Robo-AO and SOAR High-Resolution Surveys of Exoplanet Hosting Stars

In the past decade, space-based transit surveys have delivered thousands of potential planet-hosting systems. Each of these needs to be vetted and characterized using follow-up high-resolution imaging. We perform comprehensive imaging surveys of the candidate exoplanets detected by the Kepler and TESS missions using the fully autonomous Robo-AO system and the largely autonomous SOAR speckle imaging system. The surveys yielded hundreds of previously unknown close binary systems hosting exoplanets and resulted in verification of hundreds of exoplanet systems. Evidence of the interaction between binary stars and planetary systems was also detected, including a deep deficit of planets in close binary systems.

Twenty-First-Century Statistical and Computational Challenges in Astrophysics

Modern astronomy has been rapidly increasing our ability to see deeper into the Universe, acquiring enormous samples of cosmic populations. Gaining astrophysical insights from these data sets requires a wide range of sophisticated statistical and machine learning methods. Long-standing problems in cosmology include characterization of galaxy clustering and estimation of galaxy distances from photometric colors. Bayesian inference, central to linking astronomical data to nonlinear astrophysical models, addresses problems in solar physics, properties of star clusters, and exoplanet systems. Likelihood-free methods are growing in importance. Detection of faint signals in complicated noise is needed to find periodic behaviors in stars and detect explosive gravitational wave events. Open issues concern treatment of heteroscedastic measurement errors and understanding probability distributions characterizing astrophysical systems. The field of astrostatistics needsincreased collaboration with statisticians in the design and analysis stages of research projects, and joint development of new statistical methodologies. This collaboration will yield more astrophysical insights into astronomical populations and the cosmos itself.

Planetary Systems and the Hidden Symmetries of the Kepler Problem

The question of whether the solar distances of the planetary system follow a regular sequence was raised by Kepler more than 400 years ago. He could not prove his expectation, inasmuch as the planetary orbits are not transformed into each other by the regular polyhedra. In 1989, Barut proposed another relation, which was inspired by the hidden symmetry of the Kepler problem. It was found to be approximately valid for our Solar System. Here, we investigate if exoplanet systems follow this rule. We find that the symmetry-governed sequence is valid in several systems. It is very unlikely that the observed regularity is by chance; therefore, our findings give support to Kepler’s guess, although with a different transformation rule.

EQUATIONS OF PLANETARY SYSTEMS MOTION

The study of the dynamically evolution of planetary systems is very actually in relation with findings of exoplanet systems. free spherical bodies problem is considered in this paper, mutually gravitating according to Newton's law, with isotropically variable masses as a celestial-mechanical model of non-stationary exoplanetary systems. The dynamic evolution of planetary systems is learned, when evolution's leading factor is the masses' variability of gravitating bodies themselves. The laws of the bodies' masses varying are assumed to be known arbitrary functions of time. When doing so the rate of varying of bodies' masses is different. The planets' location is such that the orbits of planets don't intersect. Let us treat this position of planets is preserve in the evolution course. The motions are researched in the relative coordinates system with beginning in the center of the parent star, axes that are parallel to corresponding axes of the absolute coordinates system. The canonical perturbation theory is used on the base aperiodic motion over the quasi-canonical cross-section. The bodies evolution is studied in the osculating analogues of the second system of canonical Poincare elements. The canonical equations of perturbed motion in analogues of the second system of canonical Poincare elements are convenient for describing the planetary systems dynamic evolution, when analogues of eccentricities and analogues of inclinations of orbital plane are sufficiently small. It is noted that to obtain an analytical expression of the perturbing function main part through canonical osculating Poincare elements using computer algebra is preferably. If in expansions of the main part of perturbing function is constrained with precision to second orders including relatively small quantities, then the equations of secular perturbations will obtained as linear non-autonomous system. This circumstance meaningful makes much easier to study the non-autonomous canonical system of differential equations of secular perturbations of considering problem.

Citizen Scientist Participation in Transiting Exoplanet Science

<p>Since the discovery of the first transiting Exoplanet in 1999, shortly after the initial discovery by the radial velocity method,  over 3189 such systems have been discovered.  As a result in recent years the field has started to transition from a discovery phase to one of characterisation and understanding more about the planets discovered.  Ground based surveys with very small telescopes have been extremely successful discovery machines but the majority of known transiting exoplanets were discovered by the space borne Kepler and K2 missions, a legacy that is continuing with the NASA TESS mission.  Consequently the field of transiting exoplanet science is now a target rich environment, which combined with the relative scarcity and competition for professional telescope time, provides an ideal opportunity for participation by citizen scientists.  In this context a citizen scientist is a person or group with access to, and the knowledge to use, the equipment required to make precise photometric observations, whether this is their own telescope or through the use of shared , educational or commercial facilities.</p> <p>Exoplanet science is a field that excites and captures the imagination of both the general public, amateur astronomers and students alike.  Arguably the most successful project supporting citizen scientist participation has been the Exoplanet Transit Database (ETD) run by the Czech Astronomical Society since 2009 the database has accumulated over 10,000 lightcurves of 350+ exoplanet systems, contributed mostly by an army of nearly 1200 globally distributed amateur observers.  Although originally created as a way to search for transit timing variations, the wealth of data gathered has been used by professional astronomers including searches for orbital period decay or apsidal precession in transiting hot Jupiters.  The network of observers has also resulted in a number of pro-am collaborations producing exciting results such as the discovery of TrEs-5c.</p> <p>One of the key missions planned for this decade to help characterise transiting exoplanet atmospheres is the ESA medium class mission ARIEL (Atmospheric Remote-sensing Infrared Exoplanet Large-survey satellite), scheduled for launch sometime in 2028.  This ambitious transit spectroscopy mission aims to measure the spectra of over 1000 transiting exoplanet atmospheres to better understand their chemical composition, their formation and evolutionary histories and the links between the planets and their stellar environment.  To help achieve this, precise knowledge of all 1000+ planet ephemerides is required to optimise the science return from the 4-year mission.  The Exoclock project is an initiative run by the ARIEL Ephemerides Working Group to focus and coordinate both professional and citizen scientist observations of exoplanet transit light curves to measure transit mid-times and to monitor the stellar variability of the host stars for all the systems on the ARIEL target list.  To this end the Exoclock team have created a suite of tools, guides and educational material to help widen participation, target those systems most in need of observations and provide homogenous results to allow accurate scheduling of ARIEL observations.  ARIEL is by no means the only space science mission eliciting support from the citizen scientist and amateur astronomy community with projects also being run for the follow up of TESS observations and the PLATO amateur collaboration project.</p> <p>In this presentation I will review the growing need for citizen scientists to support flagship exoplanet science missions and look at results of some successful pro-am collaborations highlighting the contribution made by citizen scientists.  Using results obtained from multiple ~0.4m telescopes I will look at opportunities for maximising the science return from the observations obtained.</p>

