Good morning everyone and welcome back to the ERES 2015 blog. Our first session this morning in on instrumentation related to exoplanet observations, and is chaired by Yale graduate student, Joseph Schmitt.

The Habitable-zone Planet Finder Instrument: Pushing the Limits of Exoplanet Detection in the Near-Infrared (Sam Halverson, PSU)

The Habitable Zone Planet finder is am infrared doppler spectrograph with a 1 m/s precision to find habitable zone planets around M-dwarfs. The HPF team is a very large team spanning multiple universities, and multiple departments at PSU.

Why do we care about radial velocities in the near-infrared? The majority of nearby stars (from the RECONS) survey are M-dwarf stars, which primarily emit light in the NIR. There is a high frequency of planets around these M-dwarfs, almost half of them have at least one planet, and this is a population that is largely untapped by telescopes like Kepler. A habitable zone planet around one of these stars would induce an RV signal on the order of meters/second, so this instrument will be ideally placed to measure these RVs in the NIR.

The HPF will be mounted on the Hobby-Eberly Telescope (HET) at McDonald Observatory, of which PSU is a partner. The HPF borrows some of the success of HARPS in its design. It is a fiber-fed spectrograph, with science fibers and calibration fibers. It uses a HgCdTe absorbing detector, not a CCD. The entire spectrograph is contained within a cryostat chamber, similar to the APOGEE instrument. To achieve 1 m/s precision in the NIR, they plan to utilize a laser-frequency comb, but are also looking into a Fabry-Perot etalon for a frequency calibrator, which may be of use to the wider astronomical community rather than tailor-made for the HPF observations. The HPF is exploring a new area of exoplanet detection, piggybacking on the successes of previous instruments like HARPS and APOGEE in its design, and developing cutting edge solutions to the complex problem of high-precision RVs in the NIR.

Ultra Precise Environmental Control for High Precision Radial Velocity Measurements (Gudmundur Stefansson, PSU)

The search for habitable planets is exciting! (author’s note: indeed!) Improved radial velocity precision enables us to detect lower mass planets, and HPF will focus on HZ planets around M-dwarfs. M-dwarfs are currently our best bet to look for rocky, low-mass planets in the HZ. NIR detector are better suited than optical detectors to study rocky planets around M-dwarfs. HPF is aiming for the same precision as HARPS, but in the NIR instead of the optical.

HPF will push the boundaries of temperature and pressure stabilities achieved by HARPS. Temperature changes cause the echelle groove density to change, which degrades the precision. This can be on the over of 60 cm/s at a 10 mK change in temperature. Their are aiming for a temperature stability of 1 < mK precision in their cryostat. Environmental control is essential to reach 1 m/s RV precision in the NIR.

The HPF environmental control system opens the path to their 1 m/s goal precision. The components of the environmental control system are largely constructed and fabricated by PSU graduate students. Their actively controlled heaters keep HPF at 180 K with mK stability. They are currently testing and demonstrating the stabilizing effects of their thermal enclosure by testing things at HET. Right now HPF is in mid-integration phase in New York, and they plan to have the integration phase done in a month or so, whereupon they will proceed to ship the instrument to PSU for further testing.

Improve RV Precision through Better Spectral Modeling and Better Reference Spectra (Sharon Xuesong Wang, PSU)

Detecting Earth is hard, especially in RV. the RV jitter in Keck’s HIRES spectrograph for Kepler 78 is ~2 m/s. Their goal is to accurately model the stellar spectrum, and compare them to empirically derived reference spectrum. They then apply a “best guess” RV, convolve the model stellar spectrum with the instrumental PSF, and iterate until they find the best RV needed to match the reference spectrum. This reveals the radial velocity signal within the stellar spectrum, which allows them to detect planets.

There are a number of things that can confuse this straightforward process. Firstly, barycentric correction terms (see Wright & Eastman 2014 for more details on this). But if you are detecting things from the ground, you may be detecting spectral lines that are not from the star itself, but telluric lines from the Earth’s atmosphere instead. The telluric lines won’t show the same radial velocity as the stellar lines, which can mess up an RV signal. You need to add telluric lines into your model, or completely mask out regions of telluric contamination, in order to get rid of this. But, there are also micro-telluric all over the visible and IR spectrum which cannot be masked out, so you need to accurately model the tellurics in order to improve your precision.

