Very cold cores in the Taurus molecular ring as seen by ISO

L. Tóth, M. Haas, D. Lemke, K. Mattila, T. Onishi

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Three prominent cold objects of the Taurus Molecular Ring (TMR) were revealed by our ISOPHOT 200 μm map of the south-eastern part of the Heiles Cloud 2 (HCL 2) cloud complex. One corresponds to the cyanopolyyne peak region of the TMC-1 ridge, (TMC-1 CP), one is the HCL2-E cloud, and one which we call HCL2-ES lies south of TMC-1. The 200/100 μm colour temperatures and column densities of the three ISOPHOT cold clouds are ≈ 12 K, and 1.2 ± 0.7 × 1022 cm-2 respectively, as calculated from ISO/IRAS surface brightnesses. As Nagoya-4 m C18O (1-0) spectra show, these are dense molecular clouds with N(H) > 1021 cm-2 column density peaks. The ISOPHOT 200 μm surface brightness is well correlated with the C18O line intensity (con. coef. ≈ 70%). The large dust particle emissivity is found to be increased in the prototypical very dense core TMC-1 CP. As the low linewidths (Δu = 0.8 ± 0.2 km s-1) indicate, the level of turbulent energy density is 50% lower in these three clouds than in other clouds of HCL2. Dense cores were identified inside the C18O clouds by NH3 measurements with the Effelsberg-100 m telescope and Nobeyama-45 m H13CO+ data. The density of the dense cores is n ≥ 1.1 × 105 cm -3, and their kinetic temperatures are ≲10 K, in good agreement with the FIR results. The total molecular gas mass in the gravitationally bound cloud cores of TMC-1 CP and HCL2-E is about 21 M and 8 M respectively. The cores, TMC-1 CPb and HCL2-Eab are associated with 3 low mass YSO candidate 2MASS point sources, while 35 other low mass YSO candidates are seen elsewhere in TMR south, which we consider as evidence for ongoing low mass star formation.

Original languageEnglish
Pages (from-to)533-546
Number of pages14
JournalAstronomy and Astrophysics
Volume420
Issue number2
DOIs
Publication statusPublished - Jun 2004

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rings
brightness
cold
Infrared Astronomy Satellite
molecular gases
emissivity
molecular clouds
point sources
point source
star formation
ridges
flux density
dust
temperature
telescopes
color
kinetics
gas
energy

Keywords

  • Dust, extinction
  • ISM: clouds
  • ISM: individual objects: Taurus clouds
  • ISM: molecules
  • ISM: structure
  • Stars: formation

ASJC Scopus subject areas

  • Space and Planetary Science

Cite this

Very cold cores in the Taurus molecular ring as seen by ISO. / Tóth, L.; Haas, M.; Lemke, D.; Mattila, K.; Onishi, T.

In: Astronomy and Astrophysics, Vol. 420, No. 2, 06.2004, p. 533-546.

Research output: Contribution to journalArticle

Tóth, L. ; Haas, M. ; Lemke, D. ; Mattila, K. ; Onishi, T. / Very cold cores in the Taurus molecular ring as seen by ISO. In: Astronomy and Astrophysics. 2004 ; Vol. 420, No. 2. pp. 533-546.
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abstract = "Three prominent cold objects of the Taurus Molecular Ring (TMR) were revealed by our ISOPHOT 200 μm map of the south-eastern part of the Heiles Cloud 2 (HCL 2) cloud complex. One corresponds to the cyanopolyyne peak region of the TMC-1 ridge, (TMC-1 CP), one is the HCL2-E cloud, and one which we call HCL2-ES lies south of TMC-1. The 200/100 μm colour temperatures and column densities of the three ISOPHOT cold clouds are ≈ 12 K, and 1.2 ± 0.7 × 1022 cm-2 respectively, as calculated from ISO/IRAS surface brightnesses. As Nagoya-4 m C18O (1-0) spectra show, these are dense molecular clouds with N(H) > 1021 cm-2 column density peaks. The ISOPHOT 200 μm surface brightness is well correlated with the C18O line intensity (con. coef. ≈ 70{\%}). The large dust particle emissivity is found to be increased in the prototypical very dense core TMC-1 CP. As the low linewidths (Δu = 0.8 ± 0.2 km s-1) indicate, the level of turbulent energy density is 50{\%} lower in these three clouds than in other clouds of HCL2. Dense cores were identified inside the C18O clouds by NH3 measurements with the Effelsberg-100 m telescope and Nobeyama-45 m H13CO+ data. The density of the dense cores is n ≥ 1.1 × 105 cm -3, and their kinetic temperatures are ≲10 K, in good agreement with the FIR results. The total molecular gas mass in the gravitationally bound cloud cores of TMC-1 CP and HCL2-E is about 21 M⊙ and 8 M ⊙ respectively. The cores, TMC-1 CPb and HCL2-Eab are associated with 3 low mass YSO candidate 2MASS point sources, while 35 other low mass YSO candidates are seen elsewhere in TMR south, which we consider as evidence for ongoing low mass star formation.",
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AU - Onishi, T.

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AB - Three prominent cold objects of the Taurus Molecular Ring (TMR) were revealed by our ISOPHOT 200 μm map of the south-eastern part of the Heiles Cloud 2 (HCL 2) cloud complex. One corresponds to the cyanopolyyne peak region of the TMC-1 ridge, (TMC-1 CP), one is the HCL2-E cloud, and one which we call HCL2-ES lies south of TMC-1. The 200/100 μm colour temperatures and column densities of the three ISOPHOT cold clouds are ≈ 12 K, and 1.2 ± 0.7 × 1022 cm-2 respectively, as calculated from ISO/IRAS surface brightnesses. As Nagoya-4 m C18O (1-0) spectra show, these are dense molecular clouds with N(H) > 1021 cm-2 column density peaks. The ISOPHOT 200 μm surface brightness is well correlated with the C18O line intensity (con. coef. ≈ 70%). The large dust particle emissivity is found to be increased in the prototypical very dense core TMC-1 CP. As the low linewidths (Δu = 0.8 ± 0.2 km s-1) indicate, the level of turbulent energy density is 50% lower in these three clouds than in other clouds of HCL2. Dense cores were identified inside the C18O clouds by NH3 measurements with the Effelsberg-100 m telescope and Nobeyama-45 m H13CO+ data. The density of the dense cores is n ≥ 1.1 × 105 cm -3, and their kinetic temperatures are ≲10 K, in good agreement with the FIR results. The total molecular gas mass in the gravitationally bound cloud cores of TMC-1 CP and HCL2-E is about 21 M⊙ and 8 M ⊙ respectively. The cores, TMC-1 CPb and HCL2-Eab are associated with 3 low mass YSO candidate 2MASS point sources, while 35 other low mass YSO candidates are seen elsewhere in TMR south, which we consider as evidence for ongoing low mass star formation.

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KW - ISM: structure

KW - Stars: formation

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