WR_talk_FWS_volendam2014.pptx

Where we are going?

Wolf-Rayet Ring Nebulae RevisitedI.Ciuca, Durham U., UKA.Marston, ESACA.Pollock, ESAC

Wolf-Rayet and their rings a brief synopsisWhat are Wolf-Rayet Stars?Wolf-Rayet stars are believed to be the final evolutionary point of very massive stars (initial masses >25M) prior to going supernova. By the time they reach this stage of evolution their masses can be as little as 10 M. SIGNIFICANT MASS LOSS. and ring nebulae?Rings noted serendipitously in narrow-band optical emission line images in particular up to 1990s.As of mid-1990s < 200 Wolf-Rayet (WR) stars known in the galaxy. Systematic wide-field optical imaging surveys done for the first time (Miller et al, 1993; Marston et al, 1994a,b & Marston 1997).Showed approx. 30% of WR stars have associated optical ring nebulae (less than 30 arc minutes in diameter). WC sub class > WN sub class ring nebulae in diameters.Document title | Author Name | Place | Data doc | Programme | Pag. 2

In the Meantime.Many more WR stars have been found via various means more systematic surveys.More than doubled the known number (Hadfield et al 2007; Mauerhan et al, 2011; Shara et al, 2012; Kanarek et al, 2014)Also have infrared surveys that allow probes of surrounding ISM 24 micron images show hot dust (?) in nebulae well (Wachter et al, 2010)Existence of (dense) molecular gas materials in some cases (e.g. around WR16, Marston et al 1999; WR102, Arnal, 2008).Spectral clarification of stellar-processed materials in some ring nebula cases (Duronea et al 2013).BUTWe still have only limited understanding of Fractional mass-loss during the evolution of very massive starsNature and history of mass-lossExistence of WR rings and their morphologies (is 30% simply an observational bias?).

Document title | Author Name | Place | Data doc | Programme | Pag. 3

Document title | Author Name | Place | Data doc | Programme | Pag. 4Evolution of Very Massive StarsO stars on the main sequence (approx. > 25 M)

Part of APOD for 2 Oct, 2014.Star (45M) in bubble - NGC7635 (The Bubble Nebula).Bubble marks edge of fast particle wind 2000km/s.

High Mass-loss Intermediate PhasesDocument title | Author Name | Place | Data doc | Programme | Pag. 5

RSG wind ejects dense cool material in slow wind (Betelgeuse, Herschel/PACS). Also second shell seen in radio closer to star.Luminous Blue Variable (LBV) star and IR environments

On to Wolf-Rayet NebulaeDocument title | Author Name | Place | Data doc | Programme | Pag. 6

NGC 6888 (Crescent nebula). Ha shows blobby red colored nebula[OIII] shows extent of wind in blue moving into low density wind-blown shell materials (Marston, 1995; Gruendl et al 2000).

New Information wider and deeper Ha imaging (SuperCOSMOS Halpha Survey)Document title | Author Name | Place | Data doc | Programme | Pag. 7

120WR16 anon nebula discovered in 1990s.

New data shows WR16 at centre of very extended filaments.

20Ha with CO contours

WR16 original discovery and CO 1-0 map contours.Document title | Author Name | Place | Data doc | Programme | Pag. 8

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12CO molecular line emission surrounds inner nebula Significant neutral gas implied (Marston et al 1999). Duronea et al (2013) show molecular gas also out to largest new ring seen.Clear association due to CO emission line-splitting at edge of the ring caused by ring expansion.

WR102 Ha with continuum subtractionDocument title | Author Name | Place | Data doc | Programme | Pag. 9WR102 is one of the few WO sub-type stars known. Pre-supernova.

Deep image structures include large external shell.

Previously unknown outer shell.Pillar formationJet?

WISE 22 micron contour overlay on optical image of WR102Document title | Author Name | Place | Data doc | Programme | Pag. 10

Both IR and deep optical show corkscrew/helix structure

Menzel 1 -- PN

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Large-scale structures around WR30, a WC starDocument title | Author Name | Place | Data doc | Programme | Pag. 11

WR30 in Ha.Structures around 20 across. Multiple internal ring-like features.

As is quite common star off-centre.

Eclipsing binary.

ConclusionsExtending fields of view have shown structures beyond those previously known.More information indicating several phases and ejections can occur.Shown wide field view around 3 notable WR stars covering all three subtypes (WN, WC(+O), WO). Evolutionary sequence.More details seen due to improved depth of images.Complex evolutionary phases between early O and WR phases.Binarity: WR30 is in Algol-type binary system with O7 star.But checks on regions around WR stars not previously showing clear ring nebulae STILL show nothing.May be good to look more carefully in the mid-IR are we being beaten by optical obscuration?

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