Physical structure and CO abundance of low-mass protostellar envelopes

By J. Jørgensen, F. Schoeier, E. Dishoeck. 2002

249 citations recorded by the source corpus.

We present 1D radiative transfer modelling of the envelopes of a sample of 18 low-mass protostars and pre-stellar cores with the aim of setting up realistic physical models, for use in a chemical description of the sources. The density and temperature proles of the envelopes are constrained from their radial proles obtained from SCUBA maps at 450 and 850 m and from measurements of the source fluxes ranging from 60 mt o 1.3 mm. The densities of the envelopes within 10 000 AU can be described by single power-laws / r for the class 0 and I sources with ranging from 1.3 to 1.9, with typical uncertainties of0.2. Four sources have flatter proles, either due to asymmetries or to the presence of an outer constant density region. No signicant dierence is found between class 0 and I sources. The power-law ts fail for the pre-stellar cores, supporting recent results that such cores do not have a central source of heating. The derived physical models are used as input for Monte Carlo modelling of submillimeter C 18 Oa nd C 17 O emission. It is found that class I objects typically show CO abundances close to those found in local molecular clouds, but that class 0 sources and pre-stellar cores show lower abundances by almost an order of magnitude implying that signicant depletion occurs for the early phases of star formation. While the 2{1 and 3{2 isotopic lines can be tted using a constant fractional CO abundance throughout the envelope, the 1{0 lines are signicantly underestimated, possibly due to contribution of ambient molecular cloud material to the observed emission. The dierence between the class 0 and I objects may be related to the properties of the CO ices.

Subfields: Astronomy and Astrophysics, Atmospheric Science, Spectroscopy

View Paper: https://www.semanticscholar.org/paper/a540ae120bb7aac86b8c2254e3b39cfff8f35fed

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Citations in the corpus

PROSAC: a submillimeter array survey of low-mass protostars - II. The mass evolution of envelopes, disks, and stars from the class 0 through I stages (2009, methodology): “Since most of this emission is reprocessed in the larger-scale cold envelope,the xact shape and temperature of the input spectrum does not affect the distribution and strength of the emerging submillieter emission (see also Jørgensen et al. 2002, 2005b; Schöier etal.”
Molecular inventories and chemical evolution of low-mass protostellar envelopes (2003, methodology): “Jørgensen et al. (2002) (Paper I in the following) established the physical properties of the envelopes around a sample of low-mass protostars from 1D radiative transfer modeling of SCUBA dust continuum maps.”
PROSAC: A Submillimeter Array Survey of Low-Mass Protostars. I. Overview of Program: Envelopes, Disks, Outflows, and Hot Cores (2007, methodology): “…slope of 3.5Y4 for typical dust opacities, which are successfully used to explain the larger scale envelopes in detailed dust radiative trans- fermodels (for example, 1:8 at 850 mfor the coagulated dust grains, the so-called OH5 dust, of Ossenkopf & Henning 1994; used in Jørgensen et al. 2002).”
Hot corinos in NGC 1333-IRAS4B and IRAS2A (2006, methodology): “…1 × 10−7 1 × 10−7 NGC 1333-IRAS4A 6 2 × 10−8 3 × 10−9 <1 × 10−8 ≤3.5 × 10−9 NGC 1333-IRAS4B 6 3 × 10−6 1 × 10−8 7 × 10−7 9.5 × 10−8 NGC 1333-IRAS2A 16 2 × 10−7 8 × 10−10 3 × 10−7 1.5 × 10−7 a From Jørgensen et al. (2002). b Note that except in IRAS 16293 (Schöier et al. 2002), the formaldehyde…”
Evolution of Chemistry and Molecular Line Profiles during Protostellar Collapse (2004, unknown): “The beam sizes for the C18O lines have been adopted from Jørgensen et al. (2002); 33′′, 21′′, and 14′′ for 1 − 0, 2 − 1, and 3 − 2, respectively.”
Water in star-forming regions with Herschel (WISH). II. Evolution of 557 GHz 110-101 emission in low-mass protostars (2012, methodology): “The broad and medium line components have widths exceeding the line width typically seen originating from the quiescent envelope (∼1 km s−1; e.g., Jørgensen et al. 2002) and are thus likely related to the protostellar outflow.”
Astrochemistry and compositions of planetary systems (2020, background): “The rapid increase of CO around protostars due to this process has been observationally confirmed (Jørgensen et al. 2002).”
Our astrochemical heritage (2012, methodology): “The approximate structure of the envelope, as derived by observations of the continuum and line emission (e.g. Ceccarelli et al. 2000a; Jørgensen et al. 2002; Robitaille et al. 2006) is reported in Fig.”
Testing grain surface chemistry : a survey of deuterated formaldehyde and methanol in low-mass Class 0 protostars (2006, methodology): “For L1527, the opacity is likely to be even larger as suggested by the C18O/C17O measured by Jørgensen et al. (2002).”
A PARAMETRIC MODELING APPROACH TO MEASURING THE GAS MASSES OF CIRCUMSTELLAR DISKS (2013, unknown): “CO depletion via freeze-out onto dust grains was first characterized in molecular cores (Caselli et al. 1999; Tafalla et al. 2002; Jørgensen et al. 2002), then inferred in circumstellar disks (Qi et al. 2008, 2011), and now directly resolved (Rosenfeld et al. 2013a).”
A Keplerian disk around a Class 0 source: ALMA observations of VLA1623A (2013, methodology): “James Clark Webb Telescope (JCMT) observations towards VLA1623 by Jørgensen et al. (2002) detected C18O (2−1) with a flux of 12.1 K km s−1 (174 Jy km s−1, with 14.46 Jy/K).”
Does IRAS 16293–2422 have a hot core? Chemical inventory and abundance changes in its protostellar environment (2002, methodology): “In addition, the upper limits obtained for the 13C17O (J = 2→ 1) and 13C18O (J = 3→ 2) line emission are also consistent with these values.”
Testing grain-surface chemistry in massive hot-core regions (2007, methodology): “…luminosity quoted in Table 1 is provided by a single 30 000 K blackbody at the center of the envelope and fit the observed 850 µm fluxes of each source by adjusting the mass of the envelope using the DUSTY dust radiative transfer code (Ivezić et al. 1999) as described in Jørgensen et al. (2002).”