Orion Molec Velocities

Summary of molecular line spectroscopy of inner Orion nebula.

Thi is copied from /mnt/ubay/BobKPNO/README.velocities, which was originally written 25 Jun 2004

USEFUL CONVERSIONS

V_HEL = V_LSR + 18.1 km/s

OMODAKA ET AL 1994 --- 12CO 1-0 , 13CO 1-0, CS 2-1, all across the bar

At the molecular peak (10” SE of bar IF), they find: V(12CO) ~= V(13CO) ~= 10.5 km/s

Also, V(CS 2-1) ~= V(CS 1-0) ~= 11 km/s but with 1-0 being very slightly redshifted wrt 2-1, by fraction of km/s. The CS peak is further back from the bar IF (~= 20”)

12CO is bluer (~= 9.5 km/s) on far side of bar

Also bluer (~= 9 km/s) closer to Trapezium

PLUME ET AL 2000 --- large scale 13CO 5-4 and [C I] mapping

Not very relevant but does show the large-scale (~1 deg) gradient in the [C I] velocities, from 7 km/s in S to 12 km/s in N

All lines show V ~= 9.5 km/s in center (Trap/BNKL), Delta V ~ 4 km/s

They find temperatures ~100K around Trap, ~80K in Bar, ~20K in Far South

13CO column of ~= 10^{17} cm^{-2}

WILSON ET AL 2001 --- CO 7-6, 4-3 sub-mmm lines from inner region

Much is on outflows from BNKL and Orion S and so can be ignored.

Stuff on bar and main ridge: V(CO 7-6):

• Bar = 10 -- 11 km/s
• Ridge Peak = 8 km/s
• West of Ridge = 7 -- 10 km/s (redder as you go W)
• Hole around Trap: 9 km/s

Line width is around 4 km/s, escept on E side of ridge increases to ~= 6 km/s

Temperature is higher on E side of ridge

Slight evidence that higher J transitions are blueshifted by fractions of km/s wrt 1-0