Origins Institute Public Lecture with Natalie Hinkel

[Music] greetings and welcome to the fourth origins institute talk and first public lecture for the 2020-2012 academic year my name is john stone or doc rock i'm the director for the origins institute and your host we're recording the proceedings and we'll make the video available so that you can share it we'll hold a brief question and answer period following the talk please input your question in the q and a chat box at the bottom of your screen we already have received a constellation of questions some of which our speaker kindly will address during the talk we will address as many among the remaining questions during the q a period as time allows before the introduction i'd like to relay some information about the institute the origins institute is one among five research centers and institutes in the faculty of science and 70 in total at mcmaster university these centers and institutes discover solutions to complicated problems by bringing together interdisciplinary multidisciplinary and in our case transdisciplinary teams these teams collaborate with academic government and industry partners and you we're collaborating at this very moment community outreach and engagement is a priority for all centers and institutes at mcmaster university which is why we host talks in collaboration with the mcmaster alumni association the new president for the mcmaster alumni association troy hill suggested recently that we should involve in our educational pursuits sharing stories we as an audience in this sense are very fortunate our guest today is a science advocate and communicator with experience in sharing stories translating what stars beyond our solar system have to tell us about their planets dr natalie hinkle is a senior research scientist at southwest research institute in san antonio and a co-investigator for the nexus for exoplanet systems science having earned a phd at arizona state university and tenured post-doctoral research tips some swanky at the california institute of technology san francisco state university and vanderbilt university among dr hinkle's most impactful contributions to astrobiology is the hypatia catalog a database containing stellar element abundances the stuff from which stars are made and thus stories are told we continue to showcase the origins institute mandate with talks this year combining our prime research directive astrobiology with original institute themes this term the origin of space-time elements and structures in the cosmos stars planets and galaxies and i welcome dr hinkle who is qualified eminently to tell us stories that literally are written in the stars well thank you so much for that introduction want me to share my screen and begin the talk all right well thank you john and thank you to the origins institute for inviting me to give this talk also thank you to everyone tonight for joining me i'll be talking with you about planets outside of our solar system also known as exoplanets in my research to understand their habitability or whether they would be suitable for life but first i'd like to talk to you a little bit about myself so um i grew up in southern ohio um i i stayed there my entire life in in one city uh for the most part um and then i went to um undergrad at oberlin college where i studied physics math theater and dance so i'd like to think that having such a well-rounded education really helped me be who i am today and the scientist that i am today i went to graduate school at arizona state university which is in phoenix i took in quite a lot of hiking and camping this is a photo that i took of the sunset off of camelback mountain and now uh i i live in san antonio with uh these characters so uh on the left is my husband caleb wheeler who is also an astrophysicist in the middle is my 15 year old cat tater tot who i've had for a long long time and then uh to the right is the newest addition to our family and this is lasagna he is now eight months old all right but you're here to learn about uh stars and planets so if everyone is comfortable let's begin and where i always like to begin is at the big bang the only elements that were made in significant quantity at the big bang were hydrogen and helium there was nothing else it was basically hydrogen and helium floating around in the universe now the universe is not flat so when all this material went out some of it started to clump together and eventually these clumps became so massive that they collapsed in on themselves and eventually formed a star now is within these very first stars which are absolutely huge they're about a thousand times more massive than our sun so it's within these huge stars that you have fusion so this is the right temperatures and pressures such that if you have two atoms that are floating around and they slam together you get a brand new atom so you would have a few of new elements that are created so not just hydrogen and helium anymore however these first stars they uh live fast and they die young and when they died they exploded but just like everything else it was asymmetrical so you had all of this different dust and gas that was created already but then you had the seeds of these other elements now these other elements would get scooped up by the next clouds and eventually collapsed down and formed the next generation of stars now in the insides again you have fusion but you're not just building off of hydrogen and helium you're building off of the seeds that were already there for example carbon and oxygen so they would then start forming the next sets of elements for example silicon and magnesium and this kept happening through multiple generations of stars until we have the periodic table of elements now this is color-coded so you can see where these different elements came from so when this was created not by me i am not that good this is created by jennifer johnson at ohio state now the those elements that are in blue hydrogen and helium were created in the big bang like i told you but there's a variety of other places where you can get these elements from so you can get it from exploding massive stars um dying low-mass stars that sort of shed they're out of late outer layers and so that's how we really built up the majority of the periodic table now um like i said when you when you're taking all this gas and dust and all these sorts of different elements and especially now i'm talking about more recently not quite in the big bang you smoosh them together and out pops a star i love this image from a magic school bus series because this is basically the way that i talk um but at the same time that stars are formed you also have planets that is to say that planets outside of our solar system in fact our own planets within the solar system were all made at the same time as our sun and uh so and made out of the same elements of this of uh that that the star is made out of and uh and i use this but first let me tell you a little bit about exoplanets so uh this is a cumulative diagram showing you that how many exoplanets were discovered per year to date we know of 4 307 planets outside of our solar system the first one was actually detec detected in 1992 but this was kind of a weird planet it was around a weird kind of star it was a really small planet so actually people sort of ignored it they didn't trust that it was a planet it wasn't until the discovery of a of an exoplanet around a solar-like star so something that's a lot like our sun that people