Abstract: With the success of the Kepler mission, we now know of
thousands of planets orbiting stars other than the Sun. However, a
vast majority of these planets orbit low-mass stars, limiting our
understanding of planetary demographics around hot, more massive
stars. The Kilodegree Extremely Little Telescope (KELT) project is an
all-sky photometric survey for transiting planets around bright stars
(V of 8–11) and has discovered 19 planets transiting stars brighter
than V ~11 to date. An important aspect of the KELT survey is the
ability to search for planets around hot host stars (Teff > 6250K)
that were originally avoided by most transit surveys. To confirm
candidates as bona-fide planets, we obtain follow-up observations from
the KELT Follow-Up Network (KELT-FUN), a world-wide network of
small college observatories and amateur astronomers. Recently KELT
has discovered two of the brightest transiting planetary systems known,
KELT-9 and KELT-11. As a result of its short orbital period and very
hot (Teff ~10000K) host star, KELT-9b has an estimated equilibrium
temperature of ~4000K, equivalent to a late-K star. KELT-11, currently
the brightest transiting planet host in the southern hemisphere, is an
evolved sub-giant hosting a very low-density planet. I will provide an
overview on the current status of the KELT survey, and the importance
of KELT-9b and KELT-11b.
Abstract: K2 is most often responsible for discovering transiting
planet candidates, which are later vetted using ground-based
facilities. In this project the roles are reversed. We report on the
results of a campaign to monitor 25 HATSouth transiting planet
candidates with K2 during Campaign 7. We discovered a transiting hot
Jupiter with a mass of 2.79 M_J and a radius of 1.26 R_J in a 4.175d
period orbit. We also refine the properties of three previously
discovered HATSouth transiting planets (HATS-9b, HATS-11b, and
HATS-12b). In addition we also report on a further three systems that
remain as Jupiter-radius transiting exoplanet candidates. We also
report on the 18 candidates which we are now able to classify as
eclipsing binary or blended eclipsing binary systems. Our results
show the power of combining ground-based imaging and spectroscopy with
higher precision space-based photometry, and serve as an illustration
as to what will be possible with data from the TESS mission.
Abstract: The Multi-site All-Sky CAmeRA (MASCARA) is a transit survey
aimed at finding planets around the brightest stars at 4<V<8. The
northern hemisphere station on La Palma has been operational since
late 2014, while the southern station on La Silla will start observing
from April 2017. To date, MASCARA has collected more than 350
Terabytes of raw data, producing light curves for over 50,000
stars. We have detected many potentially interesting transiting
objects, and in this talk I will discuss the discovery of MASCARA-1b
the first confirmed exoplanet found by the MASCARA survey – a hot
Jupiter transiting a bright (V=8.3) A-star.
Abstract: I will introduce and the describe the Next Generation
Transit Survey (NGTS), which is a new ground-based transit survey
operating at the ESO Paranal Observatory. NGTS has been designed to
achieve better photometric precision than previous ground-based
surveys, and we aim to detect Neptune-sized planets around Sun-like
stars and sub-Neptunes around M dwarfs that are sufficiently bright
for radial velocity confirmation and mass determination. NGTS is also
optimised for ground-based follow up of exoplanet candidates from TESS
and PLATO. I will present early results from the survey and describe
the status of our HARPS follow up of exoplanet candidates.
Name: Dr Geert Barentsen
Institute: NASA Ames
Title: K2: The Final Leg
Abstract: The K2 project has expanded the legacy of the Kepler mission
by using the repurposed spacecraft to probe short-period planets
around a more diverse population of stars: probing nearby dwarfs
through distant giants; young pre-main sequence stars through evolved
white dwarfs; halo stars through bulge members. I will review the
star and planet population sampled by K2 across 14 fields so far,
highlighting several characteristics, caveats, and unexplored uses of
the public data set along the way. With fuel expected to run out in
2018, I will discuss the closing Campaigns, highlight the final target
selection opportunities, and explain the data archive and bespoke
software tools the K2 mission intends to leave behind for posterity.
Abstract: We present the detection of a new Kepler transiting
circumbinary planet, KIC 10753734. The 6.4 Rearth planet revolves
around its pair of sun-like stars every 260 days on mildly eccentric
orbit. The binary itself is a double-lined spectroscopic binary with
an orbital period of 19.4 days and a large eccentricity of
e=0.52. Both of the stars are spotted, causing relatively large (~1%)
modulations in the light curve. These variations contaminate the
stellar eclipses and skew the eclipse times, but the bias can be
statistically corrected. We can then use the eclipse times to estimate
the planet’s mass, though the ETVs are quite small – immediately
telling us it is a low-mass planet. Full photodynamical modeling gives
a good fit to the Kepler photometry and the radial velocities, and
yields a planet mass of approximately 35 Mearth. KIC 10753734 is the
12th transiting circumbinary planet, and I will conclude my talk with
a discussion of the characteristics of the Kepler CBP sample.
Abstract: Young open clusters are fruitful targets for exoplanet
searches because they represent coeval populations of shared elemental
composition, which can be dated to a precision unattainable for field
stars. Young transiting planets in these clusters are particularly
valuable as they offer a window onto the formation and early evolution
of planetary systems. However, very few such systems are known, making
them of great interest for exoplanet searches such as Kepler/K2, TESS
and PLATO.K2 recently targeted five nearby young open clusters
spanning 1-800 Myrs. I will present our program to characterise young
planets in these clusters using our innovative Gaussian process
regression techniques. I will focus on the characterisation of a small
planet transiting an M dwarf member of Praesepe using K2 photometry
and high-resolution spectroscopy. Finally, I will compare the
newly-discovered young K2 planets to the older Kepler sample, probing
the evolution of planet size and orbital eccentricity.
