The dust temperature distribution in prestellar cores

By A. Zucconi, C. Walmsley, D. Galli. 2001

149 citations recorded by the source corpus.

We have computed the dust temperature distribution to be expected in a pre-protostellar core in the phase prior to the onset of gravitational instability. We have done this under the approximation that the heating of the dust grains is solely due to the attenuated external radiation field and that the core is optically thin to its own radiation. This permits us to consider non spherically symmetric geometries. We predict the intensity distributions of our model cores at millimeter and sub-millimeter wavelengths and compare then with observations of the well studied object L1544. We have also developed an analytical approximation for the temperature at the center of spherically symmetric cores and we compare this with the numerical calculations. Our results show (in agreement with Evans et al. 2001) that the temperatures in the nuclei of cores of high visual extinction (>30 mag) are reduced to values of below ∼ 8 K or roughly half of the surface temperature. This has the consequence that maps at wavelengths shortward of 1.3 mm see predominantly the low density exterior of pre-protostellar cores. It is extremely difficult to deduce the true density distribution from such maps alone. We have computed the intensity distribution expected on the basis of the models of Ciolek & Basu (2000) and compared with the observations of L1544. The agreement is good with a preference for higher inclinations (37° instead of $16^{\circ}$) than that adopted by Ciolek & Basu (2000). We find that a simple extension of the analytic approximation allows a reasonably accurate calculation of the dust temperature as a function of radius in cores with density distributions approximating those expected for Bonnor-Ebert spheres and suggest that this may be a useful tool for future calculations of the gas temperature in such cores.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/849639e1b3c370a13364035465a5cf6bb7347fd2

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In Astronomy and Astrophysics

1. P. Caselli
2. E. Herbst
3. E. Bergin
4. M. Tafalla
5. Cecilia Ceccarelli
6. Ralf Klessen
7. R. Garrod
8. P. Myers

In Instrumentation

1. M. Tafalla
2. P. Caselli
3. P. Myers
4. E. Bergin
5. E. Herbst
6. A. Crapsi
7. Ralf Klessen
8. H. Roberts

Citations in the corpus

• Planck 2015 results - XXVIII. The Planck Catalogue of Galactic cold clumps (2015, unknown): “This is consistent with dust temperature lower limits predicted by radiative modelling of the infrared heating in dense and cold cores (see, e.g., Bernard et al. 1992; Evans et al. 2001; Zucconi et al. 2001) yielding to a dust temperature of about 6 K.”
• Observing the gas temperature drop in the high-density nucleus of L 1544 (2007, background): “…the basic questions about pre-stellar cores is whether they have a positive temperature gradient outwards (see e.g. Leung 1975; Evans et al. 2001; Zucconi et al. 2001; Galli et al. 2002; Lesaffre et al. 2005) with temperatures of the order of 6 K in their center, as one would expect from…”
• THE EFFECT OF LINE-OF-SIGHT TEMPERATURE VARIATION AND NOISE ON DUST CONTINUUM OBSERVATIONS (2009, background): “Though gas temperatures in a stable Bonnor-Ebert sphere are constant, theoretical results have suggested that dust temperatures decrease towards the center to values as low as ∼ 7 K (e.g. Leung 1975; Evans et al. 2001; Zucconi et al. 2001).”
• WATER, O2, AND ICE IN MOLECULAR CLOUDS (2008, background): “It lies at ∼160 pc, with a mean density of n ∼ 105 cm−3, an AV through the cloud center of ∼30, and a central temperature of 7 K. Extinction and dust continuum maps have recently provided a detailed view of the density and temperature structure of the cloud (Alves et al. 2001; Zucconi et al. 2001).”
• Molecular Ions in L1544. II. The Ionization Degree (2001, methodology): “However, model calculations of the dust temperature in pre–stellar cores ( Zucconi et al. 2001, Evans et al. 2001 ) predict a fall off in dust temperature from ∼ 14 K at the edge to ∼ 7 K at the center.”
• Molecular Evolution in Collapsing Prestellar Cores. III. Contraction of a Bonnor-Ebert Sphere (2004, background): “Indeed, if the center of L1544 is as cold as 7 K, for example, the central density increases to ∼ 107 cm−3 (Evans et al. 2001; Zucconi et al. 2001).”
• The Stellar Mass Spectrum from Non-Isothermal Gravoturbulent Fragmentation (2004, background): “…gas would be very difficult to observe; various efforts to model the observations have suggested central temperatures between 6 K and 10 K for the densest observed prestellar cores, whose peak densities may approach 10−17 g cm−3 (e.g., Zucconi et al. 2001; Evans et al. 2001; Tafalla et al. 2004).”
• On The Internal Structure Of Starless Cores. Physical and Chemical Properties of L1498 and L1517B (2004, unknown): “Theoretical models of the dust temperature in cores predict a slight inward decrease (Mathis et al. 1983; Evans et al. 2001; Zucconi et al. 2001), which for the case of the L1498 and L1517B cores is estimated to range between 11 K in the outer layers and 8 K in the innermost part (Evans et al.…”
• Systematic Molecular Differentiation in Starless Cores (2001, background): “…it is still possible that our 4000 resolution observations miss gas in the inner cores at significantly lower temperatures (Evans et al. 2001; Zucconi et al. 2001), the sharp central abundance increase, which biases the emission toward the innermost gas, suggests that this cold region has to…”
• Probing the Evolutionary Status of Starless Cores through N2H+ and N2D+ Observations (2004, background): “We note that the dust temperature is predicted to drop in the core nucleus (Evans et al. 2001; Zucconi et al. 2001); assuming a temperature of 8 K would cause an increase of the column density of a factor of 1.5.”