really started to pay attention so this happened in 1995 and if uh for those of you who might have been paying attention to the most um recent uh nobel prizes uh actually no it was about a year ago that this was given out to the exoplanet discovery and you could see that with time in time that the number of exoplanet detections has really increased so a lot of this is just due to more activity once we discovered uh planets outside of our solar system but also much of it is due to the kepler mission which is a very large nasa mission so when it comes down to it one of the things that i can't stress enough is that the exoplanet field is really young we've only really known about planets outside of our solar system for 28 years and that's we get a whole new field of science whereas astronomy is one of the oldest known natural sciences it's been around for literally thousands of years so there's a lot of of stuff to do there's a lot of things to look at because not everything looks like our solar system in fact a lot of it looks uh quite different from our solar system so this is a really cool plot uh it's an orary showing you all the different kinds of planets and the different kinds of systems that you uh that we we've actually observed so you can see that there's some planets that are really big but also really close to their stars and um some that uh orbit multiple stars at the same time in fact there is just this huge variety of planetary systems and that makes for a really exciting opportunity to try to understand what what the conditions might be like on those planets for example um we could have a planet that is tidally locked namely this is a planet that's so close to its star that it's gravitationally locked quite the same as the moon is for us and so what you'd end up seeing is a very hot side uh that's always facing the star and a very cold side that's always facing away from it however there could be sort of this narrow band um that which is sort of illustrated here mind you these are all artist renditions and are definitely not pictures um so there's this narrow band of a region that could actually have uh sort of normal temperatures that could be conducive to life then you have in this middle picture is a potential for an exo moon so this is a moon orbiting a planet outside of our solar system now we have hundreds of moons within our solar system so why not there will be hundreds of moons in other solar systems so that's a really interesting idea of whether or not there could be um a moon that could be habitable or conducive to life outside of the solar system and then finally on the right what you're seeing is a planet that's orbiting a very cool star that's so cool that it actually looks red and not yellow but i'll get to that later on in the talk um and then of course there's there's the age-old question of uh would it what would things be like on tatooine if you're if you have one planet circling around two stars at the same time and the answer to that is that it's actually fairly complicated because you have a planet that is sometimes looking at one star sometimes it's looking on two stars and then orbiting all the while so that's fairly complicated but what do i actually mean by habitability how does this how do we start on all of this so the definition for um sort of the the region that uh that a or sorry the distance that a planet might be from the star uh where we would expect to find liquid water is called the habitable zone so you might have also heard this referred to as the goldilocks zone uh so this is if you have water on a planet and the planet is at just the right distance then we would have liquid water on that surface so there is such a thing as being too close to the star but also too far away from the star where the planet would be uh totally covered in ice but the more that we thought about this sort of definition of the habitable zone the more we realize that it's actually real more complicated than that for example uh you need to take into account uh other properties of that planetary system are there other planets in the system um the giant planets in our system for example jupiter and saturn they actually protect us from um incoming uh asteroids and things like that so are there other planets nearby um what about the dynamics on that planet itself does it have plate tectonics does it have volcanoes these are super important for life on earth and then the star itself what is that like um is it a is it a hot star is a cooler star is there stellar activity which is actually a really big deal um so this then made us realize that there's actually even more questions than we first realized so i really like this plot or this flow chart there's there's a newer version of it but i really like this one because it conveys how complicated understanding whether or not a planet could be habitable to life and by by that i mean either humans or any kind of life that's similar to us so carbon-based life is typically the way that we think about it this is very general it's not to say that extremophiles couldn't exist but right now we're just focusing on the big picture of habitability so everything that you see in green are properties that we can measure directly everything in orange or the orange triangles are things that we can infer by using observations and then everything in the red hexagons are things that we have to just figure out by pure theory but all of these properties all of these things are really important to understanding planet habitability it's not enough to say that a planet has the same size as the earth it's the same mass it's the same radius and it's not enough to say that we found oxygen in the atmosphere of a planet because we have to understand all of these properties in order to really understand if that planet is habitable or if that signature that we think might be life is actually life but i'm going to talk about that a bit later so when it comes to this whole diagram i do not study everything that is way too much that is way beyond me so what i focus on is how to go from the stars from how to go from what we know about the stars to the planets we can't currently directly measure the interior composition of a planet or even a planet's surface and again i'm talking about planets outside of our solar system we don't have that technology uh normally when we look at planets they end up being essentially one pixel so we can't measure um what they're made out of and yet like i said before it's absolutely important that we understand what a planet uh like the interior of a planet if it has tectonics it has all these different things going on so what i do is try to go from the star to the planet in terms of its composition and make models of the planet based on what we know about the star and this is all leading back to the fact that stars and planets are made at the same time and from the same material all right but how do we actually do this like what what what do we do all right so say that you have a star now light is produced within a star it's actually one of the main differences between a star and a planet is that a star produces light so you have light coming out of the star if there is nothing other than hydrogen within this star light would come out of it and it would be totally flat however that's not the case there are actually different kinds of of elements within this star so light comes out of the star and then it then hits one of these atoms one of these elements and it gets absorbed