All Hands Meeting 2016

Group discussion after the talks

We held our second EOS All Hands Meeting at Hacienda del Sol in September 2016. It has been a fun two days of  science talks with lots of EOS results and the start of several exciting new projects!


Dinner at the All Hands Meeting

Group discussion after the talks

Fred Ciesla and Sandra Pizzarello

Serena Kim, Ilaria Pascucci, and Min Fang

Gijs Mulders and Joan Najita

DeWayne, Jacob, Krishna, and Lucy

Planet-Forming Disks

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The solar system formed when an enormous cloud of gas and dust began to collapse and rotate. As it spun faster and faster, it formed a disk which helped feed into forming the young sun in the center of it all.  From this disk, small particles of dust started sticking together, and continued to grow into objects that were centimeters, then meters, and kilometers in size. Eventually some of these planetary embryos collided, resulting in even more massive, planet sized objects or sometimes satellite moons. The characteristics that make up planet-forming disks in our solar system and in others has everything to do with the planets that are born out of it. But planet-forming disks continue to hold many mysteries about the process of planetary formation and how this process might translate to extrasolar systems across the galaxy. Uncovering the details of the process can also provide insights on how organic materials, the ingredients of life, were produced. Measuring disk masses is an important first step in answering these questions and one of the key goals of the Earths in Other Solar Systems program, according to Josh Eisner, PhD., associate professor of astronomy at the University of Arizona. Eisner and his team measured disk masses in the Orion region of the sky using the Atacama Large Millimeter Array (ALMA) to obtain high resolution images of disks in millimeter and submillimeter wavelengths. They were interested in this region because most stars in the galaxy, including the sun, probably formed in similar regions, Eisner said. What he was trying to understand is what disks were like in their initial conditions, which is before any planets start to form. What was found was that low mass disks are common, according to his paper published in April. Creating gas giants like Jupiter requires a lot of mass, and as it turns out, very few disks (ranging from 2-20%) are massive enough to create a Jupiter-sized planet. However, Jupiter-sized planets are relatively common and seem to form from disks when enough material is present, according to Joan Najita, PhD., astronomer at the National Optical Astronomy Observatories. So in order for giant planets to form, planetary formation seems to be more efficient than previously thought. Another interesting characteristic of large disks is that scientists observe more rich organic materials in systems with larger disks, according to Najita. Najita observed this by comparing the ratios of molecules containing carbon, such as hydrogen cyanide (HCN), with molecules containing oxygen, such as water in disks. What they found using the Spitzer Space Telescope was that systems with massive disks are more efficient at storing oxygen in the giant planet region further out. This prevents oxygen from locking up more carbon in the form of carbon monoxide, and instead leaves carbon available to be combined with other elements that create organic molecules, such as HCN. This and other chemical trends in disks are being followed up as part of the Earths in Other Solar Systems program. The fact that this can be determined in disks means that the ingredients for life are created pretty early in solar system formation. Overall, planet-forming disks begin making planets earlier and more efficiently than we thought. There’s still a lot of work to be done to confirm this. But “this is the next...

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Climate Stability and a Hike along a Triassic Coral Reef

