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welcome to the first science session of

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AFRICOM I am here to put the Astro in

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astrobiology by talking about the first

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two sessions which also happened to be

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the entirety of the morning session and

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okay so as the first time attended of

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this meeting I was pretty amused to see

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the diversity of topics just within one

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common theme and this was apparently

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true in previous years as well so I

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think it really emphasizes the identity

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of astrobiology as a truly

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interdisciplinary science field but you

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know that being said we do have a story

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right here so my own research is on the

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atmospheric composition modeling of a

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variety of exoplanet types from

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earth-like planets to hot Jupiters which

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are essentially Jupiter's that are at

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1/10 of the mercury sun distance from

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their host star so basically what I'm

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trying to say here is as somebody who's

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actually interested in this kind of

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stuff I found that you know I'm somebody

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who wants to look at how we like how we

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got these spectroscopic signals that we

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see when we look at planets so when we

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look at the planets with Spitzer or the

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James Webb Space Telescope or you know

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Spitzer and James Webb has launched yet

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so we are able to look at their spectra

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in the infrared and we can detect all

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these molecules and of course for the

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molecules to have gotten there they need

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to have had you know things delivered on

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their surfaces so obviously the delivery

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part which is the topics in the middle

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of these two sessions are important

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because that's how we get the molecules

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that we can see with Space Telescope so

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in that sense what we look at for

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exoplanets and what we know about solar

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systems essentially just inform each

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other and the idea is that we will be

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combining the knowledge and eventually

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end up with the

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search for life being our ultimate goal

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which is the goal of astrobiology and in

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order for us to do that to even get to

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that stage so you know we talk about the

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delivery process and we look at

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exoplanets and ultimately we want to

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look at analog sites on earth for say

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ocean worlds like deep sea regions and

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we want to explore them with robotic

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missions and we also want to look at you

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know other extreme planets where there

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might have been life in the past like

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Mars

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so talks about them will basically be

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the end of the session so we're gonna go

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how did everything get there how do we

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look at exoplanets and basically looking

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at your own solar neighborhood to

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characterize the extreme of Bayeux

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habitable zones so I think that's how

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the session here comes together okay so

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as I mentioned we've had all these

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missions and I'm sure you know all about

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them and we've had specially we have had

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Kepler which was phenomenally crucial

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for identifying all these planets around

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other solar system that are like

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earth-like and what that has meant for

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us is we have been able to draw some

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constraints all the Goldilocks zone /

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habitable zone around different types of

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stars now there's relationship for them

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what one of my code visors actually

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defined that Ravi Kokura and so now we

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can actually know the properties of the

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star and we can actually calculate

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what's the conservative habitable zone

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around them and we can even identify the

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inner habitable zone which is basically

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the limit you know beyond or rather

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before which there's going to be too

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much heat and things are just gonna like

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boil over and not remain and the other

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outer edge of the habitable zone which

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is the green house glaciation zone where

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you know it's too cold gases freeze out

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and I reflectivity albedo and you're

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done basically the inner and outer edges

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are just point of no return

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okay so right so now I'm gonna actually

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proceed to the actual warm-up talk

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having introduced all this part okay so

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let's start with some Astro

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chemistry since we're talking about

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you're gonna start with before you know

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things even formed so once there was a

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star it exploded it reset all the

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chemistry everything blew up everything

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atomized everything started from scratch

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and then things condensed back to clouds

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of gas and dust

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roughly hundreds of light years across

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and then they condense into smaller and

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smaller core and then we get protostars

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and from protostars we get disks and

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then they condense further into

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planetesimals so astrochemistry is the

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process that happens during this whole

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ordeal

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you know once things blow up and and

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begin to compress you know things get

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hotter more complex molecules are formed

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there's all sorts of weird chemistry

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driven by HBase I am there's grain

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surface chemistry ice chemistry but they

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essentially the thing is the chemistry

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doesn't really change but it's really

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just the conditions that are rapidly

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changing like density temperature and

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the fact that there is like no liquid

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phase throughout this process so

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essentially and we all know this by now

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molecules have been here before earth

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was formed and so when earth was formed

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a large number of organics was actually

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delivered to the surface and eventually

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we got more organics when when we got

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bombarded later on which we responds

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with which we think is responsible for

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current life because that delivered like

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trillions of kilograms of organics that

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would be necessary for life to actually

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start so let's get on that a little bit

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more so comets are all over right like

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we always hear about them they're just

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pushing in and out they're on a highly

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inclined plane compared to Earth's

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playing around the Sun so they're just

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crazy like you I mean you come on you

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see here so sometimes they get really

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close sometimes they get really far and

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then when they get really close they can

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you know vaporizing our atmosphere or in

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fact like during the late heavy

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bombardment that happened guilty you get

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yours for Giga years ago eight basically

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crashed into Earth and during that

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process it signed a custom declaration

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form for ingredients of life as it was

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coming from

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so to all our people who've been

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traveling from foreign countries for

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this meeting I'm sure you've had to do

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that so so did these comets and during

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that process they delivered essential

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like small molecules highly reactive

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small molecules that was used for

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elementary prebiotic chemistry so HTN

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has been detected in comets and the cool

