Planck early results: XXV. Thermal dust in nearby molecular clouds

A. Abergel (Corresponding Author), Jussi Tuovinen, Planck Collaboration

Research output: Contribution to journalArticleScientificpeer-review

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Abstract

Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around −7% and +13%, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 → 1 and J = 1 → 0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index β, and the dust optical depth at 250 μm τ250. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16 − 17 K in the diffuse regions to 13 − 14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T − β anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 μm per hydrogen atom τ250/NH. We report an increase of τ250/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.
Original languageEnglish
Article numberA25
Number of pages18
JournalAstronomy and Astrophysics
Volume536
DOIs
Publication statusPublished - 2011
MoE publication typeA1 Journal article-refereed

Fingerprint

molecular clouds
dust
optical thickness
optical depth
pixel
pixels
incident radiation
temperature
Infrared Astronomy Satellite
emissivity
systematic errors
radiation distribution
quantitative analysis
line of sight
standard deviation
hydrogen atoms
near infrared
spatial distribution
emission spectra
extinction

Keywords

  • Dust, extinction
  • evolution
  • infrared
  • ISM
  • ISM: individual objects: Taurus-Auriga molecular cloud
  • ISM. structure

Cite this

Abergel, A. ; Tuovinen, Jussi ; Planck Collaboration. / Planck early results : XXV. Thermal dust in nearby molecular clouds. In: Astronomy and Astrophysics. 2011 ; Vol. 536.
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abstract = "Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around −7{\%} and +13{\%}, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 → 1 and J = 1 → 0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index β, and the dust optical depth at 250 μm τ250. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16 − 17 K in the diffuse regions to 13 − 14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T − β anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 μm per hydrogen atom τ250/NH. We report an increase of τ250/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.",
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Planck early results : XXV. Thermal dust in nearby molecular clouds. / Abergel, A. (Corresponding Author); Tuovinen, Jussi; Planck Collaboration.

In: Astronomy and Astrophysics, Vol. 536, A25, 2011.

Research output: Contribution to journalArticleScientificpeer-review

TY - JOUR

T1 - Planck early results

T2 - XXV. Thermal dust in nearby molecular clouds

AU - Abergel, A.

AU - Ade, P.A.R.

AU - Aghanim, N.

AU - Arnaud, M.

AU - Tuovinen, Jussi

AU - Planck Collaboration

N1 - Project code: 18080

PY - 2011

Y1 - 2011

N2 - Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around −7% and +13%, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 → 1 and J = 1 → 0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index β, and the dust optical depth at 250 μm τ250. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16 − 17 K in the diffuse regions to 13 − 14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T − β anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 μm per hydrogen atom τ250/NH. We report an increase of τ250/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.

AB - Planck allows unbiased mapping of Galactic sub-millimetre and millimetre emission from the most diffuse regions to the densest parts of molecular clouds. We present an early analysis of the Taurus molecular complex, on line-of-sight-averaged data and without component separation. The emission spectrum measured by Planck and IRAS can be fitted pixel by pixel using a single modified blackbody. Some systematic residuals are detected at 353 GHz and 143 GHz, with amplitudes around −7% and +13%, respectively, indicating that the measured spectra are likely more complex than a simple modified blackbody. Significant positive residuals are also detected in the molecular regions and in the 217 GHz and 100 GHz bands, mainly caused by the contribution of the J = 2 → 1 and J = 1 → 0 12CO and 13CO emission lines. We derive maps of the dust temperature T, the dust spectral emissivity index β, and the dust optical depth at 250 μm τ250. The temperature map illustrates the cooling of the dust particles in thermal equilibrium with the incident radiation field, from 16 − 17 K in the diffuse regions to 13 − 14 K in the dense parts. The distribution of spectral indices is centred at 1.78, with a standard deviation of 0.08 and a systematic error of 0.07. We detect a significant T − β anti-correlation. The dust optical depth map reveals the spatial distribution of the column density of the molecular complex from the densest molecular regions to the faint diffuse regions. We use near-infrared extinction and Hi data at 21-cm to perform a quantitative analysis of the spatial variations of the measured dust optical depth at 250 μm per hydrogen atom τ250/NH. We report an increase of τ250/NH by a factor of about 2 between the atomic phase and the molecular phase, which has a strong impact on the equilibrium temperature of the dust particles.

KW - Dust, extinction

KW - evolution

KW - infrared

KW - ISM

KW - ISM: individual objects: Taurus-Auriga molecular cloud

KW - ISM. structure

U2 - 10.1051/0004-6361/201116483

DO - 10.1051/0004-6361/201116483

M3 - Article

VL - 536

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

SN - 0004-6361

M1 - A25

ER -