Abstract Identifying and removing binary stars from stellar samples is a crucial but complicated task. Regardless of how carefully a sample is selected, some binaries will remain and complicate interpretation of results, especially via flux contamination of survey photometry. One such sample is the data from the Gaia spacecraft, which is collecting photometry and astrometry of more than 10 9 stars. To quantify the impact of binaries on Gaia photometry, we assembled a sample of known binary stars observed with adaptive optics and with accurately measured parameters, which we used to predict Gaia photometry for each stellar component. We compared the predicted photometry to the actual Gaia photometry for each system, and found that the contamination of Gaia photometry because of multiplicity decreases nonlinearly from near-complete contamination ( ρ ≤ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> <mml:mn>15</mml:mn> </mml:math> ) to no contamination (binary projected separation, or ρ &gt; <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> <mml:mn>3</mml:mn> </mml:math> ). We provide an analytic relation to analytically correct photometric bias in a sample of Gaia stars using the binary separation. This correction is necessary because the Gaia PSF photometry extraction does not fully remove the secondary star flux for binaries with separations with ρ ≲ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>0</mml:mn> <mml:mover accent="true"> <mml:mrow> <mml:mi>.</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>″</mml:mi> </mml:mrow> </mml:mover> <mml:mn>3</mml:mn> </mml:math> . We also evaluated the utility of various Gaia quality-of-fit metrics for identifying binary stars and found that Renormalized Unit Weight Error (RUWE) remains the best indicator for unresolved binaries, but multipeak image fraction probes a separation regime not currently accessible to RUWE.

Kendall Sullivan

Adam L. Kraus

Travis A. Berger

Daniel Huber

The Astronomical Journal

《天文学杂志》发表原创的天文学研究，重点是从观测中得出的重要科学成果。 AJ 中的出版物包括对数据采集、调查、分析技术、天文解释、仪器仪表以及软件和计算的描述。

The Astronomical Journal publishes original research in astronomy, focusing on significant scientific findings derived from observations. Publications in AJ include descriptions of data collection, surveys, analytical techniques, astronomical interpretations, instrumentation, as well as software and computational methods.

《Astronomical Journal》发表原创的天文学研究，重点关注从观测中得出的重要科学成果。该期刊的出版物涵盖数据采集、调查、分析技术、天文解释、仪器仪表以及软件和计算的描述。

Category	Quartile
物理与天体物理	2
物理与天体物理, 天文与天体物理	2

Quantifying the Contamination from nearby Stellar Companions in Gaia DR3 Photometry

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Journal Info

Category	Quartile
ASTRONOMY & ASTROPHYSICS	1