Slowly-growing gap-opening planets trigger weaker vortices

The presence of a giant planet in a low-viscosity disc can create a gap edge in the disc's radial density profile sharp enough to excite the Rossby Wave Instability. This instability may evolve into dust-trapping vortices that might explain the "banana-shaped" features in recently observed asymmetric transition discs with inner cavities. Previous hydrodynamical simulations of planet-induced vortices have neglected the timescale of hundreds to thousands of orbits to grow a massive planet to Jupiter-size. In this work, we study the effect of a giant planet's runaway growth timescale on the lifetime and characteristics of the resulting vortex. For two different planet masses (1 and 5 Jupiter masses) and two different disc viscosities ($\alpha$=3$\times 10^{-4}$ and 3$\times10^{-5}$), we compare the vortices induced by planets with several different growth timescales between 10 and 4000 planet orbits. In general, we find that slowly-growing planets create significantly weaker vortices with lifetimes and surface densities reduced by more than $50\%$. For the higher disc viscosity, the longest growth timescales in our study inhibit vortex formation altogether. Additionally, slowly-growing planets produce vortices that are up to twice as elongated, with azimuthal extents well above $180^{\circ}$ in some cases. These unique, elongated vortices likely create a distinct signature in the dust observations that differentiates them from the more concentrated vortices that correspond to planets with faster growth timescales. Lastly, we find that the low viscosities necessary for vortex formation likely prevent planets from growing quickly enough to trigger the instability in self-consistent models.Comment: 12 pages, 7 figures, Accepted by MNRA

Observational diagnostics of elongated planet-induced vortices with realistic planet formation timescales

Gap-opening planets can generate dust-trapping vortices that may explain some of the latest discoveries of high-contrast crescent-shaped dust asymmetries in transition discs. While planet-induced vortices were previously thought to have concentrated shapes, recent computational work has shown that these features naturally become much more elongated in the gas when simulations account for the relatively long timescale over which planets accrete their mass. In this work, we conduct two-fluid hydrodynamical simulations of vortices induced by slowly-growing Jupiter-mass planets in discs with very low viscosity ($\alpha = 3 \times 10^{-5}$). We simulate the dust dynamics for four particle sizes spanning 0.3 mm to 1 cm in order to produce synthetic ALMA images. In our simulations, we find that an elongated vortex still traps dust, but not directly at its center. With a flatter pressure bump and disruptions from the planet's overlapping spiral density waves, the dust instead circulates around the vortex. This motion (1) typically carries the peak off-center, (2) spreads the dust out over a wider azimuthal extent $\geq 180^{\circ}$, (3) skews the azimuthal profile towards the front of the vortex, and (4) can also create double peaks in newly-formed vortices. In particular, we expect that the most defining observational signature, a peak offset of more than $30^{\circ}$, should be detectable $>30\%$ of the time in observations with a beam diameter of at most the planet's separation from its star.Comment: Accepted to MNRAS. 13 pages, 8 figures. Movies available at: https://lavinia.as.arizona.edu/~mhammer/vortex_signatures.htm

Miniature modular microwave end-to-end receiver

An end-to-end microwave receiver system contained in a single miniature hybrid package mounted on a single heatsink is presented. It includes an input end connected to a microwave receiver antenna and an output end which produces a digital count proportional to the amplitude of a signal of a selected microwave frequency band received at the antenna and corresponding to one of the water vapor absorption lines near frequencies of 20 GHz or 30 GHz. The hybrid package is on the order of several centimeters in length and a few centimeters in height and width. The package includes an L-shaped carrier having a base surface, a vertical wall extending up from the base surface and forming a corner therewith, and connection pins extending through the vertical wall. Modular blocks rest on the base surface against the vertical wall and support microwave monolithic integrated circuits on top surfaces thereof connected to the external connection pins. The modular blocks lie end-to-end on the base surface so as to be modularly removable by sliding along the base surface beneath the external connection pins away from the vertical wall

Synthesis and C−C Coupling Reactivity of a Dinuclear Ni^I−Ni^I Complex Supported by a Terphenyl Diphosphine

Mono- and bimetallic complexes of nickel supported by a terphenyl diphosphine have been synthesized. The reported complexes show diverse metal−arene interactions in the solid state. Reactions of an o,o′-biphenyldiyl dinickel complex with CO and dichloroalkanes lead to fluorene derivatives, indicating the formation of carbon−carbon bonds at a bimetallic moiety

A Comparison of Mortality Patterns in Human Populations Residing Under Diverse Ecological Conditions: A Time Series Analysis