Abstract: With the success of K2 and the upcoming launch of TESS,
transit photometry has moved into a realm of high-precision but
short-duration surveys. However, the outer regions of extrasolar
systems are an interesting & understudied regime, capable of probing
the migration mechanisms of close-in planets, the compositions of cool
planets, and even the habitable zones of solar-type stars.Therefore,
to push exoplanetary science beyond the hot inner regions of
extrasolar systems, long period planets will need to be found and
characterised from a single transit.I will show that many such
candidates are detectable with K2 & TESS, explain how accurate transit
photometry and stellar parameters can characterise both the planet
size and orbit, and present more than 40 transiting planet candidates
found in K2 photometry from fields 0-10. The candidates, for which
follow-up is on-going, span mini-Neptunes to Jupiters, around stars
from K-dwarfs to G-type sub giants, and on orbits from 50 to 500 days
Abstract: We report the discovery of non-transiting close companions
to two transiting warm Jupiters, Kepler-448b (P=17.9days, R=1.23RJup)
and Kepler-693b (P=15.4days, R=0.91RJup), via dynamical modeling of
their transit timing and duration variations (TTVs and TDVs). The
companions are likely (sub)stellar-mass objects (22MJup for Kepler-448
and 150MJup for Kepler-693), both on tight and eccentric orbits
(a=4.2au and e=0.65 for Kepler-448, a=2.8au and e=0.47 for Kepler-693)
with the periastron distances of 1.5au. The TDVs of Kepler-693b also
point to a significant mutual inclination (~50deg) between the inner
and outer orbits, while for the Kepler-448 system the data are
consistent with both aligned and misaligned configurations. We then
compute long-term evolution of the inner orbits and find that their
eccentricities can exhibit large oscillations due to the secular
perturbation from the companions. These two systems may therefore
serve as evidence for the tidal migration of warm Jupiters.
Abstract: The ESO-K2 Large Program uses the HARPS spectrograph with
the aim at precisely characterising up to 20 new low-mass transiting
planets from the K2 mission. Our objective is to measure masses of the
selected planets to a precision better than 20% to determine their
internal structure (e.g. rocky or gaseous). We are focusing on
relatively bright and quiet G – K dwarfs hosts, with transiting
planets in the radii between the Earth and Neptune. The program runs
for 70 nights spread over 2 years, and began in October 2016. In this
talk, we will present the objectives and the first results of this
program.
Abstract: NASA’s K2 mission has been successfully discovering new
transiting exoplanets around small, nearby stars located in fields
along the ecliptic. K2 is essentially acting as a pathfinder for
NASA’s TESS mission, which is slated to launch in early 2018 and will
perform an all-sky search for transiting exoplanets. The discoveries
from both K2 and TESS are important for identifying key exoplanet
targets that should be characterized with NASA’s James Webb Space
Telescope. I will present new results from an ongoing program for
near-infrared transit photometry of K2 exoplanets conducted with the
3.5m WIYN telescope at Kitt Peak National Observatory. This program of
high-precision, high-cadence, high-spatial-resolution NIR transit
photometry will ultimately provide a vetted sample of K2 exoplanets,
some of which are expected to be prime targets for detailed
characterization with JWST. This program also demonstrates WIYN’s
capabilities for observations of exoplanets to be discovered by TESS.
Abstract: The Robo-AO Kepler Planetary Candidate Survey is observing
every Kepler planetary candidate host star (KOI) in high resolution,
made possible using the unprecedented efficiency provided by
automation of LGS adaptive optics. In 3313 observations, we find 477
stars within 4 arcsecs (approximately the Kepler pixel scale) of KOIs.
These contaminating stars may be the source of false positive transit
signals or, if a bona fide planet is in the system, dilute the
observed transit signal, leading to incorrect planetary properties.
We use this large set of planet hosting multiple star systems to glean
insight into the mechanisms behind the formation and evolution of
planetary systems in our galaxy. We look at the impact to rocky,
habitable zone planets in systems with secondary stars and preview a
follow-up study of planets orbiting in quadruple stellar
systems. Finally, we discuss future all-sky, kilo-target surveys made
possible by the addition of a Southern Robo-AO analog.
Abstract: Although small planets (1 – 4 times the size of Earth) are
ubiquitous in our Galaxy, little is known about their nature
especially in terms of mass and density – key parameters to
investigate planetary composition and internal structure. Accurate
determinations of masses via Doppler spectroscopy have been possible
only for a dozen small planets mainly because of the faintness of most
of the host stars. The K2 space mission is currently targeting bright
stars, a definitive advantage for any RV follow-up. In this talk I
will present the properties of the small transiting planets discovered
and well-characterized by the KESPRINT consortium in different K2
fields. Our family portrait includes ultra-short period super-Earths
with bare rocky cores, mini-Neptunes with volatile-rich envelopes, and
warm Neptunes.
Abstract: The K2-3 planetary system contains three small planets with
orbital periods of 10.0, 24.6, and 44.6 days and radii of 2.1, 1.7,
and 1.6 RE, respectively; the outer planet orbits in the habitable
zone of the M0 dwarf primary. We report on an intensive follow up of
this system that consisted in gathering 300 high-accuracy and
high-precision radial velocities with both the HARPS-N and HARPS
spectrographs over two seasons. This case represents a benchmark for
accurate determinations of the mass of small transiting planets in the
presence of low-level stellar activity and shows how crucial is the
data temporal sampling for this purpose. We report on the mass
measures and their constraints on the internal structures of the three
planets and discuss the difficulty of accurately measuring the mass of
K2-3d whose orbital period is close to the stellar rotation period.
Abstract: I will present the recent findings and highlights of several
planetary systems observed by the K2 in the short-cadence observing
mode. The detection of starspot occultation events and the rotational
modulation in the misaligned WASP-107 system will be put in the
context of two aligned planetary systems, WASP-85 and Qatar-2, whose
lightcurve revealed recurring occultation events. We also found the
ellipsoidal modulation in the phase-curve of Qatar-2, which is the
first phase-curve modulation detection of any of the planetary systems
observed by the K2. Following our detection of stellar pulsations, we
identified WASP-118 as the first transiting exoplanet host star
exhibiting Gamma Doradus pulsations. The observations of WASP-28 and
WASP-151 will become publicly available soon and I aim to present the
analysis of these two systems as well.
