A molecular-line study of the interstellar bullet engine IRAS 05506+2414

We present interferometric and single-dish molecular line observations of the interstellar bullet-outflow source IRAS 05506+2414, whose wide-angle bullet spray is similar to the Orion BN/KL explosive outflow and likely arises from an entirely different mechanism than the classical accretion-disk-driven bipolar flows in young stellar objects. The bullet-outflow source is associated with a large pseudo-disk and three molecular outflows -- a high-velocity outflow (HVO), a medium-velocity outflow (MVO), and a slow, extended outflow (SEO). The size (mass) of the pseudo-disk is 10,350 AU x 6,400 AU (0.64-0.17 Msun); from a model-fit assuming infall and rotation we derive a central stellar mass of 8--19 Msun. The HVO (MVO) has an angular size ~5180 (~3330) AU, and a projected outflow velocity of ~140 km/s (~30 km/s). The SEO size (outflow speed) is ~0.9 pc (~6 km/s). The HVO's axis is aligned with (orthogonal to) that of the SEO (pseudo-disk). The velocity structure of the MVO is unresolved. The scalar momenta in the HVO and SEO are very similar, suggesting that the SEO has resulted from the HVO interacting with ambient cloud material. The bullet spray shares a common axis with the pseudo-disk, and has an age comparable to that of MVO (few hundred years), suggesting that these three structures are intimately linked together. We discuss several models for the outflows in IRAS 05506+2414 (including dynamical decay of a stellar cluster, chance encounter of a runaway star with a dense cloud, and close passage of two protostars), and conclude that 2nd-epoch imaging to derive proper motions of the bullets and nearby stars can help to discriminate between them.Comment: accepted for ApJ 10/05/17 (29 pages, 17 figures, 5 tables

Vanadium(V) oxo and imido calix[8]arene complexes: synthesis, structural studies, and ethylene homo/copolymerisation capability

Interaction of p-tert-butylcalix[8]areneH₈ (L⁸H₈) with in-situ generated [NaVO(Ot-Bu)₄] (from VOCl₃ and four equivalents of NaOtBu) afforded the dark brown complex [Na(NCMe)₅][(VO)₂L⁸H]·4MeCN (1·4MeCN), in which the calix[8]arene adopts a saddle-shaped conformation. Increasing (to four equivalents per L⁸) the amount of [NaVO(Ot-Bu)₄] present in the reaction, led to the formation of the yellow octa-vanadyl complex {[(Na(VO)₄L⁸)(Na(NCMe))₃] [Na(NCMe)₆}₂·10MeCN (2·10MeCN), in which the calix[8]arene adopts a pleated loop conformation. In the presence of adventitious oxygen, reaction of four equivalents of [VO(Ot-Bu)₃] (generated from VOCl₃ and 3KOtBu) with L⁸H₈ afforded the alkali-metal free green complex [(VO)₄L⁸(μ³-O)₂] (3); the solvates 3·3MeCN and 3·3CH₂Cl₂ have been isolated. In both solvates, the L⁸ ligand adopts a shallow saddle-shaped conformation, supporting a core comprising of a (VO)₄O₄ ladder. In the case of lithium, in order to obtain crystalline material, it was found necessary to reverse the order of addition such that lithium tert-butoxide was added to L⁸H₈, and then subsequently treated (at –78 ⁰C) with two equivalents of VOCl₃; crystallization from tetrahydrofuran (THF) afforded {(VO₂)₂Li₆[L⁸](thf)₂(OtBu)₂(Et₂O)₂}·Et₂O (4·Et₂O). In the structure of 4·Et₂O, vanadium, lithium and oxygen form a central lattern-type cage, which is capped top and bottom by an Li₂O₂2 diamond; the calix[8]arene is in a ‘down, down, out, out, down, down’ conformation. When the ‘same reaction’ was extracted into acetonitrile (MeCN), the salt complex [Li(NCMe)₄][(VO)₂L⁸H]·8MeCN (5.8MeCN) was formed. In 5·8MeCN, the [Li(NCMe)₄] cations reside between the anions in the clefts of L⁸H, the latter adopting a saddle-shaped conformation. Use of the imido precursors [V(Nt-Bu)(Ot-Bu)₃] and [V(Np-tolyl)(Ot-Bu)₃] and L⁸H₈, afforded, via an imido exchange, the salt [t-BuNH₃]{[V(p-tolylN)]₂L⁸H}·3½MeCN (6·3½MeCN). The molecular structures of 1 to 6 are reported; data collections for complexes 2·10MeCN, 3·3MeCN and 3·3CH₂Cl₂ required the use of synchrotron radiation. Complexes 1, 3 and 4 have been screened as pre-catalysts for the polymerization of ethylene in the presence of a variety of co-catalysts (with and without a re-activator) at various temperatures and for the co-polymerization of ethylene with propylene; results are compared versus the benchmark catalyst VO(OEt)Cl₂. In some cases, activities as high as 136,000 g/mmol.v.h were achievable, whilst it also proved possible to obtain higher molecular weight polymers (in comparible yields) versus the use of VO(OEt)Cl₂. In the case of the co-polymerization, the incorporation of propylene was 7.1 – 10.9 mol% (cf 10 mol% for VO(OEt)Cl₂), though catalytic activities were lower versus VO(OEt)Cl₂

They Were Meant for Each Other: Professor Edward Cooper and the Rules Enabling Act

This introduction to the essays in this Symposium illuminates Professor Ed Cooper\u27s years as Reporter to the Civil Rules Committee by first briefly describing those who preceded him in the position and his own background. We then describe some of Ed Cooper\u27s many contributions to the Civil Rules Committee, the Federal Rules, rulemaking, and civil procedure by examining the present state of the Rules Committees\u27 work under the Rules Enabling Act. We conclude that after almost eighty years of experience under that Act, it is working well in large part because of the sound leadership provided by Ed Cooper over his twenty years as Reporter. It was during these years that the Committee developed an approach to rulemaking that was at once transparent and empirical, with multiple opportunities for participation by members of the public, the bench, the academy, and the bar; with many informal opportunities for consultation with members of Congress and the Executive Branch; and with an understanding by the Committee of its role in relation to the courts, Congress, and the Executive. Two episodes of recent rulemaking and related activity are described as examples of how well the Rules Enabling Act is working, in large part because of the very flexibility and discretion the Act has provided since 1934. One of those episodes occurred when Judge Anthony Scirica chaired the Standing Committee and then- Judge David Levi chaired the Civil Rules Committee. The other occurred when Judge Lee Rosenthal and Judge Mark Kravitz were the chairs of the Standing and Civil Rules Committees, respectively. Both episodes provide a basis for optimism about the future. And they make clear Ed Cooper\u27s continued steady role in supporting and cultivating the robust good health of the rulemaking process and the institutional values it protects