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Liveblogging LathamCon

Jason Wright liveblogged the Dave Latham celebration yesterday, here, herehere and here. I'll continue for day 2.

The first session is The Legacy of Multi-Planet Systems and Photo-dynamics.



Dan Fabrycky is first up with It's All About Time. Before Kepler, Gl876 and the Pulsar planetary system were only systems that required dynamical fits to explain data. RVs and timing are 1-D measurements. Hard to get 3D info from 1D measurements.

Transit timing variations (TTV) technique first published circa 2005, could be used to discover planets, but initially only really used to place limits on additional planets in known transiting systems. More and more data led to more and more upper limits. Frustrating. But because companions to hot jupiters are rare. TTVs took 5 years of toil to little avail.

Kepler brought an embarrassment of riches for TTVs, seeing variations up to 1 day. What's embarrassing is that there are so many we haven't analyzed them all! Dan shows lots of TTV O-C plots.

Huge number of compact, low-mass, multi-planet systems were unexpected. Intriguing lack of pileups at 2:1 and 3:2 resonances, but are many planets just longward. TESS with only 30-day dwell time will see many multis but will have limited TTV opportunities.

"I can't give a talk without showing this." Shows Kepler Orrery II with Flight of the Valkaries in background. If he didn't include the music, Dave Latham would complain "Where's the music?!" So here's the music.



Shows example of Kepler-30 system with 1.5 day TTVs. This is a completely parameterized system, with masses, radii, inclinations and spin-orbit angle. This is a system with large planets. With small planets we're stuck with degeneracies.

There are a lot of forward-looking words in this conference: Emerging, opportunity, Push toward. Dan's session has "Legacy" in title, which is kiss of death fo ran assistant professor :)

Looking ahead the ground-based programs should capitalize on Kepler's legacy. Three projects:

1) With Kepler no longer looking at the sky, so we have to figure out masses of of potentially habitable-zone planets. RV amplitude falls off at larger P, but TTVs increase in precision at long P. In Dan's opinion, this was one of best motivations for the extended mission. How to do this now? From space since transits are shallow so it'll be hard [even with HST]. We did this for Kepler-62 to get weak mass measurements. Lisa Kaltenegger asks "What did you find?" Dan: "You can read the paper. I think you're on it :)" Lots of laughs.

2) Predict forward for future transits that can be observed from the ground later. Spend an extended TESS mission on the Kepler field with a long (~1 year) dwell time.

3) Search for secular effects, namely transit duration variations. Doing this with Sean Mills at Chicago for KOIs in Kepler database. There are some mutually-inclined systems, but they are much rarer than aligned (flat) systems. These secular effects are worth following up.

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Next up is Bekki Dawson with The Legacy of Giant Planet Dynamical Histories.

(Like Dan Fabrycky, Bekki is a good friend and frequent scientific collaborator of Mahalo.ne.Trash)

Thanks Dave for inspiration while she was at the CfA. Wonderful mix of kindness and high expectations of young people.

Imagine that you find two RV planets at 0.11 and 0.24 AU. How'd they get there? Now imagine that you find a Super-earth transiting a bright nearby star. Tempting to think this is pre- and post-Kepler. But this is the same system (55 Cnc)!

We used to think that giant planets form far away and somehow move inward to form diversity we see today. What migration process does this? Two classes: gentle disk migration, violent multi-body interactions. Gentle mech. should circularize and leave planets aligned with star. Violent should pump ecc and tilt orbits. Both can lead to hot Jupiters, but how to distinguish.

Socrates et al. (2012) predict that violent mechanism should have planets following a constant constant angular momentum tracks, with many super-eccentric proto-hot jupiters. Let's look for them. But traditionally need RVs to measure eccentricities. But Bekki developed a method called the "photoeccentric effect" to measure ecc from the light curve (Dawson & Johnson 2012). Used the method to search for super-ecc planets in Kepler sample. Didn't find as many as Socrates et al. predicted.

