3,240 research outputs found

    The Coldest Place in the Universe: Probing the Ultra-Cold Outflow and Dusty Disk in the Boomerang Nebula

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    Our Cycle 0 ALMA observations confirmed that the Boomerang Nebula is the coldest known object in the Universe, with a massive high-speed outflow that has cooled significantly below the cosmic background temperature. Our new CO 1-0 data reveal heretofore unseen distant regions of this ultra-cold outflow, out to 120,000\gtrsim120,000 AU. We find that in the ultra-cold outflow, the mass-loss rate (dM/dt) increases with radius, similar to its expansion velocity (VV) - taking VrV\propto r, we find dM/dtr0.92.2dM/dt \propto r^{0.9-2.2}. The mass in the ultra-cold outflow is 3.3\gtrsim3.3 Msun, and the Boomerang's main-sequence progenitor mass is 4\gtrsim4 Msun. Our high angular resolution (\sim0".3) CO J=3-2 map shows the inner bipolar nebula's precise, highly-collimated shape, and a dense central waist of size (FWHM) \sim1740 AU×275\times275 AU. The molecular gas and the dust as seen in scattered light via optical HST imaging show a detailed correspondence. The waist shows a compact core in thermal dust emission at 0.87-3.3 mm, which harbors (47)×104(4-7)\times10^{-4} Msun~of very large (\simmm-to-cm sized), cold (2030\sim20-30 K) grains. The central waist (assuming its outer regions to be expanding) and fast bipolar outflow have expansion ages of 1925\lesssim1925 yr and 1050\le1050 yr: the "jet-lag" (i.e., torus age minus the fast-outflow age) in the Boomerang supports models in which the primary star interacts directly with a binary companion. We argue that this interaction resulted in a common-envelope configuration while the Boomerang's primary was an RGB or early-AGB star, with the companion finally merging into the primary's core, and ejecting the primary's envelope that now forms the ultra-cold outflow.Comment: accepted ApJ, 12 Apr, 201

    High magnetic field superconducting properties of Nb3Sn films Final report

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    High magnetic field superconducting properties of niobium stannide films and shielding characterictics of stannide layer

    ALMA view of the circumstellar environment of the post-common-envelope-evolution binary system HD101584

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    We study the circumstellar evolution of the binary HD101584, consisting of a post-AGB star and a low-mass companion, which is most likely a post-common-envelope-evolution system. We used ALMA observations of the 12CO, 13CO, and C18O J=2-1 lines and the 1.3mm continuum to determine the morphology, kinematics, masses, and energetics of the circumstellar environment. The circumstellar medium has a bipolar hour-glass structure, seen almost pole-on, formed by an energetic jet, about 150 km/s. We conjecture that the circumstellar morphology is related to an event that took place about 500 year ago, possibly a capture event where the companion spiraled in towards the AGB star. However, the kinetic energy of the accelerated gas exceeds the released orbital energy, and, taking into account the expected energy transfer efficiency of the process, the observed phenomenon does not match current common-envelope scenarios. This suggests that another process must augment, or even dominate, the ejection process. A significant amount of material resides in an unresolved region, presumably in the equatorial plane of the binary system.Comment: A&A Letter, accepte

    Electromagnetic Polarizabilities and Charge Radii of the Nucleons in the Diquark-model

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    The diquark model is used to calculate the electromagnetic polarizabilities and charge radii of the nucleons for three different potentials. Making the scalar diquark lower in mass introduces a mixing angle θ\theta between the 56\left| 56\right\rangle and 70\left| 70\right\rangle states ,which allows an improvement in value of all 6 properties. Generalizing the Gamov-Teller matrix and the magnetic moment operator to the diquark model gives constraints on this mixing. We obtain for the Richardson potential θ=23.2,\theta =23.2^{\circ }, αp=7.90.9+1.0×104fm3,\overline{\alpha }_p=7.9_{-0.9}^{+1.0}\times 10^{-4}fm^3, αn=7.70.6+0.3×104fm3,\overline{\alpha }_n=7.7_{-0.6}^{+0.3}\times 10^{-4}fm^3, βp=5.40.4+1.6×104fm3,\overline{\beta }_p=5.4_{-0.4}^{+1.6}\times 10^{-4}fm^3, βn=6.70.7+1.3×104fm3,\overline{\beta }% _n=6.7_{-0.7}^{+1.3}\times 10^{-4}fm^3, r2p=0.370.03+0.02fm2,\left\langle r^2\right\rangle _p=0.37_{-0.03}^{+0.02}fm^2, r2n=0.070.02+0.03fm2.\left\langle r^2\right\rangle _n=-0.07_{-0.02}^{+0.03}fm^2. Additional pion cloud contributions could improve on all six results.Comment: 15 Pages, Latex, Figs on request, to be published Phys.Lett.B. Minor errors corrected and eqn 5,6,8,9 correcte

