An asymmetric dust ring around a very low mass star ZZ Tau IRS
  We present Atacama Large Millimeter/submillimeter Array (ALMA) gas and dust
observations at band 7 (339~GHz: 0.89~mm) of the protoplanetary disk around a
very low mass star ZZ~Tau~IRS with a spatial resolution of 0\farcs25. The
$^{12}$CO~$J=3\rightarrow2$ position--velocity diagram suggests a dynamical
mass of ZZ~Tau~IRS of $\sim$0.1--0.3~$M_{\sun}$. The disk has a total flux
density of 273.9 mJy, corresponding to an estimated mass of 24--50~$M_\oplus$
in dust. The dust emission map shows a ring at $r=$ 58~au and an azimuthal
asymmetry at $r=$ \jh{45}~au with a position angle of 135\degr. The properties
of the asymmetry, including radial width, aspect ratio, contrast, and
contribution to the total flux, were found to be similar to the asymmetries
around intermediate mass stars ($\sim$2~$M_{\sun}$) such as MWC~758 and IRS~48.
This implies that the asymmetry in the ZZ~Tau~IRS disk shares a similar origin
with others, despite the star being $\sim$10 times less massive. Our
observations also suggest that the inner and outer parts of the disk may be
misaligned. Overall, the ZZ~Tau~IRS disk shows evidence of giant planet
formation at $\sim$10 au scale at a few Myr. If confirmed, it will challenge
existing core accretion models, in which such planets have been predicted to be
extremely hard to form around very low mass stars.
