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Comments on Sexism at AAS

OK, people, so I know that we talked about this during the AAS227 meeting. In fact, there was a whole hour+ seminar about sexual harassment, sexual assault, racism, and gender bias in the astronomical and related sciences. You did go to that session, right? Good. Unfortunately, many of the people who really needed to be there are the people whose demographic was sorely under-represented in the audience of that seminar: older white males. If you know of an older white male colleague of yours who chose not to attend that seminar when they had the option, please do forward this to them.

Note: for the rest of this blog post, I am going to limit my discourse to the subtle (and not so subtle) sexual harassment I noticed at AAS227. I’ll leave my discussion of the other forms of discrimination I noticed to another day.

Here’s why I say that the demographic of older, white males in the physical sciences most need to hear this message. They grew up and were educated in a time where women were treated differently by society. That was the age where women were mostly secretaries to high-powered male bosses, coffee fetchers, “doll” and “sugar”. This is not an exaggeration. Female engineers, scientists, and bosses were a rarity. I give major props to all of the more senior female professionals in my field for finding their way through that type of blatantly hostile work environment and coming out the other side of it into a (seemingly) more tolerant world.

I also specify white males because that demographic has held a position of power and privilege in this country literally since its inception. As a group, they don’t have the experience of being discriminated against because of their personal identity (with the obvious exceptions of non-cis-gendered, non-heteronormative, non-Christian, non-able bodied, and non-neurotypical individuals, amongst others). However, because of long-standing societal discrimination against those demographics, their numbers are also very small in the physical sciences. As the most populous demographic in the physical sciences, older white males are the ones that need to adopt the changed attitude towards females and under-represented minorities (URMs), yet are the ones most resistant to change. They are the most hard-put to see the subtle discrimination against these groups, let alone to understand how it feels. This is why I am writing to them.

I hope it is blatantly obvious to everyone that if the only reason you are attending a talk (or stopping by a poster *hint hint*) is because you are physically attracted to the presenter, don’t. Just don’t. I guarantee it won’t end well for you. Go to a talk or stop at a poster because the work is interesting or thought-provoking. If it’s not, just don’t go. It’s that simple.

All right, now that we’ve gotten that out of the way, here is one example of subtle sexism that I noticed, and experienced, at this year’s AAS227 meeting. Oi vey, as a fair warning, once you see this one in action you can’t un-see it.

The infamous and dreaded questions portion after a talk. I am specifically referring to the propensity for males to take up the question time of talks by female speakers with “I have more of a comment than a question” or “I have a comment and a question.” This sort of happenstance usually takes the form of:

  1. “I want to make sure you understand that fundamental thing about your research topic or analysis method. Are you sure about that? Really sure? How about now?”
  2. “Have you considered this very tangential approach to your research that I, of course, am an expert in? No? Well let me explain to you in front of everyone why it is superior to your work.”
  3. “Do you honestly expect us to believe you when you tell us this unexpected result? My vast experience suggests otherwise.”

This happened to me for both “questions” in my research talk. I saw it happen to the other women in my talk session and others. Heck, it happened to a plenary speaker on Friday.

Sometimes comments in place of questions can be helpful to spark discussion in the room, if it’s done respectfully and equally to all types of speakers. But lest you think that this happens to all speakers in equal amounts, it doesn’t. Really, it doesn’t. Next time you’re at a AAS meeting, or at the next few departmental talks at your institution, take a census. Sure, there are always those individuals who ask these sorts of “questions” to all speakers. Those “questions” are still rude and don’t belong in the Q&A part of a talk (more on that later). But in the sessions I attended at AAS, these “questions” were only asked towards female (and POC) speakers, and only asked by males.

“Questions” 1-3 above are meant to assert authority over, establish dominance of, and diminish the accomplishments of the speaker in favor of the questioner. They say, in the subtle language of intellectuals, “I am better than you and here’s why.” Asking those “questions” in a public forum in front of the rest of the audience is attempting to humiliate/humble the speaker and elevate the questioner above her. How terrible.