by that element now that atom will actually absorb light at a very specific wavelength according to the structure of the atom so what i mean by that is that we can tell if it's carbon or if it's oxygen that absorbs this light just based on the on the structure of that atom um so when we when we then receive that data about the stellar light there's gaps within uh the spectra that we're seeing so you see that rainbow and there's gaps within it so that's actually as a result of the light being absorbed by some of these atoms and then we convert that to be a spectra and that's that line that you're seeing and depending on how deep that line is or how wide it is we can actually determine how many atoms must have been in that stellar atmosphere in order to give us the signature from there we can then calculate the abundance or the amount of that element and so that's how we get element abundances from there uh we take the uh the element abundances and we use them as a proxy for uh the composition of a planet so we say that whatever we see is in the star is in the planet we then put them into models uh that we can create using just physics that we know about planets and build up mass radius diagrams so this is trying to build up the actual interiors of the planets in order to create models of the interior structure in mineralogy of exoplanets so uh so this is a pretty much the heart of what i do and i do this based on a database that i put together so this is called the hypatia catalog what i've done is i've combined about 200 different literature sources so this is data that other people have taken and i've smashed it all together into one massive database right now i have about 9 400 stars uh all of these stars are within 500 parsecs which is the same as 1600 light years which is the same as uh 10 to the 16 miles so that's like 10 pata miles if you know what pedo means okay but uh but this is so much data because actually the hypatia catalog is one of the few multi-dimensional databases in astronomy because i have elements inside of stars measured by different groups and some of those stars have planets so actually in total i have about 350 000 abundance measurements within the hypatia catalog so what you're looking at in this plot are all of the elements that i have these are 77 different elements and the number of stars for which these elements have been measured now i love this plot because it shows you not just which elements are fairly easy to measure inside of stars but also which ones we don't know a ton about um but you don't have to take my word for it all of this data is online and available to for free to anybody who wants it i have patientcatalog.com and you can go you can look at all of the different stars you can look at stars with planets you can plot with respect to different elements as well as uh some of the stellar properties and so everything is is ready and available should you like to look at it now people always ask so i i always like to give a little bio um my database was named after uh hey patia she lived around 400 a.d in alexandria and uh she was very well respected in her field uh she taught uh on math and astronomy and philosophy philosophy in fact she's one of the first known female astronomers unfortunately because she was so well respected within her community and partially because she was a woman which was fairly rare for for somebody to sort of be at this stature um she she was killed rather brutally but uh she contributed quite a lot to the field and so i wanted to honor her by naming my database after her so um so what i'll be sort of going over with you today is how i connect um stars and planets and life all as a way to understand uh planetary habitability and so what i'll be talking with you is how to go how i go from the host star and see how it might be influenced chemically so by the element abundances um from a planet how to use the stellar abundances as a proxy for the interior composition of a planet and then found finally how i sort of delve into some astrobiological needs so this is what life outside of uh our solar system might need all right so first let's begin with going from stars to planets now um for the last i guess 15 years or so um everybody who has observed stars with and without planets has realized one major thing that if a star hosts a giant planet so this is a planet that's like on par with jupiter or saturn the star hosts a giant planet it is always enriched in iron there's tons of iron within this these stars now the reason that we think that this is true is that you have to have a certain amount of raw elements in order to form a planet that's that big and so you have to have a lot of the basic building blocks iron is a basic building block for any of the planets in fact jupiter has like about seven to ten earth masses of iron in its core there's a ton of iron in these things so so we found that if a star hosts a giant planet then it is uh likely to be very enriched in iron ladies and gentlemen i'd like to introduce you to tater tot who has joined us today but as people have uh looked at at iron they also looked at other elements and they wanted to see um whether the uh whether other elements were also enriched in these stars at host planets especially star other elements that are useful for for building planets however despite the fact that dozens of groups looked at this there was no consensus on whether or not other elements are as necessary as iron but but the more you thought about the more you realized it had to be we had to have other elements we don't have just planets made out of iron that doesn't exist we also have silicon magnesium and aluminum there's a lot of other things that go into it so i thought about it for a little bit and then and realized that maybe the problem was that people were looking at it um on a one-to-one basis they're looking at one element in stars with without planet but that's not it's not how you form planets um so what this kind of reminded me of is uh taking a multivitamin sure you can take the vitamins and and that helps you be strong and stay healthy however it's actually much better for you if you just eat the salad like you're supposed to because of the way that all those different vitamins and minerals work together within your own body so then i realized well why don't we apply sort of a similar method and do this using a machine learning algorithm in order to to see what kind of elements um are useful for for for giant planets so what i did was i i put together an algorithm that's kind of similar to netflix but for planets okay so say that you watch netflix um and uh after a while netflix learns that you really like goofy 90s comedies it then takes that premise that you like goofy 90s comedies and applies it to all of the movies in its back catalog that you haven't watched and then suggests that you watch some movies uh and and predicts actually that you will like it to a certain percentage now this um this algorithm works really similarly in that what we do is we train the algorithm on the elements inside of stars that we know have giant planets so they're confirmed planet hosts with an assay algorithm to learn the the trends within those elements and then apply those trends to stars within hypatia that do not currently have confirmed giant planets then we predict whether or not uh those those stars are likely to host planets based only on their element abundances so this is how the presence of a planet will like influences the star and