Now, they also test the reference spectra of I2 cells at PSU’s Hobby-Eberly Telescope, and found that when they tested the I2 cells recently, the reference spectra were different than what they were 20 years ago. This should not be! So they tested again, and found that the newer Fourier transform spectrum of the I2 cell appears to be more accurate than the older one. In the future, they plan to take the improved telluric calibrations and the improved I2 reference spectra to improve the codes used to calculate RVs. They want a Python/GitHub/Bayesian RV code to be implemented, which will improve the precision and accuracy of ground based. RV measurements all around.

First exoplanet transit observations with SOFIA (Daniel Angerhausen, NASA Goddard)

Spectrophotometry in 30 seconds: sometimes we are lucky to observe edge on transits, but usually we are looking at grazing or secondary transits which are more difficult to characterize. Spectrophotometry looks at the transit light curve in many many wavelengths and then compiles that into a spectrum: so spectro- because they are creating a spectrum, and photometry because they are creating these spectra from photometric measurements of transits rather than a traditional spectrograph. This can tell them about the atmospheric composition, and atmospheric structure of HJs.

SOFIA is a telescope on a plane, a Boeing 747-SP aircraft that flies higher than commercial aircraft. It’s a good compromise between a ground-based telescope and a space-based telescope: they remove some of the atmosphere (99%) that plagues ground based observations, but they can’t observe as often as the ground because of flight restrictions. It operates in the NIR (0.3 micron to 1.6 mm). It has a wide wavelength regime and is mobile, which is good all for transit observations. “SOFIA is a space telescope that comes home every day” which lets them continually update the instrumentation on the telescope, something you can’t do with space-based telescopes. This means that SOFIA will always have the cutting-edge detection methods (provided that funding exists).

SOFIA had its first exoplanet observation in October 2013 with FLIPO, planet HD189733b, and achieved “space-based” quality of 185/160 ppm precision. As that was the first observation, they expect that the precision and accuracy of their instruments will only improve as they gain further understanding of them. They are currently working on GJ-1214b transit observations. Even when JWST goes up, people will still need alternatives for transit observations, and SOFIA is the perfect not-quite-space telescope.

Suborbital Demonstrations of Starshades (Anthony Harness, University of Colorado-Boulder)

“The firefly and the lighthouse”: an Earth-like planet is 10^10 times fainter than the host star and only 0.1 arcseconds away. This is comparable to trying to detect the light from a firefly that is flying in front of a lighthouse. A starshade is a way to mask out the light from the star and only detect the light from the planet. The benefit to this is that all of the light-masking is taking place outside of you telescope, so if you want full-light measurements (like from a spectrograph) at the same time you can do both at once.

The community needs to do end-to-end system level tests of starshades so that we can prove that it works and and gain confidence amongst the community that starshades are worth it before we spend a lot of time and money making them. The best way to do this is to do real tests with real data on a smaller ground telescope to make a proof-of-concept.

They wanted to try a zepplin - but alas, no such luck. They next moved to a vertical-takeoff, vertical-landing rocket that can hover and be used as a starshade platform for a ground telescope. They want to ensure that the starshade has cm accuracy and stability - if light keeps leaking around the edges, the measurements are ruined. They plan to use two small telescopes: one for measurements and one as a guiding telescope to make sure that the science telescope is still pointed at the star. Rockets are still a bit far off, however, so their first attempts will be a simple stationary starshade on a tall peak that can be angled to follow the star’s path, and make use of a somewhat mobile telescope. They plan to attempt the stationary method this summer (2015), and their ultimate goal is to have the telescope 3km away from the starshade and detect the disk around Fomalhaut. Their initial tests have been able to detect a “planet” at a 10^-8 contrast to its “star”.

Multiband nulling coronography (Brian A. Hicks, NASA Goddard)

“Nuller” - nulling coronograph. This has similar results to a starshade, in that the starlight is “removed” from the image. Instead of directly blocking the light, a nuller works by using destructive interference of the starlight to detect fainter light that light that is also in the images. In order to detect a Jupiter around the Sun, you need 10^-8 contrast, and for Earth you need 10^-10 contrast. This is a direct-imaging technique to allow you to get down to these precision levels. HZ exo-Earths require very specific inclinations for transits (they essentially must be within a few degrees of edge-on for us to see them transiting), but direct imaging favors “face-on” planet systems rather than edge-on transit systems, so they can probe an entirely different population of planetary systems and reduce our current detection biases.