If the horribleness of this were obvious to the perpetrators, they likely wouldn’t do it (I’m casting no personal aspersions here). So let me break down to you why that’s a bad thing, for everyone.

  1. Public humiliation of a professional colleague? Really? That just looks bad and damages your reputation. “But that’s not my intent!” you say. “It doesn’t matter!” I say. That is still the end effect of the interaction you have with that person. If you step on my toes but didn’t mean to do it, you still hurt my foot. The polite thing to do after that is to apologize. The smart thing to do after that is to watch your step more carefully.
  2. You may think that what you’re really doing is making sure the speaker understands the fundamentals or subtleties of her work. OK, sure, that’s all well and good. Did you ever think that it’s not your place to do so? In all likelihood, you aren’t her boss, her academic or research advisor, her project manager, or someone with any responsibility at all over her education. The Q&A portion of a talk is not a quals exam. It’s not an interrogation. If you do have concerns about her education, the proper place to address that is in private, to her face, in a one-on-one setting. To do so in public is to insult her own intelligence and that of her supervisor and institution. And really, public insults? See Point 1 above.
  3. You are taking learning opportunities away from other colleagues and the rest of the audience. There are likely people in the audience who have legitimate comprehension questions about the talk, and you are impeding their opportunity to understand. Did you know that female audience members are more likely to ask questions of female speakers? No really, it’s true (25% female question-askers for female speakers, vs. 22% female question-askers for male speakers). So, not only are you questioning the intelligence of the speaker, you are taking opportunities away and discouraging other females from asking questions at talks. Save your “questions” until after, where they’re slightly less inappropriate.
  4. You discourage future female scientists from speaking at conferences, and from asking questions. You (or your institution) claim they want to increase gender parity in the sciences and encourage diversity. By asking “questions” like these you are actively working against those same goals. If I’m a female audience member who sees a female speaker being treated that way (and having everyone else accept it as par for the course) why would I want to put myself through the same situation? I would be more reluctant to participate in scientific discourse knowing the terrible times ahead (hint: there’s a reason that this past AAS was my first conference talk, but not my first conference presentation). If I have no choice but to give a talk (say, if I want to get a job after my dissertation) I will certainly be less confident in my work and more hesitant in asserting my authority. Is that what you want from the future generation of scientists?

If you have an honest concern about the integrity or quality of the work being presented, that is your prerogative. The appropriate place to bring that concern to the speaker’s attention is in a one-on-one discussion with the speaker after the session has ended. Here’s how you do that: *raise your hand during Q&A* “Thank you for your thought-provoking presentation. I have some ideas that I would really like to discuss with you after the session if you have time. I will stick around after. Thank you.” This acknowledges the work that the speaker has done and respectfully asks for an intellectual discussion, and then gets out of the way for other potential question-askers.

Keep in mind though, when you follow up on that request it should be a discussion, not a lecture or an interrogation. This still isn’t a quals exam. Understand that you may disagree on the best course of action on a project, and that the speaker (by virtue of it being her work with which she is intimately familiar) has an equally valid opinion. If you find that you can’t come to an agreement, THAT’S OK. As a professional person, the researcher will listen to your opinion and take it into consideration as she goes forward. That’s what the scientific process is about. If you feel so passionately about the research, do it your own way yourself and have professional disagreements about it in journals like you would with anyone else.

That’s about it for this. I’m sure that there are better ways to inform conference participants and session chairs than a blog post that (hopefully) a small fraction of the AAS membership will read. A reminder email before a meeting about how to be respectful during a Q&A? A mention during the session chair breakfast? Something. Until then, if you do notice one of your colleagues behaving this way towards a female speaker, SPEAK UP ABOUT IT! Approach that “questioner” (in private, remember?) and say that that sort of treatment of a speaker is not appropriate for a professional setting, and that next time they should bring that sort of comment to the speaker in private, not in front of their peers. Be an advocate and an ally for female speakers, and don’t let this continue to be the norm of how we treat our female scientists.