Abstract: We present the results of our method to detect small
atmospheric signals in Kepler’s close-in, sub-Saturn planet candidate
light curves. We detect an average secondary eclipse for groups of
super-Earth and Neptune-like candidates by scaling and combining
photometric data of the groups of candidates such that the eclipses
add constructively. We modify our method for averaging short cadence
light curves of multiple planet candidates (2014, ApJ, 794, 133), and
apply it to long cadence data. We then determine the average albedo
for the group from the secondary eclipse depth. In short cadence, we
found that a group of close-in sub-Saturn candidates was more
reflective than typical hot Jupiters. With the larger number of
candidates available in long cadence, we improve the resolution in
radius. We also modify our averaging technique to search for refracted
light just before and after transit in the Kepler candidate light
curves, as modeled by Misra and Meadows (2014, ApJL, 795, L14).
Abstract: Transmission spectroscopy is one of the main techniques for
exoplanet atmosphere characterisation. Planetary absorption can be
detected by comparing the stellar line depth in-transit and
out-of-transit, for example the Na D doublets. However, the intrinsic
stellar line depth varies from the centre to the limb across the
stellar disk (which is called the CLV effect). Thus the CLV effect is
important for transmission spectroscopy. We will present how the
stellar CLV affects the detection of exoplanet transmission
spectrum. In particular, we reanalyse the transit data of HD 189733b
taken with the HARPS spectrograph and the transmission light curve so
obtained shows a clear imprint of the CLV effect.
Abstract: Hot Jupiters are commonly thought to be formed beyond the
ice line and then migrate inwards, but the mechanism is still a
subject of debate. Another unexplained aspect is the considerable
number of misaligned and/or eccentric hot Jupiters.A possible cause
for inward migration is the interaction with massive
companions. Increasing the number of identified multiplanetary systems
is the best way to understand the different orbital parameters and
distinguish between migration models.In 2014, as part of the SOPHIE
TRANSIT follow-up large programme, we started a follow-up of know
transiting hot Jupiters from photometric surveys as CoRoT, Kepler,
HAT, and WASP. RV surveys present an excellent option to look for
outer companions, since by extending the observing baseline it is
relatively easy to detect trend evidencing the presence of additional
bodies in a system.We also discuss the results from the CORALIE
long-term follow up of WASP hot Jupiters, conducted in the southern
hemisphere.
Name: Mr George King
Institute: University of Warwick
Title: X-ray transit observations of HD 189733
Abstract: Detection of a transit at X-ray wavelengths would provide a
tool to probe evaporation from the planet’s atmosphere, while
additionally giving information about the structure of the host star’s
corona. However, there has only been one previous claim of the
detection of a planetary transit in X-rays being successfully
uncovered, for the nearby prototypical transiting hot Jupiter HD
189733b. We revisit this system at X-ray wavelengths, with XMM-Newton
observations covering twenty primary transits. We will present the
findings of our transit search in the obtained light curves, where for
the first time we unambiguously observe the expected W-shaped transit
profile. We fit the data with an exponentially decaying coronal
brightness profile. Finally, we comment on the observed transit depth,
comparing and contrasting our findings with those observed at visible
and infrared wavelengths, as well as theoretical studies of coronal
transits.
Abstract: Presenting SPIDERMAN, a fast code for calculating exoplanet
phase curves and secondary eclipses with arbitrary two dimensional
surface brightness distributions. SPIDERMAN uses an exact geometric
algorithm to calculate the area of sub-regions of the planet that are
occulted by the star, with no loss in numerical precision. The speed
of this calculation makes it possible to run MCMCs to marginalise
effectively over the underlying parameters controlling the brightness
distribution of exoplanets. The code is fully open source and
available over Github. We apply the code to the full phase curve of
WASP-43b, which includes multiple transits and occultations, using an
analytical surface brightness distribution, and find an excellent fit
to the data. We are able to place direct constraints on the physics of
heat transport in the atmosphere, such as the ratio between advective
and radiative timescales at different altitudes.
Abstract: Recent discoveries of exoplanets have challenged formation
models to explain the peculiarities of masses, radii, and densities
observed. Whereas models usually focus on mass-radius relationships to
constrain the composition of exoplanets, and their atmospheres, we
have combined population synthesis models with a full self-consistent
chemical model to be able to explain such features and link the
observations of exoplanets with a formation history. We present here
what the population synthesis models can bring to the analysis of
observations, and what is achievable using such models.
Abstract: Eccentricity is a fundamental orbital parameter which holds
information about planet formation and evolution, but the orbital
shape of small exoplanets remained largely elusive, because their RV
signal is extremely challenging to measure. Using photometry and
relating the duration of a planetary transit to its orbital
eccentricity, if the stellar density is known, I measured the
eccentricity of planets much smaller than previously possible. I
present measurements for 74 planets in multi-planet systems, and 50
systems with a single transiting planet. The multi-systems are nearly
circular, while the systems with a single transiting planet have
significantly higher eccentricities. I relate these findings to
obliquity measurements for multi- and single-planet systems. Finally,
I link these findings to planet formation and evolution theory and
argue that the eccentricity of systems with a single transiting planet
may be related to the presence of non-transiting planets on inclined
orbits.
Name: Dr Julia Venturini
Institute: University of Zurich
Title: The formation of mini-Neptunes
Abstract: The results of the Kepler mission show that planets smaller
than Neptune (“mini-Neptunes”), presumably composed of non-negligible
amounts of hydrogen and helium, are frequent. The formation of this
type of objects is in principle challenging for the classical
core-accretion paradigm of giant planet formation. I will show that
mini-Neptunes are a common outcome when including the effect of
envelope enrichment by icy planetesimals/pebbles in the formation
models. I will discuss as well the planetary composition/structure,
and the implications for the interpretation of exoplanet observations.
