Dense cores in the Seahorse infrared dark cloud: physical properties from modified blackbody fits to the far-infrared-submillimetre spectral energy distributions

Abstract

We used data from WISE, IRAS, and Herschel in conjuction with our previous observations with SABOCA and LABOCA, and constructed the far-IR to submillimetre spectral energy distributions (SEDs) of dense cores in the filamentary Seahorse infrared dark cloud (IRDC) G304.74+01.32. For the 12 analysed cores, which include two IR dark cores (no WISE counterpart), nine IR bright cores, and one HII region, the mean dust temperature of the cold (warm) component, the mass, luminosity, H${}_2$ number density, and surface density were derived to be $13.3\pm 1.4$ K ($47.0\pm 5.0$ K), $113\pm 29$ M${}_{\odot }$, $192\pm 94$ L${}_{\odot }$, $(4.3\pm 1.2)\times 10^5$ cm${}^{-3}$, and $0.77\pm 0.19$ g cm${}^{-3}$, respectively. The HII region IRAS 13039-6108a was found to be the most luminous source in our sample ($(1.1\pm 0.4)\times 10^3$ L${}_{\odot }$). All the cores were found to be gravitationally bound (i.e. the virial parameter ${\alpha }_{\mathrm{vir}}<2$). Seven out of 12 of the analysed cores (58%) were found to lie above the mass-radius thresholds of high-mass star formation proposed in the literature. The surface densities of $\Sigma >0.4$ g cm${}^{-3}$ derived for these seven cores also exceed the corresponding threshold for high-mass star formation. Five of the analysed cores (42%) show evidence of fragmentation into two components in the SABOCA 350 $\mu$m image. In addition to the HII region source IRAS 13039-6108a, some of the other cores in Seahorse also appear to be capable of giving birth to high-mass stars. The dense core population in the Seahorse IRDC has comparable average properties to the cores in the well-studied Snake IRDC G11.11-0.12. The Seahorse core fragmentation mechanisms appear to be heterogenous, including cases of both thermal and non-thermal Jeans instability. High-resolution follow-up studies are required to address the fragmented cores' genuine potential of forming high-mass stars.

16 pages (incl. two appendices), 9 figures, 6 tables, accepted for publication in A&A, abstract abridged for arXiv

References in corpus (15)

• Theory of Star Formation
• Dust Masses, PAH Abundances, and Starlight Intensities in the SINGS Galaxy Sample
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Star formation through gravitational collapse and competitive accretion
• The Large APEX Bolometer Camera LABOCA
• ATLASGAL --- towards a complete sample of massive star forming clumps
• The Spitzer c2d Survey of Nearby Dense Cores: I: First Direct Detection of the Embedded Source in IRAM 04191+1522
• Gravity, Magnetic Field, and Turbulence: Relative Importance and Impact on Fragmentation in the Infrared Dark Cloud G34.43+00.24
• G11.92-0.61-MM2: A Bonafide Massive Prestellar Core?
• Distance biases in the estimation of the physical properties of Hi-GAL compact sources-I. Clump properties and the identification of high-mass star forming candidates
• The accretion history of high-mass stars: An ArTéMiS pilot study of Infrared Dark Clouds
• Fragmentation and Kinematics of dense molecular cores in the filamentary infrared-dark cloud G011.11-0.12
• Probing the massive star forming environment - a multiwavelength investigation of the filamentary IRDC G333.73+0.37
• Infrared Dark Clouds and high-mass star formation activity in Galactic Molecular Clouds
• What did the seahorse swallow? APEX 170 GHz observations of the chemical conditions in the Seahorse infrared dark cloud

Cited by in corpus (1)

• ArTéMiS imaging of the filamentary infrared dark clouds G1.75-0.08 and G11.36+0.80: Dust-based physical properties of the clouds and their clumps