This paper reports the discovery of a helical molecular cloud in the central molecular zone ( CMZ ) of our Galaxy .
This ” pigtail ” molecular cloud appears at ( l,b, \hbox { $V _ { LSR } $ } ) \simeq ( -0 \hbox { $ { } ^ { \circ } $ } .7 , +0 \hbox { $ { } ^ { \circ } $ } % .0 , -70 to -30 km s ^ { -1 } ) , with a spatial size of \sim 20 \times 20 pc ^ { 2 } and a mass of ( 2 \mbox { - - } 6 ) \times 10 ^ { 5 } M _ { \hbox { $ \odot$ } } .
This is the third helical gaseous nebula found in the Galactic center region to date .
Line intensity ratios indicate that the pigtail molecular cloud has slightly higher temperature and/or density than the other normal clouds in the CMZ .
We also found a high-velocity wing emission near the footpoint of this cloud .
We propose a formation model of the pigtail molecular cloud .
It might be associated with a magnetic tube that is twisted and coiled because of the interaction between clouds in the innermost x _ { 1 } orbit and ones in the outermost x _ { 2 } orbit .