Second Earth Spectrograph - Vacuum System

• Subject Area: Astrophysics and Astronomy
• Term: Funded in 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 553389271

The past few years have seen enormous progress in our ability to find small planets. With the radial-velocity (RV) method, it is now possible to measure the masses of planets down to one Earth mass, but only if the host star is much lighter than the Sun. One of the most important goals of current research on extrasolar planets consists in refining the RV technique such that it can be used to observe true Earth analogs, i.e., planets with similar characteristics orbiting nearby Sun-like stars. It is currently not known whether this is possible at all. In addition to surmounting the considerable technical challenges of building spectrographs that can achieve the required measurement accuracy of about 10 cm/s, one must deal with the RV “jitter” induced by turbulent motions on the stellar surface, and the rotation of the host star. We intend to build and operate the Second Earth Spectrograph (2ES), within a consortium consisting of three German, one Danish, and one Chilean institution. 2ES will be installed at the 2.2 m telescope on La Silla, Chile, and receive 2/3 of the available observing time over five years. The main objective of the 2ES project is exploring the ultimate limits of the RV method by observing a small sample of bright southern Sun-like stars (i.e., stars of spectral type G and K) every night. We will build on the experience of the consortium in constructing state-of-the-art RV instruments (CARMENES and MAROON-X) to design an ultra-stable spectrograph, capable of pushing the instrumental limit into the 10 cm/s regime. Taking advantage of the generous time allocation, we will be able to probe the stellar variability with unprecedented precision. Our scientific goals can thus be summarized as follows: (1) Develop, test, and validate calibration strategies enabling radial-velocity measurements with a long-term precision of 10 cm/s. (2) Understand the processes and phenomena in the atmospheres of F, G, and K stars that limit the ultimate precision of the Doppler RV technique. (3) Develop data analysis strategies, algorithms, and tools to mitigate the effect of these processes on the derived radial velocities. (4) Provide a legacy data set of high-quality high-resolution spectra of the brightest solar-type stars in the Southern sky, with nightly temporal sampling. (5) Discover terrestrial planets orbiting nearby Sun-like stars. The development of 2ES will be co-financed by the consortium partners. In the present proposal, we seek support for the contribution of the Institute for Astrophysics and Geophysics at the Georg-August-University Göttingen.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Second Earth Spectrograph - Vacuum System
• Instrumentation Group: 0750 Spezielle astronomische Geräte (Ballon-Teleskope, Satelliteninstrumentierung)
• Applicant Institution: Georg-August-Universität Göttingen
• Leader: Professor Dr. Ansgar Reiners