AAS 227 Meetings: Pre- and Initial-Conference Thoughts

Hello all. This is the first in what will be a series of blog posts about the AAS meetings currently happening in Kissimmee, FL. I am trying to write my thoughts and experiences about the conference a day at a time, and post them as the conference is happening. These are my thoughts leading up the conference, and on the first day/impression of the conference. All thoughts are my own, and if I use ideas from others I will identify them unless they ask to remain anonymous.


So, this post is a bit different than my others will be about the AAS meeting. I’ve had most of these thoughts for a while, and while they’re not mainstream, I have heard others with similar opinions. I will preface this post by saying that I really do enjoy AAS meetings in general. I love seeing all of the people I collaborate with remotely, people I have followed (read: stalked) online, and learning all of the new science from people I have never heard of before. This post is mostly an explanation of a few issues I, and others, have with the current structure of AAS meetings, and will focus on the schedule of events, the timing, and the location. I can’t say that I have any concrete way of solving them, only suggestions of things to be done.

Organization of schedules

I’ve noticed that there are essentially two different conferences going on at the same time at most AAS meetings. In the one conference there are all of the science talks, large plenary talks, and science workshops. These are very talk heavy, full of 10 minute presentations occasionally broken up by 15 minute “D-talks” (for dissertation research) and large conference wide science talks.

The other conference I dub the “alternate” conference: science outreach, astronomy education and history, science writing, press conferences, town halls, career workshops, performing arts in science presentations, etc. While these are science related, most of those don’t have original research presentations. Rather, those are more of the professional development sessions that make you a more rounded scientist.

The problem? The science talks and “alternate” sessions happen at the same time! If you want to learn how to write your science for the public you must, perforce, miss out on some of the science you want to write about. And vice versa. While, yes, it’s impossible to go to everything (and indeed, you would quickly burn out if you tried), the schedule should be arranged so that people can attend multiple types of sessions if they want.

Also, to keep the two separate like this enforces the idea that the two are not equal, and not complementary. It enforces the mentality that if you do original research, you don’t need communication or outreach. And if you do communication or outreach, you can’t to original research. The two are not, and should not, be mutually exclusive.

Regarding the timing, specifically impacting health, inclusivity, and convenience

I’ve spoken before about my dislike of the timing of the AAS meeting. When you start going to AAS meetings, most advisors will tell you to go to the winter one, since that’s the “big meeting.” OK, that’s totally fine to have a “big meeting” where most of the community all gets together at the same time. That’s actually a really good thing.

My problem is that, somehow, the winter meeting became the “big one” and the summer one is very sparsely attended. Why is this an issue? Well, a number of reasons really (one of them is that it always conflicts with my birthday, but that’s neither here nor there).

First reason: logistics. Travelling to most of the USA in January is difficult. Especially difficult in the first week of January. There is snow everywhere (well, at least in normal, not freakish El Niño years like this one). If there isn’t snow where you are or where you are headed, there is snow in a connecting layover location. Snow leads to flight cancellations and delays and travel stress. No one likes to travel at these times, some people avoid it altogether. Also, just after New Years means that there is much higher airport traffic and higher prices due to demand.

Second reason: the start of the semester. The first week or second week of January is also the first week of classes for most academic folk. For students, this means giving up valuable prep time for classes, or missing the first week of classes altogether. For teaching faculty that means losing that last week of valuable prep time for the semester, getting last minute research done, communicating with their students, pre-semester forms and training. Also, many job applications, grad school applications, and grant applications are due just before or after the new year, and combining these with a large meeting can often be disastrous.

