J/A+A/690/A264ivo://CDS.VizieR/J/A+A/690/A264doi:10.26093/cds/vizier.36900264CDSWalsh J.R.Monreal Ibero A.Laging J.Romeijnders M.2025-02-18T20:01:05Z2024-10-11T08:59:27ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomyplanetary-nebulaespectroscopyThe optical line and continuum emission in the very-high-ionisation Galactic PN, NGC 4361, were mapped to study the distribution of ionisation, extinction, electron temperature, and density. Based on commissioning data, MUSE Wide Field (60x60 arcsec) normal-mode (4750-9300{AA}) observations of NGC 4361 were reduced. The PN is larger than a single MUSE field and only the central 1 arcmin square of the PN was observed in good conditions. Emission images in recombination and collisionally excited lines were extracted and the line ratios provided the dust extinction, electron density and temperature, and ionic abundances using standard techniques. A family of compact low-ionisation knots (dubbed 'freckles') was discovered and techniques developed to measure their spectra, independently of the extended high-ionisation medium. The nebula is confirmed as optically thin in the H-ionising continuum, based on its very low HeI emission, even to the edges of the field. The electron temperature, T_e_, is shown to have a large-scale spatially coherent structure, as indicated by a previous long-slit spectrum. Prior to this study, no low-ionisation emission had been positively detected, although MUSE revealed both weak extended [NII] and [OII] and >100 spatially unresolved knots. There are several linear associations of these knots, but none of them point convincingly back to the central star. They have low-to-moderate ionisation with T_e_~11000K, N_e_~1500cm^-3^ and generally exhibit a higher extinction than the extended high-ionisation nebula. Within the MUSE field, a low-redshift emission-line galaxy was serendipitously found to be hiding behind NGC 4361. The spectrum of this dwarf galaxy was carefully extracted from the bright foreground nebular emission and the galaxy's line and continuum properties were then determined. NGC 4361 is not completely optically thin, as indicated by several extended regions and many compact features of lower ionisation emission. The low-ionisation 'freckles' identified here do not clearly appear to differ in (He, N, O, S) abundance with respect to the extended high-ionisation gas. The spatial distribution and radial velocities of these features suggest that they belong to a thick disk oriented perpendicular to the large-scale nebular gas, which may perhaps be remnants of an earlier structure. The low-luminosity disk galaxy at ~87Mpc has bright H II regions with metallicity 12+log(O/H) ~8.4 and is suggested as a Magellanic irregular or low-mass spiral.2024A&A...690A.264Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/690/A264CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/690/A264https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/690/A264http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/690/A264https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/690/A264https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/690/A264http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/690/A264GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/690/A264/table1 (Observation log of 55 MUSE exposures)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/690/A264/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/690/A264/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/690/A264/table1?GETtext/xml+votable180.050000true186.12825-18.78488890.005555555555555556Cone search capability for table J/A+A/690/A264/table6 (Position, area, [NII] 6583{AA} flux, and radial velocities of freckles)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/690/A264/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/690/A264/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/690/A264/table6?GETtext/xml+votable180.050000true186.1728431-18.79281390.005555555555555556Cone search capability for table J/A+A/690/A264/table12 (Observed properties of HII regions in the galaxy NGC4361-BgGalJ1224290-184707)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/690/A264/table12?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/690/A264/table12?