Abstract: The haul of thousands of planets orbiting distant stars
discovered by the Kepler and K2 missions has taught us that Earth-size
planets are common. Dynamical models are powerful tools to probe the
formation and evolution of Earth-like planets in environments that
differ from our Solar System. We employ state-of-the-art N-body models
that include collisional fragmentation to numerically explore the late
stages of terrestrial planet formation in systems with different
stellar masses and giant planet architectures. These stages are
dominated by giant impacts that collectively influence their growth,
composition and habitability. By tracking water delivery, core-mass
fractions and impact history, we explore which environments are
conducive to hosting habitable Earth-like planets. We will discuss how
exoplanet observations are allowing us to constrain formation
mechanisms and, in turn, how these models can be used to help guide
target selection for future space observatories.
Abstract: The Kepler mission has discovered that close-in multiple
super-Earths are common around solar-type stars. But their period
ratios do not show strong pile-ups near mean motion resonances
(MMRs). Motivated by the discrepancy between observation and disk
migration theory, we seek for a mechanism that moves planets out of
resonances. We examine the orbital evolution of planet pairs near the
magnetospheric cavity during the gas disk dispersal phase. Our study
determines the conditions under which planets can escape resonances.
Even when planets are trapped into MMR during the early gas-rich
stage, subsequent cavity expansion during the disk dispersal would
induce substantial changes to their orbits, moving them out of
resonance. We apply this model to the Kepler planetary systems and
test both migration and in-situ formation scenarios of super-Earths
planets.
Name: Dr Luca Malavolta
Institute: Dipartimento di Fisica e Astronomia, Università degli Studi di Padova
Title: Kepler-9 and Kepler-19: two pivotal systems that reconcile RV and TTV mass determinations
Abstract: The disagreement on the density of planets from Transit Time
Variations (TTVs) and Radial Velocities (RVs) is a long-standing
problem. To assert the reliability of mass measurements obtained with
the two techniques, we gathered high-precision HARPS-N RVs of two
pivotal exoplanetary systems showing TTVs.Kepler-9 is the first system
confirmed using TTVs, but later the density of the two Jupiter-size
planets were nearly halved. We confirm the lower density of the
planets by combining 31 new RVs with TTV from all Kepler
quarters.Kepler-19b is a transiting planet showing TTVs from
undetected planets. We perform a combined fit of 91 RVs with TTVs from
all Kepler quarters to characterize its mass and two Neptune-mass
planets at a 5-sigma level. The density of Kepler-19b is consistent
with the density of other super-Earths characterized by RVs only.We
conclude by comparing our results with the latest mass determinations
of Kepler and K2 targets obtained with both RV and TTV techniques.
Abstract: The transits of a planet contain a wealth of fundamental
information both on the planet and its host star. With the study of
mid-transit time variations (TTV), it is possible to measure the
gravitational interaction of additional bodies – transiting or not –
that orbit the same center of mass. However, in addition to any
possible instrumental errors, the transit light curves can be
substantially disturbed by effects of photospheric stellar activity,
i.e. starspot occultations during the transit. Could those
spot-crossing events imitate a real TTV signal? If yes, how large
could those TTVbe and how is their period connected to the rotational
and orbital periods of the star and the planet, respectively? In order
to answer those questions I will present the resultsof our simulations
and applications in real systems. In particular I will focus on the
spot-inducedTTV of the system KOI-1452, while I will demonstrate an
easy method to distinguish between real and spot induced TTV.
Abstract: The occultation of stellar active regions by the transiting
exoplanet can generate anomalies in the high-precision photometric
transit light-curves, and lead to an inaccurate estimate of the
planetary parameters. Since the physics and geometry behind the
transit light-curve and the Rossiter-McLaughlin (RM) effect are the
same, the RM observations are expected to be affected by the
occultation of a stellar active region in a similar way. Recently,
Oshagh et al. 2016 demonstrated, by using simulations, that the
inaccurate estimation on the spin-orbit angle owing to stellar
activity can be significant (up to 40 degrees). In this talk I will
present the preliminary result obtained from our simultaneous
high-precision RM measurements (performed by HARPS) and photometric
transit light-curve (through TRAPPIST telescope) during several
consecutive transits of several transiting planets which they transit
very active stars.
Abstract: While the Solar System planets are on nearly circular
(e~0.06) and coplanar ( i~3 deg) orbits, the first several hundred
extrasolar planets discovered using the Radial Velocity technique are
commonly on eccentric orbits (e~0.3). This raises a fundamental
question: Are the Solar System and its formation special? The Kepler
mission has found thousands of transiting planets, but most of their
orbital eccentricities remain unknown. By using the precise
spectroscopic host star parameters from the LAMOST observations, we
measure the eccentricity distributions for a large and homogeneous
Kepler planet sample. We observe an eccentricity dichotomy, a common
orbital pattern and the prevalence of near-circular orbits for planets
inside and outside the Solar System, which provide insights to answer
the above fundamental question.
Abstract: The size of a planet is an observable property directly
connected to the physics of its formation and evolution. We used
precise radius measurements from the California-Kepler Survey (CKS) to
study the size distribution of 2025 Kepler planets in fine detail. We
detect a deficit in that distribution at 1.5-2.0 R⊕. This gap splits
the population of close-in (P < 100 d) small planets into two size
regimes: Rp < 1.5 R⊕ and Rp = 2.0-3.0 R⊕, with few planets in
between. Planets in these two regimes have nearly the same intrinsic
frequency based on occurrence measurements that account for planet
detection efficiencies. The paucity of planets between 1.5 and 2.0 R⊕
supports the emerging picture that close-in planets smaller than
Neptune are composed of rocky cores measuring 1.5 R⊕ or smaller with
varying amounts of low-density gas that determine their total sizes.