Third: international astronomers in the US. The American astronomical community includes a diverse spread of astronomers from around the world who have chosen to make the US their home, either permanently or temporarily. Many of those who have come here to do science have left friends and family back in their home countries that they don’t get to see often. Winter break, often being 2-3 weeks long, is usually one out of two times a year that those astronomers have the chance to travel to see their family. Making the winter meeting so critical is damaging to international astronomers who choose to travel home during this time. This is detrimental to astronomical diversity, and enforces the idea that a scientific career and healthy family life are incompatible.

Fourth, and the important reason: physical and mental health. In the winter, colds and flus run rampant, and no place is a better breeding ground for germs than a conference. Lots of new people, close meeting quarters, sharing rooms, minimal sleep. Not good. As far as mental health: winter break should be about decompressing, not extra stressing. Everyone needs a mental break now and again in order to avoid mental breakdowns. I’m deliberate when I say “need.” This is not a suggestion, or a “well, it’s normal, whatever,” or a “just deal with it,” everyone NEEDS a break sometime. Knowing that there is an important meeting coming up right after the new year means that most spend the majority of their winter break stressing about finishing their calculations, their presentation, their poster, when they could be enjoying family and winter holiday time. This is not healthy.

Location of the meetings: accessibility and affordability

The past few “big meetings” of the AAS have been in strange locations: outside of DC, Seattle, and now Orlando. Future meetings will be San Diego and Grapevine, TX (I had to look up where that was myself). If you are hosting a meeting for the astronomical population of the US, shouldn’t you have meetings in locations convenient to the astronomical population of the US? Unless you live pretty close by, it is time intensive and really expensive to travel to most of those locations. They are pretty remote, and in the far reaches of the country rather than a fair middle ground. Those locations also tend to have really expensive hotels, food, and inner-city travel, making things more difficult on a tight budget.

Another issue with remote locations is often the lack of travel options. To get to many of these places from more than a state away requires air travel (for those who are from New England, that’s how the rest of the country works). Some people just can’t afford to fly everywhere. Some people can’t fly on airplanes for health reasons, and must take trains, busses, or cars instead. These people include, but are not limited to, pregnant women mid to late in their pregnancies. When we already ask (subliminally and through lack of standard maternity leave policies) future mothers to make career sacrifices for their children, we shouldn’t make it even harder for these women to participate in our community.

Now, I understand that the AAS has a multi-year contract with Gaylord Convention centers for some reason or another. I even hear tell that they say that this is supposed to be cheaper for everyone to work with them. But personally, I haven’t seen any evidence of the cheaper nature of these conference centers. When the conference hotels cost $300 a night, that’s not cheap, or affordable for most people. That’s almost a month of groceries for me. This cost is often not including parking, food, hotel shuttles from the airport, etc. and definitely doesn’t also cost meeting registration costs. (Edit: in adding up the total cost of the conference, it comes to almost a full month’s paycheck.)

The cost of travel, hotel, registration, and food can be prohibitively expensive for many people. It is particularly difficult for undergraduates, graduate students, postdocs, and low-income staff/faculty like adjunct, assistant, and associate professors. You know, the people who tend to get the most out of a meeting through experience and networking? When you can’t afford to miss a meeting professionally, but you can’t afford to attend economically, it’s a no win situation for the most professionally transient astronomers. Missing a meeting as an upper level grad student or a post-doc leads to missed networking opportunities, missed presentation opportunities, and missed job opportunities.

Tenured professors, who generally have a stable salary and career, can afford to miss meetings, might say “well then, just don’t go to this one!” (hint: if someone tells you this, they probably don’t have your best professional interests at heart). There are indeed ways to “virtually” attend meetings. Those methods are important and valuable, too. But when networking in person makes up such an important part of the field and of the job search, virtual attendance just won’t do.

….