Alkaline exospheres of exoplanet systems: evaporative transmission spectra

ABSTRACT Hydrostatic equilibrium is an excellent approximation for the dense layers of planetary atmospheres, where it has been canonically used to interpret transmission spectra of exoplanets. Here, we exploit the ability of high-resolution spectrographs to probe tenuous layers of sodium and potassium gas due to their formidable absorption cross-sections. We present an atmosphere–exosphere degeneracy between optically thick and optically thin mediums, raising the question of whether hydrostatic equilibrium is appropriate for Na i lines observed at exoplanets. To this end we simulate three non-hydrostatic, evaporative, density profiles: (i) escaping, (ii) exomoon, and (iii) torus to examine their imprint on an alkaline exosphere in transmission. By analysing an evaporative curve of growth, we find that equivalent widths of $W_{\mathrm{Na D2}} \sim 1{\!-\!} 10\, \mathrm{m\mathring{\rm A}}$ are naturally driven by evaporation rates ∼103−105 kg s−1 of pure atomic Na. To break the degeneracy between atmospheric and exospheric absorption, we find that if the line ratio is D2/D1 ≳ 1.2 the gas is optically thin on average roughly indicating a non-hydrostatic structure of the atmosphere/exosphere. We show this is the case for Na i observations at hot Jupiters WASP-49b and HD189733b and also simulate their K i spectra. Lastly, motivated by the slew of metal detections at ultra-hot Jupiters, we suggest a toroidal atmosphere at WASP-76b and WASP-121b is consistent with the Na i data at present.

On the survival of resonant and non-resonant planetary systems in star clusters

ABSTRACT Despite the discovery of thousands of exoplanets in recent years, the number of known exoplanets in star clusters remains tiny. This may be a consequence of close stellar encounters perturbing the dynamical evolution of planetary systems in these clusters. Here, we present the results from direct N-body simulations of multiplanetary systems embedded in star clusters containing N = 8k, 16k, 32k, and 64k stars. The planetary systems, which consist of the four Solar system giant planets Jupiter, Saturn, Uranus, and Neptune, are initialized in different orbital configurations, to study the effect of the system architecture on the dynamical evolution of the entire planetary system, and on the escape rate of the individual planets. We find that the current orbital parameters of the Solar system giants (with initially circular orbits, as well as with present-day eccentricities) and a slightly more compact configuration, have a high resilience against stellar perturbations. A configuration with initial mean-motion resonances of 3:2, 3:2, and 5:4 between the planets, which is inspired by the Nice model, and for which the two outermost planets are usually ejected within the first 105 yr, is in many cases stabilized due to the removal of the resonances by external stellar perturbation and by the rapid ejection of at least one planet. Assigning all planets the same mass of 1 MJup almost equalizes the survival fractions. Our simulations reproduce the broad diversity amongst observed exoplanet systems. We find not only many very wide and/or eccentric orbits, but also a significant number of (stable) retrograde orbits.

Mirror world and planetary orbit distribution in the solar system（Geometric derivation and physical significance of the distribution law of the orbits of the solar and solar-like planets）

There are different opinions on the distribution formula of the distance between Titius-Bode's planets [1,-5] Some people use this theory to prove that exoplanet systems have the same regularity [4] , But the emergence of the Hot Jupiter has made many people less convinced of the empirical formula Titius-Bode law. The explanation of the Titius-Bode law in our past theory is not convincing because of the incorporation of too many traditional theories and concepts, and almost all the papers that explain the distribution of planets are in the present theoretical framework [2-5] To explain. In fact, the distribution law of the distance of planets is related to the cause of gravitation. I dont know the cause of the gravitation and the process of action. The "planetary distance distribution rule" cannot be interpreted correctly. To use "six-level multidimensional symmetric complex geometry" [7] to understand the genesis of the derivation of the solar system's orbit, the actual application is a simple and easy-to-understand explanation of the "gravity of six-level multidimensional symmetric complex geometry" [8] , so understanding this article requires understanding" Six-level symmetry theory of gravity' [7, 8] .