J/A+A/707/A193ivo://CDS.VizieR/J/A+A/707/A193CDSEgbo O.D.Groot P.J.Buckley D.A.H.Robrade J.Schwope A.D.Freund S.,Schneider P.C.Stelzer B.2026-04-02T06:28:33Z2026-03-12T08:50:39ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.frradio-sourcesx-ray-sourcesvisible-astronomyastrometryastronomical-object-identificationphotometrystellar-spectral-typesgalaxy-planesmilky-way-galaxyRadio emission from magnetically active stars arises primarily from non-thermal processes and provides information complementary to their high-energy X-ray emission. Recent advances in sensitive, wide-field radio and X-ray surveys have enabled the identification of larger samples of active stars across the Galaxy. We aim to identify and characterise radio and X-ray-emitting stars in the Galactic plane by combining MeerKAT radio data with soft X-ray observations, and to assess their consistency with the canonical Guedel-Benz relation, which states that the thermal coronal emission observed in soft X-rays is correlated with the non-thermal gyrosynchrotron emission detected in the radio. We cross-matched compact radio sources from the SARAO MeerKAT Galactic Plane Survey with soft X-ray counterparts from the ROSAT All-Sky Survey and the first release of the SRG/eROSITA all-sky survey, the eRASS1. We investigated their radiobrightness temperatures and computed radio and X-ray luminosities to test for consistency with the Guedel-Benz relation. We identify 137 stellar sources with both radio and X-ray detections. Their radio-brightness temperatures, T_B_, range from 10^7^ to 10^12^K, with the exception of two outliers: AXJ1600.9-5142 (T_B_=4.8+/-1.5x10^12^K) and HD 124831 (T_B_=8+/-1x10^6^K). The remaining sources are consistent with emission from incoherent gyrosynchrotron processes. The sample generally lies below the canonical Guedel-Benz relation, with the offset predominantly driven by enhanced radio luminosities at 1.3GHz relative to the canonical relation derived at 5GHz. Our results suggest that the classical Guedel-Benz relation represents an upper envelope rather than a tight correlation for active stars detected at 1.3GHz. In addition, the eROSITA detections show that early-type stars are systematically below the log(L_X_/L_bol_)~-3 relation, which is usually seen for stars of a later spectral type.2026A&A...707A.193Ehttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/707/A193CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/682/A34 : SRG/eROSITA all-sky survey catalogs (eRASS1) (Merloni+, 2024)J/A+A/588/A103 : Second ROSAT all-sky survey (2RXS) source catalogI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/707/A193https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/707/A193http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/707/A193https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/707/A193https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/707/A193http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/707/A193GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/707/A193/erosat (Radio-X-ray eRASS1 cross-matched catalog (table A1))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A193/erosat?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A193/erosat?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A193/erosat?GETtext/xml+votable180.050000true134.4775550787158-47.73769339454030.005555555555555556Cone search capability for table J/A+A/707/A193/rosat (Radio-X-ray RASS cross-matched catalog (table A1))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/707/A193/rosat?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/707/A193/rosat?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/707/A193/rosat?GETtext/xml+votable180.050000true269.1451303345028-21.98796235710010.0055555555555555566/28812 28921 29096 30617 30713 37246 37365 37367 37369 37372 37713 37715-37716 37718 37721 37743-37745 37749-37750 37754 37848-37849 37852 37861 37875 37882 37895 37897-37898 37900-37901 37903 37905-37906 37908 37912 37922 37926 37931 38016 38051 39249 39251 39271 39277-39280 39282 39288-39289 39364-39365 39373-39374 39378 39384 39396 41597-41598 41647 41651-41652 41654 41657-41660 41662 41679 41681-41682 41688 41700 41704 41764 41769 41774 41784 41801 41856 42175 42217 42377 42382 42394 42397 42401 42434 42439-42440 42446-42447 42454 42502 42504 42512 43013-43017 43019-43020 43026 43028 430441.