Tuesday, November 18, 2014

Updates from the Exolab: Characterizing a Brown Dwarf Found with Kepler

This is a guest post from my graduate student, Ben Montet. In it, he describes his work studying a brown dwarf in the Kepler field, which is documented in a recently submitted paper available on astro-ph at http://arxiv.org/abs/1411.4047.

Ben is a fourth-year graduate student in the Exolab studying M dwarfs and their companions. He is also interested in using dynamical effects in multiple-planet systems to better understand both the planets in these systems and their host stars. He has previously written for Astrobites and FiveThirtyEight. You can find him on Twitter @benmontet.
The longtime follower of this blog has no doubt read a considerable amount about exoplanets. But in my opinion readers have been underserved when it comes to their more massive cousins, the brown dwarfs. Brown dwarfs have masses to low to ignite hydrogen fusion in their cores, yet too massive to be planets (they are capable of fusing deuterium, unlike less massive gas giant planets). However, the truth is, brown dwarfs and planets aren’t that different! We discovered the first bona fide brown dwarf in 1995, the same year the first exoplanet was found orbiting a sunlike star. Today, we know of a few thousand of each.

We think there are many---perhaps billions---of free-floating planets in the Milky Way, drifting through the galaxy far away from the gravitational influence of any one star. For brown dwarfs, we know this to be true! Nearly all brown dwarfs we’ve observed are singletons, wandering through space all alone.  While this is fine for them, it makes our lives as astronomers harder. We can measure the distance to these systems (through their parallax), their luminosities, and their spectra, but that’s the only information we get.

We would like to tie these observables into physical parameters like mass, radius, and chemical composition (metallicity). Just like we can for exoplanets, we can measure these best when we find a brown dwarf transiting a bright star. Enter the Kepler telescope. In 2011, just before I joined the Exolab, John and team published a paper about LHS 6343 C, a brown dwarf in the Kepler field transiting one member of a wide binary system consisting of two M dwarfs.  They analyzed six weeks of data from Kepler, adaptive optics imaging from Palomar, and a handful of radial velocity observations from Keck to measure the mass and radius of the brown dwarf.

Now that the primary Kepler mission is over, we have the chance to do a lot more. In this paper, we analyze all the Kepler data: nearly 100 eclipses! We also have more than 30 radial velocity observations to measure the mass ratio between the brown dwarf and its host star (shown below). With these data, we can measure the mass ratio and radius ratio to half a percent each. At this point, the conventional strategy is to characterize the star as well as possible. With near-IR spectroscopy from TripleSpec at Palomar and Robo-AO visible-light adaptive optics imaging, we measure a mass and radius of the host star such that we can measure the mass and radius of the brown dwarf to about 2%. This is the best anyone has ever done for a cool, old brown dwarf!

(left) Kepler data showing the light curve, with the best-fitting transit model as a thin black line. (right) RV data over one orbit of LHS 6343 C, with the best-fitting orbital model as a thin, red line. In both cases, the residuals to the best-fitting model are shown at the bottom.

But what if we didn’t have to rely on stellar models at all? From the transit light curve, one can measure both the stellar density and the size of the transiting companion’s orbit. With these two alone, the mass ratio between the star and the companion can be calculated. Adding in the RVs, which measure the mass ratio slightly differently, one can not just measure the relative masses, but the absolute mass of each object! Then, using the stellar density again, the radius of each object can be measured.

Because we can measure the light curve shape so well, we use this technique to measure a model-independent mass and radius of the brown dwarf to a precision of about 3%. What’s really interesting is that this method predicts the stellar masses to be a little bit larger than what the models we use predict. The discrepancy isn’t big enough to make any strong claims that the models are wrong, but it is just approaching the edge of statistical significance. This is one of several results that have recently come out or will come out in the next few months suggesting that M dwarfs may be a little bigger than this particular set of models predict.

Secondary eclipse of LHS 6343 C behind its host M dwarf.
In black is the raw Kepler data; in red we bin the data
to reduce random noise. The best-fitting eclipse model
is shown in blue, with the uncertainties shown as dashed lines.
Now that we have the mass and radius, the next step is to measure the luminosity of the brown dwarf to compare to theoretical evolutionary models. To do this, we want to observe the secondary eclipse, when the brown dwarf passes behind its host star. We observe this event in the Kepler bandpass, where the brown dwarf is 0.0025% as bright as the M dwarf it orbits (shown right). We also plan to observe the eclipses in the infrared with the Spitzer telescope, where the brown dwarf should be as much as 100 times brighter relative to the M dwarf! With these observations, we should be able to determine if the brown dwarf has thick clouds in its atmosphere or not, how variable the atmosphere of the brown dwarf is in time, and if the stellar evolutionary models of brown dwarfs, never tested before in this parameter space, are accurate. Stay tuned!





