Transit Timing and Duration Variations for the Discovery and Characterization of Exoplanets in the TESS era
Year: 2017
Type: preprint
Abstract: Transiting exoplanets in multi-planet systems have non-Keplerian orbits which can cause the times and durations of transits to vary. The theory and observations of transit timing variations (TTV) and transit duration variations (TDV) are reviewed. The Kepler spacecraft has detected several hundred perturbed planets, many of which are still undergoing further study, and now TESS is adding to this sample. In a few cases, these data have been used to discover additional planets, similar to the historical discovery of Neptune in our own Solar System. However, the more impactful aspect of TTV and TDV studies has been characterization of planetary systems in which multiple planets transit. After addressing the equations of motion and parameter scalings, the main dynamical mechanisms for TTV and TDV are described, with citations to the observational literature for real examples. Constraints on model parameters from timing are elucidated, particularly the origin of the mass/eccentricity degeneracy and how it is overcome by the high-frequency component of the signal. On the observational side, derivation of timing precision and introduction to the timing diagram are given. Science results are reviewed, with an emphasis on mass measurements in multi-transiting planetary systems, from which bulk compositions may be inferred. The progress being made in studying transit timing with TRAPPIST-1 and TESS multi-planet systems is reviewed, as well as what the future may hold.
Source: arXiv (Cornell University)
Authors: Agol, Eric, Fabrycky, Daniel
Institutions: University of Washington, University of Chicago
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G3126238791, CDS&E: Development of fast, multi-dimensional Gaussian Processes for Exoplanet discovery and beyond, TO ENABLE AND ADVANCE NASA S SEARCH FOR LIFE BEYOND THE SOLAR SYSTEM THE VIRTUAL PLANETARY LABORATORY TEAM WILL FOCUS ON A COMPELLING SCIENTIFIC QUESTION: HOW DO WE RECOGNIZE WHETHER AN EXOPLANET CAN OR DOES SUPPORT LIFE? IN ADVANCE OF CHALLENGING OBSERVATIONS THE VPL WILL COMBINE SCIENTIFIC MODELS OBSERVATIONS AND FIELD AND LABORATORY DATA FROM MANY DISCIPLINES TO EXPLORE HOW A PLANET BECOMES AND REMAINS HABITABLE AND IDENTIFY NEW BIOSIGNATURES IN THE CONTEXT OF THEIR ENVIRONMENTS. THIS RESEARCH WILL INFORM TARGET SELECTION FOR JWST FROM K2 TESS AND GROUND-BASED EXOPLANET DISCOVERIES; HELP OBSERVERS RECOGNIZE THE SIGNS OF PLANETARY HABITABILITY AND LIFE; AND INFORM UPCOMING NASA MISSIONS THAT WILL OBSERVE TERRESTRIAL EXOPLANETS SUCH AS JWST AND THE HABEX OST AND LUVOIR MISSION CONCEPTS. FIVE RESEARCH TASKS WILL ADDRESS OUR SCIENTIFIC QUESTION. TASKS A-D PROVIDE A SUITE OF SELF-CONSISTENT PLANETARY ENVIRONMENTS BASED ON DATA AND MODELS THAT ARE VALIDATED AGAINST SOLAR SYSTEM