Structure & Magnetic Fields of the Star-Forming Region NGC 6334A T. H. Troland Physics & Astronomy Department University of Kentucky, USA OSU, June 21, 2006
Collaborators Elizabeth Mayo (University of Kentucky) Nick Abel (University of Kentucky) Anuj Sarma (DePaul University) Goren Sandell (NASA Ames / USRA)
Location of NGC 6334 in the Galaxy SHASSA l=351.0o, b=0.7o distance 1.7 kpc Southern H-Alpha Sky Survey Atlas (SHASSA)
Location of NGC 6334 in the Galaxy SHASSA l=351.0o, b=0.7o distance 1.7 kpc ? Cat’s Paw Nebula
Ionized gas - (H-alpha) 5 pc Optical H-alpha image from Antilhue Observatory, Chile, image by Daniel Verschatse http://www.astrosurf.com/antilhue/index.htm Antilhue Observatory
Ionized gas – 18cm radio continuum contours 5 pc Optical H-alpha image from Antilhue Observatory, Chile, image by Daniel Verschatse http://www.astrosurf.com/antilhue/index.htm Sarma et al. 2000
Molecular gas – C18O, J=2-1 5 pc H.E. Matthews, W. H. McCutcheon, G. J. White http://www.kent.ac.uk/physical-sciences/space/gw/n6334.html
Molecular gas – C18O, J=2-1 with 18 cm radio continuum contours 5 pc
2MASS
2MASS With C18O, J=2-1
2MASS With C18O, J=2-1 With 18cm radio continuum contours
2MASS
850 With 18cm radio continuum contours JMCT archival data
NGC 6334 A 850 dust continuum, contours at 0.9, 0.7, 0.5, 0.3, 0.1 Jy/beam With 18cm radio continuum contours 850 continuum, contours at 0.9, 0.7, 0.5, 0.3, 0.1 x 15 Jy/beam 1667 MHz continuum, contours at 0.9, 0.7, 0.5, 0.3, 0.1, 0.05, 0.025 x 0.98 Jy/beam 0.5 pc
Column densities and masses inferred from 850 Dust emission dust/N(H) = C computed by Cloudy (Ferland 1998) Also, dust (Jy/beam)/Tdust So N(H) (Jy/beam) / (C Tdust) Results for peak of 15 Jy/beam (NGC 6334 A): N(H)peak 1 1024 (100/Td) cm-2 Av,peak 500 (100/Td) mag Used ISM grains, Si + graphite
SiO, J=7-6 v = 4.5 km/s With 850 contours Integrated SiO line with 850 contours at 0.9, 0.7, 0.5, 0.3, 0.1, 0.05, 0.025 x 15 Jy/beam v = 4.5 km/s JMCT archival data
18 cm radio continuum Northern lobe gap 1667 MHz continuum, contours at 0.9, 0.7, 0.5, 0.3, 0.1, 0.18, 0.15, 0.1, 0.05, 0.025 0.98 Jy/beam Central shell source (2 enlarged scale) Southern lobe Carral et al. (2002), 3.5 cm
3.3 PAH With 18cm radio continuum contours 3.3 PAH image with 1667 MHz continuum contours at 0.9, 0.7, 0.5, 0.3, 0.1, 0.18, 0.15, 0.1, 0.05, 0.025 0.98 Jy/beam Burton et al. 2000 (PAH)
Zeeman effect in 1665 and 1667 MHz OH absorption lines Quasi-thermally excited OH absorption lines observed against background H+ region. Zeeman effect reveals line-of-sight magnetic field, Blos.
Blos toward central shell source (G) /home63/aipsj/emayo/BCOMB/BFIELD.ps Note that beam for 1667 MHz is 8.3 5.1 arc sec, beam for 1665 MHz is 9.1 5.5 arc sec. Combined 1665 & 1667 Blos - Cell size 1”, beam 8.7” 5.3 This is the combined data, 1665 and 1667 MHz B values, averaged together with weights proportional to one over the errors squared.
Energetics of NGC 6334 A M 1000 Msolar (850 map) R 0.3 pc (850 map) v 4.5 km s-1 (SiO line width) Btot 1.2 mG (OH Zeeman data) Gravitational energy (2T) 2.4 1047 ergs Internal kinetic energy (W) 2.3 1047 ergs Magnetic energy (M) 1.2 1047 ergs
Some Conclusions for NGC 6334 A Northern lobe is not part of a bipolar H+ region, it is detached and separately excited. Magnetic fields are energetically important in the molecular cloud if OH absorption samples a representative volume.