I have no solutions here. Only suggestions, and many of them are untenable at the moment. Emphasize the summer AAS meeting instead. Hold meetings in more accessible locations, with a variety of hotel and food options and prices. Provide travel grants to economically challenged astronomers. Adjust the schedule so participants can (are encouraged to!) attend professionally diverse sessions. These are my suggestions to you, AAS, to make your meetings more diverse, more inclusive, and less prohibitive.

Also, I have almost lost my coat twice now because I have to carry it around everywhere. We should get a coat rack.

Science Writers 2015: Notes from New Horizons in Science

SciWri15

Hello all!

I’m currently attending the New Horizons in Science presentations at the Science Writers 2015 conference. The conference ends tomorrow, but since I’m heading out early today will be my last day of the conference. I’m posting this as a place-holder for when I get around to writing up my notes from my 2-day stay at the conference. Most of the notes are science notes, some of them are thoughts about effectively communicating your science. I will do my best to provide links, hashtags, and images from the conference for each topic.

Thanks, and stay tuned!

Kimberly

Live-blogging afterthoughts

So, after a few weeks of respite from the marathon blogging session at the Emerging Researchers in Exoplanet Science Symposium hosted at PSU, I thought I would share some thoughts about my experience live-blogging and the comments that I got back about how the live-blogging went for me.

First off, I personally found the experience to be a lot of fun (a little bit of stress), but overall very rewarding for me for a number of reasons. For one, it was great practice at writing science concisely and with purpose, summarizing another scientist’s work, and interpreting it through the lens of a non-expert. This was a good exercise for me since I want to eventually find a career in science journalism. Secondly, it was a good way to make sure that I was paying attention to the conference, to actively listen to the presentations and to internalize the presentations. I certainly learned a lot more and paid attention a lot more than I have at other conferences, simply because it was my job to to do. But now, I think that I’d do something similar even it wasn’t my job because it’s so helpful. Thirdly, it was great to help out the conference participants and the people that weren’t able to participate, to talk to new people about the blog, and get the symposium more recognition on the cyber-waves. So, for those reasons, live-blogging the conference was a very rewarding experience for these and other reasons.

However, when I do this again, I might do some things differently. For ERES, I wrote a three-paragraph minimum for each of the 10 minute science talks given by participants, and following the Q&A of the panels and other featured talks. This was a lot of work. The blog for ERES was formatted more like conference proceedings than a blog, which I (and other OC members) felt was appropriate for this type of conference. Since the blog was coupled with a Twitter feed, the Twitter feed was set up more as the “thoughts and comments and clever paraphrases” format (thanks Natasha Batalha!), and the blog was set up to be more a scientific summary. When I do this again in the future, it is likely that I won’t have an accompanying Twitter feed, so I would probably do less summary and more paraphrasing, thoughts, and comments.

Also, typing that much in such a short time gave me hand cramps! It was hard work, and I might do it differently next time. But it was a really rewarding experience. If you have a proclivity for writing, or are trying to find a way to retain more information at a conference, I suggest live-blogging. It’s just like taking notes, but with more personality, and can be tons of fun!

So…yeah. Those are my thoughts on live-blogging. Now that the live-blogging is done and I have free time again, I will be continuing with semi-regularly submitted blog-posts and other goodies in the future. Thanks for tuning in!

-Kim Cartier, aka “AstroLady”

ERES Day 2 Session 4: Statistical Characterization

Our post-lunch session is chaired by recent PSU PhD, Dr. Benjamin Nelson. These talks are all related to characterization of exoplanet systems using statistical methods.


Systematics-insensitive periodic signal search with K2 (Ruth Angus, University of Oxford)

When the second reaction wheel of Kepler failed, it was recommissioned as the K2 mission. The issue with the K2 mission is that the telescope itself drifts slowly, and they need to fire the thrusters every so often to fix this issue. That mean that, as the star appear to be drifting across the CCD, the precision of K2 has decreased compared to its predecessor.