Abstract: Evaporating and disintegrating planets provide unique
insights into chemical makeup and physical constraints. The striking
variability, depth (~10-60%) and shape of the photometric transit
curves due to the minor planet orbiting white dwarf WD 1145+017 has
galvanised the post-main-sequence planetary science community. We
performed the first tidal disruption simulations of this planetary
object, and have succeeded in constraining its mass, density,
eccentricity and physical nature. We illustrate how our simulations
can bound these properties, and be used in the future for other
exoplanetary systems.
Abstract: Close-in exoplanets are thought to experience sufficient
irradiation such that evaporation of the primordial atmospheres is one
of the dominant evolutionary drivers. One of the key predictions of
recent numerical exoplanet evaporation and thermal evolution models is
the evaporation valley: a gap in the radius distribution between those
planets that retain a H/He envelope with a mass fraction of ~1% and
those which are completely stripped. I will present a basic physics
argument as to the origin of this feature and demonstrate its
robustness as well presenting a simple derivation of its
properties. Finally, as such a feature has recently been claimed to
have been detected in the transiting exoplanet population from Kepler
I will discuss its implication for improving our understanding of the
underlying photoevaporation model (e.g. energy-limited, recombination
limited, etc.) and what it can tell us about planet formation.
Abstract: Measuring the atmospheric composition and structure of a
range of planets to constrain planetary formation is an important goal
in exoplanetology. Towards this goal ongoing surveys target the
brightest stars, and find very hot-Jupiters with temperatures greater
than 2000K. However, studies have shown that the most irradiated
planets appear to have isothermal day-side spectra in the NIR, thus no
longer exhibit spectral features which are crucially needed to study
their atmospheres in detail.We present new results that demonstrate
that the atmospheric characteristics of the hottest planets can indeed
be retrieved. We illustrate this through phase-curves studies of the
very hottest planets observed with HST/WFC3. Our results suggest that
hot-Jupiters are separated into different classes depending on their
thermal structure. Our findings make the extremely irradiated
Hot-Jupiters very compelling candidates to learn about their
composition with JWST.
Abstract: We report the first results of a new model of the dust tails
of disintegrating rocky exoplanets that is coupled with the
ray-tracing code MCMax3D to generate transit light curves. This model
allows us to account for the radiation shielding in the radial
direction caused by an optically thick tail.We find for an optically
thick tail that the transit depths are wavelength independent over a
large wavelength range and that the transit depth is not indicative of
the amount of mass in the tail. When applied to Kepler-1520b
(formerly KIC12557548b), some tail masses can be excluded because they
produce light curves that differ in shape from the observed Kepler
light curves.For an optically thin tail we find that the wavelength
dependence in transit depth is small and is most pronounced for very
shallow transit depths which may be below the sensitivity of some
observations.We believe that these results can help to explain why
only some transit observations show a wavelength dependence.
Abstract: Close-in exoplanets are susceptible to increased stellar
irradiation. This energy heats up the planetary atmosphere, causing
the material to evaporate and escape into the planet orbit and form a
comet-like tail. Under suitable conditions, stellar light is absorbed
passing through the tail and can be manifested by hiding the emission
feature in the Ca II H & K profiles. WASP-12 hosts an evaporating
close-in planet and an enhanced absorption is seen in the Ca II H &
K. We present a detailed study of WASP-12 spectra observed around the
planet orbit to understand the orbital variation of the system and how
the system evolves.
Abstract: The WASP survey has pioneered the discovery of inflated hot Jupiters, and as of
today more than two hundred have been found. However evolutionary models are failing in
reproducing inflation processes in hot atmospheres accurately. Here, we present new
findings on the observed relationship of planet radius and mass with stellar irradiation.
We infer the probabilistic relation between planet radius, mass and incident flux for
a sample of 286 gas giants using a population-level hierarchical Bayesian model. We map
for the first time the incidence of mass in the degree of inflation and show that
the inflation response to incident flux decreases with increasing mass. Below a mass threshold
of 0.36+/-0.03 Mj we find that hot giants as a population are unable to maintain highly
inflated radii above 1.4 Rj, and instead get smaller with increasing incident flux.
Such a trend is potentially linked to the planet formation and evolution pathway.
We also argue that at fluxes higher than ~1.6 ×10^6 W m-2, there are no hot Jupiters
of mass 0.36-1.00 Mj that are not inflated (meaning that their radii could be explained
by evolutionary models without additional inflation sources). Our study sheds a fresh light
on one of the key questions in the field and demonstrates the importance of statistical
analysis to constrain planetary properties as a population.
Abstract: M dwarf stars make up 75% of the population of the stars in
the Galaxy. Due to their small stellar sizes, the atmospheres of
Earth-sized planets are observationally accessible through the method
of transmission spectroscopy when the planets pass in front of these
stars. Based on data gathered with MEarth and HARPS, we report the
discovery of a planet with a size of 1.4 Earth radii transiting a
small star 12 parsecs away. We measure the mass to be 6.6 times that
of the Earth, consistent with a rocky bulk composition. The planet
receives an insolation of 0.46 times that of the Earth, placing it
within the liquid water habitable zone. Due to its large surface
gravity and cool insolation, the planet may have retained its
atmosphere despite the greater luminosity of its host star in its
youth. Because the star is nearby and 18% the radius of the Sun,
telescopes currently under construction may be able to undertake a
search for atmospheric biosignature gases.
Abstract: Transits across M dwarfs give the best opportunities to
measure precise mass, density and bulk composition of small and cool
exoplanets. I will present an overview of the transiting planets
orbiting M dwarfs discovered so far from photometric ground-based and
space surveys. I will outline the performances and limitations of
existing spectrographs currently used for the radial-velocity
follow-up of transiting candidates across M dwarfs and how far their
mass and density can be constrained. I will finally present the
on-going development of two near-infrared spectrographs: SPIROU (3.6-m
CFHT) and NIRPS (3.6-m ESO) and describe their expected impact in the
follow-up of TESS transiting candidates.
