We investigate new and archival 3–5 \mu m high resolution ( \sim 3 km s ^ { -1 } ) spectroscopy of molecular gas in the inner disk of the young solar-mass star EX Lupi , taken during and after the strong accretion outburst of 2008 .
The data were obtained using the CRIRES spectrometer at the ESO Very Large Telescope in 2008 and 2014 .
In 2008 , emission lines from CO , H _ { 2 } O , and OH were detected with broad profiles tracing gas near and within the corotation radius ( 0.02–0.3 AU ) .
In 2014 , the spectra display marked differences .
The CO lines , while still detected , are much weaker , and the H _ { 2 } O and OH lines have disappeared altogether .
At 3 \mu m a veiled stellar photospheric spectrum is observed .
Our analysis finds that the molecular gas mass in the inner disk has decreased by an order of magnitude since the outburst , matching a similar decrease in the accretion rate onto the star .
We discuss these findings in the context of a rapid depletion of material accumulated beyond the disk corotation radius during quiescent periods , as proposed by models of episodic accretion in EXor type young stars .