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thing is HCN is a very simple but a very

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reactive molecule and what that means is

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that when it forms a number of

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macromolecules not polymers yet but just

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a small number of repetitive chains it

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starts the pathway to chemical evolution

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so you really start getting the nucleic

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acid we start getting basically four

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basic biomolecules as nucleic acid

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proteins lipids carbohydrates so

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basically AC and in aqueous solution is

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just very versatile it can just like

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repeat itself to follow all these

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molecules and it creates the amino acids

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which we know are essentials for like

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building blocks and so yeah so this is

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all interesting and the cool thing about

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ACN is that it has this like crazy

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strong triple bond that should have

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survived cometary impacts so we think

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like there's detectable amount of them

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like which we can quantify that would

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have been there like right after the

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heavy bombardment so let's see so the

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other thing I want to mention was I

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mentioned Spitzer so Spitzer is really

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cool because Spitzer has done a lot of

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things for us so one of the things that

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Spitzer does is it also looks at

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protoplanetary discs around like other

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stars and in doing so it was able to

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actually find some like warm evidence of

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warm you know because you can see Dustin

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infrared so warm

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carbon rich dust at the habitable zone

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of another star which basically showed

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that That star system also on just

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recently underwent a heavy bombardment

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period so that's cool you know we have

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evidence for heavy bombardment in other

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systems which we are like you know it

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could have happened with us as well so

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right so I talked about Spitzer so

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everybody knows the James Webb Space

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Telescope is coming up it will launch at

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some point I know it keeps getting

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delayed

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so that's kind of like the new happy

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Hubble which like much better bigger you

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know here's a size scale for comparison

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and one of the cool thing is like so you

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know you obviously like most flagship

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missions it has a lot of Astrophysical

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goals also it's going to look at core

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client systems and then it's also going

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to look at finder systems and the

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origins of life which is what we care

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about so one of those telescope science

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goal is to study planets that could you

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know help shed information on this

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origin of life but that doesn't mean

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exoplanets only it will also unravel

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mysteries held by object in our own

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solar systems such as like for marks

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outwards Europe Enceladus you know the

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ocean planets that may possibly Harbor

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life you know under their like icy

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plumes are actually one of Webb's first

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list of targets with guaranteed

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observing time so here are some of the

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instruments they're all into infrared

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and they can detect like lots of

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molecules but I'm not gonna go like

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crazy deep into the detail of it so and

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so that brings me to my next question is

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which what I work on and some of the

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other speakers work on is how do we look

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at exoplanets like how do we

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characterize them so when you look at

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you know spectroscopic measurements

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treatments that were Hubble Spitzer and

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will be on the James Webb Space

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Telescope there are ways that they

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actually look at the light of planet so

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when a an exoplanet transits in our line

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of sight as we're looking around the

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star as it passes the front of the star

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it just flows up the atmosphere around

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it and that process is known as primary

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transit and with that we can even

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identify trace gases in that atmosphere

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now as it of course you're looking at

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the edge of the orbit right you're

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looking at the edge of the transit race

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you can also know the planets size from

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there so a physical characteristic so as

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it goes behind the star then you know

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you you get the thermal radiation was

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blocked and then it comes out so

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basically from that process you can

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characterize the thermal radiation

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that's solely from the planet so this

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process is the secondary Eclipse when it

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goes behind the star

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and from this data we are can actually

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get the thermal structure of the planet

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so and then there's another thing you

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can do as well like if you look at the

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curves over here is as they're going

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around you know they're going to

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different phases just like the moon

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right so this allows ought to do a bit

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of like meteorology stuff so we can see

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the cyclic variations and the thermal

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phase curve in the bright like thermal

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brightness of the planet and you can

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basically assess variation of properties

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that would vary with that such as like

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the eccentricity you know how when a

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planet is much closer to the Sun then

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it's for this point and then you can and

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that's also a rotation great thing and

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really also have a speaker we'll talk

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about that too so finally since we just

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introduced how like the whole transit

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process work this is my favorite slide

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I'm sure you all know about the Trappist

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system so the Trappist system has seven

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planets in it and in 2015 three of them

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were discovered and the last year before

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other were discovered via Spitzer Space

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Telescope

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so yay Spitzer you're doing a lot for us

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and then currently three of them are

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considered to be in the habitable zone

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so that would be e FG and it's marked by

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green like even in the circle so you can

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know that but honestly like depending on

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the definition this could be up to six

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like you know if you really want to push

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the limits of like habitable zone but I

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would recommend not doing that because I

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just talked about inner and outer being

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limited by how hot and cold it gets so

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but within these plan is it can go

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anywhere from 170 Kelvin to like 330

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Kelvin and if you look at the bottom

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plot so E is very similar to Earth in

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terms of like size density and also it

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just gets about the same amount of

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radiation and then there is C which is

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the hotter one of which is still within

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this range of habitability but you know

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you would kind of question that right

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because that's overlapping with Venus so

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and we know Venus is kind of crazy right

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now so okay so I don't really have

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talked it's time to talk about anything

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else but I'm sure we have we'll have our

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you know justin talking about a little

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bit about ocean walls and we'll have my

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colleague amber Bray talking

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a little about Mars rovers later on so