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Sökning: id:"swepub:oai:research.chalmers.se:6b5c71a6-a0c6-40c9-8acc-354f6a4d355d" > Gas and dust in the...

  • Liseau, René,1949Chalmers tekniska högskola,Chalmers University of Technology (författare)

Gas and dust in the star-forming region ρ Oph A ∗, ∗∗, ∗∗∗: The dust opacity exponent β and the gas-to-dust mass ratio g2d

  • Artikel/kapitelEngelska2015

Förlag, utgivningsår, omfång ...

  • 2015-06-16
  • EDP Sciences,2015
  • electronicrdacarrier

Nummerbeteckningar

  • LIBRIS-ID:oai:research.chalmers.se:6b5c71a6-a0c6-40c9-8acc-354f6a4d355d
  • https://doi.org/10.1051/0004-6361/201525641DOI
  • https://research.chalmers.se/publication/219892URI

Kompletterande språkuppgifter

  • Språk:engelska
  • Sammanfattning på:engelska

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Klassifikation

  • Ämneskategori:art swepub-publicationtype
  • Ämneskategori:ref swepub-contenttype

Anmärkningar

  • © ESO, 2015. Aims. We aim at determining the spatial distribution of the gas and dust in star-forming regions and address their relative abundances in quantitative terms. We also examine the dust opacity exponent β for spatial and/or temporal variations. Methods. Using mapping observations of the very dense ρ Oph A core, we examined standard 1D and non-standard 3D methods to analyse data of far-infrared and submillimetre (submm) continuum radiation. The resulting dust surface density distribution can be compared to that of the gas. The latter was derived from the analysis of accompanying molecular line emission, observed with Herschel from space and with APEX from the ground. As a gas tracer we used N2H+, which is believed to be much less sensitive to freeze-out than CO and its isotopologues. Radiative transfer modelling of the N2H+ (J = 3-2) and (J = 6-5) lines with their hyperfine structure explicitly taken into account provides solutions for the spatial distribution of the column density N(H2), hence the surface density distribution of the gas. Results. The gas-to-dust mass ratio is varying across the map, with very low values in the central regions around the core SM 1. The global average, = 88, is not far from the canonical value of 100, however. In ρ Oph A, the exponent β of the power-law description for the dust opacity exhibits a clear dependence on time, with high values of 2 for the envelope-dominated emission in starless Class -1 sources to low values close to 0 for the disk-dominated emission in Class III objects. β assumes intermediate values for evolutionary classes in between. Conclusions. Since β is primarily controlled by grain size, grain growth mostly occurs in circumstellar disks. The spatial segregation of gas and dust, seen in projection toward the core centre, probably implies that, like C18O, also N2H+ is frozen onto the grains.

Ämnesord och genrebeteckningar

Biuppslag (personer, institutioner, konferenser, titlar ...)

  • Larsson, B.Alba Nova Universitetscentrum,AlbaNova University Center. Stockholm Center for Physics, Astronomy and Biotechnology (författare)
  • Lunttila, Tuomas,1978Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)lunttila (författare)
  • Olberg, Michael,1956Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)olberg (författare)
  • Rydbeck, Gustaf,1942Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)gustafr (författare)
  • Bergman, Per,1960Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)pbergman (författare)
  • Justtanont, Kay,1965Chalmers tekniska högskola,Chalmers University of Technology(Swepub:cth)justtano (författare)
  • Olofsson, G.Alba Nova Universitetscentrum,AlbaNova University Center. Stockholm Center for Physics, Astronomy and Biotechnology (författare)
  • de Vries, B. L.Alba Nova Universitetscentrum,AlbaNova University Center. Stockholm Center for Physics, Astronomy and Biotechnology,Stockholms universitet,Stockholm University (författare)
  • Chalmers tekniska högskolaAlba Nova Universitetscentrum (creator_code:org_t)

Sammanhörande titlar

  • Ingår i:Astronomy and Astrophysics: EDP Sciences5780004-63611432-0746

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