00:17:22,530
that's all I've explored modeling but

451
00:17:25,970 --> 00:17:23,459
yes there would definitely be a

452
00:17:27,350 --> 00:17:25,980
dependence on that so that would be one

453
00:17:28,820 --> 00:17:27,360
thing we've one of first explorers

454
00:17:30,770 --> 00:17:28,830
what's the dependence on your nitrogen

455
00:17:32,690 --> 00:17:30,780
partial pressure and formation of n2o

456
00:17:34,100 --> 00:17:32,700
given everything else is the same but

457
00:17:41,000 --> 00:17:34,110
that yes there there would be a

458
00:17:43,680 --> 00:17:41,010
dependence if there are no additional

459
00:17:45,170 --> 00:17:43,690
questions thank you