Direct imaging, because it favors face-on, means that they could observe a planet throughout its “seasons,” look at variations in the planetary albedo (reflectivity) over time, and possibly look at the effects of weather patters on exoplanets. If they broaden the search away from “habitable,” they could even talk about the “infestible zone,” climates where extremiphiles could live. Spectroscopy of directly imaged planets would require a large telescope, and they want to get the spectrum in a large wavelength-range.

In addition to planets, they want to detect debris disks and protoplanetary disks, and observe the evolution of planetary systems through many stages (protoplanetary, planetary, and debris). They want to design a coronograph that could work with a future space-based telescope like JWST and has capabilities in UV, visible, and IR wavelengths. Exo-C and Exo-S are potential future “Exo-coronograph” and “Exo-starshade” missions, both aimed at direct imaging of planets.

Time for coffee! And then on to the panel on alternate career paths, moderated by yours truly.

As I am also presenting a poster, this isn’t a true-live blog, but rather my thoughts from the poster session. You can see the list of poster titles on the ERES schedule. Based on my own experiences, there are a few components to a poster presentation that help with effective communication:

1. An effective poster: I can go on and on about this, and in fact I have done so. My own poster at the conference was entitled “Best Practices for Effective Poster Design,” a copy of which can be found on my personal blog. If there are three things that I can stress about effective poster design they would be:

• Keep your words clear and concise. Abstracts and large blocks of text don’t belong on a poster. You can have more details on a website if you want, or a link to your paper that has all of the big descriptions, but you poster is the visual aid for your oral pitch. It should not be your paper in visual format.

• Use graphics that are easy to understand and that aid in telling your story. Make sure that your audience knows what they should be learning from each graphic even if you’re not there to explain it to them. You can do this with annotations, captions, and other visual clues. This means that the graphics that you use on your poster might not be exactly the same as the graphics that you use in your paper or in your presentation. Use as many graphics as you need to tell your story (a picture is worth a thousand words!), but no more than is necessary.

• Make sure that whatever organization scheme you choose and the style and colors that you choose don’t distract from the content of the poster. All your stylistic choices should only aid content comprehension, and not detract from it. Things like using clear organizational structure, simple backgrounds, and only a few colors will keep your poster from looking cluttered.

2. A clear and concise oral pitch: I say that your poster is the visual aid for your oral pitch, but that means that you need to have an effective oral pitch as well. An oral pitch for your poster is usually around 5 minutes long, and should take you audience through you poster with a more in depth explanation than is on the poster itself. While you are doing this, you should be referencing graphics, charts, or numbers that are on your poster.

3. Good note-taking ability: This is perhaps the most looked over skill in a poster presentation. By note-taking, I mean you the presenter taking notes on the interactions that you have at your poster. Who did you talk to? Who showed interest? What did you talk about? Did they have ideas or followup questions? Did they leave an email for you? All of these are tools that help you, the presenter, learn during your own presentation. Following up with the people you interacted with will also help develop your networking skills.

That’s it for today folks! Thanks for tuning in and I’ll see you bright and early tomorrow morning!

Our final talk session of the day is on Multiple Planet Systems, and is chaired by PSU Postdoc Thomas Beatty.

Precise Planetary Masses, Radii and Orbital Eccentricities of Sub-Neptunes from Transit Timing (Daniel Jontof-Hutter, PSU)

Kepler’s period-radius diagram shows us that sub-Neptune planets are really common, which is interesting because we don’t see any of those planets in our own solar system. We have been able to characterize a few planets using RV as well, and some with transit timing variations. With TTVs we are looking at the very slight variations in a planetary orbital period due to slight gravitational tugs on the planet from other planets in the system.

To characterize TTV transiting planets (Kepler-79 in particular), they can assume that all of the planets are co-orbital (they have the same inclinations). They also assume that there are no non-transiting perturbing planets, since the timing variations closely match what they’d expect for that system with just the transiting planets. They can use TTVs to get the masses of these planets and very good constraints on their eccentricities. This is remarkable because the eccentricities are much lower than would be detectable using RV measurements (RV doesn’t give accurate eccentricities below ~0.1). These eccentricities are 0.2% to 2%, and are still detectable.