But did find KOI-1474 with e = 0.8 and huge TTVs (~1 hour) from non-transiting planet (Dawson et al. 2012). Photo-dynamical analysis of huge number of follow-up measurements and Kepler data give us a unique solution for perturbing body: mutually aligned with inner planet and P = 660 days. HIRES data collected by CPS team at great expense. RVs match photoeccentric ecc very well!

Back to missing super-eccentric proto-hot-jupiters. Upper limit of 33% on contribution of super-eccentric migration mechanism of Socrates et al. Consistent with Noaz et al.

Jupiters around metal-rich host stars have much higher eccentricities, while metal-poor stars have more circular orbits (Dawson & Murray-Clay 2013). Also, the period distribution is very different between high- and low-metallicity stars. The hot-jupiter "pile up" only found around metal rich stars, which may explain deficit of hot Jupiters in Kepler sample if Kepler field stars are slightly metal-poor compared to Solar neighborhood. Planets orbiting metal-rich stars show signatures of planet-planet interactions.

Lack of giant planets around metal-poor stars, but common small planets around metal-poor argues for looking for bio-signatures in transiting planets around metal-poor stars since those Earths will be less harassed by large planets in the system. Conclusion: look for small habitable-zone planets, but do not ignore the effect of large planets!

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Tsevi Mazeh is up next with BEER analysis of Kepler and CoRoT light curves: Kepler-76b: A Hot Jupiter with Evidence for Superrotation.

BEER = BEaming, Ellipsoidal & Reflection effects

Story of how Tsevi met Dave. The poster of Dave on his Ossa motorcycle used to be on Dave's door. Tsevi needed to find a collaborator who could do precise RVs. He wrote to Dave and agreed to stop by the CfA on his way from Lick to Tel Aviv and saw the poster on the door. At the time Dave was the Associate Director of the OIR division, he was very busy that day due to an emergency and couldn't meet with Tsevi. Wasn't sure if he wanted to work with such a busy person. Later decided to collaborate after all and they did an RV survey.

They focused on M dwarfs. Doh! M dwarfs don't have hot Jupiters. But did publish (Mazeh & Latham). Not many citations, but led to a great friendship. Also published a bunch of binaries. Always announced in units of 40's.

BEER algorithm: First source of effect is relativistic beaming. Star is brighter when coming toward you, fainter as it recedes. Second, tidal deformation of the star. Third, reflection of starlight off of the planet. All are periodic, but different signals that can be decomposed from a light curve. The amplitudes of effects have very different scalings with period ($P^\alpha$ where $\alpha = {-1/3, -4/3, -2}$).

BEER observed in KOI-74, but the planet was already known from transits. Want to use BEER to find new, non-transiting/non-eclipsing planets/binaries. Then confirm with RVs from collaborators such as Dave. Found seven new binaries (Faigler et al.).

Found a planet and announced last week: Kepler-76 (Faigler et al. 2013). Turns out there is a transit, a big one, too! Even an occultation. But V-shaped, so it was cataloged as an EB and wasn't a KOI. "We saved it from that horrible fate! :)"

However, for another system, the BEER-predicted Doppler amplitude is a factor of 4 larger than measured RV amplitude. "Factor of 2 you can handle. Factor of 4? Too much!" Turns out that the planet has "super rotation" with a hot-spot offset from the sub-stellar point due to atmospheric winds in planet (see Knutson et al. 2009, Showman & Guillot 2002). See this in four other cases!

Illustration of super-rotation for a hot Jupiter: surface map.

Future prospects of this new discovery method are very good! Especially for massive, close-in planets and brown dwarfs.

Instead of raising a wine glass, I toast Dave with a glass of BEER!

During Q&A, Andrea Dupree remarked that this technique doesn't require the same strict alignment as transits, so BEER light curves can be used to detect many more planets than transit light curves!

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