To compensate for this, they need to come up with a better analysis algorithm for the K2 lightcurves. This involves better modeling of the stellar systematics and convolving that with a sine wave over many many frequencies to create a systematics insensitive periodogram (SIP). The raw periodogram of K2 data shows a very large feature at the 6 hour thruster times along with aliases of that 6 hour frequency. When they redo the lightcurve periodogram with SIP they are able to remove that large systematic feature and pull out the red giant acoustic oscillations of the host stars.

Using SIP, you can also find a better estimation of the stellar rotation period, since the systematics won’t be clogging up the periodogram anymore. They were able to accurately recover the stellar rotation period once the systematics were removed from the lightcurves using SIP. They can also use this method to find other periodic signals like short period exoplanets, RR Lyrae, and eclipsing binary stars. Their code is available on GitHub (don’t use the tweated version!), and the paper recently came out on the arXiv.


*A Catalog of Transit Timing Posterior Distributions for all Kepler Planet Candidate Events* (Benjamin Montet, Caltech/Harvard)

Ben is working on a number of projects, including a transiting brown dwarf LHS-6343 and a paper on young M-dwarfs. Today he is talking about  transit timing variations (TTVs) (which Daniel Jontof-Hutter talked about yesterday). TTVs can ell us about eccentricities, inclinations, and mass ratios of planets in the same system, all of which can be really difficult to measure using another method.

When looking at TTV curves, the variations in transit timing usually follow a sinusoid, but not all points follow this trend. The current methods ignore non-Gaussian errors, assume white noise, ignore ill-fitting transits, short cadence data, and don’t marginalize over transit shape (if the transit is not properly sampled, current methods usually ignore these points). But correlated noise matters too, and needs to be included in analyses.

Posteriors can help with this. If you fit many transit model models and times of transits, infer the posterior distribution for the time of every transit observed with Kepler, you can use importance sampling to get a handle on correlated noise. Importance sampling can help speed up your computation process bu focusing your computation on places in your data that you know, a priori, that the transits will be occurring. They are currently working on all of the single-transit systems, and multiple systems are nearly ready for “prime time”. They are also looking for a cool name for the project, so give him a shout if you have an idea.


Towards a Galactic Distribution of Exoplanets (Matthew Penny, Ohio State University)

Where are the known exoplanets? Microlensing is the only technique we currently have for probing for exoplanets in multiple areas of the galaxy. RV surveys are limited to nearby stars, Kepler looked in one region, K2 will add a ring around the solar system with more nearby targets, but microlensing surveys look straight into the galactic center to find the frequency of exoplanets as a function of galactic radial position.

Question: does plane formation in the bulge differ from the disk of the galaxy? Different galactic environments can have detrimental effects on the longevity of a protoplanetary disk, or can change the temperature of the protoplanetary disk to impede planet formation. They find that, based on microlensing surveys, there are a lot fewer planets in the galactic bulge than in the disk. They determine this by varying the ratio of disk planet formation efficiency to bulge planet formation efficiency to model the current distance distribution of microlensing planets. They find in their first results that the bulge planet formation efficiency must be lower than the disk planet formation efficiency in order to approximate the microlensing planet distance distribution that they see.

They want to find out what is the most probable distance/location in the galaxy to find exoplanets. They can measure distances to microlensing planets with parallax (for nearby planets), using a Bayesian method, or using the relative proper motions of stars to calculate the distances. While there are still some kinks to work out, this mix of techniques lets them probe a wide range of planet distances and begin to map the galactic distribution of exoplanets.


Constraining the Demographics of Exoplanets Using Results from Multiple Detection Methods (Christian Clanton, Ohio State Univsersity)

There have so far been about 150 confirmed exoplanets around M-dwarf stars. Confirming these planets really takes a collaborative effort between multiple detection methods. M-dwarfs are good targets for exoplanets because they are the most numerous of stars in the galaxy, RV and microlensing surveys are also more sensitive to lower-mass stars.