Abstract: The NASA K2 mission is searching for transiting planets in
multiple fields along the ecliptic plane. While the 80-day duration of
each campaign is too short to probe the habitable zones of Sun-like
stars, K2 has already detected several potentially habitable planets
orbiting low-mass stars. In order to identify compelling targets for
atmospheric characterization and explore connections between stellar
and planetary properties, we are pursuing a multi-year, multi-facility
project to characterize planetary systems orbiting K2 cool dwarfs. Our
initial sample contains 60 planets smaller than Neptune, including
thirteen planets that are attractive targets for atmospheric
characterization with Spitzer, HST, JWST, and the next generation of
extremely large ground- and space-based telescopes. We will highlight
the most exciting systems in our sample and discuss the prospects for
using K2 data to further investigate the properties and frequency of
planetary systems orbiting cool dwarfs.
Abstract: The APACHE survey is now concluding its fifth year of
photometric monitoring of a sample of hundreds of early- to mid-M
dwarf stars, in search of transits of small-radius planets.We review
the APACHE project results of five years of observations, estimating
the APACHE ensemble sensitivity to transiting exoplanets by performing
end-to-end simulations of signal injection and retrieval, and studying
the behaviour of completeness and false positives in the limit of
small numbers of events and for threshold-crossing signals. For this
purpose, we take advantage of aggressive data analysis techniques for
the treatment of systematics and stellar astrophysical noise
simultaneously with the search and modeling of transit signals. For 2–
8 R ⊕ planets, we compare our results (including candidates and false
positives) with those from Kepler (Dressing & Charbonneau 2013) and
the MEarth ground-based photometric survey (Berta et al.,
2013). Finally, we put in context the findings from transit surveys
with the statistics from M-dwarf radial-velocity surveys such as those
carried out with HARPS@ESO-3.6m and HARPS-N@TNG.
Abstract: The explosion in the number of exoplanets detected to date
has revealed a surprising diversity. When attempting to model this
variety, it is crucial to account for the uncertainties resulting from
our limited knowledge of chemical, dynamical, and cloud formation
processes in their atmospheres. Combining a retrieval technique with
theory-driven models is the most promising way to address these
processes and constrain a physically plausible atmospheric
structure. Particularly, the formation of clouds in planetary
atmospheres leads to significant compositional and morphological
changes, as they remove absorbers from the observable atmosphere,
dramatically smoothing the spectral features and increasing the amount
of scattered light. Within our retrieval framework, we developed new
thermal stability and patchy cloud models, together with a gray cloud
parametrization. We investigate potentials and limitations of
simplified vs. more complex parametrizations implemented in
retrieval. We apply these models on synthetic data, simulating current
and future space observations, assessing which approach is
particularly useful for the data gathered with the current instruments
and which one gives more insight into the atmospheric cloud structure
using future instruments. To assess the validity of our 1D retrievals
we also compare our results to self-consistently generated 3D models.
Name: Dr Mareike Godolt
Institute: Zentrum für Astronomie und Astrophysik, Technische Universität Berlin
Title: Climate studies of Earth-like planets in the habitable zone
Abstract: We have been exploring the possible climates of planets
within the habitable zone around different main sequence stars. We
will illustrate that finding a planet within the habitable zone does
not necessarily indicate that it is habitable. We have been
investigating the influence of different aspects such as the water
vapor distribution, the surface albedo and the impact of outgassing
from the planetary interior upon the climate of Earth-like planet
using a 1D climate model and compare our results to those of 3D model
calculations.We show different climate states could be realized at a
certain location (hence stellar irradiation) in the habitable zone,
including habitable and non-habitable climates, which is consistent
with 3D modeling results. Furthermore, limited outgassing of water
vapor and carbon dioxide from the interior may narrow the width of the
habitable zone.
Abstract: Water-worlds — planets with bulk water content in the tens
of percent, are predicted as an outcome of planet formation
(e.g. Léger et al. 2004, Raymond et al. 2008). Yet tying the water
abundance derived from atmospheric observations to a planet’s bulk
water abundance is not straightforward. Models must be used to relate
the water content of the planet’s interior to that of its atmosphere.
In these models, the partitioning of water into disparate layers of
the planet and across phase boundary transitions must be carefully
accounted for. In this talk, I will describe efforts to build a
self-consistent whole-planet modeling framework by coupling together
calculations of interior structure and atmospheres to determine the
observable signatures of a planet with a specified water content. The
aim of this work is to have a modeling toolkit at the ready to
capitalize on atmospheric observations of water-rich exoplanets and
provide the first unambiguous detection of water-worlds with JWST.
Abstract: We present near-infrared transmission spectroscopy of the
transiting hot Jupiter HD 189733b with the GIANO spectrograph on the
Telescopio Nazionale Galileo (TNG). GIANO offers the opportunity to
probe at high spectral resolution the planet’s atmosphere
simultaneously over the Y-H-J-K bands, a 21-fold increase in
wavelength coverage with respect to the existing studies based on
CRIRES data. We adapt the high-dispersion spectroscopy technique
described in e.g., Brogi et al. (2016) to the GIANO data and carry out
a cross-correlation analysis with model planetary spectra to obtain a
detection of H2O in the atmosphere of HD 189733b at high
confidence. We discuss the prospects for detection of the individual
contributions of other molecular species (e.g., methane, carbon
dioxide, hydrogen cyanide) and for constraining the planet C/O ratio
with the GIANO data, ultimately gauging the prospects for establishing
GIANO among the leading instruments for characterizing exoplanet
atmospheres.
