[ITAL]Hubble Space Telescope[/ITAL] Observations of the Windblown Nebula NGC 7635

Moore, B. D.; Walter, Donald K.; Hester, J. J.; Scowen, Paul A.; Dufour, R. J.; Buckalew, B.

doi:10.1086/344596

Cited by 21 publications

(53 citation statements)

References 22 publications

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“…Further work is required to determine whether ISM turbulence and substructure (Medina et al 2014) has a significant effect on SWBs that are contained within H  regions. As an example, NGC 7635 has an apparently spherical SWB even though is it located right at the edge of a molecular cloud with many A114, page 12 of 16 pillars and bright-rimmed clouds nearby (Christopoulou et al 1995;Moore et al 2002).…”

Section: Mixing Model For Dust In H II Regionsmentioning

confidence: 99%

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Detecting stellar-wind bubbles through infrared arcs in H ii regions

Mackey

Haworth

Gvaramadze

et al. 2016

A&A

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Mid-infrared arcs of dust emission are often seen near ionizing stars within H  regions. A possible explanations for these arcs is that they could show the outer edges of asymmetric stellar wind bubbles. We use two-dimensional, radiation-hydrodynamics simulations of wind bubbles within H  regions around individual stars to predict the infrared emission properties of the dust within the H  region.We assume that dust and gas are dynamically well-coupled and that dust properties (composition, size distribution) are the same in the H  region as outside it, and that the wind bubble contains no dust. We post-process the simulations to make synthetic intensity maps at infrared wavebands using the  code. We find that the outer edge of a wind bubble emits brightly at 24 µm through starlight absorbed by dust grains and re-radiated thermally in the infrared. This produces a bright arc of emission for slowly moving stars that have asymmetric wind bubbles, even for cases where there is no bow shock or any corresponding feature in tracers of gas emission. The 24 µm intensity decreases exponentially from the arc with increasing distance from the star because the dust temperature decreases with distance. The size distribution and composition of the dust grains has quantitative but not qualitative effects on our results. Despite the simplifications of our model, we find good qualitative agreement with observations of the H  region RCW 120, and can provide physical explanations for any quantitative differences. Our model produces an infrared arc with the same shape and size as the arc around CD −38• 11636 in RCW 120, and with comparable brightness. This suggests that infrared arcs around O stars in H  regions may be revealing the extent of stellar wind bubbles, although we have not excluded other explanations.

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Section: Mixing Model For Dust In H II Regionsmentioning

confidence: 99%

“…These two factors (that bubbles are only spherical and bright when they are very young) are responsible for the paucity of circular bubbles around isolated massive main sequence stars. Only one such bubble is known in the Galaxy: NGC 7635 or the Bubble Nebula (Christopoulou et al 1995;Moore et al 2002).…”

Section: Radiation Pressure and The Decoupling Modelmentioning

confidence: 99%

Detecting stellar-wind bubbles through infrared arcs in H ii regions

Mackey

Haworth

Gvaramadze

et al. 2016

A&A

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“…4 -show larger values of n e . Rodríguez (1999), Moore et al (2002b) and Mesa-Delgado & Esteban (2010) Table 3. continued Figure 4), so the determination is highly confident.…”

Section: Physical Conditionsmentioning

confidence: 99%

“…4 of NGC 7635 -corresponding to the bright dense knot -shows O/H and N/O ratios of 8.27 ± 0.03 and −0.57 ± 0.07 dex, respectively, which are slightly different from the bubble values. In their detailed study of HS T data, Moore et al (2002b) indicate that the knots close to the central star of NGC 7635 are the ionised edges of a large mass of neutral material, with strong photoevaporative flows toward the central star. Moore et al (2002a) demonstrate that the strong density gradients of the knots may produce deviations in the spectrally derived elemental abundances at a level exceeding typical observational errors.…”

Section: Ngc 7635mentioning

confidence: 99%

The chemical composition of Galactic ring nebulae around massive stars

Esteban

Mesa‐Delgado

Morisset

et al. 2016

Mon. Not. R. Astron. Soc.

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We present deep spectra of ring nebulae associated with Wolf-Rayet (WR) and O-type stars: NGC 6888, G2.4+1.4, RCW 58, S 308, NGC 7635 and RCW 52. The data have been taken with the 10m Gran Telescopio Canarias and the 6.5m Clay Telescope. We extract spectra of several apertures in some of the objects. We derive C 2+ and O 2+ abundances from faint recombination lines in NGC 6888 and NGC 7635, permitting to derive their C/H and C/O ratios and estimate the abundance discrepancy factor (ADF) of O 2+ . The ADFs are larger than the typical ones of normal H ii regions but similar to those found in the ionised gas of star-forming dwarf galaxies. We find that chemical abundances are rather homogeneous in the nebulae where we have spectra of several apertures: NGC 6888, NGC 7635 and G2.4+1.4. We obtain very high values of electron temperature in a peripheral zone of NGC 6888, finding that shock excitation can reproduce its spectral properties. We find that all the objects associated with WR stars show N enrichment. Some of them also show He enrichment and O deficiency as well as a lower Ne/O than expected, this may indicate the strong action of the ON and NeNa cycles. We have compared the chemical composition of NGC 6888, G2.4+1.4, RCW 58 and S 308 with the nucleosynthesis predicted by stellar evolution models of massive stars. We find that non-rotational models of stars of initial masses between 25 and 40 M ⊙ seem to reproduce the observed abundance ratios of most of the nebulae.

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“…This nebula is an interstellar bubble formed by the interaction of the stellar wind of the O6.5 IIIf star, BD+60 2522, with the surrounding interstellar medium. Recently, it has been assumed that the ram pressure of the stellar wind is balanced by the surrounding gas pressure because of the similarity between the velocities of the molecular cloud and the bright nebulosity places of the nebula (Christopoulou et al 1995; Moore et al 2002). The study of physical conditions and chemical abundances in NGC 7635 has been restricted to some selected zones (Talent & Dufour 1979; Rodríguez 1999; Moore et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Small-spatial-scale variations of nebular properties and the abundance discrepancy in three Galactic H ii regions★

Mesa‐Delgado¹,

Esteban²

2010

Monthly Notices of the Royal Astronomical Society

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We present the results of long‐slit spectroscopy in several slit positions that cover different morphological structures of the central parts of three bright Galactic H ii regions: M8, M17 and NGC 7635. We study the spatial distributions of a large number of nebular parameters, such as the extinction coefficient, line fluxes, physical conditions and ionic abundances at the maximum spatial resolution attainable with our instrumentation. Particularly, our goal is to study the behaviour of the abundance discrepancy factor of O2+[ADF(O2+)], defined as the logarithmic difference of the O2+ abundances derived from collisionally excited and recombination lines. We find that ADF(O2+) remains fairly constant along the slit positions of M8 and M17. For NGC 7635, we only detect the O ii recombination lines in the integrated spectrum along the whole slit, where ADF(O2+) reaches a remarkably high value of about 0.59 dex. We compare our results with previous results obtained for the Orion Nebula. We find much evidence to suggest the presence of a candidate Herbig–Haro object in M8.

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[ITAL]Hubble Space Telescope[/ITAL] Observations of the Windblown Nebula NGC 7635

Cited by 21 publications

References 22 publications

Detecting stellar-wind bubbles through infrared arcs in H ii regions

Detecting stellar-wind bubbles through infrared arcs in H ii regions

The chemical composition of Galactic ring nebulae around massive stars

Small-spatial-scale variations of nebular properties and the abundance discrepancy in three Galactic H ii regions★

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