Toward Understanding the Origin of Turbulence in Molecular Clouds: Small Scale Structures as Units of Dynamical Multi-Phase Interstellar Medium

In order to investigate the origin of the interstellar turbulence, detailed observations in the CO J=1--0 and 3--2 lines have been carried out in an interacting region of a molecular cloud with an HII region. As a result, several 1,000 to 10,000 AU scale cloudlets with small velocity dispersion are detected, whose systemic velocities have a relatively large scatter of a few km/s. It is suggested that the cloud is composed of small-scale dense and cold structures and their overlapping effect makes it appear to be a turbulent entity as a whole. This picture strongly supports the two-phase model of turbulent medium driven by thermal instability proposed previously. On the surface of the present cloud, the turbulence is likely to be driven by thermal instability following ionization shock compression and UV irradiation. Those small scale structures with line width of ~ 0.6 km/s have a relatively high CO line ratio of J=3--2 to 1--0, 1 < R(3-2/1-0) < 2. The large velocity gradient analysis implies that the 0.6 km/s width component cloudlets have an average density of 10^{3-4} cm^{-3}, which is relatively high at cloud edges, but their masses are only < 0.05 M_{sun}.Comment: 12 pages, 9 figures. To be published in the Astrophysical Journa

Hom-versions of the Combinatorial Grothendieck Conjecture II: Outer Representations of PIPSC- and NN-type

In the present paper, we continue our study, which was initiated in the previous paper of the present series of papers, of combinatorial anabelian geometry of (not necessarily bijective) continuous homomorphisms between PSC-fundamental groups of semi-graphs of anabelioids of PSC-type. In particular, we continue to study certain Hom-versions of the combinatorial versions of the Grothendieck conjecture established in some previous works, i.e., to study certain sufficient conditions of certain group-theoretic compatibility properties described in terms of outer representations. The outer representations we mainly concern in the present paper are of PIPSC-type and of NN-type, both of which are of substantial importance in the study of algebro-geometric anabelian geometry of configuration spaces of hyperbolic curves. We also include, as a preparation for one of the main results, a presentation of a “reduction technique”, namely, a technique of reduction to the “compactified quotients” of (various open subgroups of) the PSC-fundamental groups under consideration, in a similar vein to the previous paper where we included other two “reduction techniques”

Hom-versions of the Combinatorial Grothendieck Conjecture I: Abelianizations and Graphically Full Actions

Semi-graphs of anabelioids of PSC-type and their PSC-fundamental groups (i.e., a combinatorial Galois-category-theoretic abstraction of pointed stable curves over algebraically closed fields of characteristic zero and their fundamental groups) are central objects in the study of combinatorial anabelian geometry. In the present series of papers, which consists of two successive works, we investigate combinatorial anabelian geometry of (not necessarily bijective) continuous homomorphisms between PSC-fundamental groups. This contrasts with previous researches, which focused only on continuous isomorphisms. More specifically, our main results of the present series of papers roughly state that, if a continuous homomorphism between PSC-fundamental groups is compatible with certain outer representations, then it satisfies a certain “group-theoretic compatibility property”, i.e., the property that each of the images via the continuous homomorphism of certain VCN-subgroups of the domain are included in certain VCNsubgroups of the codomain. Such results may be considered as Homversions of the combinatorial version of the Grothendieck conjecture established in some previous works. As in the case of previous works (i.e., the Isom-versions), the proof requires different techniques depending on the types of outer representations under consideration. In the present paper, we will treat the case where the outer representations under consideration are assumed to be “l-graphically full”, i.e., to satisfy a certain condition concerning “weights” considered with respect to the “l-adic cyclotomic character”, where l is a certain prime number. In addition, to prepare for this purpose, we include detailed expositions on “reduction techniques”, namely, techniques of reduction to the maximal pro-Σ quotients and to the abelianizations of (various open subgroups of) the PSC-fundamental groups under consideration, where Σ is a certain set of prime numbers. Though the discussions of these “reduction techniques” are all essentially wellknown to experts, we present the results in a highly unified／generalized fashion

Newly Collected Specimens of the Sleeper Eleotris acanthopoma (Teleostei: Eleotridae) from French Polynesia Indicate a Wide and Panmictic Distribution in the West and South Pacific.

v. ill. 23 cm.QuarterlyThe morphology of Eleotris acanthopoma collected from Moorea in French Polynesia is described. This is the first record of this species from French Polynesia, greatly expanding the known range, which was previously only considered to extend from southern Japan to New Caledonia. Nucleotide sequences of the mitochondrial ND5 gene of several Eleotris species and related genera indicate that E. acanthopoma from Moorea belongs to the same lineage as E. acanthopoma from Japan and the Philippines. Despite being separated by a distance of approximately 10,000 km, two of the specimens from Moorea and one from the Philippines had identical nucleotide sequences. Results of this study indicate that extensive dispersal occurs during the pelagic larval stage of this species

Search for Remnant Clouds Associated with the TW Hya Association

We report on a search for the parental molecular clouds of the TW Hya association (TWA), using CO emission and Na I absorption lines. TWA is the nearest young (~ 50 pc; ~ 10 Myr) stellar association, yet in spite of its youth, there are no detection of any associated natal molecular gas, as is the case for other typical young clusters. Using infrared maps as a guide, we conducted a CO cloud survey toward a region with a dust extinction of E(B-V) > 0.2 mag, or AV > 0.6 mag. CO emission is detected toward three IR dust clouds, and we reject one cloud from the TWA, as no interstellar Na absorption was detected from the nearby Hipparcos stars, implying that it is too distant to be related. The other two clouds exhibit only faint and small-scale CO emission. Interstellar Na I absorptions of Hipparcos targets, HIP 57809, HIP 64837, and HIP 64925 (at distances of 133, 81, and 101 pc, respectively) by these couds is also detected. We conclude that only a small fraction of the interstellar matter (ISM) toward the IR dust cloud is located at distance less than 100 pc, which may be all that is left of the remnant clouds of TWA; the remaining remnant cloud having dissipated in the last ~ 1 Myr. Such a short dissipation timescale may be due to an external perturbation or kinematic segregation that has a large stellar proper motion relative to the natal cloud.Comment: 7 pages, 5 figures. PASJ accepte