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From the DistantEarths blog of Daniel Apai After two hours of hike up on a rocky trail in the Italian Alps, finally I stand at an elevation just above 2,500 meters, staring at a breathtaking and unique mountain range, the Dolomites, that holds an exciting clue to the habitability of our planet. With gigantic sharp white-gray peaks emerging from the lush green of Alpine meadows, these mountains rise where the African continental plate has been slamming violently into the European plate for millions of years, forcing rocks up thousands of meters  — and giving birth to the geologically young Alps. In a trip zig-zagging Europe — visiting observatories, universities, and workshops — I stopped briefly in South Tirol for a few hikes. The most picturesque of them took me up to the Three Peaks of Lavaredo (or Tre Cime di Lavaredo), three 3,000m-high peaks, one of the gems of the Alps. Dotted by rifugi (mostly little huts, but at the easier trails often with nice cafes) the trails are popular among both tourists and locals. They offer an incredible view ascending towards the peaks, before joining an old network of high-altitude Alpine hiking trails, many of which take a week to complete. The Dolomites are a unique mountain range within the Alps: their composition and history is different from any other in the Alps. They also hold an exciting clue to the process that keeps our planet habitable. Named after a relatively rare form and unusually stable form of carbonate rocks, dolomite, the mountain range’s unique color and composition was noted long ago and, for some time, posed one of the mysteries of geology. Now we know that the majestic dolomite layers in the Dolomite mountains are — amazingly — the work of tiny organisms: it is a very thick layer of ancient coral reefs. During part of the Triassic period (about 255-199 million years ago) the region was part of a shallow sea, which was slowly pulled deeper and deeper. But corals, only capable of living in the upper photic zone of the sea (where enough light is present for photosynthesis), kept on building their reefs higher and higher, managing to always keep the top layer of the coral reef close to the sea surface. With the sea floor sinking and the coral reef growing higher, these tiny animals constructed one of the giant carbonate deposits of the Triassic period. As most geological periods, the Triassic also did not end well: in fact, it ended with the Triassic-Jurassic mass extinction, one of the greatest extinctions known, which eradicated about 50% of the known marine species. This extinction — occuring just before the Pangea super-continent began to break apart — paved the way for dinosaurs to become the dominant land animals in the Jurassic period that followed. The giant coral reefs of the Dolomites sank further and were covered by sedimentary layers and laid in depth for the next two hundred million years. Only recently, when the African continental plate collided again with the European plate, were the ancient coral reefs forced to resurface again. Together with other Triassic layers these rocks — once a seafloor — were now pushed up thousands of meters to become the dramatic high peaks of the new-born Alps. Once exposed to snow, ice, rain, and wind, the layers began to rapidly erode, creating the picturesque formations I was able to see today. But the Dolomites’s story also holds a clue to why we are here: amazingly, the...

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Taking Pictures of Alien Worlds

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We know of a lot of exoplanets. Most, though, we know of only by indirect means – typically via the planet occulting some of the starlight during an eclipse or changing the star’s velocity due to the planet’s own gravity. As of today (June 29, 2016) the exoplanet database lists 2,933 confirmed planets, with another 2,504 probable candidates, totaling to about 5,000 bona fide planet detections. Of these, only seven have been successfully imaged. Why, if we know of so many planets, do we only have images of so few?   The answer is, as you may guess, complicated. Some of the challenges are technical – for example the size of current telescopes and the distortion of the Earth’s atmosphere restrict imaging capabilities to the outer parts of alien solar systems (typically past the orbit of Saturn). Other challenges are more fundamental. The capable targets are necessarily the youngest and most massive, which translate into the brightest since planets cool as they age. These limitations are so extreme, in fact, that imaging other planets is only currently possible for worlds that are less than about 2% the age of the Earth. This leaves very few stars, on the order of a few thousand, that are close enough and of the right age that their planets may be directly imaged. HR 8799: The first directly imaged extrasolar planetary system. Planets b, c, d, and e together consist of roughly twenty times the mass of our own solar system. (Images from Marois et al. 2010).   In suit, directly imaged exoplanets are quite rare – but the results of the few successes showcase the beautiful complexity of other planetary systems. For instance, the HR 8799 hosts four planets that are each roughly five to ten times as massive as Jupiter – accounting for more than twenty times the mass of our own solar system, all outside of the distance of Saturn’s orbit (Marois et al. 2008, 2010). Monstrous planetary systems such as this exemplify the existence of solar systems that would have been considered science fiction prior to their discovery. Extreme Adaptive Optics Systems SPHERE (left) and GPI (right). Two of the current planet hunting instruments installed on 8-meter class telescopes. EOS scientists are conducting a search for giant planets using SPHERE, pictured left. Image credits: ESO (left) and Marshall Perrin (right).   Currently there are several ground-based instruments with unprecedented sensitivity that are beginning to discover gas-giant planets in the outer regions of nearby solar systems. EOS scientists Kevin Wagner and project lead Daniel Apai are conducting a search for planets using SPHERE – the most complex and expensive of the latest generation of planet finding instruments (stay tuned for results!). Soon, bigger ground-based telescopes will push capabilities to smaller masses (e.g. Saturn-like worlds) in orbits more like those of the planets in our own solar system. But still, the potential to image an Earth-like plant remains for the distant future. Succession of NASA flagship space telescope primary mirrors. The proposed HDST (“High Definition Space Telescope”), if selected for mission development, will explore alien Earths for atmospheric biosignatures, and will allow the first scientific survey for life outside of Earth. Image credit: C. Godfrey (STScI).   Perhaps the best possibility for detecting truly Earth-like planets is direct imaging with a large (12-16...

