Study of exoplanetary systems via transit timing variations -- Multisite photometric follow-up of Kepler targets using middle-class telescopes around the world

• Applicant: Professor Dr. Stefan Dreizler
• Subject Area: Astrophysics and Astronomy
• Term: from 2015 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 264005490

During its four years of continuous observations the Kepler space telescope has detected thousands of exoplanet candidates. To exclude the possibility that a candidate is actually of stellar nature, an upper limit on its mass is required. In this context the transit timing variation (TTV) method has been a successful tool to constrain the masses of exoplanet candidates without the need for ground-based radial velocity measurements. However, now that Kepler mission has come to a premature end there are still multiple candidates which display TTVs on such long time scales that a sufficient fit to constrain the planetary masses or to dynamically characterize the system cannot be attained. To overcome this predicament we have organized KOINet, a unique near-global photometric follow-up network consisting of twenty middle-sized telescopes headquartered at the Institut fuer Astrophysik Goettingen. On one hand, large-aperture collecting areas will allow us to obtain precise photometry. This, in turn, will permit the detection of shallow primary transit events, beating one of the strongest observational biases: our Earth's atmosphere and its implications over photometric data. On the other hand the network's telescopes, strategically distributed between the United States and China, will allow almost 24 hours of continuous monitoring. Thus, we will exploit the combined power of KOINet to follow-up any event, regardless its duration or frequency. All together, KOINet will collect transit light curves with timing precisions competitive with Kepler's, and will have the potential to complete some of the science the Kepler mission could not accomplish due to its early termination. Therefore, the goal of the overarching project is to characterize the TTVs of 58 systems in total, in order to 1) confirm or reject the possible planetary nature of the Kepler-detected transiting objects, 2) to significantly improve the existing constraints on the masses of the planetary candidates, and 3) to constrain non-transiting plants in the system by analyzing their effect on the TTVs. The project will provide a significant number of well determined planet parameters (mass, radius, mean density) and planetary system architectures, henceforth increasing our knowledge about the exoplanet population. It is only by its distinctive features that we will be able to shed some light into unknowns so fundamental as how do planets form and evolve, and maybe the truthfulness about a long-established human thought: the uniqueness of our Solar System.

• DFG Programme: Research Grants
• International Connection: Israel
• Participating Persons: Dr. Carolina Essen; Dr. Frederic Hessman, Ph.D.; Dr. Tim-Oliver Husser; Dr. Aviv Ofir