Clerking for God’s Grandfather: Chauncey Belknap’s Year with Justice Oliver Wendell Holmes, Jr.

Most of what we know about law clerks comes from the clerks themselves, usually in the form of law review articles memorializing their Justices and their clerkships or in interviews with reporters and legal scholars. In a few instances, however, law clerks have contemporaneously memorialized their experiences in diaries. These materials provide a rare window into the insular world of the Court. While the recollections contained in the diaries are often infused with youthful hero worship for their employer—in contradistinction to Justice Oliver Wendell Holmes, Jr.’s claim that no man is a hero to his valet— they offer a real-time, unfiltered peek at the personalities who populated the bench and the issues with which the Court was grappling. Just such a snapshot in time is provided by the diary of Chauncey Belknap, a remarkable Harvard Law School graduate who clerked for Justice Holmes during October Term 1915. Through Belknap’s near-daily records of his clerkship, as well as his encounters with the glittering social set of pre-war Washington, we are permitted a singular and fascinating glimpse into the colorful experience of working for one of the Court’s most famous jurists

Migration then assembly: Formation of Neptune mass planets inside 1 AU

We demonstrate that the observed distribution of `Hot Neptune'/`Super-Earth' systems is well reproduced by a model in which planet assembly occurs in situ, with no significant migration post-assembly. This is achieved only if the amount of mass in rocky material is $\sim 50$--$100 M_{\oplus}$ interior to 1 AU. Such a reservoir of material implies that significant radial migration of solid material takes place, and that it occur before the stage of final planet assembly. The model not only reproduces the general distribution of mass versus period, but also the detailed statistics of multiple planet systems in the sample. We furthermore demonstrate that cores of this size are also likely to meet the criterion to gravitationally capture gas from the nebula, although accretion is rapidly limited by the opening of gaps in the gas disk. If the mass growth is limited by this tidal truncation, then the scenario sketched here naturally produces Neptune-mass objects with substantial components of both rock and gas, as is observed. The quantitative expectations of this scenario are that most planets in the `Hot Neptune/Super-Earth' class inhabit multiple-planet systems, with characteristic orbital spacings. The model also provides a natural division into gas-rich (Hot Neptune) and gas-poor (Super-Earth) classes at fixed period. The dividing mass ranges from $\sim 3 M_{\oplus}$ at 10 day orbital periods to $\sim 10 M_{\oplus}$ at 100 day orbital periods. For orbital periods $< 10$ days, the division is less clear because a gas atmosphere may be significantly eroded by stellar radiation.Comment: 41 pages in preprint style, 15 figures, final version accepted to Ap

Calibration of Equilibrium Tide Theory for Extrasolar Planet Systems II

We present a new empirical calibration of equilibrium tidal theory for extrasolar planet systems, extending a prior study by incorporating detailed physical models for the internal structure of planets and host stars. The resulting strength of the stellar tide produces a coupling that is strong enough to reorient the spins of some host stars without causing catastrophic orbital evolution, thereby potentially explaining the observed trend in alignment between stellar spin and planetary orbital angular momentum. By isolating the sample whose spins should not have been altered in this model, we also show evidence for two different processes that contribute to the population of planets with short orbital periods. We apply our results to estimate the remaining lifetimes for short period planets, examine the survival of planets around evolving stars, and determine the limits for circularisation of planets with highly eccentric orbits. Our analysis suggests that the survival of circularised planets is strongly affected by the amount of heat dissipated, which is often large enough to lead to runaway orbital inflation and Roche lobe overflow.Comment: submitted to ApJ, 58 pages in preprint style, 31 figure

Calibration of Equilibrium Tide Theory for Extrasolar Planet Systems

We provide an 'effective theory' of tidal dissipation in extrasolar planet systems by empirically calibrating a model for the equilibrium tide. The model is valid to high order in eccentricity and parameterised by two constants of bulk dissipation - one for dissipation in the planet and one for dissipation in the host star. We are able to consistently describe the distribution of extrasolar planetary systems in terms of period, eccentricity and mass (with a lower limit of a Saturn mass) with this simple model. Our model is consistent with the survival of short-period exoplanet systems, but not with the circularisation period of equal mass stellar binaries, suggesting that the latter systems experience a higher level of dissipation than exoplanet host stars. Our model is also not consistent with the explanation of inflated planetary radii as resulting from tidal dissipation. The paucity of short period planets around evolved A stars is explained as the result of enhanced tidal inspiral resulting from the increase in stellar radius with evolution.Comment: 47 pages, 19 figures in ApJ ms style; to appear in Ap

Networking - A Statistical Physics Perspective

Efficient networking has a substantial economic and societal impact in a broad range of areas including transportation systems, wired and wireless communications and a range of Internet applications. As transportation and communication networks become increasingly more complex, the ever increasing demand for congestion control, higher traffic capacity, quality of service, robustness and reduced energy consumption require new tools and methods to meet these conflicting requirements. The new methodology should serve for gaining better understanding of the properties of networking systems at the macroscopic level, as well as for the development of new principled optimization and management algorithms at the microscopic level. Methods of statistical physics seem best placed to provide new approaches as they have been developed specifically to deal with non-linear large scale systems. This paper aims at presenting an overview of tools and methods that have been developed within the statistical physics community and that can be readily applied to address the emerging problems in networking. These include diffusion processes, methods from disordered systems and polymer physics, probabilistic inference, which have direct relevance to network routing, file and frequency distribution, the exploration of network structures and vulnerability, and various other practical networking applications.Comment: (Review article) 71 pages, 14 figure

Status of Muon Collider Research and Development and Future Plans

The status of the research on muon colliders is discussed and plans are outlined for future theoretical and experimental studies. Besides continued work on the parameters of a 3-4 and 0.5 TeV center-of-mass (CoM) energy collider, many studies are now concentrating on a machine near 0.1 TeV (CoM) that could be a factory for the s-channel production of Higgs particles. We discuss the research on the various components in such muon colliders, starting from the proton accelerator needed to generate pions from a heavy-Z target and proceeding through the phase rotation and decay ($\pi \to \mu \nu_{\mu}$) channel, muon cooling, acceleration, storage in a collider ring and the collider detector. We also present theoretical and experimental R & D plans for the next several years that should lead to a better understanding of the design and feasibility issues for all of the components. This report is an update of the progress on the R & D since the Feasibility Study of Muon Colliders presented at the Snowmass'96 Workshop [R. B. Palmer, A. Sessler and A. Tollestrup, Proceedings of the 1996 DPF/DPB Summer Study on High-Energy Physics (Stanford Linear Accelerator Center, Menlo Park, CA, 1997)].Comment: 95 pages, 75 figures. Submitted to Physical Review Special Topics, Accelerators and Beam

The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey

This document is the Accepted Manuscript version of the following article: R. Paul Butler, et al, The LCES HIRES/Keck Precision Radial Velocity Exoplanet Survey, The Astronomical Journal, Vol 153 (5), 19 pp., published 13 April 2017. The Version of Record is available online at doi: https://doi.org/10.3847/1538-3881/aa66ca. Paper data available at: http://home.dtm.ciw.edu/ebps/data/. © 2017. The American Astronomical Society. All rights reserved.We describe a 20-year survey carried out by the Lick-Carnegie Exoplanet Survey Team (LCES), using precision radial velocities from HIRES on the Keck-I telescope to find and characterize extrasolar planetary systems orbiting nearby F, G, K, and M dwarf stars. We provide here 60,949 precision radial velocities for 1,624 stars contained in that survey. We tabulate a list of 357 significant periodic signals that are of constant period and phase, and not coincident in period and/or phase with stellar activity indices. These signals are thus strongly suggestive of barycentric reflex motion of the star induced by one or more candidate exoplanets in Keplerian motion about the host star. Of these signals, 225 have already been published as planet claims, 60 are classified as significant unpublished planet candidates that await photometric follow-up to rule out activity-related causes, and 54 are also unpublished, but are classified as "significant" signals that require confirmation by additional data before rising to classification as planet candidates. Of particular interest is our detection of a candidate planet with a minimum mass of 3.9 Earth masses and an orbital period of 9.9 days orbiting Lalande 21185, the fourth-closest main sequence star to the Sun. For each of our exoplanetary candidate signals, we provide the period and semi-amplitude of the Keplerian orbital fit, and a likelihood ratio estimate of its statistical significance. We also tabulate 18 Keplerian-like signals that we classify as likely arising from stellar activity.Peer reviewedFinal Accepted Versio

A nearby m star with three transiting super-earths discovered by k2

I. J. M. Crossfied, “A Nearby M Star with Three Transiting Super-Earths Discovered by K2”, The Astrophysical Journal, Vol 804(1), April 2015. © 2015. The American Astronomical Society.Small, cool planets represent the typical end-products of planetary formation. Studying the architectures of these systems, measuring planet masses and radii, and observing these planets' atmospheres during transit directly informs theories of planet assembly, migration, and evolution. Here we report the discovery of three small planets orbiting a bright (Ks = 8.6 mag) M0 dwarf using data collected as part of K2, the new ecliptic survey using the re-purposed Kepler spacecraft. Stellar spectroscopy and K2 photometry indicate that the system hosts three transiting planets with radii 1.5-2.1 , straddling the transition region between rocky and increasingly volatile-dominated compositions. With orbital periods of 10-45 days the planets receive just 1.5-10x the flux incident on Earth, making these some of the coolest small planets known orbiting a nearby star; planet d is located near the inner edge of the system's habitable zone. The bright, low-mass star makes this system an excellent laboratory to determine the planets' masses via Doppler spectroscopy and to constrain their atmospheric compositions via transit spectroscopy. This discovery demonstrates the ability of K2 and future space-based transit searches to find many fascinating objects of interest.Peer reviewe

Transits of Known Planets Orbiting a Naked-Eye Star

© 2020 The American Astronomical Society. All rights reserved.Some of the most scientifically valuable transiting planets are those that were already known from radial velocity (RV) surveys. This is primarily because their orbits are well characterized and they preferentially orbit bright stars that are the targets of RV surveys. The Transiting Exoplanet Survey Satellite (TESS) provides an opportunity to survey most of the known exoplanet systems in a systematic fashion to detect possible transits of their planets. HD 136352 (Nu2 Lupi) is a naked-eye (V = 5.78) G-type main-sequence star that was discovered to host three planets with orbital periods of 11.6, 27.6, and 108.1 days via RV monitoring with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph. We present the detection and characterization of transits for the two inner planets of the HD 136352 system, revealing radii of 1.482-0.056+0.058 R ⊕ and 2.608-0.077+0.078 R ⊕ for planets b and c, respectively. We combine new HARPS observations with RV data from the Keck/High Resolution Echelle Spectrometer and the Anglo-Australian Telescope, along with TESS photometry from Sector 12, to perform a complete analysis of the system parameters. The combined data analysis results in extracted bulk density values of ρb = 7.8-1.1+1.2 g cm-3 and ρc = 3.50-0.36+0.41 g cm-3 for planets b and c, respectively, thus placing them on either side of the radius valley. The combination of the multitransiting planet system, the bright host star, and the diversity of planetary interiors and atmospheres means this will likely become a cornerstone system for atmospheric and orbital characterization of small worlds.Peer reviewe