CYGOB2XMM ivo://nasa.heasarc/cygob2xmm NASA/GSFC HEASARC Rauw 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source 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 . 2011A&A...536A..31R https://heasarc.gsfc.nasa.gov/W3Browse/all/cygob2xmm.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cygob2xmm& GET text/xml 180 99999 true 308.47416667 41.12080556 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cygob2xmm GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cygob2xmm&Action=More+Options&Action=Parameter+Search&ConeAdd=1 XMM-NEWTON 0.0166666666666667 X-ray public cygob2xmm Cygnus OB2 Association XMM-Newton X-Ray Point Source Catalog alt_name Alternative Catalog-Based Source Designation meta.id char nullable name Source Designation meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable pn_sb_rate EPIC-pn Count Rate in the Soft Band ct/s phot.count;em.X-ray.soft double nullable pn_mb_rate EPIC-pn Count Rate in the Medium Band ct/s phot.count;em.X-ray.soft double nullable pn_hb_rate EPIC-pn Count Rate in the Hard Band ct/s phot.count;em.X-ray.medium double nullable jmag J Magnitude of 2MASS Counterpart mag phot.mag;em.IR.J double nullable vmag V Magnitude of Optical Counterpart from Massey & Thompson (1991) mag phot.mag;em.opt.V double nullable bv_color B-V Color of Optical Counterpart from Massey & Thompson (1991) mag phot.color;em.opt.B;em.opt.V double nullable m2_mb_num_obs Number of Observations in the EPIC-MOS2 Medium Band meta.number;obs short nullable m1_hb_rate EPIC-MOS1 Count Rate in the Hard Band ct/s phot.count;em.X-ray.medium double nullable bii Galactic Latitude degree pos.galactic.lat double nullable m1_sb_prob_constant Probability That the Source Be Constant in the EPIC-MOS1 Soft Band stat.probability;phot.count;em.X-ray.soft double nullable uvw1mag_ab Mean UVW1 AB-Magnitude of OM Counterpart mag phot.mag;em.UV.200-300nm double nullable pn_sb_prob_constant Probability That the Source Be Constant in the EPIC-pn Soft Band stat.probability;phot.count;em.X-ray.soft double nullable pn_sb_num_obs Number of Observations in the EPIC-pn Soft Band meta.number;obs short nullable m2_hb_rate EPIC-MOS2 Count Rate in the Hard Band ct/s phot.count;em.X-ray.medium double nullable comments Comments on Spectral Type and Commonly Used Designation of the Source meta.note char nullable m1_mb_num_obs Number of Observations in the EPIC-MOS1 Medium Band meta.number;obs short nullable m1_mb_prob_constant Probability That the Source Be Constant in the EPIC-MOS1 Medium Band stat.probability;phot.count;em.X-ray.soft double nullable m2_hb_prob_constant Probability That the Source Be Constant in the EPIC-MOS2 Hard Band stat.probability;phot.count;em.X-ray.medium double nullable pn_hb_prob_constant Probability That the Source Be Constant in the EPIC-pn Hard Band stat.probability;phot.count;em.X-ray.medium double nullable m2_mb_prob_constant Probability That the Source Be Constant in the EPIC-MOS2 Medium Band stat.probability;phot.count;em.X-ray.soft double nullable om_source_number Identification Number of OM Counterpart meta.id.cross short nullable ub_color U-B Color of Optical Counterpart from Massey & Thompson (1991) mag phot.color;em.opt.U;em.opt.B double nullable m2_sb_rate EPIC-MOS2 Count Rate in the Soft Band ct/s phot.count;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable twomass_flag Flag Indicates Either Zero, Two, or Three 2MASS Counterparts or Quality meta.code;src char nullable m2_mb_rate EPIC-MOS2 Count Rate in the Medium Band ct/s phot.count;em.X-ray.soft double nullable m2_sb_prob_constant Probability That the Source Be Constant in the EPIC-MOS2 Soft Band stat.probability;phot.count;em.X-ray.soft double nullable pn_hb_num_obs Number of Observations in the EPIC-pn Hard Band meta.number;obs short nullable m1_hb_prob_constant Probability That the Source Be Constant in the EPIC-MOS1 Hard Band stat.probability;phot.count;em.X-ray.medium double nullable pn_mb_prob_constant Probability That the Source Be Constant in the EPIC-pn Medium Band stat.probability;phot.count;em.X-ray.soft double nullable m2_hb_num_obs Number of Observations in the EPIC-MOS2 Hard Band meta.number;obs short nullable m1_sb_num_obs Number of Observations in the EPIC-MOS1 Soft Band meta.number;obs short nullable hmag H Magnitude of 2MASS Counterpart mag phot.mag;em.IR.H double nullable m1_mb_rate EPIC-MOS1 Count Rate in the Medium Band ct/s phot.count;em.X-ray.soft double nullable m1_hb_num_obs Number of Observations in the EPIC-MOS1 Hard Band meta.number;obs short nullable uvm2mag_ab Mean UVM2 AB-Magnitude of OM Counterpart mag phot.mag;em.UV.200-300nm double nullable ks_mag Ks Magnitude of 2MASS Counterpart mag phot.mag;em.IR.K double nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable m2_sb_num_obs Number of Observations in the EPIC-MOS2 Soft Band meta.number;obs short nullable pn_mb_num_obs Number of Observations in the EPIC-pn Medium Band meta.number;obs short nullable m1_sb_rate EPIC-MOS1 Count Rate in the Soft Band ct/s phot.count;em.X-ray.soft double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable