J/A+A/658/A54ivo://CDS.VizieR/J/A+A/658/A54doi:10.26093/cds/vizier.36580054CDSColombo D.Duarte-Cabral A.Pettitt A.R.Urquhart J.S.Wyrowski F.,Csengeri T.Neralwar K.R.Schuller F.Menten K.M.Anderson L.,Barnes P.Beuther H.Bronfman L.Eden D.Ginsburg A.Henning T.,Koenig C.Lee M.-Y.Mattern M.Medina S.Ragan S.E.Rigby A.J.,Sanchez-Monge A.Traficante A.Yang A.Y.Wienen M.2022-08-25T11:21:22Z2022-01-31T08:49:42ZCDS support team

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

cds-question@unistra.frgalaxy-planesmilky-way-galaxyinterstellar-mediummolecular-cloudsThe morphology of the Milky Way is still a matter of debate. In order to shed light on the uncertainty surrounding the Galactic structure, in this paper, we study the imprint of spiral arms on the molecular gas distribution and properties. To do so, we take full advantage of the SEDIGISM (Structure, Excitation and Dynamics of the Inner Galactic Interstellar Medium) survey that observed a large area of the inner Galaxy in the ^13^CO(2-1) line at an angular resolution of 28". We analyse the influences of spiral arms by considering the features of the molecular gas emission as a whole across the longitude- velocity map built from the full survey. Additionally, we examine the properties of the molecular clouds in the spiral arms compared to those in the inter-arm regions. Through flux and luminosity probability distribution functions, we find that the molecular gas emission associated with the spiral arms does not differ much from the emission between the arms. On average, spiral arms show masses per unit length of ~10^5^-10^6^M_{sun}_/kpc. This is similar to values inferred from data sets in which emission distributions were segmented into molecular clouds. By examining the cloud distribution across the Galactic plane, we infer that the molecular mass in the spiral arms is a factor of 1.5 higher than that of the inter-arm medium, similar to what is found for other spiral galaxies in the local Universe. We observe that only the distributions of cloud mass surface densities and aspect ratio in the spiral arms show significant differences compared to those of the inter-arm medium; other observed differences appear instead to be driven by a distance bias. By comparing our results with simulations and observations of nearby galaxies, we conclude that the measured quantities would classify the Milky Way as a flocculent spiral galaxy, rather than as a grand-design one.2022A&A...658A..54Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/658/A54CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/658/A54https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/658/A54http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/658/A54https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/658/A54https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/658/A54http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/658/A54GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/658/A54/table1 (Molecular cloud association to spiral arms)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/658/A54/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/658/A54/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/658/A54/table1?GETtext/xml+votable180.050000true187.755451-63.01068720.0055555555555555565/7202-7203 7206-7207 7228-7229 7275 7278 7376 10419-10420 10444 10451 10453 10542-10543 10556 10595 10624 6/28802-28803 28818 28848-28849 28852-28853 28874-28875 28878-28879 28896-28897 28900-28901 28903 28925 29090-29091 29094 29096-29097 29118-29119 29162 29457 29460-29461 41598-41599 41653-41655 41657-41662 41671 41673-41675 41684-41686 41688 41696-41698 41758-41759 41763 41766-41770 41772-41773 41780-41781 41784 41799 41801-41803 41810-41811 41816-41817 41820 41824 41856 42155 42158-42159 42206-42207 42210-42211 42213-42217 42220 42228-42229 42377-42379 42387 42390-42394 42396-42397 42400 42434-42435 42438-42441 42444-42445 42450-42451 42454-42457 42460-42461 42500-42501 42512 43013-43015 43020-43021 43024-43026https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/658/A54?format=asciidefaultJ/A+A/658/A54/table1Molecular cloud association to spiral armsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/10663] Unique cloud ID numbermeta.idintNameCloud name as per the SEDIGISM naming scheme, i.e. SDG followed by the Galactic coordinates of the cloud (SDGLLL.lll+B.bbb)meta.id;meta.maincharSpiralArmName of the closest spiral arm (1)meta.id;src.morph.paramcharDistMinDistance to the closest spiral arm calculated on the Galactocentric xy planekpcpos.distancefloatDeltaVVelocity offset with respect to the closest spiral armkm/sphys.veloc;arith.difffloatPvaluep-value from the chi2 test that associates cloud position to the spiral arm model on the Galactocentric xy planestat.fit.goodnessfloatLocationLocation of the molecular cloud: spiral arms (SA) or inter-arm region (IA)meta.codechar_GlonPosition from Name (longitude part)degpos.galactic.lonindexed_GlatPosition from Name (latitude part)degpos.galactic.latindexed_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexed