J/A+A/685/A74ivo://CDS.VizieR/J/A+A/685/A74doi:10.26093/cds/vizier.36850074CDSPeeters E.Habart E.Berne O.Sidhu A.Chown R.Van De Putte D.,Trahin B.Schroetter I.Canin A.Alarcon F.Schefter B.Khan B.,Pasquini S.Tielens A.G.G.M.Wolfire M.G.Dartois E.Goicoechea J.R.,Maragkoudakis A.Onaka T.Pound M.W.Vicente S.Abergel A.Bergin E.A.,Bernard-Salas J.Boersma C.Bron E.Cami J.Cuadrado S.Dicken D.,Elyajouri M.Fuente A.Gordon K.D.Issa L.Joblin C.Kannavou O.,Lacinbala O.Languignon D.Le Gal R.Meshaka R.Okada Y.Robberto M.,Roellig M.Schirmer T.Tabone B.Zannese M.Aleman I.Allamandola L.,Auchettl R.Baratta G.A.Bejaoui S.Bera P.P.Black J.H.Boulanger F.,Bouwman J.Brandl B.Brechignac P.Bruenken S.Buragohain M.,Burkhardt A.Candian A.Cazaux S.Cernicharo J.Chabot M.,Chakraborty S.Champion J.Colgan S.W.J.Cooke I.R.Coutens A.,Cox N.L.J.Demyk K.Donovan Meyer J.Foschino S.Garcia-Lario P.,Gerin M.Gottlieb C.A.Guillard P.Gusdorf A.Hartigan P.He J.,Herbst E.Hornekaer L.Jaeger C.Janot-Pacheco E.Kaufman M.,Kendrew S.Kirsanova M.S.Klaassen P.Kwok S.Labiano A.Lai T.S.-Y.,Lee T.J.Lefloch B.Le Petit F.Li A.Linz H.Mackie C.J.Madden S.C.,Mascetti J.McGuire B.A.Merino P.Micelotta E.R.Misselt K.,Morse J.A.Mulas G.Neelamkodan N.Ohsawa R.Paladini R.Palumbo M.E.,Pathak A.Pendleton Y.J.Petrignani A.Pino T.Puga E.Rangwala N.,Rapacioli M.Ricca A.Roman-Duval J.Roser J.Roueff E.Rouille G.,Salama F.Sales D.A.Sandstrom K.Sarre P.Sciamma-O'Brien E.,Sellgren K.Shenoy S.S.Teyssier D.Thomas R.D.Togi A.Verstraete L.,Witt A.N.Wootten A.Ysard N.Zettergren H.Zhang Y.Zhang Z.E.,Zhen J.2025-07-31T20:00:59Z2024-05-14T09:51:54ZCDS support team

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

cds-question@unistra.frh-ii-regionsinfrared-sourcesmilky-way-galaxyinterstellar-mediumspectroscopyJWST has taken the sharpest and most sensitive infrared (IR) spectral imaging observations ever of the Orion Bar photodissociation region (PDR), which is part of the nearest massive star-forming region the Orion Nebula, and often considered to be the 'prototypical' strongly illuminated PDR. We investigate the impact of radiative feedback from massive stars on their natal cloud and focus on the transition from the HII region to the atomic PDR -- crossing the ionisation front (IF) --, and the subsequent transition to the molecular PDR -- crossing the dissociation front (DF). Given the prevalence of PDRs in the interstellar medium and their dominant contribution to IR radiation, understanding the response of the PDR gas to far-ultraviolet (FUV) photons and the associated physical and chemical processes is fundamental to our understanding of star and planet formation and for the interpretation of any unresolved PDR as seen by JWST. We used high-resolution near-IR integral field spectroscopic data from NIRSpec on JWST to observe the Orion Bar PDR as part of the PDRs4All JWST Early Release Science programme. We constructed a 3"x25" spatio-spectral mosaic covering 0.97-5.27 micrometer at a spectral resolution R of ~2700 and an angular resolution of 0.075"-0.173". To study the properties of key regions captured in this mosaic, we extracted five template spectra in apertures centred on the three H_2_ dissociation fronts, the atomic PDR, and the HII region. This wealth of detailed spatial-spectral information was analysed in terms of variations in the physical conditions -- incident UV field, density, and temperature -- of the PDR gas. The NIRSpec data reveal a forest of lines including, but not limited to, HeI, HI, and CI recombination lines; ionic lines (e.g. FeIII and FeII); OI and NI fluorescence lines; aromatic infrared bands (AIBs, including aromatic CH, aliphatic CH, and their CD counterparts); pure rotational and ro-vibrational lines from H_2_; and ro-vibrational lines HD, CO, and CH+, with most of them having been detected for the first time towards a PDR. Their spatial distribution resolves the H and He ionisation structure in the Huygens region, gives insight into the geometry of the Bar, and confirms the large-scale stratification of PDRs. In addition, we observed numerous smaller-scale structures whose typical size decreases with distance from theta 1 Ori C and IR lines from CI, if solely arising from radiative recombination and cascade, reveal very high gas temperatures (a few 1000K) consistent with the hot irradiated surface of small-scale dense clumps inside the PDR. The morphology of the Bar, in particular that of the H_2_ lines, reveals multiple prominent filaments that exhibit different