ALMA detection of water vapour in the low mass protostar IRAS
  16293$-$2422
  The low mass protostar IRAS 16293$-$2422 is a well-known young stellar system
that is observed in the L1689N molecular cloud in the constellation of
Ophiuchus. In the interstellar medium and solar system bodies, water is a
necessary species for the formation of life. We present the spectroscopic
detection of the rotational emission line of water (H$_{2}$O) vapour from the
low mass protostar IRAS 16293$-$2422 using the Atacama Large
Millimeter/submillimeter Array (ALMA) band 5 observation. The emission line of
H$_{2}$O is detected at frequency $\nu$ = 183.310 GHz with transition
J=3$_{1,3}$$-$2$_{2,2}$. The statistical column density of the emission line of
water vapour is $N$(H$_{2}$O) = 4.2$\times$10$^{16}$ cm$^{-2}$ with excitation
temperature ($T_{ex}$) = 124$\pm$10 K. The fractional abundance of H$_{2}$O
with respect to H$_{2}$ is 1.44$\times$10$^{-7}$ where $N$(H$_{2}$) =
2.9$\times$10$^{23}$ cm$^{-2}$.
