An In-Depth Review of the JWST General Observer (GO) Programs Cycle 1 - Companion HD 206893 B with NIRISS/AMI

The launch of the James Webb Space Telescope (JWST), a premier observatory for infrared and submillimeter astronomy, marked a significant milestone in modern astrophysics. Among its many scientific objectives was to conduct an exhaustive review of approved General Observer (GO) programs during Cycle 1. As part of this endeavor, our focus will be on the fascinating companion star system HD 206893 B, led by PI Jens Kammerer and Co-PI Tomas Stolker.

### Introduction

HD 205986 is a young substellar object located approximately 95 AU from its host A9V primary star. Discovered in July 2017 using the SPHERE/IFS instrument on the Very Large Telescope (VLT), this companion was initially thought to be a rogue planet due to its low mass and lack of detected orbit around any known stellar body.

### Background

The detection of HD 205986 B serves as an intriguing example of how advanced observational techniques can reveal hidden companions within our solar neighborhood. As part of the larger Exoplanet Encyclopedy, this object was initially classified under the name V2017b due to its uncertain nature and lack of proper nomenclature.

### Observational Context

The observations leading up to the discovery were conducted using the Subaru Coronagraphic Extreme Adaptive-Optics Near-Infrared/Amorphous-Metallic-Silicon (SCExAO+HiCIAO) instrument mounted on the Subaru Telescope's 8.2-metre Main Optical and Infrared Keck Observatory/Northwestern University ESO/NAU NOIRLab/SKAI/Maunakealuna Observatories/NOIRLab/PI: Jens Kammerer, Co-PIs Tomas Stolker, etc.).

### Results

The observations reveal HD 205986 B to be a substellar object with an estimated mass of approximately 27±4 Jupiter masses (Mjup). Its projected separation from the primary star is found to be about 3.5 ± 0.2 arcseconds at a position angle of -45+/-10 degrees east of north.

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The discovery and characterization of HD 205986 B highlight the power of modern observational techniques in unveiling previously unknown substellar companions within our own solar system's periphery. These findings not only contribute significantly to our understanding of planetary formation processes but also underscore the importance of continued monitoring efforts using advanced ground-based and space-borne instrumentation.

### Acknowledgments

This work was supported by funding from various sources, including grants from NASA/STScI (GO-12345) under award number . The authors would like to extend their deepest gratitude to all those who have contributed towards this research through their scientific insights, technical expertise, and unwavering support.

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