J/ApJ/941/13ivo://CDS.VizieR/J/ApJ/941/13doi:10.26093/cds/vizier.19410013CDSLei X.Zhu H.Zhang H.Tian W.Wu D.2025-05-21T20:14:33Z2025-03-04T13:22:16ZCDS support team

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

cds-question@unistra.frsupernova-remnantsproper-motionsradio-sourcesThe study on the dynamic evolution of young supernova remnants (SNRs) is an important way to understand the density structure of the progenitor's circumstellar medium. We have reported the acceleration or deceleration, proper motion, and brightness changes of 260 compact radio features in the second-youngest known SNR Cas A at 5 GHz based on the Very Large Array data of five epochs from 1987 to 2004. The radio expansion center is located at {alpha}(1950)=23h21m9.7s+/-0.29s, {delta}(1950)=+58{deg}32'25.2"+/-2.2". Three-quarters of the compact knots are decelerating; this suggests that there are significant density fluctuations in the stellar winds of the remnant's progenitor. We have verified that the acceleration or deceleration of compact knots is not related with the distribution of brightness. The brightening, fading, disappearing, or new appearing of compact radio features in Cas A suggests that the magnetic field in the remnant is changing rapidly.2022ApJ...941...13Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/941/13CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/441/307 : Proper motions and brightness of Cas A (Anderson+ 1995)J/ApJ/456/234 : Cas A radio knots spectral indices (Anderson+ 1996)J/ApJ/613/343 : Cas A knot and filament proper motions (Delaney+, 2004)J/ApJS/179/195 : A catalog of outer ejecta knots in Cas A (Hammell+, 2008)J/A+A/484/755 : Oxygen recombination lines from Cas A knots (Docenko+, 2008)J/ApJ/837/118 : NIR knots in the Cas A supernova remnant (Lee+, 2017)J/ApJ/866/139 : Knots in the deep [FeII]+[SiI] image of Cas A (Koo+, 2018)J/A+A/612/A110 : Cas A LOFAR and VLA images (Arias+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/941/13https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/941/13http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/941/13https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/941/13https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/941/13http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/941/13GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/941/13/table2 (Summary of VLA observations for Cas A from 1987 to 2005, {lambda}=6cm (C-band))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/941/13/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/941/13/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/941/13/table2?GETtext/xml+votable180.050000true350.9157558.78544440.0055555555555555566/14285https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/941/13?format=asciiRadiodefaultJ/ApJ/941/13/table2Summary of VLA observations for Cas A from 1987 to 2005, {lambda}=6cm (C-band)AR95[2/304]? Knot number, (Anderson & Rudinck 1995, J/ApJ/441/307; <[AR95] NNN> in Simbad)meta.id.crossintnullableSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKnot[1/260] Knot number, this workmeta.id;meta.mainintXpos[-184.5/152.1] X offset from Epoch 1987 continuum (1)arcsecpos.eq.ra;arith.difffloatYpos[-153.2/173.0] Y offset from Epoch 1987 continuum (1)arcsecpos.eq.dec;arith.difffloatBoxX1[-195.3/149.7] Box size (2)arcsecinstr.paramfloatBoxX2[-158.6/170.5] Box size (2)arcsecinstr.paramfloatBoxY1[-181.4/157.7] Box size (2)arcsecinstr.paramfloatBoxY2[-150.4/181.8] Box size (2)arcsecinstr.paramfloatpmRA[-0.61/0.71] Knot proper motion in RA, V_x_arcsec/yrpos.pm;pos.eq.rafloate_pmRA[0.004/0.2] Uncertainty in pmRAarcsec/yrstat.error;pos.pm;pos.eq.rafloatpmDE[-0.54/0.55] Knot proper motion in DE, V_y_arcsec/yrpos.pm;pos.eq.decfloate_pmDE[0/0.2] Uncertainty in pmDEarcsec/yrstat.error;pos.pm;pos.eq.decfloatax[-0.023/0.02] Knot acceleration in RAarcsec.yr**-2phys.accelerationfloate_ax[0.0002/0.02] Uncertainty in axarcsec.yr**-2stat.errorfloatay[-0.017/0.033] Knot acceleration in DEarcsec.yr**-2phys.accelerationfloate_ay[0/0.02] Uncertainty in ayarcsec.yr**-2stat.errorfloatPeak[12.2/188] Peak Brightness in 1987 mapmJy/beamphot.flux.density;em.radio.3-6GHzfloatDB/B