Monday, November 17, 2014

How to apologize when you've been called out

I've noticed that the hardest thing for white people to do is to properly apologize when their insensitive, privileged words have a negative impact on people around them. What can you do? Learn how to apologize properly. Here's a handy 9-minute video:

Sunday, November 16, 2014

Owen wins his first $1 buy-in, heads-up tournament


I went up 2:1 in chips early in the game. But Owen took a walk into the kitchen, drank some cold water, and mounted his comeback. He made a great lay-down in a tough spot, bluffed the socks off of me in a big pot, and in the end snap-called my bluff with KK on an Ace-high board. 

That's my boy!

Thursday, November 13, 2014

Some questions from readers

A Black scientist wrote to me in response to my list of white privileges:
I prefer to stay out of discussions about race for personal reasons, but in reading your most recent blog post, I keep feeling that there is an undercurrent of "class-ism" that is generally overlooked.  For example, I would add to Dr. McIntosh's list something along the lines of "I can enjoy a meal in a wealthier part of town without having my presence questioned because of my race," the assumption being that I must be too poor or uneducated to be in such an establishment given my race.  I imagine that this would be an unlikely occurrence for a member of a majority group.  Is this something you have come across?
My answer:
I agree with your addition to Dr. McIntosh's list. This highlights how class and race are intertwined.  
I strongly encourage you to read Seeing White. Chapter 5 covers the intersection of socioeconomic class and white privilege.  
In that chapter, the authors point out that the things we associate with upper class (classical music, art, wine) are things that are also a part of white society. For example, a person from India might enjoy classical music that has roots that go back centuries further than Beethoven, but Indian classical music, while a class signifier in India, is not in our country. For an Indian person in the US, they need to switch to listening to Western European classical music to have the proper musical signifier of class. They need to be more white to be more upper class. 
The reason upper class is associated with white is because throughout history Black people in particular have been forced into a lower socioeconomic class. Even today, a Black family earning $150K/year is much more likely to live near poverty than a white family earning the same amount. And no matter the income of a Black family, there exists a 18:1 wealth gap (where wealth = assets - debts).  
Finally, class is mutable. A white person from Appalachia can go to Hollywood, make it big, and enter into an upper class. Or they can go to college, graduate to Wall Street, and become upper class. But a Black person, no matter their accomplishments, will remain a Black person. When people see Oprah, they may see a successful woman. But they more likely see a successful Black woman first. But when people see Martha Stewart, despite her criminal record, she's just a successful woman, with no mention of her whiteness. 
In a discussion about racism, focusing on class is like walking into a room full of people with tuberculosis and saying, "Jeez, I wish someone would do something about all this coughing!" Yes, coughing is bad. It spreads germs. It's a problem. But the root is the disease (tuberculosis). The root of class differences for Black people is racism. Racism is the disease, and we have an epidemic in our country. 
I hope this helps!
From a white scientist:

Wednesday, November 12, 2014

Owning my privilege - one white woman's perspective

Guest post by Erin

A couple Saturdays ago I attended an anti-racism meet-up in Boston.  I was struck by a number of things, but the first thing that made me pause was the meeting space itself.  The Yvonne Pappenheim Library on Racism is hidden gem tucked just off of Boston Common, with walls lined from floor to ceiling with books about our country’s history of racism.  Thousands of books written on a topic that even I, a self-described liberal, progressive woman, will only discuss in highly guarded environments.  Here’s a topic that I’m able to dance around because of my privilege.  I’ve tried my damnedest to shift discussions that veer too close to race to subjects of class, socioeconomic status, under-privileged, underrepresented minorities without addressing the role that white privilege plays in our society. Yet, there I was, surrounded by thousands of published accounts of the reality in which we live.