TTVs also allow them to characterize the star Kepler-79 very well, with only 2% errors. Knowing the star really well, they can characterize the planets very well. Planet d in the system has a super-Earth mass, but a density of only 0.1 g/cm^3, comparable to atmospherics density on Earth’s surface! This means that the planet must have a much larger radius. When we compare the sample of planets characterized by RV to those by TTV, we see that TTV is looking at a very different sample of planets. Each method has their own biases, so they are finding different types of planets. With TTVs we can find super-Earth massed planets at up to 200 day orbital period, but just because they are super-Earth mass, doesn’t mean that they are rocky! They can have a huge range of bulk densities.

On the Origin and Evolution of the Kepler-36 System (Thomas Rimlinger, UMD)

Kepler-36 is a Sun-like star with two planets in a 7:6 mean-motion orbital resonance, one a super-Earth and one a sub-Neptune. This is a very unusual orbital configuration: one is high density, one is low density; they are very tightly packed; this resonance is very rare. How did this happen? Most planet formation models can’t do this.

Theory: protoplanets form far out and migrate inwards, are bombarded by Mars-sized embryos, one gets its mantle stripped, one gets mass accreted. However, few simulations result in a 7:6 resonance. This makes this particular method very unlikely, because there are a few serendipitous things that must happen to make this system via this method.

Their method: take this theory above, and modify it. Their method would not require mantle stripping, originally starting in the strange 7:6 resonance, the planets don’t have to swap places. They would start in the outer parts in a 2:1 resonance, and migrate inwards. The inner planet then just sweeps up leftover rocky material to become the super-Earth, and the outer one is left as a lower density material. They modeled this in a simulation and were able to accurately replicate this system with minimal fine-tuning of the model.

Spacing of Kepler Planets: Sculpting by Dynamical Instability (Bonan (Michael) Pu, University of Toronto)

What can the orbits of multiplanet systems tell us about their formation? There are some systems, like Kepler-11, that have many many planets packed into a very small space. These systems are also so-called “dynamically cold,” with low eccentricities, no real variations, similar inclinations. Looking at the distributions of Kepler multiplanet systems, we see two distinct families of multiplanet systems: those with many planets that are dynamically “cold” and those with fewer planets that are dynamically “hot”, that have the freedom to have large eccentricities, inclinations, or more widely spaced orbits.

Are these many planet, cold systems really stable over long times? They simulated a Kepler-11 type system - planets that are all super-Earths and tightly spaced - and dynamically ran the system to see how long something like that could survive. At planetary spacing of about 11 times the Hill Radius, all of the simulation runs survived for the full simulation time (1 billion years). At that spacing, they found that inclined and eccentric orbits destabilized the systems within 1 million years. You would need to increase the spacing even more to stabilize those systems.

They conclude that some of the Kepler multiplanet systems are at the edge of stability, and so they must have been “sculpted” over eons. There must have once been many more multiplanet systems that developed in unstable formations and dynamically evolved to their lower-number planet states.

Implications for the False-Positive Rate in Kepler Planet Systems From Transit Duration Ratios (Robert C. Morehead, PSU)

This talk only applies to the multiple planet systems detected by Kepler. As a reminder, Kepler has very low-resolution CCDs: each pixel is 4 arcseconds wide. And so there is a lot of room in the Kepler photometry for false-positive, blend scenarios, and binary star systems. When we look at these stars at higher resolution we can find out more about them, but we can’t do that for everything.

The ratio of transit duration can probe whether two planets orbit the same star. This is especially useful for systems where we know there is more than one star, or when we suspect that there is a blending scenario going on. The orbit’s eccentricity and the impact parameter affect transit duration ratio. We expect mostly that these systems have co-planar planets, since they are all transiting. They use simulations to calculate the likelihood of the observed duration ratio under different scenarios: all around one star, and a suite of false-positive scenarios.

They find that most multiplanet systems have a high probability of being associated with the same star. Now, the problem with this is that the parameters used here are the original Kepler stellar parameters, ignoring any followup observations made. So, while they conclude that most multis are likely around the same star, there is always the chance that there is a blended source and therefore a more complicated system than one might originally think.