Name: Dr Jayne Birkby
Institute: Harvard-Smithsonian Center for Astrophysics/University of Amsterdam
Title: Transiting Planets at High Spectral Resolution: a Powerful Ground-based Tool for Characterizing Exoplanet Atmospheres
Abstract: High-resolution spectroscopy (HRS, R>25,000) is a robust and
powerful tool in exoplanet characterization. It uses changes in
Doppler shift to disentangle the direct planet spectrum from its host
star. It is sensitive to the depth, shape, and position of spectral
lines, revealing information about the planet’s composition,
atmospheric structure, mass, global wind patterns, and
tidal-locking. I will present new, exciting results from MEASURE: the
MMT Exoplanet Atmosphere SURvEy, which used infrared HRS to study one
of the best candidates for a planet with an inverted
atmosphere. Inversion layers result in spectra with emission lines
that are distinctly different at high spectral resolution to the
absorption features of non-inverted atmospheres, and permit us to
place stringent constraints on the much-debated existence of inversion
layers in hot giant planets. I will also discuss the complementary of
HRS to low-resolution spectra, and its power in studying our nearest
rocky neighbours.
Abstract: During the May 9th 2016 transit, Big Bear Solar
Observatory’s Fast Imaging Solar Spectrograph recorded atmospheric
absorption by the sodium D1 & D2 lines. Spatial, spectral and
temporal resolution make this data set unique. The absorption
equivalent width peaks near 25 mA and is directly proportional to
column densities of ~10^10 cm^-2. 1000 km altitudes show a 1.2 km/s
blue shift that is mirrored about the planet’s center from its
emission structure, as expected from an an escaping sodium tail and
radiation pressure. Barometric scale heights range from 107+12 km at
dawn to 140+9 km in the south, indicating higher energy sources here,
likely from sputtering by ions precipitating at the southern
cusp. This is the first data set to resolve the ~15 min response time
of Mercury’s sodium atmosphere to its magnetosphere. We will also
discuss other sodium and potassium observations of this transit and
implications for absorption light curves of these species in eccentric
transiting exoplanets
Abstract: EMBARGOED
Abstract: In this talk, we will introduce 2 multi-color simultaneous
cameras, named MuSCAT and MuSCAT2. MuSCAT (Multi-color Simultaneous
Camera for studying Atmospheres of Transiting exoplanets) is a 3-color
simultaneous camera installed on the 188cm telescope at Okayama
Astrophysical Observatory in Japan. MuSCAT2 is a 4-color simultaneous
camera under development for the TCS 1.5m telescope in Teide
Observatory, Canaries, Spain. First light observations of MuSCAT2 are
planned just after this conference. I will talk about specifications
of those instruments, latest results, and future plans.
Abstract: We present a new ground-based optical transmission spectrum
of the Hot Jupiter WASP-43b (M = 2.03 MJ, R = 1.04 RJ) obtained with
the Inamori-Magellan Areal Camera and Spectrograph (IMACS) on the
Baade Telescope at Las Campanas Observatory. These observations were
made as part of the ACCESS survey, which aims at providing a uniform,
large sample of visible transmission spectra of giant exoplanets that
will become key in the era of JWST and comparative
exoplanetology. Using multi-object differential spectrophotometry, we
produce a high precision spectrum of this planet between 400 and 900
nm, combining three different transit epochs. In this analysis, we
search for signals of Na I and K I, as well as for the presence of
hazes/clouds.
Abstract: By observing the occultation of a transiting planet by its
host star in the (near-)IR, the thermal emission of its dayside can be
retrieved. Using this technique at different wavelengths allows to
probe the emission spectrum of the planet’s dayside, from which
insights on the vertical thermal structure and chemical composition of
its atmosphere can be gained. Very hot and inflated gas giants in
very-short-period orbits around their stars are the most favorable
targets for such measurements, thanks to their high temperature and
large size. The atmospheres of such ultra-hot Jupiters are expected to
be conducive for gaseous TiO and VO, which could cause thermal
inversions (i.e. stratospheres) by reprocessing incident UV/visible
irradiation to heat in the upper atmospheric layers. In this talk, I
will present results of an intense ground-based photometric campaign
aiming at probing the emission spectra of WASP-103b and WASP-121b, two
ultra-hot Jupiters orbiting close to their Roche limit.
Abstract: To directly detect an Earth-like planet in the habitable
zone of a Sun-like star, a contrast of 1E-10 needs to be achieved. Our
group has proposed to combine high-contrast direct-imaging and
high-dispersion spectroscopy to reach this contrast on an ELT (Snellen
et. al, 2015). This needs a high-dispersion, AO assisted
integral-field spectrograph. The planet is separated from the stellar
PSF by spatially resolving it, and by simultaneously cross-correlating
with a model spectrum. We show that with existing instruments this
technique already provides significant potential: In archival SINFONI
(VLT) K-band IFU spectra of β-Pic b we detect H2O and CO at high
significance. We call this method Molecular Mapping, which is able to
simultaneously discover a companion and perform a spectroscopic
characterization using a spatial map of the cross-correlation
function. Our work gives a new impulse to the development of METIS at
the E-ELT, which will be perfectly suited for these kinds of studies.
Abstract: I present the results from a ground-based transmission
spectroscopy analysis of WASP-80b. The analysis is based on two
spectroscopic time series covering 525 nm to 900 nm observed with the
OSIRIS spectrograph installed in the 10.4 m Gran Telescopio Canarias
(GTC), and three publicly available high-quality broadband datasets
covering 27 transit light curves observed in visible and NIR
passbands. The analysis uses Bayesian approach where we model the two
spectroscopic datasets jointly with model parameter priors based on
joint-modelling of the broadband data, and use Gaussian processes to
model the systematics.
Abstract: Many transiting planets have extended atmospheres, and
absorption and scattering processes within these atmospheres cause the
measured radius of a planet to depend on wavelength. Transmission
photometry is the method of measuring these radius variations via
band-integrated photometry, from which constraints on the atmospheric
composition, temperature structure and amount of cloud or haze can be
obtained. I present the detection of an atmosphere around the
1.6-Jupiter-mass planet GJ 1132b, from an elevated z-band radius
attributable to opacity from water and/or methane, making it by far
the lowest-mass exoplanet with a detected atmosphere. I also present
new results for the hot Jupiter XO-1 based on transits observed in the
u, g, r, Halpha, I and z bands as well as published HST/WFC3 data
covering 1.1-1.7 microns. I show that the treatment of limb darkening
is sufficiently important as to modify the atmospheric properties
deduced for both GJ 1132b and XO-1b.
