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We report on the source Gaia 19ajj, identifying it as a young star associatedwith a little-studied star-forming region seen along a complex line-of-sightthrough the Gum Nebula. The optical lightcurve recently recorded by Gaiaexhibits a slow and unsteady 5.5 mag rise over about 3 years, while themid-infrared lightcurve from NEOWISE over the same time period shows a 1.2 magrise having similar structure. Available color information is inconsistent withpure extinction reduction as the cause for the photometric brightening. Opticalspectroscopic characteristics in the current bright phase include: little inthe way of absorption except for the hallmark Li I 6707 A signature of youthplus weak e.g. Ca I and notably Ba II; strong wind/outflow in Ca II, Mg I b, NaI D, Halpha, K I, O I; jet signatures in [O I], [S II], [Ca II], [Fe II], and[Ni II]; and narrow rest-velocity emission in neutral species such as Fe I, NiI, and Mg I. The infrared spectrum is also characterized by outflow andemission, including: a hot He I wind, jet lines such as [Fe II] and H2; andweak narrow rest-velocity atomic line emission. The 12CO bandheads are weaklyin emission, but there is also broad H2O absorption. Gaia 19ajj exhibited aprevious bright state in the 2010-2012 time frame. The body of photometric andspectroscopic evidence suggests that the source bears resemblance to V2492 Cyg(PTF 10nvg) and PV Cep, both of which similarly experience bright phases thatrecur on long timescales, with large-amplitude photometric variations andemission-dominated spectra. We interpret the behavior of Gaia 19ajj as causedby cycles of enhanced disk accretion accompanied by reduced extinction.

Gaia 19ajj: A Young Star Brightening Due to Enhanced Accretion + Reduced Extinction