    Some Effects of 30 Years of Weir-Management on Coastal Marsh Aquatic Vegetation and Implications to Waterfowl Management

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    Aquatic vegetation was compared between weir-managed and unmanaged brackish marsh ponds at Marsh Island, Louisiana, parts of which have been weir-managed since 1958. Coverage by aquatic vegetation was greater in weir-managed ponds than in unmanaged ponds, but weir-management affected individual species differently. Eleocharis parvula was more common in unmanaged ponds than in managed ponds during the early 1960s but has not occurred in any ponds sampled since then. Ceratophyllum demersum and the dominant plants Myriophyllum spicatum and Ruppia maritima were more common in weir-managed ponds than in unmanaged ponds, although the magnitude of the difference varied greatly among sample dates. Because Myriophyllum spicatum and Ruppia maritima are important and preferred duck foods in Louisiana brackish marsh, it was concluded that weir-management improved habitat quality for migrant and resident ducks at Marsh Island. Weir-managed ponds contained more aquatic vegetation than unmanaged ponds in 1988, even though the crest of weirs had lost 15 cm of elevation relative to rising sea level and the accreting marsh surface. This suggests that aquatic vegetation can be increased with a greater degree of water exchange than previously believed, which is desired to reduce interference to juvenile fish and crustacean movement. Weir-managed and unmanaged ponds did not differ in pond depth, which suggests that weir-management did not affect sedimentation

    The Breathing Modes of the B=2B=2 Skyrmion and the Spin-Orbit Interaction

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    The coupling of the breathing and rotational modes of the skyrmion-skyrmion system leads to a nucleon-nucleon spin-orbit interaction of short range, as well as to spin-orbit potentials for the transitions NNN(1440)NNN \to N(1440)N, NNNN(1440)NN \to NN(1440) and NNN(1440)N(1440)NN \to N(1440)N(1440). The longest range behaviour of these spin-orbit potentials is calculated in closed form.Comment: Latex, figures not include

    The middle Pleistocene transition by frequency locking and slow ramping of internal period

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    The increase in glacial cycle length from approximately 4141 to on average 100100 thousand years around 11 million years ago, called the Middle Pleistocene Transition (MPT), lacks a conclusive explanation. We describe a dynamical mechanism which we call Ramping with Frequency Locking (RFL), that explains the transition by an interaction between the internal period of a self-sustained oscillator and forcing that contains periodic components. This mechanism naturally explains the abrupt increase in cycle length from approximately 4040 to 8080 thousand years observed in proxy data, unlike some previously proposed mechanisms for the MPT. A rapid increase in durations can be produced by a rapid change in an external parameter, but this assumes rather than explains the abruptness. In contrast, models relying on frequency locking can produce a rapid change in durations assuming only a slow change in an external parameter. We propose a scheme for detecting RFL in complex, computationally expensive models, and motivate the search for climate variables that can gradually increase the internal period of the glacial cycles.Comment: 14 pages, 12 figure

    Cardiovascular changes after administration of aerosolized salbutamol in horses: five cases

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    Prevention and treatment of intraoperative hypoxemia in horses is difficult and both efficacy and safety of therapeutic maneuvers have to be taken into account. Inhaled salbutamol has been suggested as treatment of hypoxia in horses during general anesthesia, due to safety and ease of the technique. The present report describes the occurrence of clinically relevant unwanted cardiovascular effects (i.e. tachycardia and blood pressure modifications) in 5 horses undergoing general anesthesia in dorsal recumbency after salbutamol inhalation. Balanced anesthesia based on inhalation of isoflurane in oxygen or oxygen and air and continuous rate infusion (CRI) of lidocaine, romifidine, or combination of lidocaine and guaifenesine and ketamine was provided. Supportive measures were necessary to restore normal cardiovascular function in all horses but no long-term adverse effects were noticed in any of the cases
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