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3491. Cygnus OB2 Association XMM-Newton X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/cygob2xmm
Title:
Cygnus OB2 Association XMM-Newton X-Ray Point Source Catalog
Short Name:
CYGOB2XMM
Date:
09 May 2025
Publisher:
NASA/GSFC HEASARC
Description:
Cyg OB2 is one of the most massive associations of O-type stars in our Galaxy. Despite the large interstellar reddening towards Cyg OB2, many studies, spanning a wide range of wavelengths, have been conducted to more clearly understand this association. X-ray observations provide a powerful tool to overcome the effect of interstellar absorption and study the most energetic processes associated with the stars in Cyg OB2. The author analyses XMM-Newton data to investigate the X-ray and UV properties of massive O-type stars as well as low-mass pre-main sequence stars in Cyg OB2. Six XMM-Newton observations of the core of Cyg OB2 were obtained. In the analysis, the author paid particular attention to the variability of the X-ray bright OB stars, especially the luminous blue variable candidate Cyg OB2 #12. He found that X-ray variability is quite common among the stars in Cyg OB2. While short-term variations are restricted mostly to low-mass pre-main sequence stars, one third of the OB stars display long-term variations. The X-ray flux of CygO B2 #12 varies by 37%, over timescales from days to years, while its mean log L<sub>X</sub>/L<sub>bol</sub> amounts to -6.10. These properties suggest that Cyg OB2 wind. Two other X-ray bright O-type stars (MT91 516 and CPR2002A11) display variations that suggest they are interacting wind binary systems. This table lists the general properties of the X-ray sources detected in Cyg OB2 with the EPIC cameras onboard XMM-Newton as given in Table 2 of the reference paper. An additional list of the properties of the sources detected inside Cyg OB2 with the two UV filters of the OM instrument onboard XMM-Newton which was contained in Table 4 of the reference paper is not included herein. This table was created by the HEASARC in December 2011 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/536/A31">CDS Catalog J/A+A/536/A31</a> file table2.dat. This is a service provided by NASA HEASARC .
3492. Cygnus OB2 DANCe: Proper motion study
ID:
ivo://CDS.VizieR/J/MNRAS/460/2593
Title:
Cygnus OB2 DANCe: Proper motion study
Short Name:
J/MNRAS/460/2593
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present a high-precision proper motion study of 873 X-ray and spectroscopically selected stars in the massive OB association Cygnus OB2 as part of the DANCe project. These were calculated from images spanning a 15-year baseline and have typical precisions <1mas/yr. We calculate the velocity dispersion in the two axes to be 13.0^+0.8^_-0.7_ and 9.1^+0.5^_-0.5_km/s, using a 2-component, 2-dimensional model that takes into account the uncertainties on the measurements. This gives a 3-dimensional velocity dispersion of 17.8+/-0.6km/s implying a virial mass significantly larger than the observed stellar mass, confirming that the association is gravitationally unbound. The association appears to be dynamically unevolved, as evidenced by considerable kinematic substructure, non-isotropic velocity dispersions and a lack of energy equipartition. The proper motions show no evidence for a global expansion pattern, with approximately the same amount of kinetic energy in expansion as there is in contraction, which argues against the association being an expanded star cluster disrupted by process such as residual gas expulsion or tidal heating. The kinematic substructures, which appear to be close to virial equilibrium and have typical masses of 40-400M_{sun}_, also do not appear to have been affected by the expulsion of the residual gas. We conclude that Cyg OB2 was most likely born highly substructured and globally unbound, with the individual subgroups born in (or close to) virial equilibrium, and that the OB association has not experienced significant dynamical evolution since then.