There have been individual exoplanet censuses of M-dwarfs using separate methods. Some constrain the actual frequency of planets around these stars, other non-detections (direct imaging) place upper limits on this number. If they combine the results from these various techniques (microlensing + RV, and now direct imaging), they can confirm quite a few planets around M-dwarfs and get a constrain on long-period giant planets around these stars. They ask: is there a single planet population distribution that is consistent with all of these M-dwarf exoplanet surveys?

They map the distribution of planets into distributions of the observables relevant to each technique (microlensing+RV+direct imaging). They then determine the number of expected detections for each survey, and compare that with the actual reported results and determine a likelihood of that particular planet population, and repeat for a variety of planet populations. They can then constrain the planetary mass function and power law slope of this distribution very well for M-dwarfs. What this means is that the results of the microlensing, RV, and direct imaging surveys are consistent with a single planet population distribution. They also want to include the results from Kepler to add constraints from transit surveys as well.


Sifting Through the Noise – Recalculating the Frequency of Earth-Sized Planets Around Kepler-Stars (Ari Silburt, University of Toronto)

Kepler has been invaluable in attempting to answer the age-old question of: is our planet unique? Unfortunately, we haven’t yet found a true Earth-analog. We can estimate the frequency of Earth-like planet by extrapolating our results past our detection biases. We first have to overcome our geometric bias: only certain planetary systems are transiting, and there’s a large population of planets that we simply don’t see in transiting surveys because of this detection bias. This is a strong function of planetary radius and orbital semi-major axis.

This bias causes a lot of large error bars and false-positives in the Kepler data – mainly because we don’t understand the stars themselves. Such large error bars can skew our estimation of the number and frequency of Earth-sized planets. What they’ve done is a new way of accounting for the uncertainty in planetary radius by applying our known Kepler detection probabilities for planets based on their radii and combining that with the probability curve of the planet size. For example, the uncertainties of a detection may include a very small size, but we know that detecting something that small is very unlikely, so that value is downweighted. This allows them to correct our error distribution and use this to improve our estimate of the frequency of Earth-sized planets.

They find that with these corrections, the frequency of Earth-sized planets in the Kepler sample is eta_Earth = 6.4%, which is about half of what it would be if they haven’t accounted for the detection biases of Kepler. They anticipate that the Gaia spacecraft will help better understand the stellar exoplanet hosts, which will further increase the accuracy of their eta-Earth value.


A population-based Habitable Zone perspective (Andras Zsom, MIT)

Most people visualize a habitable zone as a stripe around a star that is capable of supporting liquid water. If you look at it in a population perspective, you can see which planets fall interior to the HZ and are covered in water vapor, those exterior to the HZ with ice on their surface (or like Mars that falls right on the ice/vapor limit), and those inside the HZ which can have liquid water.

From observations we have good estimates on the stellar properties and planetary orbital properties, but we don’t know much about the planet properties and surface climate. How can we know the surface climate without knowing the planetary atmosphere?  They describe the HZ as a probability function to estimate the occurrence rate of HZ planets based on this HZ probability. If you treat the stellar and planet properties as random variables, you can create probability density functions out of them. They then sample each variable and use a 1D climate model to calculate the surface climate, repeat this to create an ensemble of climates, and then study the habitable sub-population and calculate their probabilistic HZ.

They find that the most probable area of HZ planets around M-dwarfs occurs around a few times the radius of the Earth, and around 0.5-1 times the stellar flux received at Earth (author’s note: this is a really cool 2D HZ probability plot!). So, they find that the occurrence rate of HZ planets is 0.001-0.3 planet/star for M-dwarfs, but that the surface pressure and atmosphere type strongly impact the surface climate and occurrence rate. We need better estimate of the potential atmospheres of exoplanets. Their code is called HUNTER and is available on GitHub.


The session following the coffee break will be co-chaired by me (Kimberly), so that blog post will be written by Ben Nelson.

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