so what we found is that the algorithm returned a about 350 stars that had a greater than 90 probability of hosting a giant planet which is actually really cool i'm working right now to try to follow up and see if we can confirm some of these planet hosts because predicting a planet and then finding that planet would maybe be the coolest thing in my career on top of that though we also found that uh the right combination of elements uh that were important for forming planets was not just iron but it was our iron carbon oxygen and sodium and so it's not to say that uh the stars with these giant predicted giant planets are enriched in all of these elements that there's tons of carbon and oxygen now it's that that uh that these stars have the right mixture of these elements that um that meant that they are likely to host giant planets now this is really exciting because there's a variety of upcoming missions exoplanet missions both from nasa as well as the european space agency that is going after uh stars with planets and so having an idea before you start looking before you start spending all this telescope time on on these different um stars would be very very useful so that's one of the applications of this machine learning algorithm all right now so i've talked to you about going from how the planet might influence the star now what do we do when we want to understand uh the interior of a planet so some colleagues and i decided to look at the trappist-1 system now trappist-1 is um is a very small star it's very cool star it's about 12 parsecs away in the aquarius constellation and there were seven planets that were detected around it now this system is so small uh that um on the bottom you can see the comparison of the trappist-1 system compared to the our solar system so that's what you're seeing at the bottom so this is absolutely tiny in fact it's better to compare it to the moons of jupiter which is located at the top um because that's how tiny this system is and i do want to note these are these are not real photos these are artist renditions and um so we found this this uh system with seven detective planets and three of the planets plants e f and g we astronomers are not the most um imaginative when it comes to naming things my apologies other trappist one was named after beer so that's cool um all right so but the planets e f and g are located in the habitable zones so if there is water on their surface it's likely to be habitable my colleagues and i we we looked at the uh the mass and the radius of these of these planets and we realized that they were actually kind of puffy they seemed too light so what we decided to do is we took the element abundances within these different within the star and we made models of these planets based on their mass and their radius and so what this looks like is this so these is a it's called a phase diagram but the way you can think about it is that it's like a smooshed out pie chart and so that's what you're looking at at the bottom so that's what the 0 to 100 means it's just a pie chart then on the on the y-axis so on the up and down part the bottom is the core and the top is the surface now i won't get into all the mineralogy about it but the biggest thing that i want you to see is how much ice is there there is a huge amount of ice in fact trappist-1c on the left has eight weight percent water and trappist-1 f has 50 weight percent water in comparison earth has 0.02 weight percent water this is a tiny fraction compared to these trappist planets now this is super important because we with so many planets that were within the habitable zone people got very excited they kept saying oh we're these are definitely habitable planets we're so excited we should go and look at this blah blah blah but when you have this much water sitting on top of a planet it actually makes it really difficult for life for one thing when you have a planet you need that planet to be active you need there to be cycles moving different kinds of minerals around and constantly refreshing different energy supplies within that planet when you have this much water sitting on top of the planet it's really hard to have active geochemical cycles on top of that even if there was life on these planets the um the signature of that life would be completely drowned out pun intended by all of this water we wouldn't be able to distinguish it from the water so this is a really big deal namely if planets have to have active geochemical cycles in order to create a large biome for for life so they can start and also take hold this is absolutely necessary so here you're seeing a figure sort of showing what some of these geochemical cycles might look like um however and so right now while we can't measure the surface of a planet we can see the atmospheres of some of these planets and um but the problem is is that in order to see in order to really understand if these signals that we're seeing in the atmosphere are coming from life we have to be able to disentangle them from the signals that we that could be coming from these different cycles some of these cycles produce different kinds of gases and they could actually mimic the what we would expect to see from life for example um you have volcanoes and that shoots a lot of different kinds of material into the atmosphere if then we observe it we have to be able to say see what came from the volcano and what came from life and this is super important because ultimately when we're thinking about uh exoplanets and and their habitability we're really concerned with life and and we with that in mind we also need to make sure that um we have ever that life has all of the different raw ingredients available on the surface of that planet so this is very key so what you're seeing here is a normal pie chart with the average elemental proportions of the earth's crust so you can see there's a huge variety of different elements that are available to life and that help um help feed and and enrich the life that we have on earth so um my one of my colleagues and i decided uh what if we try to look at this from a star's perspective namely like i said we can't measure the surface of a planet um and it is difficult to measure the atmospheres of planets we may be measured about 20 or 30 different planetary atmospheres it's just it's really hard geometry has to be just right so what if we take this idea of going from the stars composition to the planet's composition and then take into account all of that with respect to life in other words are there elements available that life needs so um and i will start start out by saying that the colleague i worked with was uh hilary hartnett and she does um biology so this was a lot of new material for me um but uh but when it comes down to it life needs just the right things in the right proportions in order to in order to exist it's like baking a cake if your recipe calls for three eggs and you only have two that cake is not going to come out right and when it comes to life we want it to come out right so an example of that of applying that cake metaphor is is the photosynthesis equation now you can ignore pretty much everything except for what i've color-coded so um what these colors mean and sort of that top line is that in order for photosynthesis to take place you need 106 carbon atoms 16 nitrogen atoms and one phosphorus atom so you if you add all of those together and just those uh ratios then what you get out is life and so that's what you're seeing on that that uh