This is the published version. Copyright 1983 Wayne State University Press.During the last century, a number of epidemics have swept across the world causing similar mortality peaks in diverse human populations. In particular, the effects of the influenza epidemic of 1918 can be seen in urban and rural human aggregates separated by continents and thousands of miles. This paper examines mortality periodicity, due to diverse population structures, ecology, and exposure to similar pathogens, through the use of time series analyses. Specifically, raw yearly mortality figures for two Italian alpine communities, Acceglio and Bellino, are compared with those of a Mennonite congregation living in Kansas, United States, for the same time periods. Crosscorrelation, autocorrelation, and power spectrum analyses have been applied in order to identify possible mortality periodicity and to compare these cycles across populations. The mortality cycles occur at approximately 10 years in the Mennonite series, and 13 in Acceglio and Bellino. Explanations are proposed for these data and for the significant correlations exhibited by the three time series. The last century of human existence saw a number of major demographic changes on a world-wide basis resulting from a variety of technological breakthroughs and medical developments. For example, as a result of innovations in transportation, there has been a rapid breakdown of reproductive and geographical isolation of small human populations such as the Mennonites. Due in part to this geographical isolation, communities that were exposed to specific pathogens periodically experienced disease epidemics, and mortality patterns were unique to each population. The incidence and duration of these epidemics depended in part on the demographic structure of the population and the unique historical events that introduced the pathogen into the community. The purpose of this paper is to explore the mortality patterns of three human populations living under diverse ecological conditions with exposure to various pandemic diseases. In particular, we examine the periodicity of mortality patterns using power spectral, cross-correlation and autocorrelation analyses, and explore some variables which may contribute to this periodicity

Hybrid meson decay from the lattice

We discuss the allowed decays of a hybrid meson in the heavy quark limit. We deduce that an important decay will be into a heavy quark non-hybrid state and a light quark meson, in other words, the de-excitation of an excited gluonic string by emission of a light quark-antiquark pair. We discuss the study of hadronic decays from the lattice in the heavy quark limit and apply this approach to explore the transitions from a spin-exotic hybrid to $\chi_b \eta$ and $\chi_b S$ where $S$ is a scalar meson. We obtain a signal for the transition emitting a scalar meson and we discuss the phenomenological implications.Comment: 18 pages, LATEX, 3 ps figure

Is ambient noise tomography across ocean basins possible?

International audienceBased on year-long cross-correlations of broad-band seismic records obtained at sixty-six stations within or adjacent to the Pacific Basin, we show that broad-band ambient noise is observed to propagate coherently between island stations and between island and continent stations. For many station pairs, high signal-to-noise ratio (SNR) fundamental mode Rayleigh wave Green functions are observed, which establishes the physical basis for ambient noise tomography across the Pacific. Similar trends for continental and oceanic stations are observed in the relationship between the ambient noise level at a station and the ''noise coherence distance'' – the longest distance at which a high SNR cross-correlation signal is observed for a station. Because locally generated noise obscures long distance coherent noise, situating stations at quiet locations on islands is necessary for the success of ambient noise tomography. Local noise poses a particular challenge at atoll sites and, on the basis of analysis of data from station H2O, at ocean bottom sites at periods above $25 sec

VI-Band Follow-Up Observations of Ultra-Long-Period Cepheid Candidates in M31

The ultra-long period Cepheids (ULPCs) are classical Cepheids with pulsation periods exceeding $\approx 80$ days. The intrinsic brightness of ULPCs are ~1 to ~3 mag brighter than their shorter period counterparts. This makes them attractive in future distance scale work to derive distances beyond the limit set by the shorter period Cepheids. We have initiated a program to search for ULPCs in M31, using the single-band data taken from the Palomar Transient Factory, and identified eight possible candidates. In this work, we presented the VI-band follow-up observations of these eight candidates. Based on our VI-band light curves of these candidates and their locations in the color-magnitude diagram and the Period-Wesenheit diagram, we verify two candidates as being truly ULPCs. The six other candidates are most likely other kinds of long-period variables. With the two confirmed M31 ULPCs, we tested the applicability of ULPCs in distance scale work by deriving the distance modulus of M31. It was found to be $\mu_{M31,ULPC}=24.30\pm0.76$ mag. The large error in the derived distance modulus, together with the large intrinsic dispersion of the Period-Wesenheit (PW) relation and the small number of ULPCs in a given host galaxy, means that the question of the suitability of ULPCs as standard candles is still open. Further work is needed to enlarge the sample of calibrating ULPCs and reduce the intrinsic dispersion of the PW relation before re-considering ULPCs as suitable distance indicators.Comment: 13 pages, with 14 Figures and 4 Tables (one online table). AJ accepte