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We aim to clarify the link between mass accretion and ejection by analyzingDG Tau's jet observations from optical and near-infrared data spanning 1984 to2019, alongside photometric variations between 1983 and 2015. We classified 12moving knot groups among 17 total knot groups based on their constant propermotions and comparable radial velocities. A strong correlation emerges betweendeprojected flow velocities of the knots and the photometric magnitudes of DGTau. From 1983 to 1995, as the deprojected ejection velocities surged from$\sim$ 273 $\pm$ 15 km s$^{-1}$ to $\sim$ 427 $\pm$ 16 km s$^{-1}$, thephotometric magnitudes ($V$) concurrently brightened from 12.3 to 11.4.Notably, when DG Tau became brighter than 12.2 in the $V$ band, its ($B-V$)color shifted bluer than its intrinsic color range of K5 to M0. During thisperiod, the launching point of the jet in the protoplanetary disk moved closerto 0.06 AU from the star in 1995. Following a $V$ magnitude drop from 11.7 to13.4 in 1998, the star may have experienced significant extinction due to adust wall created by the disk wind during the ejection of the high-velocityknot in 1999. Since then, the magnitude became fainter than 12.2, the ($B-V$)and ($V-R$) colors became redder, and the deprojected velocities consistentlyremained below 200 km s$^{-1}$. The launching point of the jet then moved awayto $\sim$ 0.45 AU by 2008. The prevailing factor influencing photometricmagnitude appears to be the active mass accretion causing the variable massejection velocities.

Ejection Patterns in the DG Tau Jet Over the Last 40 Years: Insights into Mass Accretion Variability