This concludes our science talks for the day. After this we have another poster pop session and our poster session, followed by dinner.

A Poster Pop is a sixty second advertisement for a poster. You get one slide to supplement your presentation, and the goal is to attract people to your poster. Poster pops are a challenge, since you have to squeeze in your message in a short time. It’s a good time to practice your “elevator pitch”: describe your work to someone who doesn’t already know what you’re doing, and do it effectively in a short time (as if you only have the length of an elevator ride). The trick here is that you’re not talking about everything that you’re doing, but rather just on what your poster is presenting.

I myself am presenting both a Poster Pop and a poster. My poster pop is in the later session, so this poster pop presentation post is only related to the early session. Keep in mind, these are my own opinions about what makes an effective poster pop presentation. If you disagree, I encourage discussion!

Alright, now after the poster pops are done, here are some of my thoughts about what makes an effective poster pop:
1. The slide:
- Do: make your figure easy to read
- Do: summarize the takeaway message of you poster
- Do: make your slide somehow related to what you’re saying. If I looked at your slide long enough, would I be able to figure out what’s going on?
- Do: make sure to credit all of your co-authors on the paper
- Do: make sure that the text and background are highly contrasted for easy reading
- Don’t: give away the all of the milk for free. Leave them a reason to go to your poster.
- Don’t: make your slide completely un-readable.

2. The content of your pitch:
- Do: say what is unique about your poster. Why should I go to yours over someone else’s?
- Do: tell us where to find your poster
- Do: be excited and speak clearly!
- Do: have good timing! Don’t go over time!
- Do: make what you’re saying related to what’s on your slide.
- Do: make sure that you have a clear beginning, middle, and end.
- Don’t: say the same thing you’re saying in your oral pitch of your poster. This has a different purpose.
- Don’t: just read what you poster says.
- Don’t: stare down at your notes the whole time.
- Don’t: write your whole script out. Be flexible!
- Don’t: make fun of someone else’s work

Phew! That is a lot to fit in to a 60 second pitch. Granted, for our poster pops we have 2 minutes, but that’s still pretty tight.Now that I’ve seen some of these poster pops, I will be well prepared (hopefully!) for my own poster-pop later this afternoon.

Aaaand…we’re back! After our scintillating lunch discussion, we’re back in the ballroom for our next wave of science talks. This is our second of two sessions on Planetary Atmospheres, chaired by Cornell University Research Associate Ramses Ramirez.

The Pale Orange Dot: The Climactic and Spectral Effects of Haze in Archaen Earth’s Atmosphere (Giada Arney, University of Washington)

Giada is from the University of Washington Astronomy and Astrobiology Program. While we want to know about the habitability of distant exoplanet, Earth will always be the best-studied habitable planet. So, we want to study the habitability of Earth throughout its history. She studies the Earth through the Archean period. During this period (~3.8-3.5 billion years ago), life first developed. We had a lot of methanotrophes (methane-eating bacteria), which were prolific because methane was much more abundant than oxygen in the atmosphere. We can look at Saturn’s moon, Titan, to get a modern-day example of a methane-rich atmosphere. We think that the Archean Earth had an orange atmosphere with a methane haze, like Titan does. Since we think that the Earth at one point was hazy, this is a good phenomenon to study to understand potentially habitable worlds.

What would the climate be like on a hazy Earth-like world? As you increase the amount of methane in the atmosphere, you are increasing the methane haze. At around 30% methane the haze starts to cool the planet by shielding the sunlight, but at some point the cooling bottoms out. Conclusion: hazy worlds can be habitable. In the right conditions, it can work like a reverse greenhouse effect, cooling the planet to make it habitable.

How can we detect hazy atmospheres? Methane haze absorbs a lot of light in blue wavelengths, so objects that are missing portions of blue light in their reflection spectra are likely to be hazy. For transit transmission spectra, when you add haze into the atmosphere you can’t see as deeply into the atmosphere, so your characteristic absorption features are more muted than normal. The spectrum at the ground of a hazy planet shows that the majority of the harmful UV light is blocked, so a hazy planet might have a greater chance at habitability, since the harmful types of light are reduced. As the haze on the early Earth was biologically produced and regulated, they might even be a signature of life.