Cartoon from: jamietheignorantamerican.tumblr.com
I believe it’s guilt that has kept me from exploring this for so long.  The notion that I am in some way to blame for something I feel I’ve not personally contributed to.  It doesn’t feel good to look at the ways I’ve benefited from my whiteness and privilege.  In her well known essay, “White Privilege: Unpacking the Invisible Knapsack,” Peggy McIntosh, PhD, refers to privilege as “unearned power conferred systemically”. I’d always thought of my advantages as earned, e.g. I’ve worked so hard to get to this point.  I’d not thought about the fact that I can stand before a school board and present an idea without my words being generalized to represent those of all white people.  I’d not considered that I can seek medical help without my race working against me, or there being doubt about my ability to pay for services. And while I may have earned respect along the way for the merit of my work, I was a beneficiary of systematic advantage granted to me by nothing more than the color of my skin.

Those who know me best will tell you that I’m a peace-keeper, a bridge-builder---a lover, not a fighter. Sometimes this is to a fault. When I’m real with myself, I can see that because of this I’ve thought of myself as more virtuous than many white people. I’ve guess I’ve thought of myself as a member of a separate group of white people whose love is not limited to those with a predetermined level of melanin in their skin. After all, I married a Black man!

A friend of mine likes to remind me that I’m not a poster-child for interracial marriage. She makes me laugh, but the essence of her jest is so right. I’m still a white woman, and that’s how the world sees me. What I mean is that yes, I deeply love and am committed to share my life with a Black man. We have two brilliant and beautiful boys. But these facts of my life don't give me a "pass" on issues of race. Because I'm white, I am in a position to challenge instances where subtle acts of racism play out in various interactions.


From the goodmenproject.com
On the other hand, as a white person I’m able to read about things like the murder of Michael Brown in Ferguson, MO and then close that browser tab and think about those officers as “not my people”.  But, indeed, those sworn to protect and serve murdered a young man in cold blood. Because of my privilege I’m able to think about this and talk about it in a way that keeps distance between myself and the officers who shot an unarmed teenager. I’m able to think about them in a way that divides me from them.  Doing so comforts me and helps me sleep at night. But choosing to draw a distinction between myself and those who commit acts of racism helps me feel that the world my boys live in is somehow better, more colorblind. It’s only the most heinous acts of racism that get media attention. But the daily micro-aggressions towards people of color don’t even register for me or other white people unless we choose to enter a given situation asking ourselves, “how does my whiteness affect me?" This approach is very new to me.

But people of color don’t have this privilege.  A young black man in 2014 doesn’t share my privilege. My husband does not have this privilege.  My sons will not have this privilege.   And that scares the shit out of me, because my love is not enough to protect them. And the people I want to protect them from are my people. And as long as I'm being honest, I threw up in my mouth a little bit when I wrote that last sentence. This truth is jarring to me.

White people don’t think of ourselves as having privilege. Or as beneficiaries of a system of privilege. As a matter of fact, we do everything we can to think of ourselves as normal. We are individuals. We are taught about the American dream and the value of hard work from such a young age that we never question the reality that this is not available to all Americans. We are taught that our parents worked hard, and therefore were able to save up enough money to purchase a home in a “nice” neighborhood with a relatively low amount of surrounding poverty.
From sfss.ca: Anti-Racism Discussion & Support Group

But for many years in the Houston-area, working-class neighborhood where I grew up had deed restrictions that  prohibited non-whites from purchasing homes within its boundaries. My parents' ability to purchase a home in the US when they did is a marker of my privilege. Denying this may make me feel better, but doesn’t make it any less true. Until reading Seeing White: An Introduction to White Privilege, Understanding White Privilege, White Like Me, watching clips of lectures by Tim Wise like Pathology of Privilege, and through frank and uncomfortable discussions in which I regularly struggle to not take things personally, that I am becoming more and more conscious of the real systemic privilege that exists.

Back to the anti-racism meet-up: 15 people, 11 white, 4 black gathered in the library to engage in “real talk.” It felt simultaneously terrifying and wonderful.  Terrifying in that I knew that my thinking would be challenged, and that I might say something that would make someone think of me as racist. Wonderful in that it was a place that encouraged discussion that white people, myself included, avoid at all costs. For purposes of confidentiality, they use the motto “What’s said here, stays here. What’s learned here, leaves here.

