Thermally Dominated Carbon Monoxide Emission in the Taurus Molecular Cloud Complex

Ladd, E. F.; Covey, Kevin R.

doi:10.1086/308926

Cited by 5 publications

(2 citation statements)

References 35 publications

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“…Since typical C 18 O line profiles in regions of the Taurus cloud away from embedded sources are much narrower than the broad components detected here (Onishi et al 1998;Ladd & Covey 2000), we believe that these broad components are intimately associated with the young sources. Although the broad-component intensity and derived column density vary with transition, there is good agreement in both velocity and velocity width of this component among the three transitions.…”

Section: Origin Of the Broad Componentmentioning

confidence: 52%

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

Fuller

Ladd

2002

ApJ

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Studies of the properties of the circumstellar material around young embedded sources can provide important insights into the relative importance of infall and outflow in clearing the circumstellar environment. In this paper we report one such study of 20 of the most deeply embedded young stars in the Taurus molecular cloud using the J ¼ 1 ! 0, J ¼ 2 ! 1, and J ¼ 3 ! 2 transitions of C 18 O and C 17 O. The profiles comprise a narrow component, with a line width of $0.7 km s À1 plus in many cases a second broader component that contains a similar mass of material. The broad-component line width decreases with increasing source age as measured by the source bolometric temperature, consistent with what would be expected if the broad component traces the interaction between a stellar wind and ambient material. The momentum flux of the broadcomponent emission in the immediate vicinity of the forming star is comparable to that in the spatially extended outflows from these sources and also decreases with increasing source age. Comparison with models of this interaction provide a reasonable match to the behavior of the broad component with source age. The derived total column density toward the sources shows a systematic decrease with increasing bolometric temperature and implies a circumstellar mass-loss rate that varies from $10 À4 M yr À1 for the youngest sources to $10 À8 M yr À1 for sources in the late Class I phase. The broad components are sufficiently massive and energetic to clear the circumstellar environment on timescales of $10 5 yr, and we argue that the broad component of the C 18 O line profiles is the dense, low-velocity inner part of the outflow from the sources and may be the material being directly swept up by the stellar wind. The widths of the broad and narrow components are correlated, indicating that the narrow-component material is already being stirred by the stellar wind, even in the youngest sources.

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Section: Origin Of the Broad Componentmentioning

confidence: 52%

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

Fuller

Ladd

2002

ApJ

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“…The error beam of the FCRAO telescope at the 13 CO 1-0 frequency has a width of about 100 ′′ . The main beam efficiency is about 48 % and the measured moon efficiency 72 % (Ladd & Covey, 2000). Repeating the deconvolution exercise for this smaller error beam gives a relatively constant ratio of about 0.45 for most of the map which is only slightly smaller than the ratio between error beam and main beam efficiency.…”

Section: Discussionmentioning

confidence: 79%

Spectroscopic [C i] mapping of the infrared dark cloud G48.65-0.29

Ossenkopf

Ormel

Simon

et al. 2010

A&A

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Aims. We report the first spectroscopic mapping of an atomic carbon line in an infrared dark cloud (IRDC). By observing the spatial distribution of the [C i] emission in an IRDC, comparing it with the 13 CO emission and the known distribution of internal heating sources, we can quantify the role of internal and external UV irradiation in the production of atomic carbon.Methods. We used the 2 × 4 pixel SMART receiver of the KOSMA observatory on Gornergrat to map the [C i] 3 P 1 − 3 P 0 line in the IRDC G48.65-0.29 and compared the resulting spectra with data from the BU-FCRAO 13 CO 1-0 Galactic Ring Survey.Results. The [C i]/ 13 CO effective beam temperature ratio falls at about 0.3 with local deviations by less than a factor two. All velocity components seen in 13 CO are also detected in [C i]. We find, however, significant differences in the morphology of the brightest regions seen in the two tracers. While 13 CO basically follows the column density distribution derived from the near-infrared (NIR) extinction and the submm continuum, the [C i] emission peaks at the locations of the two known NIR point sources. We find C i/CO abundance ratios between 0.07 and 0.13 matching the lower end of the range previously measured in star-forming regions. Conclusions. Evaluating the relative importance of the irradiation by embedded sources and by the Galactic interstellar UV field, we find that in G48.65-0.29 most [C i] emission can be attributed to externally illuminated surfaces. Embedded sources have a significant impact on the overall abundance distribution of atomic carbon as soon as they are found in an evolved state with noticeable NIR flux.

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H¹³CO⁺and CH₃OH Line Observations of Prestellar Dense Cores in the TMC‐1C Region. II. Internal Structure

Takakuwa

Kamazaki²,

Saito

et al. 2003

ApJ

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Thermally Dominated Carbon Monoxide Emission in the Taurus Molecular Cloud Complex

Cited by 5 publications

References 35 publications

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

Spectroscopic [C i] mapping of the infrared dark cloud G48.65-0.29

H¹³CO⁺and CH₃OH Line Observations of Prestellar Dense Cores in the TMC‐1C Region. II. Internal Structure

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Thermally Dominated Carbon Monoxide Emission in the Taurus Molecular Cloud Complex

Cited by 5 publications

References 35 publications

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

The Evolution of the Circumstellar Environment of Embedded Young Stars from Observations of Rare Species of Carbon Monoxide

Spectroscopic [C i] mapping of the infrared dark cloud G48.65-0.29

H13CO+and CH3OH Line Observations of Prestellar Dense Cores in the TMC‐1C Region. II. Internal Structure

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H¹³CO⁺and CH₃OH Line Observations of Prestellar Dense Cores in the TMC‐1C Region. II. Internal Structure