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Building Planetary Systems: The Genesis Database

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  The planets of our solar system formed out of a swirling disk of gas and dust billions of years ago. The material that accreted to become the Earth lacked water and organic material because it formed at a distance that was too close to the sun for such materials to condense and collect on the new-born planet. Despite Earth’s rocky start, life organized, evolved, and now dominates this small, terrestrial planet orbiting 93 million miles away from the sun. How can this be? Earth now exists within the habitable zone, which means that now liquid water can exist on the surface without freezing or boiling off into space. The water and organic ingredients for life that we have today were delivered to Earth objects after its formation and the atmospheric pressure on Earth allowed stable liquid water to exist. Scientists understand this delivery process (and more) using computer models that simulate the formation of our solar system. “By applying these models to other planetary systems, we can investigate if exoplanets receive water and organics in the same way as Earth,” said Gijs Mulders, PhD., post-doctoral researcher in the Lunar and Planetary Laboratory at the University of Arizona. The Genesis Database is a new tool and resource that will allow scientists to model the final stages of planet formation, according to Fred Ciesla, PhD., associate professor in the Department of the Geophysical Sciences at the University of Chicago. What makes this database so innovative is that it will run thousands of models at once—a whole order of magnitude more than the number of simulations that have previously been run, Mulders said. More models allow for more examples of what can happen for a variety of planetary architectures. Both Ciesla and Mulders are interested in characterizing rare events. The Genesis Database will allow them to have a large set of simulations that reflect both the diversity in exoplanetary systems and some of the specific details of our solar system. “If we change where we start each body, even just a little bit, we can get very different results. The number of planets may be different, their masses, or their compositions.” Ciesla said. “So if we want to understand the likelihood of getting something like the Earth, then we have to run a very large number of these simulations and think about the probability of getting different outcomes.” Building a Model To understand this, we first have to understand the basic model for solar system formation. First, disks containing the material for planets swirl around a star. Planets form like giant snowballs: Van der Waals’ interactions start to stick micrometer and millimeter-sized particles together, they then combine to form meter-sized objects, then kilometer-sized objects. These then coalesce and eventually form planetary embryos, roughly the size of Mars. In our solar system, this is roughly the largest body objects that can grow while the disk is still present. Once the disk is gone, the giant impact phase begins. The giant impact phase is where most modeling begins. “This is an extremely important stage in planet formation because water and organics are delivered to the Earth,” Gijs Mulders said. “And we expect this to be the case in other planetary systems as well.” Models start with many planetary embryos scattered around a star....

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The Future of Exoplanet Research