3493. Cygnus OB2 e-MERLIN 21cm survey (COBRaS)
ID:
ivo://CDS.VizieR/J/A+A/637/A64
Title:
Cygnus OB2 e-MERLIN 21cm survey (COBRaS)
Short Name:
J/A+A/637/A64
Date:
21 Oct 2021
Publisher:
CDS
Description:
The role of massive stars is central to an understanding of galactic ecology. It is important to establish the details of how massive stars provide radiative, chemical, and mechanical feedback in galaxies. Central to these issues is an understanding of the evolution of massive stars, and the critical role of mass loss via strongly structured winds and stellar binarity. Ultimately, and acting collectively, massive stellar clusters shape the structure and energetics of galaxies. We aim to conduct high-resolution, deep field mapping at 21cm of the core of the massive Cygnus OB2 association and to characterise the properties of the massive stars and colliding winds at this waveband. We used seven stations of the e-MERLIN radio facility, with its upgraded bandwidth and enhanced sensitivity to conduct a 21cm census of Cygnus OB2. Based on 42 hours of observations, seven overlapping pointings were employed over multiple epochs during 2014 resulting in 1{sigma} sensitivities down to ~21{mu}Jy and a resolution of ~180mas. A total of 61 sources are detected at 21cm over a ~0.48{deg}x0.48{deg} region centred on the heart of the Cyg OB2 association. Of these 61 sources, 33 are detected for the first time. We detect a number of previously identified sources including four massive stellar binary systems, two YSOs, and several known X-ray and radio sources. We also detect the LBV candidate (possible binary system) and blue hypergiant star of Cyg OB2 #12. The 21cm observations secured in the COBRaS Legacy project provide data to constrain conditions in the outer wind regions of massive stars; determine the non-thermal properties of massive interacting binaries; examine evidence for transient sources, including those associated with young stellar objects; and provide unidentified sources that merit follow-up observations. The 21cm data are of lasting value and will serve in combination with other key surveys of Cyg OB2, including Chandra and Spitzer.
3494. Cygnus OB1-OB4 O stars radial velocities
ID:
ivo://CDS.VizieR/J/A+A/550/A27
Title:
Cygnus OB1-OB4 O stars radial velocities
Short Name:
J/A+A/550/A27
Date:
21 Oct 2021
Publisher:
CDS
Description:
Establishing the multiplicity of O-type stars is the first step towards accurately determining their stellar parameters. Moreover, the distribution of the orbital parameters provides observational clues to the way that O-type stars form and to the interactions during their evolution. Our objective is to constrain the multiplicity of a sample of O-type stars belonging to poorly investigated OB associations in the Cygnus complex and for the first time to provide orbital parameters for binaries identified in our sample. Such information is relevant to addressing the issue of the binarity in the context of O-type star formation scenarios.
3495. Cygnus OB2 O stars spectroscopic analysis
ID:
ivo://CDS.VizieR/J/A+A/642/A168
Title:
Cygnus OB2 O stars spectroscopic analysis
Short Name:
J/A+A/642/A168
Date:
21 Oct 2021
Publisher:
CDS
Description:
Cygnus OB2 provides a unique insight into the high-mass stellar content in one of the largest groups of young massive stars in our Galaxy. Although several studies of its massive population have been carried out over the last decades, an extensive spectroscopic study of the whole known O-star population in the association is still lacking. In this work, we created the most complete spectroscopic census of O stars carried out so far in Cygnus OB2 using already existing and new spectroscopy. We present the spectra for 78 O-type stars, from which we identify new binary systems, obtain the distribution of rotational velocities, and determine the main stellar parameters for all the stars in the region that have not been detected as double-line spectroscopic binaries. We also derive radii, luminosities, and masses for those stars with reliable Gaia astrometry, in addition to creating the Hertzsprung- Russell Diagram to interpret the evolutionary status of the association. This work has shown the improvement reached when using accurate spectroscopic parameters and astrometry for the interpretation of the evolutionary status of a population, revealing, in the case of Cygnus OB2, at least two star-forming bursts at ~3 and ~5Myr. We find an apparent deficit of very fast rotators in the distribution of rotational velocities. The inspection of the dynamical distribution of the sample has allowed us to identify nine O stars with peculiar proper motions and discuss a possible dynamical ejection scenario or past supernova explosions in the region.
3496. Cygnus OB2 region 610MHz sources
ID:
ivo://CDS.VizieR/J/A+A/472/557
Title:
Cygnus OB2 region 610MHz sources
Short Name:
J/A+A/472/557
Date:
21 Oct 2021
Publisher:
CDS
Description:
The modern generation of Cherenkov telescopes has revealed a new population of gamma-ray sources in the Galaxy. Some of them have been identified with previously known X-ray binary systems while other remain without clear counterparts a lower energies. Our initial goal here was reporting on extensive radio observations of the first extended and yet unidentified source, namely TeV J2032+4130. This object was originally detected by the HEGRA telescope in the direction of the Cygnus OB2 region and its nature has been a matter of debate during the latest years. The situation has become more complex with the Whipple and MILAGRO telescopes new TeV detections in the same field which could be consistent with the historic HEGRA source, although a different origin cannot be ruled out. We aim to pursue our radio exploration of the TeV J2032+4130 position that we initiated in a previous paper but taking now into account the latest results from new Whipple and MILAGRO TeV telescopes. The data presented here are an extended follow up of our previous work.
