Wall emission in circumbinary disks: the case of CoKu Tau/4

A few years ago, the mid-IR spectrum of a Weak Line T Tauri Star, CoKu Tau/4, was explained as emission from the inner wall of a circumstellar disk, with the inner disk truncated at ~10 AU. Based on the SED shape and the assumption that it was produced by a single star and its disk, CoKu Tau/4 was classified as a prototypical transitional disk, with a clean inner hole possibly carved out by a planet, some other orbiting body, or by photodissociation. However, recently it has been discovered that CoKu Tau/4 is a close binary system. This implies that the observed mid-IR SED is probably produced by the circumbinary disk. The aim of the present paper is to model the SED of CoKu Tau/4 as arising from the inner wall of a circumbinary disk, with parameters constrained by what is known about the central stars and by a dynamical model for the interaction between these stars and their surrounding disk. In order to fit the Spitzer IRS SED, the binary orbit should be almost circular, implying a small mid-IR variability (10%) related to the variable distances of the stars to the inner wall of the circumbinary disk. Our models suggest that the inner wall of CoKu Tau/4 is located at 1.7a, where a is the semi-major axis of the binary system (a~8AU). A small amount of optically thin dust in the hole (<0.01 lunar masses) helps to improve the fit to the 10microns silicate band. Also, we find that water ice should be absent or have a very small abundance (a dust to gas mass ratio 0, the model predicts mid-IR variability with periods similar to orbital timescales, assuming that thermal equilibrium is reached instantaneously.Comment: 42 pages, 15 Postscript figure

Negative mass corrections in a dissipative stochastic environment

We study the dynamics of a macroscopic object interacting with a dissipative stochastic environment using an adiabatic perturbation theory. The perturbation theory reproduces known expressions for the friction coefficient and, surprisingly, gives an additional negative mass correction. The effect of the negative mass correction is illustrated by studying a harmonic oscillator interacting with a dissipative stochastic environment. While it is well known that the friction coefficient causes a reduction of the oscillation frequency, we show that the negative mass correction can lead to its enhancement. By studying an exactly solvable model of a magnet coupled to a spin environment evolving under standard non-conserving dynamics we show that the effect is present even beyond the validity of the adiabatic perturbation theory.We are grateful to M Kolodrubetz for the careful reading of the manuscript and helpful comments. This work was partially supported by BSF 2010318 (YK and AP), NSF DMR-1506340 (LD and AP), AFOSR FA9550-10-1-0110 (LD and AP), ARO W911NF1410540 (LD and AP) and ISF grant (YK). LD acknowledges the office of Naval Research. YK is grateful to the BU visitors program. (2010318 - BSF; DMR-1506340 - NSF; FA9550-10-1-0110 - AFOSR; W911NF1410540 - ARO; ISF grant)Accepted manuscrip

"Household Wealth Distribution in Italy in the 1990s"

This paper describes the composition and distribution of household wealth in Italy. First, the evolution of household portfolios over the last 40 years is described on the basis of newly reconstructed aggregate balance sheets. Second, the characteristics and quality of the main statistical source on wealth distribution, the Bank of Italy’s Survey of Household Income and Wealth, are examined together with the statistical procedures used to adjust for nonresponse, nonreporting and underreporting. The distribution of household net worth is then studied using both adjusted and unadjusted data. Wealth inequality is found to have risen steadily during the 1990s. The increased concentration of financial wealth was an important factor in determining this path.

Millimeter Dust Emission in the GQ Lup System

We present Submillimeter Array observations of the GQ Lup system at 1.3 millimeters wavelength with 0\farcs4 ($\sim$60 AU) resolution. Emission is detected from the position of the primary star, GQ Lup A, and is marginally resolved. No emission is detected from the substellar companion, GQ Lup B, 0\farcs7 away. These data, together with models of the spectral energy distribution, suggest a compact disk around GQ Lup A with mass $\sim 3$ M$_{Jup}$, perhaps truncated by tidal forces. There is no evidence for a gap or hole in the disk that might be the signature of an additional inner companion body capable of scattering GQ Lup B out to $\sim100$ AU separation from GQ Lup A. For GQ Lup B to have formed {\it in situ}, the disk would have to have been much more massive and extended.Comment: 16 pages, 2 figures, accepted to A

Research in Dynamical Astronomy and the Quest for Planet Nine

The field of dynamical systems theory, greatly advanced by Henri Poincar´e in the late 19th century, has made invaluable contributions to celestial mechanics, helping to describe motion in the solar system and beyond. Poincar´e famously employed the techniques of dynamical systems to address the Three-Body Problem. In recent years, a myriad of research has addressed the possibility of the existence of a new planet (“Planet Nine”) beyond Neptune, based on evidence from the unique structure of various objects observed in the Kuiper Belt. Initial research out of the California Institute of Technology has engendered significant controversy over concerns of selection bias and lack of evidence, despite claims of a high level of certainty in their results. We created simulations in Wolfram’s Mathematica and Universe Sandbox to visualize and further study perturbations caused by Planet Nine on numerous objects in the Kuiper Belt. A Lagrange contour plot was produced in Python to observe Planet Nine’s possible effect on the solar system. From this research, the existence of Planet Nine cannot be positively established, but a better understanding of the dynamics of a system including Planet Nine can be achieved through the use of simulations and dynamical studies

Thermally isolated Luttinger liquids with noisy Hamiltonians

We study the dynamics of a quantum-coherent thermally isolated Luttinger liquid with noisy Luttinger parameter. To characterize the fluctuations of the absorbed energy in generic noise-driven systems, we first identify two types of energy moments, which can help tease apart the effects of classical (sample-to-sample) and quantum sources of fluctuations. One type of moment captures the total fluctuations due to both sources, while the other one captures the effect of the classical source only. We then demonstrate that in the Luttinger liquid case, the two types of moments agree in the thermodynamic limit, indicating that the classical source dominates. In contrast to equilibrium thermodynamics, in this driven system the relative fluctuations of energy do not decay with the system size. Additionally, we study the deviations of equal-time correlation functions from their ground-state value, and find a simple scaling behavior.Comment: 11 pages, 2 figure

Zločin i mentalni poremećaj na suprotnim obalama Jadrana: moralno ludilo (moral insanity) u talijanskim i hrvatskim psihijatrijskim diskursima

In the 19th century, fervid debates arose in the young psychiatric science about how to deal with and to scientifically categorize human behaviour which was perceived as dangerous to society, and as criminal. There were two concepts that stood out in these transnationally held discussions; namely moral insanity and later on, psychopathy. Following recent approaches in the cultural and social history of psychiatry, we understand moral insanity and psychopathy as social constructs, which are determined by the evolution in psychiatric knowledge, and also by laws, codes and social norms of particular historical timeframes. Our task is to discuss the evolution and adoption of these concepts in two linguistically different, but still historically profoundly entangled regions, namely in Italian and Croatian psychiatric discourses at the turn from the 19th to the 20th century. Our analysis of two of the most important medical and psychiatric journals of the time shows that psychiatric debates on antisocial and criminal behaviour were in numerous ways entangled and shaped by the way the two societies scientifically, legally, and institutionally struggled over the question of how to detect and control the mentally incapacitated criminal offender.Unutar devetnaestostoljetne, novoosnovane psihijatrijske znanosti nastaju gorljive rasprave o tome kako se skrbiti i znanstveno kategorizirati ljudsko ponašanje koje se percipiralo kao opasno za društvo i/ili kao kriminalno. Dva su se koncepta isticala u tim međunacionalnim raspravama: moralna ludost i, u kasnijem razdoblju, psihopatija. U skladu sa suvremenim pristupima u kulturnoj i društvenoj povijesti psihijatrije, moralno ludilo i psihopatiju tumačimo kao društvene konstrukte onoga vremena određene razvojem psihijatrijskog znanja, ali i zakonima, propisima i društvenim normama toga povijesnog okvira. Osnovni je zadatak ovoga rada analiza evolucije i usvajanja navedenih pojmova u dva jezično različita, ali još uvijek povijesno duboko isprepletena prostora: talijanski i hrvatski psihijatrijski diskurs na prijelazu iz 19. u 20. stoljeće. Naša analiza dvaju najvažnijih medicinskih i psihijatrijskih časopisa toga vremena pokazuje da su psihijatrijske rasprave o antisocijalnom i kriminalnom ponašanju na različite načine bile oblikovane prema tome kako su se dva društva znanstveno, pravno i institucionalno odnosila prema pitanju otkrivanja i kontroliranja mentalno onesposobljenih počinitelja

The Solar Nebula on Fire: A Solution to the Carbon Deficit in the Inner Solar System

Despite a surface dominated by carbon-based life, the bulk composition of the Earth is dramatically carbon poor when compared to the material available at formation. Bulk carbon deficiency extends into the asteroid belt representing a fossil record of the conditions under which planets are born. The initial steps of planet formation involve the growth of primitive sub-micron silicate and carbon grains in the Solar Nebula. We present a solution wherein primordial carbon grains are preferentially destroyed by oxygen atoms ignited by heating due to stellar accretion at radii < 5 AU. This solution can account for the bulk carbon deficiency in the Earth and meteorites, the compositional gradient within the asteroid belt, and for growing evidence for similar carbon deficiency in rocks surrounding other stars.Comment: To appear in ApJ Letter

Accretion Disks Around Young Objects. III. Grain Growth

We present detailed models of irradiated T Tauri disks including dust grain growth with power-law size distributions. The models assume complete mixing between dust and gas and solve for the vertical disk structure self-consistentlyincluding the heating effects of stellar irradiation as well as local viscous heating. For a given total dust mass, grain growth is found to decrease the vertical height of the surface where the optical depth to the stellar radiation becomes unit and thus the local irradiation heating, while increasing the disk emission at mm and sub-mm wavelengths. The resulting disk models are less geometrically thick than our previous models assuming interstellar medium dust, and agree better with observed spectral energy distributions and images of edge-on disks, like HK Tau/c and HH 30. The implications of models with grain growth for determining disk masses from long-wavelength emission are considered.Comment: 29 pages, including 11 figures and 1 table, APJ accepte