c106 h263 that is life that is that is biomass and on top of that you get o2 that is the biosignature that we often look for but i'll come back to that and so that's what i was talking about before like when we uh when we need the oxygen signature is that that's where it's coming from however phosphorus is pretty difficult to get uh when when you are uh thinking about life and so this is really what we focused our energy on is trying to understand phosphorus from a stellar perspective so phosphate is difficult because the way that you get phosphate in there for phosphorus is that uh that rocks are weathered and eventually eroded such that it releases some of the phosphorus but this takes a really long time so it ends up being the bottleneck in the whole on the whole process um so so that was another reason why we wanted to see what all of this looked like in terms of of uh stars their planets and their life so what we decided to do is look at this this ratio of the 106 to 16 to one and see how that compared with uh nearby stars but also nearby planets so all right so this is just a fairly simple little table that we're looking at so plankton is what we're looking at before with the photosynthesis so you see the 106 to 16 to one and then you have uh the earth's crust uh bulk silicate earth silicate mars the sun as well as nearby stars and so uh all of this put together the way that we compared uh the sun and also uh nearby stars and planets is that we realize that the sun and nearby planets are actually enriched in phosphorus they have quite a lot of phosphorus and this was interesting because in comparison to other nearby stars uh there's actually not a lot of phosphorus within these other stars so our sun is preferentially enriched in phosphorus now that's really great for us because that meant that there was enough phosphorus on on earth in order for life to to take hold and uh and keep going however if there's not enough phosphorus that is available on exoplanets so planets outside of our solar system because these stars already didn't have a lot to begin with then that could be really really detrimental to life on other planets the hard part though is that um when when looking at all of the data uh there's actually not a lot of phosphorus measurements in nearby stars in fact we based all of this on only 100 stars which is not a lot of data remember the hypatia catalog in general has like 10 000 stars so uh this actually made us realize how badly we need to get more phosphorus measurements in order to understand those really critical bioessential element so those are elements that are absolutely important for life so that way we have a better understanding of the ultimate habitability of a planet now uh going back to that o2 signature i was talking about so this is trying to to put together the net planetary biological production so that's trying to see how much of an o2 signature is a result of biology but also how much is a result of geochemistry so at the end of the day when we're trying to understand is there life on this planet could there be life on this planet what's going on with this planet we need to see that there is a very very large o2 signature from that photosynthesis equation in order to really confirm that there's life on another planet we don't want to do a you know boy who cries wolf or and and uh say that there's life somewhere and then later uh realize that we were wrong we absolutely want to be sure that when we find life that we actually find life but in order to do that we we absolutely have to consider the geochemistry and the biochemistry of that planet um so going back to that really big plot that i showed you before um now i've taken all the different elements and have color coded them so uh those elements that are important for forming rocks and planets are in blue those are important for life uh are in yellow and since yellow plus blue equals green um if an element is good for both rocks and life then uh then that's in green now uh so we see that a lot of these really important elements uh they they've been measuring a lot of different stars but there's a handful of them that actually we don't know very well so that's nitrogen fluorine phosphorus chlorine and potassium so these are are important for for for life and for for planets and yet we've only been able to measure them in a relatively small number of stars um and uh but so it's but the reason that these are hard it's not because uh people like you know astronomers are lazy it's not because they didn't care it's because they're really hard to measure in stars um and it was for that reason and a number of other things that i actually started looking not just at solar-like stars so stars that are like our sun but i also started i've now started working uh at uh looking at em dwarf stars um so m dwarf stars are the smallest sort of normal star we call say that they're on the main sequence they're they're able to uh have fusion within their interiors and um and in fact uh the way that we can sort of compare them is that if that big white thing uh at the in the top corner is the sun then you can see that the the em dwarf star is the the small low mass star then there's a brown dwarf which is not quite a star jupiter which is a planet and then earth so you can see this different comparison so these and dwarf stars are absolutely tiny um and they're also really cool and they're cool because they have convection in our in their core um which is just not a very good way to get light and and uh outside and so you've all seen convection before there's convection ovens but there's also convection when you are boiling noodles so this is convection so this is just material churning itself within the star but because it's going in these different loops it's hard to get um energy out of that star and therefore m star m dwarfs are fairly uh not only they're small but they're also quite cool all right but getting back to sun like stars versus these m dwarf stars so uh some like stars make up about 22 percent of stars in our galaxy you can see this really nice image that i found online which outlines all of the different kinds of stars um uh the the standard methodology for uh astronomical names of stars is o stars are the biggest and then it goes oba fgkm uh like i said astronomers are not awesome at naming things so there's a rhyme and reason but they normally dig back thousands of years anyway so uh so sun-like stars make up about 22 percent of stars in the galaxy and it's around a sun-like star that we know of uh are the only habitable planet us um so as a result the uh some like stars make up about 88 of confirmed exoplanet host stars in comparison m dwarfs make up 76 of stars in our galaxy they are by far the most prevalent stars in our galaxy but they only make up four percent of confirmed exoplanet host stars now this gets a little tricky because when we're trying to detect a star or a planet around a star the way that we do it is we try to see how that planet influences the star for example you could have the planet go in front of the star and it dims the light this is called a transit another other way is that you can have a planet gravitationally influence like actually affect the star such that it kind of wobbles so this is called the radial velocity technique now when you are detecting planets using these two methods you are going to find bigger planets first it's easier to see bigger dips than light curve it's easier to see bigger wobbles so that what that means