PLANETS. THESE PLANETARY ENVIRONMENTS ARE THEN INPUT TO TASK E TO SIMULATE PLANETARY OBSERVATIONS AND DETERMINE THE DETECTABILITY OF SIGNS OF HABITABILITY AND LIFE. TASK A: SOLAR SYSTEM ANALOGS FOR EXOPLANETS. WE WILL USE OBSERVATIONS AND ATMOSPHERIC MODELS OF EARTH AND VENUS AS WELL AS REALISTIC SIMULATIONS OF THE DISTANT SOLAR SYSTEM AND OTHER PLANETARY SYSTEMS TO EXPLORE PROCESSES AND REMOTE-SENSING DISCRIMINANTS RELEVANT TO HABITABLE ENVIRONMENTS BIOSIGNATURES AND FALSE POSITIVES. TASK B: THE EARTH THROUGH TIME. WE WILL UNDERTAKE AN INTERDISCIPLINARY SYNTHESIS OF FIELD LABORATORY AND MODELING EFFORTS TO CONSTRAIN ENVIRONMENTAL ECOLOGICAL AND REMOTELY OBSERVABLE PARAMETERS OF EARLY EARTH AND SIMILAR EXOPLANETS AROUND OTHER STARS AS A FUNCTION OF DOMINANT METABOLISM. TASK C: THE HABITABLE PLANET. WE WILL DEVELOP AND USE COUPLED STELLAR ORBITAL INTERIOR AND 1-D TO 3-D ATMOSPHERIC MODELS TO EXPLORE TERRESTRIAL EXOPLANET FORMATION DYNAMICS COMPOSITION ATMOSPHERIC EVOLUTION AND HABITABILITY. THESE ANALYSES WILL INFORM HABITABILITY ASSESSMENTS TO PRIORITIZE PROMISING EXOPLANETS FOR BIOSIGNATURE SEARCHES. TASK D: THE LIVING PLANET. WE WILL INTEGRATE FIELD AND LABORATORY RESEARCH WITH COUPLED CHEMICAL CLIMATE AND ECOSYSTEM MODELS TO EXPLORE THE NATURE AND DETECTABILITY OF BIOSIGNATURES FOR DIFFERENT GEOCHEMICAL AND STELLAR ENVIRONMENTS. WE WILL IDENTIFY NEW REMOTESENSING ATMOSPHERIC SURFACE AND TEMPORAL BIOSIGNATURES AND THEIR FALSE POSITIVES AND NEGATIVES AND QUANTIFY THE ENVIRONMENTAL LIMITS TO PHOTOSYNTHETIC PRODUCTIVITY. TASK E: THE OBSERVER. WE WILL COMBINE OBSERVATIONS ANALYSIS TECHNIQUES AND SIMULATIONS TO IMPROVE THE DETECTION AND CHARACTERIZATION OF POTENTIALLY HABITABLE EXOPLANETS. WE WILL IMPROVE RETRIEVAL OF PLANETARY PROPERTIES FROM EXOPLANET MAPPING AND FROM DIRECT IMAGING TRANSIT TRANSMISSION AND HIGH-RESOLUTION SPECTROSCOPY. OUR ANALYSES WILL DETERMINE OPTIMAL MEASUREMENTS AND OBSERVATION STRATEGIES FOR TERRESTRIAL EXOPLANET CHARACTERIZATION. THE PROPOSED EFFORT BENEFITS ASTROBIOLOGY AND THE NAI WITH A PROVEN PRODUCTIVE INTERDISCIPLINARY SCIENCE TEAM WHOSE RESEARCH ADDRESSES KEY ASTROBIOLOGY PROGRAM GOALS INCLUDING CONSTRUCTING HABITABLE WORLDS IDENTIFYING EXPLORING AND CHARACTERIZING ENVIRONMENTS FOR HABITABILITY AND BIOSIGNATURES AND THE COEVOLUTION OF LIFE AND THE PHYSICAL ENVIRONMENT. THE UW S ASTROBIOLOGY DUAL-TITLE PHD PROGRAM AND OUR ASTROBIOLOGY RESEARCH OPPORTUNITIES FOR MINORITY UNDERGRADUATES STRONGLY SUPPORT THE TRAINING OF THE NEXT GENERATION OF ASTROBIOLOGISTS. OUR TEAM MEMBERS WILL CONTINUE TO PROVIDE KEY SCIENTIFIC LEADERSHIP FOR RELEVANT NASA MISSIONS. THE VPL WILL LEVERAGE THE MASSIVELY INTERDISCIPLINARY COLLABORATION ENABLED BY THE NAI TO PROVIDE A UNIQUE SYNTHESIS OF NASA PLANETARY AND EARTH SCIENCE MISSION DATA MODELING AND RETRIEVAL TECHNIQUES THAT INFORM AND SUPPORT NASA ASTROBIOLOGY AND ASTROPHYSICS MISSION OBJECTIVES.
OpenAlex ID: W3099532758