Probing Highly Ionized regions in Carina and G333.6-0.2 with [NIII] 57um

Principal Investigator

Jorge Pineda

Proposal ID

09_0020

Category

ISM_AND_CIRCUMSTELLAR_MATTER

Keywords

• H II REGIONS
• INTERSTELLAR AND INTERGALACTIC MEDIUM
• STAR FORMATION

Abstract

Radiative feedback from massive stars into their surrounding interstellar medium plays an important role on the regulation of star formation in galaxies, which is in turn a key driver in galaxy evolution. In the close vicinity of massive star clusters, a significant portion of the radiative energy is in extreme ultraviolet (EUV) and gives rise to a highly ionized layer adjacent to the photon dominated regions of molecular gas clouds. Characterizing the EUV layer is critical to understanding the energy balance in the ISM and the transfer of energy from stars to gas. An important probe of the EUV environment is the [N iii] fine structure line at 57 μm, because EUV photons >29.6 eV must be present to ionize nitrogen to states higher than N+ . Combining EUV probes with those at lower ionization states is critical to understand the energetics of star forming regions. We propose to map the [NIII] 57μm line with the FIFI–LS instrument on SOFIA to char- acterize the EUV radiation field environments in the Carina and G333.6-0.2 massive star forming regions. We will combine the FIFI–LS [N iii] observations with existing ISO, SPIFI, KAO, and SOFIA 4GREAT archival observations of [NII] 205μm and 122μm to characterize the EUV environments of massive star forming regions. These observations will provide fundamental infor- mation on the relative importance different radiative and mechanical feedback mechanisms have in regulating star formation. The Carina and G333.6-0.2 massive star formation regions will be mapped over large scales with the ASTHROS balloon in the [N ii] 122μm and [N ii] 205μm lines, enabling the construction of high spectral resolution maps of the electron density in these regions. The proposed FIFI–LS research will provide the foundation for interpreting these large scale maps of such regions. By mapping [N iii] 57μm with the FIFI–LS instrument in SOFIA we will determine the spatial extent of such highly ionized regions, and together with ancillary [N ii] data, will enable an accurate determination of the EUV and FUV field strengths, distributions, and role in the energetics between star formation and ISM.