APEX Observations of the CO Envelope around the Young FUor-type Star
  V883 Ori
  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.
