The accretion-driven outbursts of young FU Orionis-type stars may be a common stage of pre-main sequence evolution and can have a significant impact on the circumstellar environment as it pertains to the growth of solids and eventually planets. This episodic accretion is thought to be sustained by additional gas in-falling from the circumstellar envelope and disk. We present APEX observations of the CO gas in the envelope around V883 Orionis, a young outbursting star. The observations mapped the $^{ 12}$CO(4-3), $^{ 12}$CO(3-2), and $^{ 13}$CO(3-2) lines with the FLASH$^{ +}$ instrument and the $^{ 12}$CO(6-5) line with the SEPIA instrument. We detected high signal-to-noise emission extending out to radii $>10000$ au and calculated integrated fluxes of $1100~\rm Jy~km~s^{ -1}$ for $^{ 12}$CO(6-5), $2400~\rm Jy~km~s^{ -1}$ for $^{ 12}$CO(4-3), $1600~\rm Jy~km~s^{ -1}$ for $^{ 12}$CO(3-2), and $450~\rm Jy~km~s^{ -1}$ for $^{ 13}$CO(3-2). We used the thermo-chemical code P{ \small RO}D{ \small I}M{ \small O} to test several models and find the data are best described by an envelope structure with $\rm M_{ env}\approx 0.2-0.4\,M_{ \odot}$ and a mass-infall rate of $\rm \dot{ M}_{ inf}=1-2\times10^{ -6}\,M_{ \odot}\,yr^{ -1}$. We infer that the observed envelope and outflow structure around V883 Ori could be caused by multiple outbursts, consistent with episodic accretion.
Categories: astro-ph.EP astro-ph.GA astro-ph.SR