Evaluating the Impact of Optical Axis Stability on Exoplanet Detection

The Standards of Fundamental Astronomy (SOFA) is a service provided by the International Astronomical Union (IAU) that offers algorithms and software for astronomical calculations, which was released in two versions by FORTRAN 77 and ANSI C, respectively. \textbf{In this work, we implement the python package PyMsOfa for SOFA service by three ways: (1) a python wrapper package based on a foreign function library for Python (ctypes), (2) a python wrapper package with the foreign function interface for Python calling C code (cffi), and (3) a python package directly written in pure python codes from SOFA subroutines.} The package PyMsOfa has fully implemented 247 functions of the original SOFA routines. In addition, PyMsOfa is also extensively examined, which is exactly consistent with those test examples given by the original SOFA. This python package can be suitable to not only the astrometric detection of habitable planets of the Closeby Habitable Exoplanet Survey (CHES) mission \citep{ji2022ches}, but also for the frontiers themes of black holes and dark matter related to astrometric calculations and other fields. The source codes are available via https://github.com/CHES2023/PyMsOfa.

Section: Python Feature Of the Packagesupporting

confidence: 53%

PyMsOfa: A Python Package for the Standards of Fundamental Astronomy (SOFA) Service

Ji,

Tan,

Bao

et al. 2023

“…Static and temporal varying shape errors of the primary mirror will cause a shift in the centroid of the star image, but this shift is common over the full FOV. For relative astrometry, its impact on measurement accuracy is small and negligible (Tan et al 2022). However, temporal variation of the shape of mirrors after the primary mirror would produce uncommon centroid shifts.…”

Section: Calibration Of Telescope Optical Distortionmentioning

confidence: 99%

CHES: A Space-borne Astrometric Mission for the Detection of Habitable Planets of the Nearby Solar-type Stars

Zhang

et al. 2022

Self Cite

The Closeby Habitable Exoplanet Survey (CHES) mission is proposed to discover habitable-zone Earth-like planets of the nearby solar-type stars ($\sim 10~\mathrm{pc}$ away from our solar system) via micro-arcsecond relative astrometry. The major scientific objectives of CHES are: to search for Earth Twins or terrestrial planets in habitable zones orbiting 100 FGK nearby stars; further to conduct a comprehensive survey and extensively characterize the nearby planetary systems. The primary payload is a high-quality, low-distortion, high-stability telescope. The optical subsystem is a coaxial three-mirror anastigmat (TMA) with a $1.2 \mathrm{~m}$-aperture, $0.44^{\circ} \times 0.44^{\circ}$ field of view and $500 \mathrm{~nm}-900 \mathrm{~nm}$ working waveband. The camera focal plane is composed of 81 MOSAIC scientific CMOS detectors each with $4 \mathrm{~K} \times 4 \mathrm{~K}$ pixels. The heterodyne laser interferometric calibration technology is employed to ensure micro-arcsecond level (1 $\mu$as) relative astrometry precision to meet the requirements for detection of Earth-like planets. CHES satellite operates at the Sun-Earth L2 point and observes the entire target stars for 5 years. CHES will offer the first direct measurements of true masses and inclinations of Earth Twins and super-Earths orbiting our neighbor stars based on micro-arcsecond astrometry from space. This will definitely enhance our understanding of the formation of diverse nearby planetary systems and the emergence of other worlds for solar-type stars, and finally to reflect the evolution of our own solar system.

“…The detection of a habitable Earth-sized planet orbiting around a Sun-like star located 10 pc away from us would require a precision of sub-μas, which is hardly achieved by the current astrometry observation such as Gaia (Perryman et al 2014). However, it is very promising in the near future with the coming of a new era with high astrometry precision of μas (Yu et al 2019;Jin et al 2022;Tan et al 2022).…”

Section: Introductionmentioning

confidence: 99%

The Possibility of Detecting our Solar System through Astrometry

2023

Searching for exoplanets with different methods has always been the focus of astronomers over the past few years. Among multiple planet detection techniques, astrometry stands out for its capability to accurately determine the orbital parameters of exoplanets. In this study, we examine the likelihood of extraterrestrial intelligent civilizations detecting planets in our solar system using the astrometry method. By conducting injection-recovery simulations, we investigate the detectability of the four giant planets in our solar system under different observing baselines and observational errors. Our findings indicate that extraterrestrial intelligence could detect and characterize all four giant planets, provided they are observed for a minimum of 90 years with signal-noise ratios exceeding 1. For individual planets such as Jupiter, Saturn, and Neptune, a baseline that surpasses half of their orbital periods is necessary for detection. However, Uranus requires longer observing baselines since its orbital period is roughly half of that of Neptune. If the astrometry precision is equal to or better than 10 $\mu$as, all 8,707 stars located within 30 pcs of our solar system possess the potential to detect the four giant planets within 100 years. Additionally, our prediction suggests that over 300 stars positioned within 10 pcs from our solar system could detect our Earth if they achieve an astrometry precision of 0.3 $\mu$as.