is that a lot of the star or a lot of the planets that we've detected so far are giant planets like jupiter but life is not super awesome out of jupiter it'd actually be really hard to live um so we want to find smaller rocky planets like the earth so it makes sense then to go for to try to find small planets around small stars so that's really important then and it's a good reason to try to look at these m dwarf stars we can find a lot of smaller planets and this is what's happening for um a number of upcoming missions that are sort of changing their focus to try to look at some of these small stars now on top of that um it gets a little trickier because we see with our eyes and so that means that we see in the optical band as named because of optics and some like stars are actually very very their spectra coming out of them are very easy to see they're very nice they look great so this is what you're seeing for the fg and k so flat lines you can see little dips in their curves it looks really good however when you look at the spectra of an m star in the optical band it looks like a mess you cannot tell what is going on here it's not obvious like where these lines might be and how how how deep these lines are and that's a problem because uh most of our telescopes are actually geared towards the optical band however with m dwarfs they actually do much much better not on the optical but in the infrared so this is a spectrum of an end dwarf star in the infrared it's very clean you can see the individual lines which have been measured by a collaborator of mine zach moss and so it's it's much easier to see but that gets into sort of another problem is that when you are on the ground and you're looking out at the stars it's really easy to see through our earth's atmosphere and the optical we can see the stars and so that's great however when we stitch switch to looking in the infrared a lot of earth's atmosphere which has water in it it blocks the infrared and so that makes things really really difficult and so um this is actually one thing that i'm sort of starting to to try to work on with respect to these mdorf stars is trying to understand better ways to measure them because if we find planets rocky planets around these small stars we want to be able to say like if they even could possibly be habitable so we need to be able to understand the elements within these m dwarfs but because it's so hard to measure them because they're dim because they're cool because their their spectra is best in the infrared to date we only know the um elemental abundances of about 150 m dwarfs only 150 that's so little we know almost nothing and yet they're the most prevalent stars it's so ridiculous however uh i've actually recently put together this really great project that i'm excited about that will allow my collaborators and i to try to measure some of these these m dwarfs and um we're doing it on the ground and eventually ideally we're going to try to do this in space so this is a big plan that i have to first measure them on the ground get what we can get but then take out everything that we do and then apply it to um one is a is a balloon that i have i'm hoping to try to to launch in antarctica i don't have money for it yet but i've recently submitted a proposal to nasa but also then to to try to launch a satellite which is one of the the goals that i have and so what do we want to do with all of this all right so what we want to do is actually pretty exciting we want to measure the some of the key uh elements that are important for forming rocky planets so that's um iron magnesium and silicon these are absolutely critical to forming rocky planets they make up about 95 of most rocky planets that's how that's how important these elements are and so what we're going to do is create a new methodology for measuring and then measuring these abundances in in these stars but then what we can do with this information is we can actually classify the planets so not every rocky star is going to be is going to be like the earth you could have a bunch of different kinds of things going on for example the um the planet in the top left that you're seeing um this this could be a super earth so much much bigger than earth but smaller than jupiter so we don't actually know what that kind of planet is going to be like is it going to be just like a bigger version of us or would it be a smaller version of a gas giant planet which is pretty crazy um the the planet that's on the top right kepler 107c that actually could be classified more closely to like a super mercury so it's a very dense very compact but but bigger than mercury is for us um in the bottom left is 55 cancri e which is probably closer to a super puff planet so it has a huge amount of gas and a smaller core and so it's more like a smaller version of jupiter um and then uh k2229b uh we're not even sure what it might be because there's a wide variety but like i said we have all these different uh planets and their different properties and so it's really important for us to understand uh what these planets might look like if they're similar to earth or if they come from a variety of different sources all right but with that i just want to say i've come at you with a lot of information today i started by talking to you about the first generations of stars the way that they lived and died and how they influenced the the rest of the universe i showed you how the elements in the periodic table are created inside stars and then how we're actually able to measure the stellar elemental abundances then i walked you through my personal research uh connecting elements in stars to planets and life all in the pursuit of exploring what it means for a planet to be habitable this was a lot of ground but that's a good thing because i wanted to show you the interconnection between all of these phenomena how the stars can influence the planets and how planets can affect the stars all of this in just one tiny chunk of our milky way galaxy that we can see in our backyard the more we look outside of our solar system the more we can observe um variations in the stars their colors their sizes but also their planets and the way that those can vary from us and also from each other all of these questions hold so much for potential for exploration and for wonder from planetary habitability to galactic archaeology so with that thank you excellent thank you very much dr hinkle and we had received many questions before the talk and several since the talk started so i'm trying to combine them together and i think i managed to condense them into uh five or so hope that's okay that's great and uh just a comment uh on how you handled the catios all right which are i guess cameos by cats during your time very very well done and you guys couldn't tell but uh she was around the whole time she was circling she was underneath me so it's just the one catio but it could have been many many more a star was born okay so the first question um was do you think or what evidence exists that life exists elsewhere so i love this question because um i i think it's it's really at the heart of everything that i do so i look i look for signs of life um because i ultimately think that they do exist i i do think that um you know given the sheer number of stars and the number of planets and like even if you have to have just the right conditions that those conditions have to pop up in other places so i do honestly think that there is life outside of of our solar system