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By Daniel Apai Includes interview with Nick Siegler and Shawn Domagal-Goldman Over the weekend, at the Hilton on the San Diego Bay, a small group met to speak about the present and future of NASA’s Exoplanet Exploration program. To someone not in the field of exoplanets the talks and debates may have resembled science fiction: giant space telescopes, rockets and spacewalks, hyper-precise measurements of stellar motion, search for alien life, exploration of volcanism on exoplanets, laser-combs, starshades, and other Earths across the Galaxy were just a few of the topics that were debated. The memorable images included cows illuminated by lasers in a Nevada desert. It was a fun meeting and a timely one, too. The field of exoplanets is hotter than ever: we learned that planets are literally everywhere and that planets with sizes similar to Earth are the most common among the known planets. Many of the stars (probably 1 in 4) harbor about-earth-sized planets with stellar heating similar to Earth. Not only did we learn about the frequency of the planets, but also about their properties. New missions and instruments are being built and planned, conferences and school galore, and amazing discoveries are made almost weakly. The enthusiasm is palpable in the field; yet. we know that reaching our grand goal of finding extraterrestrial life is going to be anything but easy. We can only find life if it produces a signature that is detectable from vast – literally astronomical – distances. Seen from space humans, trees, elephants, or even whales are undetectable and unremarkable, yet Earth would reveal its secret to an outside observer through the surprising abundance of a highly reactive gas, molecular oxygen. Oxygen is and has been produced by  advanced photosynthetic organisms, first in the ocean and then on land. About 2.3 billion years ago oxygen has saturated the planet’s surface and rapidly accumulated in vast amounts in our atmosphere, From that point on Earth’s atmosphere became a glowing indicator of life for the entire Galaxy – at least, for civilizations that are slightly better in building telescopes than we are. So, starting from the only example we have, NASA’s Exoplanet Exploration program is aiming to build a telescope that will look for oxygen or other similarly odd gases in other earth-like planets atmospheres as possible signatures of life. In a perhaps unusual consensus, the exoplanet community is united behind the most important goal, surveying nearby exo-earths for biosignatures. Few other approaches to detecting extraterrestrial life seem feasible. Although the goal is clear, possible approaches and ideas are plenty: the abundance of proposed approaches stems from the fact that no telescope that exists today (or at least, accessible to astronomers) is capable enough to directly search for biosignatures in known exo-earths. Building one that will be up for the job is not going to be easy: in fact, right now, we do not know how good exactly that telescope would need to be, what capabilities it would have to have — and we don’t know how we would build it. Guided by the vision of finding extraterrestrial life, astronomers, astrobiologists, technologists, engineers, project managers are all working together to come up with concrete plans for such telescopes. Our goal is to create at least two different designs for life-finding telescopes by 2019. The year is important, because in 2020 the astronomical community will issue a major report, the Decadal Survey. This study...

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Meteorites: Time Capsules of the Solar System

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Just before 4 a.m. on June 2, Arizona’s night sky seemed to momentarily catch fire. A meteor, about 5-feet across, burned through the atmosphere at 40,200 mph, according to NASA estimates. The small debris that reached the Earth’s surface are called meteorites, and can be used to study the origins of the solar system. Credits: NASA/MEO Meteorites can be made out of iron, stone or rarely, both. Scientists at Project EOS are most interested in a subclass of stony meteorites called chondrites, because they congealed during the formation of the solar system and have been left virtually unchanged ever since. They are, in essence, time capsules from more than 4.5 billion years ago possibly carrying the starting materials from the early solar system to Earth, according to Maitrayee Bose, PhD., assistant research professor in the School of Molecular Sciences at Arizona State University and member of EOS. “What we’re doing in this part of the project [EOS] is we are trying to understand the organic inventory of the early solar system and to do that, we’re studying organic compounds in meteorites,” said Tom Zega, PhD., associate professor in the Lunar and Planetary Laboratory at the University of Arizona. Of the different kinds of chondrites, those called carbonaceous chondrites are the most interesting for EOS scientists, because they contain relic materials from the early solar system. The materials remained virtually unchanged prior to being delivered to Earth and contain ingredients for life in the form of organic compounds. “The finding of compounds that are also part of the biosphere, such as amino acids… has led to hypotheses that the input of these compounds might have helped the origins of terrestrial life, and maybe could do so in other stellar systems,” said Sandra Pizzarello, PhD., emeritus professor and research professor in the School of Molecular Sciences at Arizona State University. Opening the time capsule Meteorites provide many clues about the past. Scientists can determine what a meteorite is composed of, the concentration of elements within the meteorite and where the grains from within the meteorite originated. So how is this done? First, Bose receives a sample of a meteorite in her lab from Johnson Space Center. The sample is only tens of micrometers thick—less than half the width of a human hair. She surveys the meteorite’s surface using a secondary ion mass spectrometer capable of measuring at the nano-scale (NanoSIMS). This tool allows her to map the meteorite for carbon, hydrogen and nitrogen isotopes within the sample and determine the ratios of each isotope. Isotopes are different forms of the same kind of element which contain an equal number of protons but a different number of neutrons.   The mapping reveals tiny, less than 1 micrometer-sized locations in the meteorite whose isotopic compositions can differ throughout the meteorite as a whole. The meteorite’s composition can then be compared against the isotopic composition measurements taken from other meteorites within our solar system and also with astronomical structures outside of our solar system including material in the interstellar medium (ISM), stellar nebulae, ancient stars or dust shells around other stars using radio telescopes. From this information, Bose can confirm the meteorite’s origin. Zega then takes the sample and focuses on an area of interest, such as an area with an isotopic composition suggesting...