How can I translate these learnings into actions for life as I move forward?  A few ideas with which I’m starting:



  • Acknowledge your shared humanity with a person of color - Initiate a friendly conversation with someone of color. Make eye contact and smile. Take off your headphones and say hello to the person you see every day on the train.
  • I'm white. Don't take it personally. But at the same time, take it VERY personally. I have to fight the urge to defend my privilege when it arises in conversation. I remind myself that the question posed is not an accusation, and dig in for the deeper meaning and understanding. I regularly ask myself, "How does my whiteness affect this conversation." It's the intentional insertion of this reverse "WTF_was_that_racist" background process that helps me understand the lived experience of those I love so dearly.
  • Ask uncomfortable questions. If a white woman can't question a person's rationale for moving to a segregated community, who can? This is a struggle for me (remember, I'm no trouble-maker) but that's exactly why I'm committed to do it. There's a risk here of people not liking me, but there's also a freedom that comes with honest conversation.
  • Seek out others doing this work in your community. Maybe it's a meetup.com group, maybe it's a book club examining racism. Maybe it's a class at your local community college. Find people who share this awareness and learn from one another.

Tuesday, November 11, 2014

Race and Racism: Listing White Privileges

A friend of mine trained in psychology rolls his eyes at the mention of Peggy McIntosh's Invisible Knapsack. "She's been on that analogy for more than 20 years now. Does anyone even own a knapsack anymore?" He's saying this tongue-in-cheek since he's well aware of white privilege, even his own. But while the analogy of a backpack filled with invisible tools and benefits is possibly overused in psychology circles, I think it's far less familiar to astronomers. So I figured I'd reproduce Dr. McIntosh's list here for reference since it is so germane to the discussion of white privilege, race and racism in our field. After perusing it, I challenge you to name some of your own privileges if you are white. If you are non-white, yet heterosexual (heteronormative) then I challenge you to list your privileges as a straight person, or like me, your male privilege. 

A visible knapsack listed at usuablebag.com
Keeping our privilege out of our pockets (or knapsacks) and in the foreground is one of the best ways of mitigating the damage that privileges can cause. Remember, just because you have privilege doesn't make you a bad person. Yes, you can be a terrible person and still enjoy privilege. Or you can be an anti-racism activist and still have daily privileges. The difference between the two is that the latter is less likely to use their privilege to reinforce existing inequalities, and is far more likely to leverage their privilege for the good of their fellow humans. 

If having your privilege pointed out to you makes you feel uncomfortable or like you're being accused of being a racist, check out this article (yes, I recently poopoo'd it on Twitter. But after actually reading it, I think it's an excellent resource. h/t Jessica Lu). If you'd like to become a privileged ally, check out this helpful guide

Finally, here's Dr. McIntosh's list of white privileges

Sunday, November 9, 2014

Race and Racism: Seriously? Another post about privilege?


I've felt simultaneously heartened and saddened by the recent introduction of the word "privilege" into the lexicon of astronomy diversity discussions. I'm heartened because awareness about one's privilege is a vital step in actually doing something about inequality in astronomy and the world in general. On the other hand, I'm saddened by the most common reaction from privileged individuals, namely a short period of feeling disoriented, confused and/or guilty, followed by a shrug and a return to business as usual (Well, that sucks, but what can be done?). With the use of the word followed by those shrugs, I fear that the word "privilege" is slowly losing power because people aren't changing. I feel the word already slipping into the realm of buzzwords. This would be tragic, because privilege is one of the primary manifestations of racism (and sexism, and heterosexism, and ablism) in our society today.

By saddened I don't mean to imply any sort of surprise. Far from it. Indeed, being able to think about privilege for some period time and then put it aside while moving on with one's life is a privilege in and of itself, and extremely valuable one at that. If you can do this, then you can devote extra CPU cycles to your work without having to process strange race/gender-related interactions, microaggressions and entire power structures (no background process called WTF_was_that_racist). You can just be an average astronomer doing what average astronomers do.

Here's a fairly typical liberal-white-person comment on Twitter:


Yeah, dude. Racism makes me sad and upset, too. It also directly impacts my life and the lives of people who look like me. It causes me to worry about my Black sons and their futures. I can't unknow what I know about their relatively limited set of options in life, despite their economic starting advantage thanks to my sweet professor job. Our society will always see me and my sons as Black males first, and people second, if at all. And because of the way media portrays us, and society has always looked upon us, we are a threat to white people, especially whenever more than a few of us gather in one place.