with that in mind um i unfortunately do not think that it's as much like star trek as i would like it to be that there's not just like you know other life other civilizations that are just sort of nearby happen to be around the corner i think ultimately life is going to be fairly few and far between so while i of course would love to see detections of life in my lifetime i am i'm not holding my breath i see that you also have a friend with you today yeah i've been visited it seems it's contagious um okay we had a question about um i guess it's best phrased as can students use the hypatia catalog for machine learning projects and i would turn that around to say how could educators use yeah everybody can use the hypatia catalog so so it's set up to be as fairly easy as you want or as complicated as you might like it to be so i showed an image of of like the database itself and i've set a number of defaults so that way you don't have to make any decisions if you don't want to but all of the data you can you can access it you can have students look at it online you can play with the different buttons see the different um uh patterns that you can get but you can also download the data you don't have to be on in your web browser you can just download it uh any old way that a programmer might like and then and then play with it in that way and so um i've had a number of people talk to me about ways that they might use this in their classroom and i'm more than happy to have have people use it to try to get their students excited about elements inside of stars and just as a bit of an add-on to that question how does one validate the um the catalog the the context of the catalog so this is um actually one of the biggest issues that i hit when i was a graduate student when i first started putting together all this data so i mentioned that the hypatia catalog is multi-dimensional so that what that really means is that multiple people have measured the same element within the same star and so what i've done with the hypatia database is that you can actually see everybody who's ever measured it and what they got i did a little bit of fine tuning i won't get into that but um so you can see how similar the these different results are and then if you choose to you can actually remove some of the data if you don't think it quite matches or you can download it all you can even download individual data sets so um there's a lot more i could go into but it's fairly technical so i will i will just leave it at that you can see how well everybody agrees or not um within the database i have to just click on the numbers in the table okay and i think this is from one of our younger viewers uh what advice would you give to a young girl who wants to be an astronomer oh i love this question um all right so um i have a number of things that i've thought of and also i have a lot of resources online at um on my my website which is nataliehinkle.com um so one of the the main things i like to tell people is that studying astrophysics studying astronomy it's not it's not about being smart um it's actually it's more about working hard it's about being determined and and about really following something that you love i've always loved math i took extracurricular math classes when i was in middle school because i was a giant nerd i'm still a giant nerd um but uh but it's about really pursuing something that that you love and just continuing to follow through on that and so it means if you don't get something it doesn't mean you're dumb it just means you need to take some more time to really try to understand that so so determination is is really one of the big things um the other thing i i do try to have remind people because i also try to remind myself is um not to compare yourself to other people um i am what i consider to be a fairly well-rounded person um i i can do math i can do physics i can also i like reading um i'm also i do athletics i do different sports um but i'm not the most awesome at any of them i've never been the best i have never won first um i've always sort of been like pretty good at a lot of things but never the best at one thing and for a long time i really struggled with that because i saw people around me just getting like you know straight a's in all of their college classes and i was not getting that and it made me feel really bad about myself but then i realized um you know academia it's not just about the math and the physics it's also giving talks it's also writing papers and it's trying to communicate and that is a skill that i had that they sort of lacked and that when i realized that that um my well-roundedness made me unique and made me who i am and that that was my strength and so that that helped me a lot was to not stop comparing myself to other people so actually when we get back exams i stopped asking what other people got um there was this one time when uh i thought for sure i had failed an exam i thought for sure i had failed it and i got it back and i got a b plus and i was so happy that like i was like oh my gosh i did like way better than i thought and then the person next to me told me that they got an a and i felt so bad about myself and like all of this happened in one minute like one minute and i was just like okay i need to stop like this is ridiculous and i can't i can't put myself through that okay and the final thing my final piece of advice is uh to celebrate the wins to celebrate your victories um in academia you write a lot of applications for for um you know graduate school um for jobs for postdocs uh you write proposals and you get a lot of rejections and it it hurts it hurts every time even if you're expecting it um yeah i've i lost count of how many different kinds of applications to things that i've written so uh so what i then try to do is that when i get something when i win something is that i celebrate it so hard because it's it's a rare thing it's not expected it's hoped for but it should never be expected and so you know i will post about it i will treat myself to sush like huge sushi feasts i will get like ridiculous thing like i'll buy myself presents i will to tell people and continue telling people and hey by the way have i told you that i got this thing because it's so critical to just celebrate your win celebrate yourself and all the hard work that you did because lord knows that there are so many other times when you got rejected and and it just didn't follow through so i think those are my my main pieces of advice good advice um and then here's a three-part question what impact would technological advances have basically on your research or on your type of research and it's divided into three parts um on the basis of the many questions we received the one first one has to do with the james webb space telescope and bio signatures okay wait that is that one the first part yeah okay okay all right uh okay so uh so james webb um is gonna be uh once it launches would be really awesome because um it's not only going to do a lot of stuff like in in the very far parts of the universe but it's also going to be measuring um a lot of exoplanets and so one of the cool things is that it will be able to measure the composition of exoplanet atmospheres and so this will really impact my science because one of the things i really want to do is go not just from the start of the planet but then go from the start of the planet to the atmosphere and have this whole cycle connected from not only um the observations but also how