• DOI:10.1093/mnras/stv1514
• Corpus ID: 54831173

The RMS survey: ammonia mapping of the environment of massive young stellar objects

@article{Urquhart2015TheRS,
  title={The RMS survey: ammonia mapping of the environment of massive young stellar objects},
  author={J. S. Urquhart and Charles C. Figura and Toby Moore and Timea Csengeri and S. L. Lumsden and Thushara G. S. Pillai and Maggie Thompson and David J. Eden and Larry Morgan and Mpifr and Wartburg College and Ljmu and Leeds and Herts and Universit'e de Strasbourg and Met Office},
  journal={Monthly Notices of the Royal Astronomical Society},
  year={2015},
  volume={452},
  pages={4029-4053}
}

• J. Urquhart, C. Figura, +13 authors Met Office
• Published 8 July 2015
• Physics, Geology
• Monthly Notices of the Royal Astronomical Society

We present the results of ammonia observations towards 66 massive star forming regions identified by the Red Midcourse Space Experiment Source survey. We have used the Green Bank Telescope and the K-Band Focal Plane Array to map the ammonia (NH3) (1,1) and (2,2) inversion emission at a resolution of 30 arcsec in 8 arcmin regions towards the positions of embedded massive star formation. We have identified a total of 115 distinct clumps, approximately two-thirds of which are associated with an embedded massive young stellar object or compact H ii region, while the others are classified as quiescent. There is a strong spatial correlation between the peak NH3 emission and the presence of embedded objects. We derive the spatial distribution of the kinetic gas temperatures, line widths, and NH3 column densities from these maps, and by combining these data with dust emission maps we estimate clump masses, H2 column densities and ammonia abundances. The clumps have typical masses of ∼1000 M⊙ and radii ∼0.5 pc, line widths of ∼2 km s−1 and kinetic temperatures of ∼16–20 K. We find no significant difference between the sizes and masses of the star-forming and quiescent subsamples; however, the distribution maps reveal the presence of temperature and line width gradients peaking towards the centre for the star-forming clumps while the quiescent clumps show relatively uniform temperatures and line widths throughout. Virial analysis suggests that the vast majority of clumps are gravitationally bound and are likely to be in a state of global free fall in the absence of strong magnetic fields. The similarities between the properties of the two subsamples suggest that the quiescent clumps are also likely to form massive stars in the future, and therefore provide an excellent opportunity to study the initial conditions of massive pre-stellar and protostellar clumps.