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Dust grains, frogs, and the formation of habitable planets

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The Sun’s planetary system, like the many other systems discovered in the last 2 decades, formed out of a protoplanetary disk. These disks are a natural by-product of star formation (almost every young star has one) and consist of a lot of gas (mostly hydrogen) and a small amount of solid dust particles. On timescales of hundreds of thousands of years, these dust grains collide and stick together, forming larger and larger bodies that eventually become asteroids, comets, and planetary embryos. While the Sun’s protoplanetary disk is now long gone (disks typically dissipate on a timescale of a few million years), the planets hold clues to the disk’s properties. For example, the fact that the planets all lie in the same plane indicates that the disk was relatively flat, and the observation that the inner terrestrial planets are small and rocky while the outer planets are massive gas giants indicates that the snowline (inside of which water ice could not survive) was located somewhere between Mars and Jupiter. It is clear then that the properties of planets reflect, on some level, the environment in which they formed, and that understanding the physical and chemical structure of protoplanetary disks is a crucial step to understanding the ubiquity and diversity of planetary systems. After moving to Chicago and becoming part of the EOS team in October 2015, I have been working on one question in particular: the vertical distribution of dust grains in planet-forming disks. It is usually assumed that, while small dust grains are well-mixed vertically, large grains are concentrated in the disk’s midplane. This picture comes from comparing the processes of gravitational settling (which acts to bring solids to the midplane) and turbulent diffusion (which tries to mix solids back up to the disk atmosphere). For large grains, settling is more efficient. For small grains, mixing is thought to win. However, this approach neglects collisions between dust particles which might limit the mobility of the grains. In a way, it is like constructing an approach for crossing a busy road without taking into account collisions with passing cars (please don’t!). Continuing along these lines, a more accurate depiction of what happens when collisions are included is the classic video game Frogger (readers born in the 90’s or later are encouraged to play a few rounds before reading further). In the game, the player tries to navigate a frog (or, a dust grain) from one side of the road (the disk midplane) to the other (the disk atmosphere), while trying to avoid cars (other dust grains). Experienced players can tell you that successfully crossing the road becomes harder when the number of cars is increased, or when the frog moves much slower than the cars. This is precisely what Fred Ciesla and myself found when simulating vertical diffusion/settling in the presence of collisions: efficient vertical mixing of small grains is not possible when the dust content is high, or when the turbulence is weak. This trapping of small grains could have important consequences for certain astro-chemical processes. For example, the surfaces of small grains play an important role in the formation and transport of water and other volatiles. Collaborating with Ted Bergin (University of Michigan), we are now beginning to couple dust evolution models to astro-chemical models in order to study how dust...