But unlike the tweep above, I and other Black people can't just turn away in disgust after reading about an incident of racism, or viewing the stats on e.g. the wealth gap. We can't just set it down, and pick it up later when it's time to be an ally. And if we should try to ignore racism, it's to our detriment because the consequences of forgetting your non-white race can be dire (to white guy's credit, he did eventually pledge to read the book. But if he doesn't, there will be no meaningful consequence resulting from his continued ignorance. Meanwhile, if my son doesn't know about famous white people and whitewashed history in general, he gets bad grades in school).
The Katrina disaster and aftermath wasn't racist, right? Right? Anyone? 

Also, when you have privilege it's extremely hard to see it and its consequences for others. This is the basic premise behind the title and thesis of the book Seeing White, which I've challenged white astronomers to read (#TweetingWhite). Namely, whiteness is hugely important yet completely invisible to most white people (see also Understanding White Privilege, White Like Me, and especially for white feminists Ain't I A Woman: Black Women and Feminism by bell hooks). However, the theory of epistemic privilege (or standpoint theory in feminist scholarship) posits that those who are oppressed see the rules and structures of their oppression most clearly, while those who are the oppressors are generally ignorant (here's a good post on this idea, or see quotes of white slave owners talking about how happy their slaves are. Blech.).

This is because as normative members of society it is easy and very desirable for white people to be seen as individuals rather than members of a distinct racial group. "I got here because of my hard work" is a more desirable claim than "I got here thanks to help from my fellow white people and policies established by past white power structures designed to benefit people who look like me." Minorities on the other hand are frequently and without hesitation referred to as...well, "minorities." That we belong to a distinct class in society is rarely overlooked, nor should it be! But the flip side is that white people need to recognize that they, too, have a group in this country, even if that group is often simply called "Americans."

(Aside: I don't like the use of "underprivileged minorities" because the logical counterpart "overprivileged majorities" is not used in equal proportion. If people like me have less privilege than we should, it only follows that white people have more than they should. But by focusing on the underprivileged, the overprivileged get to pat themselves on the back for reaching down to help those poor black and brown people. To help the underprivileged, I'm strongly motivated to help overprivileged people come to terms with their white identities. Hence, this post. h/t Chanda Prescod-Weinstein for this revelation, and many others over the past year.)

What does it mean to see whiteness? What is privilege, why does it matter and what can be done about it? These questions all get at the root of racism in our community. Increasing the number of people of color participating in astronomy depends less on getting Black and brown high-schoolers and undergrads involved in astronomy research. Rather, it depends vitally on white astronomers coming to terms with their whiteness, and the lack of color in the power structures of astronomy and academia. If not, then we'll just repeat the same patterns seen over the past 50 years. Despite the passage of the Civil Rights Act 50 years ago, our field of science will remain one of the most segregated corners of American society as white people forget who they are and how their whiteness affects minorities around them (fun fact: US astronomy is >90% white). I seriously doubt that this is what most people in astronomy would want for their field. But this is our reality.
Screengrab from Julie Perini's video "The White Lady Diaries." Image via julieperini.org.
Still from Julie Perini’s video “The White Lady Diaries” (2013) (image via julieperini.org)
Want to help? Here are some suggestions
  1. Read. See my extensive bibliography in my previous posts
  2. Read. Seriously. Learn your real history, not the propagandistic tripe taught in K-12. As long as white astronomers remain ignorant about the way the world actually works, people will continue asking me the #1 FAQ: "So what can I do?"
  3. Read. Learn about your privilege (see links above). Once you learn to recognize your own privilege, from your family's history to your present-day interactions, you'll start seeing white privilege all around you. You'll start seeing the world as non-white people see it. And you'll start seeing solutions rather than relying on non-white people like me to do all the reading and spell things out for you.
  4. Search for a local anti-racism group. I'm part of the Boston Knapsack Anti-Racism Group, which stays in touch via Meetup.com. Many Americans have fooled themselves into thinking they live in a "diverse," racially-mixed world. We so do not. Sitting in a room of 30 people talking openly about race and racism---talking together as Black people and white people as they really are---was one of the first times I saw meaningful interactions between disparate racial groups. It was amazing. An inclusive, open, honest, accountable community is extremely powerful when you actually see and experience it. I'd love to have such a community in astronomy.
  5. Once you learn how anti-racism discussions work, initiate one (some) in your own department. 
If any or all of this sounds too hard (I don't have time to read books. It's job application/proposal season.), just remember one thing: It's hard to be non-white in America. It's hard every damn day, and the associated difficulties cannot just be set aside by non-white people while they try to do astronomy. So please share the burden by forgoing that marathon session of House of Cards, or some other Washington DC-based web series with a white-dominated cast.