J/ApJ/837/118ivo://CDS.VizieR/J/ApJ/837/118doi:10.26093/cds/vizier.18370118CDSLee Y.-H.Koo B.-C.Moon D.-S.Burton M.G.Lee J.-J.2018-01-19T08:29:22Z2017-11-23T09:38:11ZCDS support team

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

cds-question@unistra.frsupernova-remnantsinfrared-astronomyspectroscopyradial-velocityextinctioninterstellar-mediumWe report the results of broadband (0.95-2.46{mu}m) near-infrared spectroscopic observations of the Cassiopeia A supernova remnant. Using a clump-finding algorithm in two-dimensional dispersed images, we identify 63 "knots" from eight slit positions and derive their spectroscopic properties. All of the knots emit [FeII] lines together with other ionic forbidden lines of heavy elements, and some of them also emit H and He lines. We identify 46 emission line features in total from the 63 knots and measure their fluxes and radial velocities. The results of our analyses of the emission line features based on principal component analysis show that the knots can be classified into three groups: (1) He-rich, (2) S-rich, and (3) Fe-rich knots. The He-rich knots have relatively small, <~200km/s, line-of-sight speeds and radiate strong He I and [FeII] lines resembling closely optical quasi-stationary flocculi of circumstellar medium, while the S-rich knots show strong lines from O-burning material with large radial velocities up to ~2000km/s indicating that they are supernova ejecta material known as fast-moving knots. The Fe-rich knots also have large radial velocities but show no lines from O-burning material. We discuss the origin of the Fe-rich knots and conclude that they are most likely "pure" Fe ejecta synthesized in the innermost region during the supernova explosion. The comparison of [FeII] images with other waveband images shows that these dense Fe ejecta are mainly distributed along the southwestern shell just outside the unshocked ^44^Ti in the interior, supporting the presence of unshocked Fe associated with ^44^Ti.2017ApJ...837..118Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/837/118CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/ApJ/428/693 : Rosette Nebula and Maddalena Cloud structures (Williams+ 1994)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/A+A/484/755 : Oxygen recombination lines from Cas A knots (Docenko+, 2008)J/ApJS/179/195 : A catalog of outer ejecta knots in Cas A (Hammell+, 2008)J/ApJS/188/32 : Breit-Pauli transition probabilities for SII (Tayal+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/837/118https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/837/118http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/837/118https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/837/118https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/837/118http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/837/118GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/837/118/table2 (Physical parameters of 63 identified knots)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/837/118/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/837/118/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/837/118/table2?GETtext/xml+votable180.050000true350.868916758.84655560.0055555555555555566/14285https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/837/118?format=asciiInfraredOpticaldefaultJ/ApJ/837/118/table2Physical parameters of 63 identified knotsSlit[1/8] Slit numbermeta.noteintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKnotKnot numbermeta.id;meta.maincharf_Knot[e] Flag on Knot (1)meta.codecharLDisplay the NIR line parameters for this knot (link to table 3)meta.ref.urlintnullableRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainSize[1.7/9.8] Size along the slit lengtharcsecinstr.setupfloatTypeKnot type (2)src.classcharAv[3.3/15.4] Visual extinction (3)magphys.absorption;em.opt.Vfloate_Av[0/3.6] Av uncertaintymagstat.errorfloatRV[-2234/1924] Radial velocitykm/sphys.veloc;pos.heliocentricinte_RV[2/20] RV uncertaintykm/sstat.errorintFeII[34/4959] [FeII]1.644um Flux; in 10^-17^erg/s/cm^2^ units1e-20W.m**-2phot.fluxinte_FeII[3/13] FeII uncertainty (4)1e-20W.m**-2stat.errorintJ/ApJ/837/118/table3Observed NIR line parameters of knotsKnotKnot Numbermeta.id;meta.maincharNoteNote (2)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSlitSlit Numbermeta.noteintLineLine identification (Transition: lower-upper)meta.id;spect.linelamAir[0.9/2.3] Rest Wavelength in airumem.wldoubleFWHM[3.4/37]? FWHM of lines in Angstroms0.1nmspect.line.widthfloatnullablee_FWHM[0.1/10]? The 1{sigma} uncertainty in FWHM0.1nmstat.error;phys.angSizefloatnullableFlux[3/13213]? Observed flux in 1E-17 erg/s/cm^2^1e-20W.m**-2phot.fluxintnullablee_Flux[1/903]? The 1{sigma} uncertainty in Flux (1)1e-20W.m**-2stat.error;phot.fluxintnullable