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Hubble Directly Measures Rotation of Cloudy ‘Super-Jupiter’

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Astronomers using NASA’s Hubble Space Telescope have measured the rotation rate of an extreme exoplanet by observing the varied brightness in its atmosphere. This is the first measurement of the rotation of a massive exoplanet using direct imaging. “The result is very exciting,” said Daniel Apai of the University of Arizona in Tucson, leader of the Hubble investigation. “It gives us a unique technique to explore the atmospheres of exoplanets and to measure their rotation rates.” The planet, called 2M1207b, is about four times more massive than Jupiter and is dubbed a “super-Jupiter.” It is a companion to a failed star known as a brown dwarf, orbiting the object at a distance of 5 billion miles. By contrast, Jupiter is approximately 500 million miles from the sun. The brown dwarf is known as 2M1207. The system resides 170 light-years away from Earth. Hubble’s image stability, high resolution, and high-contrast imaging capabilities allowed astronomers to precisely measure the planet’s brightness changes as it spins. The researchers attribute the brightness variation to complex clouds patterns in the planet’s atmosphere. The new Hubble measurements not only verify the presence of these clouds, but also show that the cloud layers are patchy and colorless. Astronomers first observed the massive exoplanet 10 years ago with Hubble. The observations revealed that the exoplanet’s atmosphere is hot enough to have “rain” clouds made of silicates: vaporized rock that cools down to form tiny particles with sizes similar to those in cigarette smoke. Deeper into the atmosphere, iron droplets are forming and falling like rain, eventually evaporating as they enter the lower levels of the atmosphere. “So at higher altitudes it rains glass, and at lower altitudes it rains iron,” said Yifan Zhou of the University of Arizona, lead author on the research paper. “The atmospheric temperatures are between about 2,200 to 2,600 degrees Fahrenheit.” The super-Jupiter is so hot that it appears brightest in infrared light. Astronomers used Hubble’s Wide Field Camera 3 to analyze the exoplanet in infrared light to explore the object’s cloud cover and measure its rotation rate. The planet is hot because it is only about 10 million years old and is still contracting and cooling. For comparison, Jupiter in our solar system is about 4.5 billion years old. The planet, however, will not maintain these sizzling temperatures. Over the next few billion years, the object will cool and fade dramatically. As its temperature decreases, the iron and silicate clouds will also form lower and lower in the atmosphere and will eventually disappear from view. Zhou and his team have also determined that the super-Jupiter completes one rotation approximately every 10 hours, spinning at about the same fast rate as Jupiter. This super-Jupiter is only about five to seven times less massive than its brown-dwarf host. By contrast, our sun is about 1,000 times more massive than Jupiter. “So this is a very good clue that the 2M1207 system we studied formed differently than our own solar system,” Zhou explained. The planets orbiting our sun formed inside a circumstellar disk through accretion. But the super-Jupiter and its companion may have formed throughout the gravitational collapse of a pair of separate disks. “Our study demonstrates that Hubble and its successor, NASA’s James Webb Space Telescope, will be able to derive cloud maps for...

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The curious case of KIC 8462852

