Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region

Kraemer, K. E.; Hora, J. L.; Egan, M. P.; Adams, Joshua J.; Allen, Lori; Bontemps, Sylvain; Carey, Sean; Fazio, G. G.; Gutermuth, Robert; Keto, Eric; Koenig, X.; Megeath, S. Thomas; Mizuno, D. R.; Motte, F.; Price, S. D.; Schneider, N.; Simon, R.; Smith, H. A.

doi:10.1088/0004-6256/139/6/2319

Cited by 15 publications

(15 citation statements)

References 43 publications

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“…Apart from moderately intense, broad emission features near 5600 Å and 5800 Å and some likely variability at the 0. (Douglass et al 2000); 4) M8e Mira variable (Cameron & Nassau 1956); 5) Late type (this work); 6) possible misidentification between USNO-B and 2MASS due to high proper motion; 7) flare star (Pettersen et al 1988); 8) M8 (Vogt 1973); 9) R:, infrared bipolar nebula (Kraemer et al 2010); 10) A2 (based on Vilnius photometry); 11) A0 (based on Vilnius photometry). …”

Section: Discussionmentioning

confidence: 84%

New members of the massive stellar population in Cygnus

Comerón¹,

Pasquali

2012

A&A

109

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Context. The Cygnus OB2 association and its surroundings display the richest collection of massive stars in our nearby Galactic environment and a wealth of signposts of the interaction between these stars and the interstellar gas. Aims. We perform a magnitude-limited, homogeneous census of O and early B-type stars with accurate spectral classifications in the blue, in a 6• × 4• region centered on Cygnus OB2 that includes most of the Cygnus X complex, a sizeable fraction of the adjacent Cygnus OB9 association, and a large area of the field surrounding these complexes. Methods. By using reddening-free indices based on BJHK magnitudes from the USNO-B and 2MASS catalogs, we are able to produce a highly complete, highly uncontaminated sample of O and early B stars, which nearly duplicates any previous census of the region for the same range of spectral types. We provide the spectral types of 60 new O and B stars, as well as a list of an additional 60 candidates pending spectroscopic confirmation. In addition, the UBV imaging of the surroundings of three apparently isolated O stars is used to investigate the possible presence of small clusters of young stars around them. Results. Early-type stars are consistent with similar distances for Cygnus OB2, OB9, and the field stars surrounding them. We confirm previous findings of an older population in Cygnus OB2 spatially offset from where the stellar density of the association peaks. Some new remarkable objects are identified, including BD+40 4210, a B0 supergiant member of Cygnus OB2 that is among the brightest members of the association sharing some characteristics with luminous blue variable (LBV) candidates, located at a projected distance of 5 pc from another LBV candidate. A new O5If member of Cygnus OB9 is found, as well as several other O stars and B supergiants. On the other hand, while no obvious clustering is found around the apparently isolated O stars, the fields around two of them seem to contain objects with strong ultraviolet excesses, which perhaps indicates that they are accreting, although their nature and possible relationship to the O stars in the field are unclear. Conclusions. Star formation in Cygnus has been taking place in a sustained manner for well over 10 Myr, with a large-scale trend of proceeding from lower to higher Galactic longitudes. Star formation inside Cygnus OB2 follows this trend, with indications of intense star formation activity having started in the southern (lower galactic latitude) part of the association about 10 Myr ago and probably continuing at present in the north.

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Section: Discussionmentioning

confidence: 84%

New members of the massive stellar population in Cygnus

Comerón¹,

Pasquali

2012

A&A

109

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“…However, the distance to the IRDC is still a matter of debate, with distances ranging from 800 to 1700 pc (Redman et al 2003;Kraemer et al 2010). A close inspection of the infrared images and submillimeter continuum emission of a large field of view (20 × 20 ) including G79.29+0.46 reveals that the IRDC is interrupted in two positions: the SW region (e.g.…”

Section: Critical Revision Of the Distancesmentioning

confidence: 99%

“…A close inspection of the infrared images and submillimeter continuum emission of a large field of view (20 × 20 ) including G79.29+0.46 reveals that the IRDC is interrupted in two positions: the SW region (e.g. Kraemer et al 2010;Jiménez-Esteban et al 2010;Umana et al 2011), and the position of DR15 (see Fig. 2 of Redman et al 2003).…”

Section: Critical Revision Of the Distancesmentioning

confidence: 99%

“…It is projected in between two star-forming regions: the Hii region DR 15 to the south-east (see Fig. 11 of Kraemer et al 2010), and the infrared dark cloud IRDC G79.3+0.3 (hereafter the IRDC) towards the southern and western borders (Redman et al 2003). The local arm is seen tangentially in this direction (Dame & Thaddeus 1985;Rygl et al 2012), which makes it difficult to determine distances and to identify mutual associations among targets associated with the Cyg X region.…”

Section: Introductionmentioning

confidence: 99%

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Ammonia observations in the LBV nebula G79.29+0.46

