The young and well-studied planetary nebula (PN) NGC 7027 harbors significant molecular gas that is irradiated by luminous, pointlike UV (central star) and diffuse (shocked nebular) X-ray emission. This nebula represents an excellent subject to investigate the molecular chemistry and physical conditions within photon- and X-ray-dominated regions (PDRs and XDRs). As yet, the exact formation routes of CO+and HCO+in PN environments remain uncertain. Here we present ∼2″ resolution maps of NGC 7027 in the irradiation tracers CO+and HCO+obtained with the IRAM NOEMA interferometer, along with SMA CO and HST 2.12
Molecular emission was imaged with ALMA from numerous components near and within bright H2-emitting knots and absorbing dust globules in the Crab Nebula. These observations provide a critical test of how energetic photons and particles produced in a young supernova remnant interact with gas, cleanly differentiating between competing models. The four fields targeted show contrasting properties but within them, seventeen distinct molecular clouds are identified with CO emission; a few also show emission from HCO+, SiO, and/or SO. These observations are compared with Cloudy models of these knots. It has been suggested that the Crab filaments present an exotic environment in which H2emission comes from a mostly neutral zone probably heated by cosmic rays produced in the supernova surrounding a cool core of molecular gas. Our model is consistent with the observed CO
- Award ID(s):
- 1816537
- NSF-PAR ID:
- 10361965
- Publisher / Repository:
- DOI PREFIX: 10.3847
- Date Published:
- Journal Name:
- The Astrophysical Journal
- Volume:
- 925
- Issue:
- 1
- ISSN:
- 0004-637X
- Format(s):
- Medium: X Size: Article No. 59
- Size(s):
- ["Article No. 59"]
- Sponsoring Org:
- National Science Foundation
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