The 2.12 \mu m v=1–0 S ( 1 ) line of molecular hydrogen has been imaged in the Hourglass region of M8 .
The line is emitted from a roughly bipolar region , centred around the O7 star Herschel 36 .
The peak H _ { 2 } 1–0 S ( 1 ) line intensity is 8.2 \times 10 ^ { -15 } erg s ^ { -1 } cm ^ { -2 } arcsec ^ { -2 } .
The line centre emission velocity varies from -25 km { s } ^ { -1 } in the SE lobe to +45 km { s } ^ { -1 } in the NW lobe .
The distribution is similar to that of the CO J=3–2 line .
The H _ { 2 } line appears to be shock-excited when a bipolar outflow from Herschel 36 interacts with the ambient molecular cloud .
The total luminosity of all H _ { 2 } lines is estimated to be \sim 16 L _ { \odot } and the mass of the hot molecular gas \sim 9 \times 10 ^ { -4 } M _ { \odot } ( without any correction for extinction ) .