Rizzo

Palau

Jiménez-Esteban

et al. 2014

A&A

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Context. The surroundings of luminous blue variable (LBV) stars are excellent laboratories to study the effects of their high UV radiation, powerful winds, and strong ejection events onto the surrounding gas and dust. Aims. We aim at determining the physical parameters of the dense gas near G79.29+0.46, an LBV-candidate located at the centre of two concentric infrared rings, which may interact with the infrared dark cloud (IRDC) G79.3+0.3. Methods. The Effelsberg 100 m telescope was used to observe the NH 3 (1, 1) and (2, 2) emission in a field of view of 7 × 7 including the infrared rings and a part of the IRDC. In addition, we observed particular positions in the NH 3 (3,3) transition toward the strongest region of the IRDC, which is also closest to the ring nebula. Results. We report here the first coherent ring-like structure of dense NH 3 gas associated with an evolved massive star. It is well traced in both ammonia lines, surrounding an already known infrared ring nebula; its column density is two orders of magnitude lower than the IRDC. The NH 3 emission in the IRDC is characterized by a low and uniform rotational temperature (T rot ∼10 K) and moderately high opacities in the (1, 1) line. The rest of the observed field is spotted by warm or hot zones (T rot >30 K) and characterized by optically thin emission of the (1, 1) line. The NH 3 abundances are about 10 −8 in the IRDC, and 10 −10 -10 −9 elsewhere. The warm temperatures and low abundances of NH 3 in the ring suggest that the gas is being heated and photo-dissociated by the intense UV field of the LBV star. An outstanding region is found to the south-west (SW) of the LBV star within the IRDC. The NH 3 (3, 3) emission at the centre of the SW region reveals two velocity components tracing gas at temperatures >30 K. Of particular interest is the northern edge of the SW region, which coincides with the border of the ring nebula and a region of strong 6 cm continuum emission; here, the opacity of the (1, 1) line and the NH 3 abundance do not decrease as expected in a typical clump of an isolated cold dark cloud. This strongly suggests some kind of interaction between the ring nebula (powered by the LBV star) and the IRDC. We finally discuss the possibility of NH 3 evaporation from the dust grain mantles due to the already known presence of low-velocity shocks in the area. Conclusions. The detection of the NH 3 associated with this LBV ring nebula, as well as the special characteristics of the northern border of the SW region, confirm that the surroundings of G79.29+0.46 constitute an exemplary scenario, which merits to be studied in detail by other molecular tracers and higher angular resolutions.

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“…The shell, even the faint outer halo seen at 24 μm, shows no signs of interaction with Cyg OB2, indicating considerable separation. Kraemer et al (2010b) have quantified this using the stellar parameters, obtaining a distance of 3 kpc. Figure 28 shows an interesting long filament that shows up well in the 24 μm image, in emission but changing to absorption in front of a bright band of cirrus.…”

Section: Irdcsmentioning

confidence: 99%

THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2005: A 10 deg²SURVEY OF STAR FORMATION IN CYGNUS X

Roy

Ade

Bock

et al. 2011

ApJ

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We present Cygnus X in a new multi-wavelength perspective based on an unbiased BLAST survey at 250, 350, and 500 μm, combined with rich data sets for this well-studied region. Our primary goal is to investigate the early stages of high-mass star formation. We have detected 184 compact sources in various stages of evolution across all three BLAST bands. From their well-constrained spectral energy distributions, we obtain the physical properties mass, surface density, bolometric luminosity, and dust temperature. Some of the bright sources reaching 40 K contain well-known compact H ii regions. We relate these to other sources at earlier stages of evolution via the energetics as deduced from their position in the luminosity-mass (L-M) diagram. The BLAST spectral coverage, near the peak of the spectral energy distribution of the dust, reveals fainter sources too cool (∼10 K) to be seen by earlier shorter-wavelength surveys like IRAS. We detect thermal emission from infrared dark clouds and investigate the phenomenon of cold "starless cores" more generally. Spitzer images of these cold sources often show stellar nurseries, but these potential sites for massive star formation are "starless" in the sense that to date there is no massive protostar in a vigorous accretion phase. We discuss evolution in the context of the L-M diagram. Theory raises some interesting possibilities: some cold massive compact sources might never form a cluster containing massive stars, and clusters with massive stars might not have an identifiable compact cold massive precursor.

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Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region

Cited by 15 publications

References 43 publications

New members of the massive stellar population in Cygnus

New members of the massive stellar population in Cygnus

Ammonia observations in the LBV nebula G79.29+0.46

THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2005: A 10 deg²SURVEY OF STAR FORMATION IN CYGNUS X

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Circumstellar Structure Around Evolved Stars in the Cygnus-X Star Formation Region

Cited by 15 publications

References 43 publications

New members of the massive stellar population in Cygnus

New members of the massive stellar population in Cygnus

Ammonia observations in the LBV nebula G79.29+0.46

THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2005: A 10 deg2SURVEY OF STAR FORMATION IN CYGNUS X

Contact Info

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THE BALLOON-BORNE LARGE APERTURE SUBMILLIMETER TELESCOPE (BLAST) 2005: A 10 deg²SURVEY OF STAR FORMATION IN CYGNUS X