Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present high spatial resolution (CO)-C-12 (J = 1-0) images taken by the Nobeyama 45 m telescope toward a 48' x 48' area, including the L1641-N cluster. The effective spatial resolution of the maps is 21 '', corresponding to 0.04 pc at a distance of 400 pc. A recent 1.1 mm dust continuum map reveals that the dense gas is concentrated in several thin filaments. We find that a few dust filaments are located at the parts where (CO)-C-12 (J = 1-0) emission drops sharply. Furthermore, the filaments have two components with different velocities. The velocity difference between the two components is about 3 km s(-1), corresponding to a Mach number of 10, significantly larger than the local turbulent velocity in the cloud. These facts imply that the collision of the two components (hereafter, the cloud-cloud collision) possibly contributed to the formation of these filaments. Since the two components appear to overlap toward the filaments on the plane of the sky, the collision may have occurred almost along the line of sight. Star formation in the L1641-N cluster was probably triggered by such a collision. We also find several parsec-scale CO shells whose centers are close to either the L1641-N cluster or the V 380 Ori cluster. We propose that these shells were created by multiple winds and/or outflows from cluster young stellar objects, i.e., "protocluster winds." One exceptional dust filament located at the western cloud edge lies along a shell; it is presumably part of the expanding shell. Both the cloud-cloud collision and protocluster winds are likely to influence the cloud structure and kinematics in this region.

DOI： 10.1088/0004-637X/746/1/25

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present the results of CO (J = 3 - 2) and CO (J = 1 - 0) mapping observations toward the active cluster-forming clump, L1688, in the rho Ophiuchi molecular cloud. From the CO (J = 3 - 2) and CO (J = 1 - 0) data cubes, we identify five outflows, whose driving sources are VLA 1623, EL 32, LFAM 26, EL 29, and IRS 44. Among the identified outflows, the most luminous outflow is the one from the prototypical Class 0 source, VLA 1623. We also discover that the EL 32 outflow located in the Oph B2 region has very extended blueshifted and redshifted lobes with wide opening angles. This outflow is most massive and has the largest momentum among the identified outflows in the CO (J = 1 - 0) map. We estimate the total energy injection rate due to the molecular outflows identified by the present and previous studies to be about 0.2 L-circle dot, larger than or at least comparable to the turbulence dissipation rate [approximate to(0.03 - 0.1)L-circle dot]. Therefore, we conclude that the protostellar outflows are likely to play a significant role in replenishing the supersonic turbulence in this clump.

DOI： 10.1088/0004-637X/726/1/46

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Using the archive data of the H(13)CO(+) (J = 1-0) line emission taken with the Nobeyama 45 m radio telescope with a spatial resolution of similar to 0.01 pc, we have identified 68 dense cores in the central dense region of the rho Ophiuchi main cloud. The H13CO+ data also indicate that the fractional abundance of H(13)CO(+) relative to H(2) is roughly inversely proportional to the square root of the H2 column density with a mean of 1.72 x 10(-11). The mean radius, FWHM line width, and LTE mass of the identified cores are estimated to be 0.045 /- 0.011 pc, 0.49 +/- 0.14 km s(-1), and 3.4 +/- 3.6 M(circle dot), respectively. The majority of the identified cores have subsonic internal motions. The virial ratio, the ratio of the virial mass to the LTE mass, tends to decrease with increasing LTE mass and about 60% of the cores have virial ratios smaller than 2, indicating that these cores are not transient structures but self-gravitating. The detailed virial analysis suggests that the surface pressure often dominates over the self-gravity and thus plays a crucial role in regulating core formation and evolution. By comparing the rho Oph cores with those in the Orion A molecular cloud observed with the same telescope, we found that the statistical properties of the core physical quantities are similar between the two clouds if the effect of the different spatial resolutions is corrected. The line widths of the rho Oph cores appear to be nearly independent of the core radii over the range of 0.01-0.1 pc and deviate upward from the Heyer & Brunt relation. This may be evidence that turbulent motions are driven by protostellar outflows in the cluster environment.

DOI： 10.1088/0004-637X/714/1/680

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We consider the formation of molecules in primordial prestellar clumps and evaluate the line luminosities to assess detectability by next-generation observational facilities. If the initial H-2 fraction is sufficiently high, HD becomes an important coolant in the clumps. The luminosity from such HD cooling clumps is lower than that from H-2 cooling ones because of the lower temperature (< 100K). As for Li reactions, we include the three-body LiH formation approximately. The Li molecular fraction remains very low (< 10(-3)) throughout the evolution, owing to the high dissociative reaction rate of LiH + H -> Li + H-2. LiH does not become an important coolant in any density range. The luminous emission lines from the prestellar cores include H-2 rovibrational lines [1-0 Q(1), 1-0 O(3), 1-0 0(5)] and pure rotational lines [0-0 S(3), 0-0 S(4), 0-0 S(5)]. The next-generation facilities SPICA and JWST are able to detect H-2 emission in a large pre-galactic cloud that forms metal-free stars at a high rate of similar to 10(3) M-circle dot yr(-1) at a redshift of z < 10. We also derive an analytical expression for the luminosity that reproduces the numerical results.

DOI： 10.1093/pasj/57.6.951

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