306.01 — How to detect forming planets?
Judit Szulagyi1
1 Institute for Computational Science, University of Zurich (Zurich, Switzerland)
Giant- and immediate mass planets are surrounded by their circumplanetary disk during the last stage
of their formation. In order to detect nascent plan- ets, therefore, we need to understand the character- istics of this disk, since this is what we are going to observe. The planet is embedded within the circum- planetary disk, therefore we would not be able to see that directly, as simulations show. I create mock observations on various wavelengths by combining 3D radiative hydrodynamic simulations and Monte- Carlo radiative transfer to create synthetic images, and spectral energy distributions (SEDs). In my talk I will show how these images look like at sub-mm and radio wavelengths, at near/mid-infrared and at polarized scattered light for the various current and near-future instrumentation, such as ALMA, SPHERE/GPI, ERIS/NaCo etc. The spectral energy distribution of the circumplanetary disk will be also discussed and compared with the circumstellar disk SED, in order to identify the wavelength range where the best contrast can be achieved to detect the circum- planetary disk and the forming planet. Finally, I will talk about what line fluxes we can expect regarding detecting H-α from these sources. I will try to give an answer why previous attempts of detection of cir- cumplanetary disks often failed, what are the diffi- culties to face with, and what systems we could de- tect with current/near future instrumentation based on my simulations. To understand how forming planets should look like on observations, also help us distinguishing forming planets from other circum- stellar disk features. I will highlight, that in the for- mation phase, unfortunately we cannot estimate the planet mass based on the observed brightness, be- cause the fluxes are always contaminated by the cir- cumplanetary disk contribution, and therefore the brightness will depend mainly on the disk proper- ties (temperature, dust-to-gas ratio, density, viscos- ity, etc.), less about the planet luminosity.
306.02 — Astrometric orbits of tight substellar bi- naries
Johannes Sahlmann1
1 Space Telescope Science Institute (Baltimore, Maryland, United States)
We present new results from the high-precision astrometric monitoring of nearby very-low-mass stars brown dwarfs with Gemini/GMOS and VLT/FORS2. The goals of these projects are the characterisation of known spectral binaries and the discovery of companions down to sub-Jupiter mass, respectively. We will give an overview of the program, report on the orbit determination of spectral binaries, and present an update on our planet-search results. We will put these results
into the context of efforts to determine the tight binary fraction of ultracool dwarfs and to explore the occurrence of planets around these objects.
306.03 — What we’ll see when we’ve seen what we see that we can see
Zephyr Penoyre1; Emily Sandford2
1 University of Cambridge, Institute of Astronomy (Cambridge, United Kingdom)
2 Department of Astronomy, Columbia University (New York, New York, United States)
Improving instrumental precision is like a receding tide, revealing the geological shapes underneath the water’s surface. New signals rise out of the noise, take shape and gain familiarity, until it is hard to imagine ever not having known them.
Out-of-transit effects — tides, beaming and reflec- tions in particular — are one such family of signals which will transition from near-invisible to common- place. As photometric precision drops from 100s of parts per million to 10s and below, these signals will go from being occasional to ubiquitous in light curves, especially for massive, close-in or eccentric planets.
We can leverage these signals as tools for con- straining planetary properties, confirming candi- dates and detecting new planets — but doing so re- quires a detailed, intuitive and accurate theoretical understanding of the physics at play and the obser- vational signatures.
Here we present analytic models of these effects, of sufficient simplicity to allow easy intuition and cal- culation, whilst encoding a full physical picture able to capture the behaviour of the broad exoplanet zoo.
306.04 — The potential of direct detection of exo- planets by optical interferometry
Sylvestre Lacour1
1 LESIA, Observatoire de Paris (Meudon, France)
With over 4000 exoplanets discovered, the focus of exoplanet research progressively shifts from census to characterization. Direct imaging targets a differ- ent planet population than transit spectroscopy: it is possible to obtain spectra of young, far-out exoplan- ets. And in that field, optical interferometry is on the verge of playing a major role: with baselines of hun- dred meters, its spectral and differential imaging ca- pacities surpass by order of magnitudes those of sin- gle dish telescopes. During this talk, I will present the interferometric technique which enables direct
observations of exoplanets. I will present the detec- tion of HR8799e by the GRAVITY instrument, and discuss the capability of the technique for future de- tections.
306.05 — Alkaline Signatures of an Active Exo- moon
Apurva V. Oza1; Robert E. Johnson2; Emmanuel Lellouch3; Carl Schmidt4; Nick Schneider5; Chenliang Huang6; Diana Gamborino1; Andrea Gebek1,7; Aure- lien Wyttenbach8; Brice-Olivier Demory9; Christoph Mordasini1; Prabal Saxena11; David Dubois10; Arielle Moullet10; Nicolas Thomas1
1 Physikalisches Institut, Universität Bern (Bern, Switzerland) 2 AMES Research Center, NASA (Moffett Field, California, United States)
3 Goddard Space Flight Center, NASA (Greenbelt, Maryland, United States)
4 Engineering Physics, University of Virginia (Charlottesville, Virginia, United States)
5 LESIA, Observatoire de Paris (Meudon, France)
6 Center for Space Physics, Boston University (Boston, Mas- sachusetts, United States)
7 LASP, University of Colorado Boulder (Boulder, Colorado, United States)
8 Physics and Astronomy, University of Las Vegas (Las Vegas, Nevada, United States)
9 Physik, Eidgenossische Technische Hochschule Zurich (Zurich, Switzerland)
10 Leiden Observatory, Leiden University (Leiden, Netherlands) 11 Center for Space and Habitability, Universität Bern (Bern, Switzerland)
Exomoons are generally too small to be detected by nominal searches. By analogy to the most ac- tive body in the Solar System, Io, we describe how sodium (Na I) and potassium (K I) gas could be a signature of the geological activity venting from an otherwise hiddenexo-Io. Analyzing a dozen close- in gas giants hosting robust alkaline detections, we show that an Io-sized exomoon can be stable against orbital decay below a planetary tidal Qp < 1011. This tidal energy is focused into the satellite driv- ing ∼105 times more mass loss than Io’s supply to Jupiter’s Na exosphere, based on a simple atmo- spheric loss model. The remarkable consequence is that several exo-Io column densities are on av- erage more than sufficient to provide the 1010±1Na cm−2required by the equivalent width of exoplanet
transmission spectra. Furthermore, the benchmark observations of both Jupiter’s extended (∼1000 RJ) Na exosphere and Jupiter’s atmosphere in transmis-