Very massive stars are infrequently found in the unvierse. However, their influence is substantial in terms of ionization flux and total stellar wind luminosity in local star forming regions. They are also believed to be very important in the earliest star forming era of the universe where metallicities are low and more massive stars are prefentially formed. Evolved massive stars later become the sites of type II supernova explosions. However, our understanding of the evolution of very massive stars is relatively limited, and many evolutionary sequences are still possible. A fundamental set of properties for understanding the evolution of very massive is there historical mass-loss. This is, in effect, imprinted on their surroundings. Wolf-Rayet stars are believed to be the evolutionary end points of very massive main-sequence O stars before they become supernovae. Many are known to have ring nebulae of material, most frequently found from the detection of ionized shells. Probing these shells should provide better constraints as to the mass of materials (and evolution of these materials) lost during the heavy mass-loss phases that are believed to occur prior to the Wolf-Rayet phase of a star. But the lack of understanding of particularly cooler material in ejecta has made this task difficult. The use of higher resolution far-infrared sata from {it Herschel} PACS and SPIRE data on large nebulae should enable the structures of cool materials to be finally determined and masses measured in such nebulae. In the proposed project, we investigate the environments of five Wolf-Rayet stars at high galactic latitude, which considerably reducing line of sight and confusion problems found in the plane of the galaxy. Most have evidence of molecular/neutral materials from prior measurements. Our intent is to measure the mass, indicate the extent of clumping and cool materials in the nebulae,... plus searching for evidence of extended low-level emission structures and any evidence of multiple ejections.
Publication
Instrument
PACS_PacsPhoto_largeScan, SPIRE_SpirePhoto_large
Temporal Coverage
2012-02-29T21:44:44Z/2012-10-30T14:02:12Z
Version
SPG v14.2.0
Mission Description
Herschel was launched on 14 May 2009! It is the fourth 'cornerstone' mission in the ESA science programme. With a 3.5 m Cassegrain telescope it is the largest space telescope ever launched. It is performing photometry and spectroscopy in approximately the 55-671 µm range, bridging the gap between earlier infrared space missions and groundbased facilities.
European Space Agency, 2013, Mapping The Ejecta Around Massive Stars At High Galactic Latitudes, SPG v14.2.0, European Space Agency, https://doi.org/10.5270/esa-d12zzeh