3497. Cygnus TeV Source Chandra X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/cygtevcxo
Title:
Cygnus TeV Source Chandra X-Ray Point Source Catalog
Short Name:
CYGTEVCXO
Date:
09 May 2025
Publisher:
NASA/GSFC HEASARC
Description:
A 50 ks Chandra observation of the unidentified TeV source in Cygnus reported by the High Energy Gamma-Ray Astronomy (HEGRA) collaboration reveals no obvious diffuse X-ray counterpart. However, 240 pointlike X-ray sources are detected within or nearby the extended TeV J2032+4130 source region, of which at least 36 are massive stars and two may be radio emitters. That the HEGRA source is a composite, having as a counterpart the multiple pointlike X-ray sources that are observed, cannot be ruled out. Indeed, the distribution of pointlike X-ray sources appears nonuniform and concentrated broadly within the extent of the TeV source region. A hypothesis is offered for the origin of the very high energy gamma-ray emission in Cyg OB2 based on the local acceleration of TeV-range cosmic rays and the differential distribution of OB versus less massive stars in this association. The region of TeV J2032+4130 was observed by Chandra on 2004 July 12 for a total effective exposure time of 48,728 seconds using the Advanced CCD Imaging Specrometer imaging array (ACIS-I). The observation was centered on J2000.0 coordinates (RA, Dec) = )20 32 07.0, +41 30 30). This table contains the list of the 240 pointlike sources which were detected in the ACIS-I data and their 2MASS near-IR counterparts, if any are found within 3&quot; of the X-ray sources. 130 (54%) of the 240 X-ray sources have 2MASS counterparts within these error radii. This table was created by the HEASARC in February 2007 based on the electronic version of Table 1 from the above reference which was obtained from the ApJ website. This is a service provided by NASA HEASARC .
3498. Cygnus-X Archive
ID:
ivo://irsa.ipac/Spitzer/Catalog/Cygnus-X/CygXArchive
Title:
Cygnus-X Archive
Short Name:
CygXArchive
Date:
01 Oct 2018 20:27:17
Publisher:
NASA/IPAC Infrared Science Archive
Description:
The Cygnus-X project is a Cycle 4 Legacy program (PID 40184) on the Spitzer Space Telescope. The survey imaged a ~24 square degree region centered near 20:30:25, +40:00 (J2000) with IRAC and the MIPS 24 micron band. Two catalog data products are provided, the Catalog and the Archive. The Catalog has more stringent constraints on S/N and detections in multiple bands, so in principle it is more reliable than the Archive. However, the lists differ mostly in the sources included at the faint end, including more sources that satisfy the S/N criterion in both IRAC 3.6 and 4.5 m bands. A detailed comparison between the Archive sources and the mosaics indicates that most of the sources are likely real, but a conservative estimate of the S/N has pushed them slightly outside of the requirement for inclusion in the Catalog.
3499. Cygnus-X Catalog
ID:
ivo://irsa.ipac/Spitzer/Catalog/Cygnus-X/CygXCatalog
Title:
Cygnus-X Catalog
Short Name:
CygXCatalog
Date:
01 Oct 2018 20:27:17
Publisher:
NASA/IPAC Infrared Science Archive
Description:
The Cygnus-X project is a Cycle 4 Legacy program (PID 40184) on the Spitzer Space Telescope. The survey imaged a ~24 square degree region centered near 20:30:25, +40:00 (J2000) with IRAC and the MIPS 24 micron band. Two catalog data products are provided, the Catalog and the Archive. The Catalog has more stringent constraints on S/N and detections in multiple bands, so in principle it is more reliable than the Archive. However, the lists differ mostly in the sources included at the faint end, including more sources that satisfy the S/N criterion in both IRAC 3.6 and 4.5 m bands. A detailed comparison between the Archive sources and the mosaics indicates that most of the sources are likely real, but a conservative estimate of the S/N has pushed them slightly outside of the requirement for inclusion in the Catalog.
3500. Cygnus-X CO and SiO outflows datacubes
ID:
ivo://CDS.VizieR/J/A+A/570/A1
Title:
Cygnus-X CO and SiO outflows datacubes
Short Name:
J/A+A/570/A1
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present the results from a PdBI study of six massive dense cores in Cygnus-X, with CO (2-1) and SiO (2-1) emission. We studied the outflows of the individual protostars with CO (Duarte-Cabral et al., 2013A&A...558A.125D), and investigated the interstellar shocks responsible for the SiO emission (in Duarte-Cabral et al. 2014A&A...570A...1D).

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