Closeby Habitable Exoplanet Survey (CHES). II. An Observation Strategy for the Target Stars

TL;DR

The paper presents a detailed observation strategy for the CHES mission aimed at detecting habitable exoplanets around nearby solar-type stars, optimizing observation time and prioritization for efficient planet detection within five years.

Contribution

It introduces a comprehensive five-year observation plan for CHES, including target prioritization, observation scheduling, and verification through simulations, enhancing mission efficiency.

Findings

Strategy covers all targets within six months

Simulations confirm the strategy's effectiveness for exoplanet detection

Approximately 86% of observation time allocated to target stars

Abstract

The Closeby Habitable Exoplanet Survey (CHES) constitutes a mission intricately designed to systematically survey approximately 100 solar-type stars located within the immediate proximity of the solar system, specifically within a range of 10 parsecs. The core objective of this mission is the detection and characterization of potentially habitable Earth-like planets or super-Earths within the habitable zone of these stars. The CHES mission obtains high-precision astrometric measurements of planets orbiting the target stars by observing angular distance variations between the target star and reference stars. As a result, we surveyed the relevant parameters of both target and reference stars in detail, conducting a thorough analysis and calculation of the required observation accuracy, the number of observations, and the priority assigned to each target star. Observational emphasis will be concentrated on targets considered of higher priority, ensuring the effectiveness of their observation capabilities. Through this approach, we formulate a five-year observation strategy that will cover all the target stars within a six-month timeframe. The strategy not only fulfills the required observing capability but also exhibit high efficiency simultaneously, providing an executable program for future mission. Over the span of the mission's five-year duration, a cumulative observation time of 29,220 hours will be available. Approximately 86 percent of this, totaling 25,120 hours, is allocated for the observation of target stars. This allocation leaves approximately 4,100 hours for extended scientific observation programs. We have also performed simulated observations based on this strategy and verified its observational capability for exoplanets.