we can we can um understand the planet itself and so like i said right now we only have about 20 to 30-ish exoplanet atmosphere measurement and so once james webb goes up there will be so much data and that's going to be really really exciting in fact i have a student right now who um when we were talking about james webb he kept calling it the james fricken web telescope because he's so excited for it so we referred to that in class for like the whole the rest of the time um so with that once we have the compositions then we'll be able to see if there are certain planets that might have like hints of bio signatures and then we can try to observe those a bit more get the abundances of the star and then understand the planets you know it'll be it'll be actually this like huge suite of data just to like attack with everything that we have so that'll be pretty pretty exciting okay i'm just making a note to refer to it now as the jf yeah yeah it's little f big j big w little f good point um and the second part of that about technological advances and impacts would be on circumbinary planets so okay circuit binary plan so i showed um that little uh movie at the beginning this is actually from a paper that uh that i wrote a couple years ago and so um circumbinary planets are are interesting but we haven't observed a ton of them um i think to date there's maybe i'd say 50 where we've been able to observe these planets and so uh so that um i'm not sure what that would be like as far as technology because while they're interesting it's not like the focus is to find more circumbinary planets they end up being kind of um fortuitous that we happen to observe them because part of it is also that uh we we are able to confirm that not just you have two stars that are fairly close to one another but that also has a planet because actually a lot of stars have binaries but some of these binaries are very very very very very very far away and so then does it count as a circumbinary if like the planet's not really getting influenced by a star so yes i'm not sure how how big um any technological advances will will really change that it just it might just be more of a matter of time so we could observe these these planets around different kinds of stars okay and then the third part of that has maybe it's more of a timeline question about um direct observations of surfaces and or atmospheres yeah okay so this um could probably happen um not maybe not quite the way you think but probably in about 20 years maybe okay so i actually uh was a co-author on a paper where we discussed the steps to go through and actually do this so um once you find a planet that's uh sort of the right size has the right kind of star you have the abundances for it and so everything sort of looks good kind of the next steps after that are to observe this this planet using different color uh photometry and so so that's um actually the way that you see a lot of normal astronomy pictures is our photo photon photometry um unlike spectroscopy which i described to you and so what we would first do is look at photometry in different colors and i actually mean like different colors so like one would be blue and one is red and one's yellow i think and so you combine those to get ultimately the color of what that planet looks like if the planet is a bright blue then that's going to be indicative that it is um there's water some water on the surface that's reflecting back some of the the light so hence why it's bright if it's a pale blue there might be a huge chunk of clouds uh on top of that um but likely still uh you know still some water if it's like a yellowish color then it might be more like venus um and then uh with like you know just all sorts of weird uh molecules in the atmosphere but if it's red then then it might be more like mars uh where there is basically no atmosphere we're just looking at dirt and nothing else so uh so that would be the next step um after that uh then we start really having to rely on large telescopes that are in the works but haven't really been um built yet so this is the 30 meter telescope and the giant magellanic telescope um and so then we'd need to be able to take a decent amount of time to uh to observe these planets to see if we can um if we can see reflectance of the light from the star off potential water so that's really how we would observe the surface it's not quite directly the surface but it's some of the surface then if we spend even longer on it i'm not going to get into the specifics but ultimately what we want to do is make sure that um not only we seeing the surface but we're seeing some cloud variation and possibly signatures of vegetation and so yeah so that will take i think those telescopes are slated to be built in like 20 30-ish and then with all of that time that you need to to observe this and by time i mean like hundreds to thousands of hours uh maybe another 10 years after that so so that's kind of the hope that in about 20-ish years that we'd be able to observe a planet that has hints of life and then the final question is um what chemical ingredients are considered necessary for life this builds nicely on some of the previous talks we've had in this series and you mentioned the ingredients so i think it's a good way yeah so um so actually that was a lot of that one um histogram that i showed so uh i'm not a biologist and i don't pretend to be so uh basically i'm just gonna read it off of that slide um [Laughter] so you need carbon and oxygen oh also nitrogen uh sodium magnesium phosphorus sulfur chlorine potassium calcium scandium and fluorine sorry i just yeah i don't know it as well but i know that those are um actually took a poll of a bunch of uh biologists to be like what elements do we absolutely need to measure in the stars so we could try to understand them in planets and therefore have them available to life and so these were all the elements that they came back to me and told me okay well and having mentioned uh catios and seeing uh especially with cats with names derived from foodstuffs and seeing uh noodles in your talk i'm reminded that it's just an hour past your dinner time because of the time zone difference so but we're out of time uh apologies to people whose questions have not been asked we will try to get you answers for them um and we just really want to thank you very much for your time today it's uh very inspirational especially for talking with our audience and our graduate students earlier today so thank you very much once again well thank you so much for having me i really enjoyed it and if people uh want to reach out to me you can find me on twitter at natalie underscore hinkle h-i-n-k-e-l that's a fairly common misspelling um also my website which you can spell right or wrong it'll still get you to the right place um i have a lot of information there um i also have a variety of different um online articles that i've written you know public articles uh to explain for example why we have planets of certain sizes and not other sizes why we don't have giant rocky planets or really tiny gaseous planets um as as well as a couple of ted talks that i've given um this is the kind of outreach that i like to do so um yeah and if you have any questions feel free to email me um everything's my name natalie.hinkel at

gmail and um yeah and i'm more than happy to take your questions so yeah so thank you all for having me thank you very much once again

2020-12-24 16:48

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