characteristics. This leaves the impression of a "terraced" transition from the predominantly atomic surface region to the CO-rich molecular zone deeper in. We attribute the different characteristics of the H2 filaments to their varying depth into the PDR and, in some cases, not reaching the C+/C/CO transition. These observations thus reveal what local conditions are required to drive the physical and chemical processes needed to explain the different characteristics of the DFs and the photochemical evolution of the AIB carriers. This study showcases the discovery space created by JWST to further our understanding of the impact radiation from young stars has on their natal molecular cloud and proto-planetary disk, which touches on star and planet formation as well as galaxy evolution.2024A&A...685A..74Phttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/685/A74CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/685/A75 : PDRs4All IV. Orion Bar MRS template spectra (Chown+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/685/A74https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/685/A74http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/685/A74https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/685/A74https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/685/A74http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/685/A74GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapInfrareddefaultJ/A+A/685/A74/t-g140hFive template spectra: grating G140H ([0.9699629, 1.8899879] um)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelengthumem.wldoubleHII-SBHII region template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_HII-SBHII region template: Surface Brightness uncertaintyMJy/srstat.errorfloatAPDR-SBAtomic PDR template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_APDR-SBAtomic PDR template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF1-SBDF1 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF1-SBDF1 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF2-SBDF2 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF2-SBDF2 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF3-SBDF3 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF3-SBDF3 template: Surface Brightness uncertaintyMJy/srstat.errorfloatJ/A+A/685/A74/t-g235hFive template spectra: grating G235H ([1.6599748, 3.1699228] um)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelengthumem.wldoubleHII-SBHII region template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_HII-SBHII region template: Surface Brightness uncertaintyMJy/srstat.errorfloatAPDR-SBAtomic PDR template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_APDR-SBAtomic PDR template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF1-SBDF1 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF1-SBDF1 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF2-SBDF2 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF2-SBDF2 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF3-SBDF3 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF3-SBDF3 template: Surface Brightness uncertaintyMJy/srstat.errorfloatJ/A+A/685/A74/t-g395hFive template spectra: grating G395H ([2.8700916, 5.2700766] um)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelengthumem.wldoubleHII-SBHII region template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_HII-SBHII region template: Surface Brightness uncertaintyMJy/srstat.errorfloatAPDR-SBAtomic PDR template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_APDR-SBAtomic PDR template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF1-SBDF1 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF1-SBDF1 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF2-SBDF2 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF2-SBDF2 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF3-SBDF3 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF3-SBDF3 template: Surface Brightness uncertaintyMJy/srstat.errorfloatJ/A+A/685/A74/t-combFive template spectra: grating G140H, G235H, and G395H combined ([0.9699629, 5.2700766] um)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintWaveWavelengthumem.wldoubleHII-SBHII region template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_HII-SBHII region template: Surface Brightness uncertaintyMJy/srstat.errorfloatAPDR-SBAtomic PDR template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_APDR-SBAtomic PDR template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF1-SBDF1 