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/707/A193?format=asciiX-rayOpticalRadiodefaultJ/A+A/707/A193/erosatRadio-X-ray eRASS1 cross-matched catalog (table A1)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSMGPSSMGPS unique source identifier (SMGPS_id)meta.id;meta.maincharFileNameName of the FITS or data file (fileName)meta.id;meta.fitscharGLONSource galactic longitude (lon)degpos.galactic.lonGLATSource galactic latitude (lat)degpos.galactic.latdoubleSimbadNameSimbad column added by the CDSmeta.idcharnullableRA_ICRSSource right ascension (ICRS) at (J2019.4) (ra)degpos.eq.ra;meta.mainDE_ICRSSource declination (ICRS) at (J2019.4) (dec)degpos.eq.dec;meta.maine_RA_ICRSUncertainty in right ascension (ra_err)arcsecstat.error;pos.eq.radoublee_DE_ICRSUncertainty in declination (dec_err)arcsecstat.error;pos.eq.decdoubleePosError in both RA and Dec (radec_err)arcsecstat.errordoubleFpeakMaximum measured flux density (peak_flux)mJy/beamphot.flux.density;em.radio.750-1500MHzdoublee_FpeakUncertainty in peak flux (err_peak_flux)mJy/beamstat.errordoubleSSource integrated flux density (int_flux)mJyphot.flux.density;em.radio.750-1500MHzdoublee_SUncertainty in integrated flux (err_int_flux)mJystat.errordoubleIAUIAU name ERO/2RXS of eRASS1/RASS source (ERO/2RXS)meta.idcharFXX-ray flux (0.2-2.4 keV, coronal) (FX)mW.m**-2phot.flux;em.X-raydoubleFXujyX-ray flux converted to uJy (FX_ujy)uJyphot.flux;em.X-raydoublep? Probability source is coronal for ERO-eRASS1 and source is stellar for 2RXS-RASS (p-coronal/pstellar)stat.probabilitydoublenullableGaiaDR3Gaia DR3 source identifier (Source)meta.id.assocRAGdegGaia right ascension (ICRS) at (J2016.0) (RA_ICRS)degpos.eq.raDEGdegGaia declination (ICRS) at (J2016.0) (DE_ICRS)degpos.eq.decGmagGaia broad-band G magnitude (Gmag)magphot.mag;em.optdoubleBP-RP? Gaia colour index (BP-RP)magphot.color;em.opt.B;em.opt.RdoublenullablergeoGaia geometric distance estimate (rgeo)pcpos.distancedoubleGMagAbsolute G magnitude (mgg)magphot.mag;em.optdoubleTb? Stellar radio brightness temperature (b_temp)Kphys.temperaturedoublenullableLradRadio luminosity at 1.3 GHz (r_lum)1e-07W.Hz**-1phys.luminosity;em.radiodoubleLXX-ray luminosity (x_lum)1e-07Wphys.luminosity;em.X-raydoubleLbolBolometric luminosity (Lerg)1e-07Wphys.luminositydoubleSIMBADMain identifier from Simbad (main_id) (1)meta.idcharLTypeObject type label from Simbad (otype_lbl)src.classcharOTypeObject type from Simbad (main_type)src.classcharSpTypeStellar spectral type Gaia DR3 (SpType-ELS)src.spTypecharn_OTypeAdditional classification notes (type_note)meta.notecharSepSMGPS-Gaia separation (sep_arcsec)arcsecpos.angDistancedoubleJ/A+A/707/A193/rosatRadio-X-ray RASS cross-matched catalog (table A1)GLATSource galactic latitude (lat)degpos.galactic.latdoubleGMagAbsolute G magnitude (mgg)magphot.mag;em.optdoubleTb? Stellar radio brightness temperature (b_temp)Kphys.temperaturedoublenullableLradRadio luminosity at 1.3 GHz (r_lum)1e-07W.Hz**-1phys.luminosity;em.radiodoubleLXX-ray luminosity (x_lum)1e-07Wphys.luminosity;em.X-raydoubleSepSMGPS-Gaia separation (sep_arcsec)arcsecpos.angDistancedoubleSimbadNameSimbad column added by the CDSmeta.idcharnullableIAUIAU name ERO/2RXS of eRASS1/RASS source (ERO/2RXS)meta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSMGPSSMGPS unique source identifier (SMGPS_id)meta.id;meta.maincharFileNameName of the FITS or data file (fileName)meta.id;meta.fitscharGLONSource galactic longitude (lon)degpos.galactic.lonRA_ICRSSource right ascension (ICRS) at (J2019.4) (ra)degpos.eq.ra;meta.mainDE_ICRSSource declination (ICRS) at (J2019.4) (dec)degpos.eq.dec;meta.maine_RA_ICRSUncertainty in right ascension (ra_err)arcsecstat.error;pos.eq.radoublee_DE_ICRSUncertainty in declination (dec_err)arcsecstat.error;pos.eq.decdoubleePosError in both RA and Dec (radec_err)arcsecstat.errordoubleFpeakMaximum measured flux density (peak_flux)mJy/beamphot.flux.density;em.radio.750-1500MHzdoublee_FpeakUncertainty in peak flux (err_peak_flux)mJy/beamstat.errordoubleSSource integrated flux density (int_flux)mJyphot.flux.density;em.radio.750-1500MHzdoublee_SUncertainty in integrated flux (err_int_flux)mJystat.errordoubleFXX-ray flux (0.2-2.4 keV, coronal) (FX)mW.m**-2phot.flux;em.X-raydoubleFXujyX-ray flux converted to uJy (FX_ujy)uJyphot.flux;em.X-raydoublep? Probability source is coronal for ERO-eRASS1 and source is stellar for 2RXS-RASS (p-coronal/pstellar)stat.probabilitydoublenullableGaiaDR3Gaia DR3 source identifier (Source)meta.id.assocRAGdegGaia right ascension (ICRS) at (J2016.0) (RA_ICRS)degpos.eq.raDEGdegGaia declination (ICRS) at (J2016.0) (DE_ICRS)degpos.eq.decGmagGaia broad-band G magnitude (Gmag)magphot.mag;em.optdoubleBP-RP? Gaia colour index (BP-RP)magphot.color;em.opt.B;em.opt.RdoublenullablergeoGaia geometric distance estimate (rgeo)pcpos.distancedoubleLbolBolometric luminosity (Lerg)1e-07Wphys.luminositydoubleLTypeObject type label from Simbad (otype_lbl)src.classcharOTypeObject type from Simbad (main_type)src.classcharSIMBADMain identifier from Simbad (main_id) (1)meta.idcharSpTypeStellar spectral type Gaia DR3 (SpType-ELS)src.spTypecharn_OTypeAdditional classification notes (type_note)meta.notechar