Abstract: Optical narrow-band transmission spectroscopy is a method
for understanding the chemical and physical properties of upper
exoplanetary atmospheres. Our aim is to detect exoplanetary sodium by
optimizing the high-resolution narrow-band transmission
spectroscopy. We used single transit observations of HD189733b (with
UVES/VLT) and WASP-17b (with MIKE/Magellan) as test targets. We
obtained the excess absorption light curves in narrow wavelength bands
inside each sodium line. We modeled the external effects of stellar
flaring activity, differential limb-darking, and changing planetary
radial velocity on the light curves. After mitigation of the external
effects, we detected sodium in both targets and measured the
additional absorption of sodium in different passbands, as well as the
depth and width of exoplanetray sodium line. The framework that we
developed is ready for quick application on other targets.
Abstract: We presents results from the first comprehensive survey
program dedicated to probing transiting exoplanet atmospheres using
transmission spectroscopy with a multi-object spectrograph (MOS). Our
four-years survey focussed on ten close-in giant planets for which the
wavelength dependent transit depths in the visible were measured with
Gemini/GMOS. We present the complete analysis of all the targets
observed (50 transits, 300 hours), as well as the main results and
conclusions from this survey. We show that the precision achieved by
this survey permits to distinguish hazy atmospheres from cloud-free
ones. We discuss the challenges faced by such an experiment, and the
lessons learnt for future MOS survey. We present the opportunity that
the MOS technique offers for the follow-up of targets that will be
detected by TESS, CHEOPS and NGTS. Our survey is paving the way for
future atmospheric reconnaissance of habitable worlds with
multi-object spectrographs as a complementary tool to JWST.
Abstract: We will present first results of high resolution
transmission spectroscopy measurements observed with CARMENES (Calar
Alto high-Resolution search for M dwarfs with Exoearths with
Near-infrared and optical Échelle Spectrographs). The spectrograph
was used to obtain time series of high resolution spectra in the
optical and near infra-red during two transits of the well-studied hot
Jupiter HD189733b. These spectra can be used to probe the atmosphere
of this highly inflated planet for absorption features of the alkali
metals sodium and potassium in the optical and water in the near
infra-red. The planet has been subject of several low, medium and high
resolution studies of this kind and was chosen as a benchmark test. We
aim to establish the suitability of the CARMENES instrument for its
potential contributions to the field of exoplanet atmosphere
exploration in addition to the CARMENES survey’s main purpose of
discovering Earth-like planets around M dwarf stars.
Abstract: To understand the compositions and formation processes of
giant exoplanets, also need to understand the structure of their
atmospheres. I will discuss the results of some recent ground- and
space-based spectroscopic observations of a transiting brown dwarf and
a hot Jupiter, which indicate a transition in atmospheric structure as
a function of planetary surface gravity. This transition agrees with
predictions made by “cold-trap” atmosphere models, and these results
are one of the first pieces of observational evidence for cold-trap
processes occurring in hot Jupiters. Its exploration should allow us
to arrive at a better physical understanding of the temperature
structure and cloud properties of these planets.
Abstract: As the field of extrasolar planets evolves with numerous discoveries of new
and diverse planets, we can start thinking in more challenging (observationally talking)
scientific cases that can bring up new, hidden, pieces of the exoplanetary
science puzzle. This is the case of the TROY project, a multi-technique
effort to look for the first co-orbital planets and to provide estimates
of the occurrence rate of these bodies dow to the Earth-mass regime.
Despite being missed in our Solar System, where only kilometer-size (or smaller)
bodies co-rotate with most of the planets, theory allows even equal-mass planets
to co-exist in the same orbit. In this talk I will present
the first results, in the context of TROY, regarding our transit search
for trojan planets including both Kepler/K2 data and new dedicated observations of
the transit of the Lagrangian points of known planets.
Abstract: FINESSE (Fast INfrared Exoplanet Spectroscopy Survey
Explorer) is a proposed space mission dedicated to performing a
statistical census of transiting exoplanet atmospheres. The objectives
of FINESSE are to test theories of planetary origins and climate,
enable comparative planetology, and open up discovery space on
atmospheric chemistry, planetary evolution, and other topics. The
baseline design for FINESSE is a 75 cm telescope observing from
L2. The FINESSE instrument is a high throughput spectrometer with
continuous coverage from 0.5 to 5.0 microns in a single shot. FINESSE
will survey on order of 1000 exoplanets with a combination of
transmission, dayside emission, and phase-resolved emission
spectroscopy during a two year mission. FINESSE was proposed for the
NASA Medium-Class Explorers (MIDEX) announcement of opportunity in
December 2016. I will present an overview of FINESSE, including the
mission concept, science drivers, and expected results from extensive
simulations.
Abstract: Over the last 20 years, humanity has entered the Exoplanet
Age. First one, then tens, and now thousands of planets have been
discovered orbiting distant stars. The next two decades will see us
move from finding only the largest and most obvious planets, to
finding myriad Earth-like worlds – the birth of the exo-Earth era.At
the University of Southern Queensland, we are in the process of
building MINERVA-Australis – a dedicated Australian Exoplanet
Observatory designed to follow-up and characterise Earth-like planets
around the brightest stars. MINERVA-Australis will eventually feature
six telescopes, all feeding to a single high-quality
spectrograph. Capable of taking both spectroscopic and photometric
observations, MINERVA-Australis will be a versatile and powerful
planet detection and analysis machine. MINERVA-Australis will be a key
facility in the follow-up and analysis of planets discovered in the
next wave of Exoplanet discovery, and will see first light in late
2017.
WASP Planets 