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The curious case of KIC 8462852 by Theodora Karalidi   Discovering the first planet, other than our Earth, that hosts life is one of the holy grails of astronomy. This is a difficult task since planets that could host life are pretty small compared to their parent star, and they are so far away from us that all the information on possible life, clouds, oceans or continents on the planet is hidden in one pixel. Theorists like myself are developing codes that model the signal of different worlds and try to match it with the signals we observe from exoplanets. Trying to get as much information as possible from one pixel is a pretty challenging, but also fun work! Recently, amateur astronomers inspecting Kepler observations noticed something weird was happening around star KIC 8462852: the observations showed lots of dips in the star light, like one or more objects were passing in front of the stellar disk. However, the dips did not match one or more planets eclipsing their parent star. Professional astronomers took over and observed KIC 8462852 with different telescopes and instruments to try to figure out what was going on. Did it have a big disk of material around it that was blocking the starlight (like the one Kevin showed on a previous post, but edge-on)? Were these weird dips the aftermath of a huge collision of two planets, like the one that we think created our Earth-Moon system? Was it a family of comets or, more intriguingly, was it signs of an alien civilization? Could it be that the dips were due to some form of alien mega-structures passing in front of the stellar disk? SETI, the Search for Extra Terrestrial Intelligence project, observed KIC 8462852 and tried to look for signs of an advanced civilization around the star. SETI looked for radio signals, laser pulses and visible signs of that civilization, but their efforts did not give any positive results. The case of KIC 8462852 became even more curious when an astronomer reported that after inspecting old observations spanning 100 years, he discovered that the star appeared to be dimming in an unprecedented rate. The rate at which the star was dimming could not be matched by any astrophysical mechanism, leading people to think that maybe there were aliens living around that star after all! Unfortunately for the people trying to find life on other worlds, another team of astronomers inspected the same observations again, and found that the reported dimming of KIC 8462852 was seen in other stars as well. So the dimming was not hinting to a special property of the star, but rather an inconsistent calibration of data over a century of observations. Currently, the most plausible scenario is that the observed dips of KIC 8462852 are due to a family of comets orbiting the star. Astronomers tried to fit a model of a comet family to the last 100 days of the observations and found a good match! Creating such a large family of comets that could produce the series of dips we observe would need a large body breaking into pieces to become comets. The idea these astronomers proposed was that maybe there is another planet around KIC 8462852 that “pushed” the broken pieces into the comet orbits we...

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Exoplanets around Red Dwarf Stars

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Exoplanets around Red Dwarf Stars by Gijs Mulders   Since the discovery in 1995 of the first exoplanet over two-thousand exoplanets have been discovered. Most exoplanets, such as those discovered by the Kepler spacecraft, orbit stars similar in mass to the sun. Directly imaged planets, such as those discussed by Kevin Wagner in a previous blog post, are mainly discovered around stars more massive than the sun (A or F stars). However, most stars in the galaxy, around 75%, are lower mass stars called red dwarfs, or M stars (See Figure 1). These stars burn slowly through what little fuel they have. These stars are faint and red, like the smoldering ashes leftover then the flames of a campfire have died out. They are so faint that they are invisible to the naked eye, and famous red dwarfs like Kapteyn’s star can only be seen with binoculars. The closest star to the sun, proxima centauri, a companion of alpha centauri, is also a red dwarf. It seems crazy to look for planets around these faint red dwarfs, yet they have a few advantages. Because the stars are much smaller in size than the sun, a transiting planet covers a larger fraction of its surface, and is therefore easier to detect. When the earth moves in front of the sun it blocks about 0.01% of its light. M stars can be up to 10 times smaller, which means a transiting earth-like planet can block up to 1% of the stellar light: a signal that is much easier to detect. Because the stars are also faint, planets can be located close to the star and still have a temperature that supports liquid water on the surface. Cool, small planets are therefore easier to find around red dwarfs, and to date, most of the planets discovered in the “habitable zone” of a star have been found around stars much lower in mass than the sun. I started working on planets around low-mass stars back in 2013. I had just finished my PhD in Amsterdam working on protoplanetary disks, the birth-sites of planets, and I was ready for a new endeavor. I looked across the pond, and was hired as a postdoc in Arizona to work on formation of planets around lower mass stars. The chair of my PhD-thesis committee joked about Arizona: “The good news about Arizona it that it’s only 45 degrees (110 F) in the shade. The bad news is that there is no shade.” Excited by the prospect of working on exoplanets, I was ready to abandon my Dutch lifestyle of cycling around and getting rained on frequently. As it turns out, I still cycle around in Tucson and what being rained on lacks in frequency, it makes up for in intensity. The Sonoran desert and its monsoon storms are truly impressive (Figure 2). We (myself and EOS members Ilaria Pascucci, Fred Ciesla, and Daniel Apai) were planning to run simulations on planet formation around low-mass stars. So we thought it would be a good idea to look at the Kepler planets. Kepler (Figure 3) observed over 100.000, mainly sun-like stars, but also a few thousand red dwarfs. A paper showing what protoplanetary disks masses were needed to form the Kepler planets around sun-like stars just appeared online. It made...

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