Hierarchical Fragmentation of the Orion Molecular Filaments

Autor(en)

Satoko Takahashi, Paul T. P. Ho, Paula S. Teixeira, Luis A. Zapata, Yu-Nung Su

Abstrakt

We present a high angular resolution map of the 850 μm continuum

emission of the Orion Molecular Cloud-3 (OMC 3) obtained with the

Submillimeter Array (SMA); the map is a mosaic of 85 pointings covering

an approximate area of 6.'5 × 2.'0 (0.88 × 0.27 pc). We

detect 12 spatially resolved continuum sources, each with an

H2 mass between 0.3-5.7 M ⊙ and a projected

source size between 1400-8200 AU. All the detected sources are on the

filamentary main ridge (n_{H_2}≥ 10^6 cm-3), and

analysis based on the Jeans theorem suggests that they are most likely

gravitationally unstable. Comparison of multi-wavelength data sets

indicates that of the continuum sources, 6/12 (50%) are associated with

molecular outflows, 8/12 (67%) are associated with infrared sources, and

3/12 (25%) are associated with ionized jets. The evolutionary status of

these sources ranges from prestellar cores to protostar phase,

confirming that OMC-3 is an active region with ongoing embedded star

formation. We detect quasi-periodical separations between the OMC-3

sources of ≈17''/0.035 pc. This spatial distribution is part of a

large hierarchical structure that also includes fragmentation scales of

giant molecular cloud (≈35 pc), large-scale clumps (≈1.3 pc), and

small-scale clumps (≈0.3 pc), suggesting that hierarchical

fragmentation operates within the Orion A molecular cloud. The

fragmentation spacings are roughly consistent with the thermal

fragmentation length in large-scale clumps, while for small-scale cores

it is smaller than the local fragmentation length. These smaller

spacings observed with the SMA can be explained by either a helical

magnetic field, cloud rotation, or/and global filament collapse.

Finally, possible evidence for sequential fragmentation is suggested in

the northern part of the OMC-3 filament.

Organisation(en)

Institut für Astrophysik

Externe Organisation(en)

Academia Sinica - Taiwan, Harvard-Smithsonian Center for Astrophysics, Universidad Nacional Autonoma de Mexico

Journal

The Astrophysical Journal: an international review of astronomy and astronomical physics

Band

763

Anzahl der Seiten

13

ISSN

0004-637X

DOI

https://doi.org/10.1088/0004-637X/763/1/57

Publikationsdatum

01-2013

Peer-reviewed

Ja

ÖFOS 2012

103004 Astrophysik, 103003 Astronomie

Schlagwörter

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/3388e814-b00b-41b3-a22b-9d7a36ea1000