The robustness of using near-UV observations to detect and study exoplanet magnetic fields (Jake Turner, UVA)

The magnetic fields of planets give us insight into the internal structures and rotation period of exoplanets, atmospheric dynamics, formation and evolution of exoplanets, potential exomoons, habitability, and allow us to compare to solar system objects. Their method involved detecting asymmetries in the near-UV and infrared light curves. In the near-UV, you can detect the bow shock in front of the planet, like a boat going through water. This light curve should have an extended ingress and a shortened egress.

They used the Kuiper Telescope in the near-UV on 15 targets looking for exoplanet magnetic fields. On WASP-77b, they note that the transit does not look like their predicted bow-shocked magnetic field. In their 15 planets, they did not see any asymmetric transit shapes, which puts an upper limit on the potential magnetic fields of those planets. So, either those magnetic fields are really small, or perhaps this effect is not observable using that particular telescope or in that particular wavelength.

They use CLOUDY to simulate the ionization, chemical, and thermal states of the bow shock to see what the simulations say about their ability to detect the asymmetry. They find that with this, there are no species in the near-UV to cause an asymmetric transit, so their non-detections are due to their observing parameters, not a physical property of the planets. They find that near-UV transits are not robust for detecting magnetic fields, and near-UV planetary radii show variations that can be used to constrain their atmospheres.

Characterizing Transiting Exoplanet Atmospheres with Gemini/GMOS: First Results (Catherine Huitson, University of Colorado)

Main aims of Gemini/GMOS is to measure the dominant atmospheric absorbers in exoplanet atmospheres. They have broad-band, low resolution optical coverage. Their 9 planet sample has low densities and good comparison star, is comparative study , and want to understand the systematic noise sources. The survey length is 3 years, which lets them improve signal/noise and increase repeatability. With GMOS, they can get similar precision to HST, but with fewer gaps in the data which allows for better fitting of the transit curve and more accurate planetary and stellar parameters.

MOS = Multi-object spectroscopy. The two spectra are the target and the reference star of the same spectral type, so that they can compare the two stars one wavelength at a time. They get a frame every 50 seconds to build a transit light curve, and as they go wavelength-by-wavelength they can see changes in the transit light curves with wavelength, and so build a transmission spectrum. Using this method they find that WASP-4b is a cloud dominated hot Jupiter.

There are a number of observational challenges that they face during their analysis, and they are finding clever ways of solving each and every problem that arises. They can find through this method that XO-2b is a cloud-free hot Jupiter. Their first important results is that while WASP-4b and XO-2b are very similar planets in some respects, they have very different atmospheric structures, and they can detect that.

Hot and Heavy: Transiting Brown Dwarfs (Thomas Beatty, PSU)

Interesting presentation technique: start with your conclusions!

Conclusion 1: The brown dwarf desert may have an oasis.
Conclusion 2: transiting brown dwarfs provide links between hot Jupiters and field brown dwarfs, allowing us to use observations of one to understand the other (KELT-1b in particular)

Our understanding of the brown dwarf desert has evolved over the past 10 years or. As of last year, we have found 7 BD companions in this region, all around F stars (~6250 K) which are more rapidly rotating than the Sun. KELT, unlike other transiting surveys, don’t ignore F stars, which have sort of been ignored before because RV detections are difficult. But now we see that F stars may have an oasis in the BD desert.

The atmospheres of planets and dwarfs behave differently. There’s a very distinct “kink” in the color-magnitude diagram of BDs at the L/T transition (where methane becomes dominant) that doesn’t exist for planets of the same temperature. BDs have a very tight color-temperature sequence, and HJs are much more scattered. The different behavior tells us how the atmospheres are behaving, particularly with regards to carbon monoxide and methane. People postulate that the methane of HJs shouldn’t be there, because the species is highly irradiated by the star, which it wouldn’t be for BDs.

Well…KELT-1b is a highly irradiated BD in a tight orbit around its primary star. The day side of KELT-1b looks just like a field BD, a late-M or early L dwarf. They want to look at the night side of the BD to see if there’s some chemical gradient between the day and night sides. If so…well, that would be very interesting indeed and tell us about the L/T transition for irradiated BDs, and how that impacts HJs and directly imaged planets.

We now move on to the first of our poster-pop sessions. I will do my best to capture some of the dos and don’t of how to give a poster pop once I have some examples of them to work with!