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/690/A264/table12?GETtext/xml+votable180.050000true186.1192194-18.78730560.0055555555555555566/25008https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/690/A264?format=asciiOpticaldefaultJ/A+A/690/A264/table1Observation log of 55 MUSE exposuresAirmassAirmassobs.airMassfloatDIMM? DIMM seeingarcsecinstr.obsty.seeingfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTargetTarget pointing namemeta.id;meta.maincharRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainPAPosition angle of MUSEdegpos.posAngintObs.dateDate of observation with dataset time stampstime.epochnullableJ/A+A/690/A264/table2Wavelengths and fluxes of emission lines detected in full MUSE fieldlambdaLine wavelength (Angstroem)0.1nmem.wl;spect.linefloatIDLine species (1)meta.id;meta.maincharObsFlObserved flux (H-beta=100) (2)phot.flux;arith.ratiofloate_ObsFlObserved flux errorstat.errorfloatDerFlDereddened flux (H-beta=100) (2)phot.flux;arith.ratiofloate_DerFlDereddened flux errorstat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintJ/A+A/690/A264/table6Position, area, [NII] 6583{AA} flux, and radial velocities of frecklesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNoIdentification indexmeta.id;meta.mainintoRARight Ascension offset position (1)arcsecpos.eq.ra;arith.difffloatoDEDeclination offset position (1)arcsecpos.eq.dec;arith.difffloatAreaSurface areaarcsec**2phys.areafloatN2FlObserved flux in [NII] 6583{AA} (in 10^-20^erg/cm^2^/s)1e-23W.m**-2phot.fluxintVelHeliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricintDelVelRadial velocity - local radial velocitykm/sphys.veloc;arith.diffint_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.mainJ/A+A/690/A264/table7Emission line spectra of the frecklesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNoIdentification index (1)meta.id;meta.mainintFHaObserved H-alpha flux (erg/cm^2^/s)mW.m**-2phot.flux;em.line.HalphadoubleFHbObserved flux H-beta 4861{AA} (H-alpha=100)phot.flux;em.line.HbetafloatFO3-4959Observed flux [OIII] 4959{AA} (H-alpha=100)phot.flux;arith.ratiofloatFO3-5007Observed flux [OIII] 5007{AA} (H-alpha=100)phot.flux;arith.ratiofloatFHe2-5412Observed flux HeII 5412{AA} (H-alpha=100)phot.flux;arith.ratiofloatFN2-5755Observed flux [NII] 5755{AA} (H-alpha=100)phot.flux;arith.ratiofloatQualQuality flag (A, B or C) (2)meta.code.qualcharFHe1-5876Observed flux HeI 5876{AA} (H-alpha=100)phot.flux;arith.ratiofloatFO1-6300Observed flux [OI] 6300{AA} (H-alpha=100)phot.flux;arith.ratiofloatFS3-6312Observed flux [SIII] 6312{AA} (H-alpha=100)phot.flux;arith.ratiofloatFO1-6364Observed flux [OI] 6364{AA} (H-alpha=100)phot.flux;arith.ratiofloatFN2-6583Observed flux [NII] 6583{AA} (H-alpha=100)phot.flux;arith.ratiofloatFS2-6716Observed flux [SII] 6716{AA} (H-alpha=100)phot.flux;arith.ratiofloatFS2-6731Observed flux [SII] 6731{AA} (H-alpha=100)phot.flux;arith.ratiofloatFHe1-7065Observed flux HeI 7065{AA} (H-alpha=100)phot.flux;arith.ratiofloatFAr3-7136Observed flux [ArIII] 7136{AA} (H-alpha=100)phot.flux;arith.ratiofloatFO2-7319Observed flux [OII] 7319{AA} (H-alpha=100)phot.flux;arith.ratiofloatFO2-7330Observed flux [OII] 7330{AA} (H-alpha=100)phot.flux;arith.ratiofloatFAr5-7751Observed flux [ArV] 7751{AA} (H-alpha=100)phot.flux;arith.ratiofloatFS3-9069Observed flux [SIII] 9069{AA} (H-alpha=100)phot.flux;arith.ratiofloatFP9-9229Observed flux H P09 9229{AA} (H-alpha=100)phot.flux;arith.ratiofloatJ/A+A/690/A264/table9Derived parameters for freckles with quality bands A and BrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNoIdentification indexmeta.id;meta.mainintN2/HaObserved flux ratio [NII]6583/H-alphaphot.flux;arith.ratiofloatcLogarithmic extinction at H-betaobs.atmos.extinctionfloatS2Ne? Electron density from [SII] 6716/6731{AA}cm**-3phys.density;phys.electronintnullableN2Te? Electron temperature from [NII] 5755/6583{AA}Kphys.temperature.electron;phys.electronintnullableS3Te? Electron temperature from [SIII] 6312/9069{AA}Kphys.temperature.electron;phys.electronintnullableJ/A+A/690/A264/table12Observed properties of HII regions in the galaxy NGC4361-BgGalJ1224290-184707recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNo[1/39] HII region identification indexmeta.id;meta.mainintoRARight Ascension offset position (1)arcsecpos.eq.ra;arith.difffloatoDEDeclination offset position (1)arcsecpos.eq.dec;arith.difffloatRadiusRadius of HII regionarcsecphys.angSize;obs.fieldfloatLHaH-alpha luminosity (2)solLumphys.luminosity;em.line.HalphafloatVel? Radial velocity (3)km/sspect.dopplerVelocintnullable_RAComputed Right Ascension for Equinox: J2000degpos.eq.ra;meta.main_DEComputed Declination for Equinox: J2000degpos.eq.dec;meta.mainJ/A+A/690/A264/table14Observed line ratios and metallicities for HII regions of NGC4361-BgGalJ1224290-184707e_F5007? Observed [OIII] 5007A flux error (H-alpha=100)stat.errorfloatnullableF6583? Observed [NII] 6583A flux (H-alpha=100) (2)phot.flux;arith.ratiofloatnullablee_F6583? Observed [N II] 6583A flux error (H-alpha=100)stat.errorfloatnullableF6716? Observed [SII] 6716A flux (H-alpha=100) (2)phot.flux;arith.ratiofloatnullablee_F6716? Observed [SII] 6716A flux error (H-alpha=100)stat.errorfloatnullableZ? Metallicity Z(O3/N2) 12 + log(O/H) (3)phys.abund.Zfloatnullablee_Z? Metallicity Z(O3/N2) errorstat.error;src.redshiftfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNo[1/39] HII region identification indexmeta.id;meta.mainintFHaHII region observed H-alpha flux (1)1e-20W.m**-2phot.flux;em.line.Halphafloate_FHaHII region observed H-alpha flux error1e-20W.m**-2stat.errorfloatF5007? Observed [OIII] 5007A flux (H-alpha=100) (2)phot.flux;arith.ratiofloatnullable