The Cygnus II Association: II. The Distribution of Stars and Interstellar Matter

Reddish, V. C.; Lawrence, L. C.; Pratt, N. M.

doi:10.1093/mnras/136.4.428

Cited by 3 publications

(3 citation statements)

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“…Figure 4 shows a spatial map of the extinction across Cyg OB2 in the form of a Voronoi tessellation. The extinction distribution varies smoothly across the association, from AV ∼ 4-5 mag in the north-west (where a known 'reddening hole' exists, Reddish et al 1967) to AV ∼ 6-7 to the south of the association and on the outskirts.…”

Section: The Extinction Of Cygnus Ob2 Membersmentioning

confidence: 97%

The massive star population of Cygnus OB2

Wright

Drew

Mohr-Smith

2015

Monthly Notices of the Royal Astronomical Society

125

256

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We have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a 'universal' power-law slope of Γ = 1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7 Myr ago, in agreement with studies of low-and intermediate mass stars in the association. We identify a nearby young pulsar and runaway O-type star that may have originated in Cyg OB2 and suggest that the association has already seen its first supernova. Finally we use the census and mass function to calculate the total mass of the association of 16500 +3800 −2800 M ⊙ , at the low end, but consistent with, previous estimates of the total mass of Cyg OB2. Despite this Cyg OB2 is still one of the most massive groups of young stars known in our Galaxy making it a prime target for studies of star formation on the largest scales.

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Section: The Extinction Of Cygnus Ob2 Membersmentioning

confidence: 97%

The massive star population of Cygnus OB2

Wright

Drew

Mohr-Smith

2015

Monthly Notices of the Royal Astronomical Society

125

256

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“…It was first identified as a group of early-type stars by Münch & Morgan (1953), labelled as an O-association by Johnson & Morgan (1954, who obtained some of the first spectral types for the O stars in the region) and given the name VI Cygni by Schulte (1956). As the second of nine OB associations listed by Ruprecht (1966) it became Cygnus OB2 and recognised as the massive association that we know now by Reddish et al (1967).…”

Section: Cygnus Ob2mentioning

confidence: 99%

OB Associations and their origins

Wright

2020

New Astronomy Reviews

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OB associations are unbound groups of young stars made prominent by their bright OB members, and have long been thought to be the expanded remnants of dense star clusters. They have been important in astrophysics for over a century thanks to their luminous massive stars, though their low-mass members have not been well studied until the last couple of decades. This has changed thanks to data from X-ray observations, spectroscopic surveys and astrometry from Gaia that allows their full stellar content to be identified and their dynamics to be studied, which in turn is leading to changes in our understanding of these systems and their origins, with the old picture of Blaauw (1964a) now being superseded. It is clear now that OB associations have considerably more substructure than once envisioned, both spatially, kinematically and temporally. These changes have implications for the star formation process, the formation and evolution of planetary systems, and the build-up of stellar populations across galaxies.

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“…Since the pioneering spectroscopy and photometry of Johnson and Morgan [19] and subsequent works [20], this region has been known to harbor a large population of massive and early type stars, which have been found to be highly reddened. The first comprehensive study of this stellar association [21,22,23] identified a few hundred OB stars as possible members based on photographic photometry. Other photometric and spectroscopic studies [24] were carried out during following years confirming and extending the first results.…”

Section: Cygnus Ob2 In a Nutshellmentioning

confidence: 99%

TeVγrays and neutrinos from photodisintegration of nuclei in Cygnus OB2

et al. 2007

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TeV γ-rays may provide significant information about high energy astrophysical accelerators. Such γ-rays can result from the photo-de-excitation of PeV nuclei after their parents have undergone photo-disintegration in an environment of ultraviolet photons. This process is proposed as a candidate explanation of the recently discovered HEGRA source at the edge of the Cygnus OB2 association. The Lyman-α background is provided by the rich O and B stellar environment. It is found that (1) the HEGRA flux can be obtained if there is efficient acceleration at the source of lower energy nuclei; (2) the requirement that the Lorentz-boosted ultraviolet photons can excite the Giant Dipole Resonance implies a strong suppression of the γ-ray spectrum compared to an E −2 γ behavior at energies 1 TeV (some of these energies will be probed by the upcoming GLAST mission); (3) a TeV neutrino counterpart from neutron decay following helium photo-disintegration will be observed at IceCube only if a major proportion of the kinetic energy budget of the Cygnus OB2 association is expended in accelerating nuclei.

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The Cygnus II Association: II. The Distribution of Stars and Interstellar Matter

Cited by 3 publications

References 0 publications

The massive star population of Cygnus OB2

The massive star population of Cygnus OB2

OB Associations and their origins

TeVγrays and neutrinos from photodisintegration of nuclei in Cygnus OB2

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