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF1-SBDF1 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF2-SBDF2 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF2-SBDF2 template: Surface Brightness uncertaintyMJy/srstat.errorfloatDF3-SBDF3 template: Surface BrightnessMJy/srphot.flux.density.sbdoublee_DF3-SBDF3 template: Surface Brightness uncertaintyMJy/srstat.errorfloatJ/A+A/685/A74/table3Line intensities (observed and corrected for extinction using foreground and intermingled formalisms) and column densities of selected H2 lines in v=0 and v=1 states for the five templatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTemplateTemplate spectrum (Template)meta.notecharWaveWavelength (Wave)umem.wldoubleIntObsObserved intensity (Int_obs)mW.m**-2.sr**-1spect.line.intensitydoubleb_IntObsObserved intensity - lower bound (Int_obs_low_bound)mW.m**-2.sr**-1spect.line.intensity;stat.mindoubleB_IntObsObserved intensity - upper bound (Int_obs_upp_bound)mW.m**-2.sr**-1spect.line.intensity;stat.maxdoubleIntExtcor-fgExtinction corrected intensity (foreground formalism) (Int_extcorr_fg)mW.m**-2.sr**-1phys.absorptiondoubleb_IntExtcor-fgExtinction corrected intensity (foreground formalism) lower bound (Int_extcorr_fg_low_bound)mW.m**-2.sr**-1phys.absorption;stat.mindoubleB_IntExtcor-fgExtinction corrected intensity (foreground formalism) upper bound (Int_extcorr_fg_upp_bound)mW.m**-2.sr**-1phys.absorption;stat.maxdoubleIntExtcor-int? Extinction corrected intensity (intermingled formalism) (Int_extcorr_int)mW.m**-2.sr**-1phys.absorptiondoublenullableb_IntExtcor-int? Extinction corrected intensity (intermingled formalism) lower bound (Int_extcorr_int_low_bound)mW.m**-2.sr**-1phys.absorption;stat.mindoublenullableB_IntExtcor-int? Extinction corrected intensity (intermingled formalism) upper bound (Int_extcorr_int_upp_bound)mW.m**-2.sr**-1phys.absorption;stat.maxdoublenullableNExtcor-fgColumn density (foreground formalism) (N_extcorr_fg)cm**-2phys.columnDensitydoubleb_NExtcor-fgColumn density (foreground formalism) lower bound (N_extcorr_fg_low_bound)cm**-2phys.columnDensity;stat.mindoubleB_NExtcor-fgColumn density (foreground formalism) upper bound (N_extcorr_fg_upp_bound)cm**-2phys.columnDensity;stat.maxdoubleNExtcor-int? Column density (intermingled formalism) (N_extcorr_int)cm**-2phys.columnDensitydoublenullableb_NExtcor-int? Column density (intermingled formalism) lower bound (N_extcorr_int_low_bound)cm**-2phys.columnDensity;stat.mindoublenullableB_NExtcor-int? Column density (intermingled formalism) upper bound (N_extcorr_int_upp_bound)cm**-2phys.columnDensity;stat.maxdoublenullableLineIDH2 Line identification (Line_ID)meta.id;spect.linecharJ/A+A/685/A74/tableb1Observed line intensities and line identification of detected lines in the five templatesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNLine? Sequential number for overlapping linesmeta.recordintnullableWave? Wavelength in vacuumumem.wlfloatnullableHIIwavefit? Wavelength of peak position Gaussian fitumem.wlfloatnullableHIIInt? HII region template: Observed line intensitymW.m**-2.sr**-1spect.line.intensity;obs.fielddoublenullablee_HIIInt? HII region template: Observed line intensity uncertaintymW.m**-2.sr**-1stat.errordoublenullableAPDRwavefit? Atomic PDR template: Wavelength of peak position Gaussian fitumem.wlfloatnullableAPDRInt? Atomic PDR template: Observed line intensitymW.m**-2.sr**-1spect.line.intensitydoublenullablee_APDRInt? Atomic PDR template: Observed line intensity uncertaintymW.m**-2.sr**-1stat.errordoublenullableDF1wavefit? DF1 template: Wavelength of peak position Gaussian fitumem.wlfloatnullableDF1Int? DF1 template: Observed line intensitymW.m**-2.sr**-1spect.line.intensitydoublenullablee_DF1Int? DF1 template: Observed line intensity uncertaintymW.m**-2.sr**-1stat.errordoublenullableDF2wavefit? DF2 template: Wavelength of peak position Gaussian fitumem.wlfloatnullableDF2Int? DF2 template: Observed line intensitymW.m**-2.sr**-1spect.line.intensitydoublenullablee_DF2Int? DF2 template: Observed line intensity uncertaintymW.m**-2.sr**-1stat.errordoublenullableDF3wavefit? DF3 template: Wavelength of peak position Gaussian fitumem.wlfloatnullableDF3Int? DF3 template: Observed line intensitymW.m**-2.sr**-1spect.line.intensitydoublenullablee_DF3Int? DF3 template: Observed line intensity uncertaintymW.m**-2.sr**-1stat.errordoublenullableLineLine identification (1)meta.id;spect.linecharn_Line[+] Note for overlapping lines (1)meta.notechar