J/ApJ/919/121ivo://CDS.VizieR/J/ApJ/919/121doi:10.26093/cds/vizier.19190121CDSHajduk M.Haverkorn M.Shimwell T.Olech M.Callingham J.R.,Vedantham H.K.White G.J.Iacobelli M.Drabent A.2023-05-26T09:28:38Z2023-03-14T13:55:14ZCDS support team

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

cds-question@unistra.frplanetary-nebulaeradio-continuum-emissionWe present observations of planetary nebulae with the LOw Frequency ARray (LOFAR) between 120 and 168MHz. The images show thermal free-free emission from the nebular shells. We have determined the electron temperatures for spatially resolved, optically thick nebulae. These temperatures are 20%-60% lower than those estimated from collisionally excited optical emission lines. This strongly supports the existence of a cold plasma component, which co- exists with hot plasma in planetary nebulae. This cold plasma does not contribute to the collisionally excited lines, but does contribute to recombination lines and radio flux. Neither of the plasma components are spatially resolved in our images, although we infer that the cold plasma extends to the outer radii of planetary nebulae. However, more cold plasma appears to exist at smaller radii. The presence of cold plasma should be taken into account in modeling of radio emission of planetary nebulae. Modelling of radio emission usually uses electron temperatures calculated from collisionally excited optical and/or infrared lines. This may lead to an underestimate of the ionized mass and an overestimate of the extinction correction from planetary nebulae when derived from the radio flux alone. The correction improves the consistency of extinction derived from the radio fluxes when compared to estimates from the Balmer decrement flux ratios.2021ApJ...919..121Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/919/121CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/127 : MASH Catalogues of Planetary Nebulae (Parker+ 2006-2008)J/ApJS/117/361 : PNe in NRAO VLA Sky Survey (Condon+ 1998)J/A+A/373/1032 : Radio emission from planetary nebulae (Siodmiak+, 2001)J/MNRAS/428/3443 : PNe and HII regions plasma diagnostics (McNabb+, 2013)J/A+A/598/A104 : LOFAR Two-metre Sky Survey (Shimwell+, 2017)J/A+A/622/A1 : LOFAR Two-metre Sky Survey DR1 source cat. (Shimwell+, 2019)J/MNRAS/503/2887 : PNe angular diameters from SED modeling (Bojicic+, 2021)J/A+A/648/A104 : LOFAR LBA Sky Survey. I. (de Gasperin+, 2021)J/A+A/659/A1 : LOFAR Two-metre Sky Survey (LoTSS) DR2 (Shimwell+, 2022)http://lofar-surveys.org/lotss-tier1.html : LOFAR surveys current statushttp://202.189.117.101:8999/gpne/dbMainPage.php : HASH PN database 4.6https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/919/121https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/919/121http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/919/121https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/919/121https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/919/121http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/919/121GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/919/121/table1 (The flux densities and diameters taken from Frew+ (2016MNRAS.455.1459F) of PNe detected in the LOFAR Two-Metre Sky Survey (LoTSS))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/919/121/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/919/121/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/919/121/table1?GETtext/xml+votable180.050000true5.00187562.98421110.005555555555555556Cone search capability for table J/ApJ/919/121/table3 (Upper limits for nebular flux densities at 144MHz and corresponding brightness temperatures)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/919/121/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/919/121/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/919/121/table3?GETtext/xml+votable180.050000true100.980908661.79018250.0055555555555555566/1051 1179 1200 1399 1451 1455-1456 1552 1562 2522 2883 2887 3039 3056 3059 3070 3749 3803 3819 4690 5037 5996 6015 6202 6292 6654 6857 7134 7392 8719 9233 9276 9461 9806 10378 11605 11612 12222 12938 12960 12963 12967 12971-12974 12984 12986-12987 13076 13190 13215 13224-13225 13234 13307 13786 13814 13992 13995 13997 14008 14245 14251 14258 14336 14338-14339 14342-14344 14348-14349 14354 14360 14368 14491 14596 14608 14827 14834 14853 14872 14876 15113 15118 15145 15172 15351 15561 15598 15615 15621 15627-15628 15632 15641 15655 15873 15988 16036 19796 20400 23389 28126 30335 30421 30428 30430-30431 30453 30593 30595 30598 30603-30604 30606-30607 30624-30626 30629 30631 30635 30637 30642 30709 30711 30713-30714 30719 31670 31775 31847 31895 31902 32001 32083-32084 32092 32094 32571 32581 326459.54153977050123e-26 9.54153977050123e-26https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/919/121?format=asciiRadiodefaultJ/ApJ/919/121/table1The flux densities and diameters taken from Frew+ (2016MNRAS.455.1459F) of PNe detected in the LOFAR Two-Metre Sky Survey (LoTSS)SimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNamePN namemeta.id;meta.maincharF144MHz[0.95/191] Flux density at 144MHzmJyphot.flux.density;em.radio.100-200MHzfloate_F144MHz[0.2/69] F144MHz uncertaintymJystat.errorfloatdDiam1[5.7/185.9]? Deconvolved diameter 1, {Theta}_d_ (1) (2)arcsecphys.angSizefloatnullabledDiam2[3.6/182.8]? Deconvolved diameter 2, {Theta}_d_ (1) (2)arcsecphys.angSizefloatnullablecDiam[8/45.8]? Corrected diameter, {Theta} (1)arcsecphys.angSizefloatnullablee_cDiam[0.57/11]? cDiam uncertainty (1)arcsecstat.errorfloatnullableODiam1[2.7/208]? Optical diameter 1arcsecphys.angSizefloatnullableODiam2[2.7/202]? Optical diameter 2arcsecphys.angSizefloatnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJ/919/121/table3Upper limits for nebular flux densities at 144MHz and corresponding brightness temperaturesSimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNamePlanetary nebula namemeta.id;meta.maincharrms[0.27/10.2] Upper limit of nebular flux density at 144MHz (3xrms) (1)mJy/beamphot.flux.density;em.radio.100-200MHz;stat.maxfloatTb[639/23976] Brightness temperature (T_B_) (1)Kphys.temperatureint_RAPositions from SIMBAD or from the HASH PN database4.6 (http://202.189.117.101:8999/gpne/dbMainPage.php) (right ascension part)degpos.eq.ra;meta.mainnullable_DEPositions from SIMBAD or from the HASH PN database4.6 (http://202.189.117.101:8999/gpne/dbMainPage.php) (declination part)degpos.eq.dec;meta.mainnullable