Critical phenomena and renormalization-group theory

Astronomical data analysis software and systems

Non-perturbative renormalization flow in quantum field theory and statistical physics

The size of a planet is an observable property directly connected to the physics of its formation and evolution. We used precise radius measurements from the California-Kepler Survey to study the size distribution of 2025 Kepler planets in fine detail. We detect a factor of ≥2 deficit in the occurrence rate distribution at 1.5–2.0 R⊕. This gap splits the population of close-in (P < 100 days) small planets into two size regimes: R_p < 1.5 R⊕ and R_p = 2.0-3.0 R⊕, with few planets in between. Planets in these two regimes have nearly the same intrinsic frequency based on occurrence measurements that account for planet detection efficiencies. The paucity of planets between 1.5 and 2.0 R⊕ supports the emerging picture that close-in planets smaller than Neptune are composed of rocky cores measuring 1.5 R⊕ or smaller with varying amounts of low-density gas that determine their total sizes.

/pdf/the-california-kepler-survey-iii-a-gap-in-the-radius-4a0vsnybgl.pdf

The California-Kepler Survey. III. A Gap in the Radius Distribution of Small Planets*

The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona and upper transition region emission lines in the wavelength ranges 170 – 210 A and 250 – 290 A. The line centroid positions and profile widths will allow plasma velocities and turbulent or non-thermal line broadenings to be measured. We will derive local plasma temperatures and densities from the line intensities. The spectra will allow accurate determination of differential emission measure and element abundances within a variety of corona and transition region structures. These powerful spectroscopic diagnostics will allow identification and characterization of magnetic reconnection and wave propagation processes in the upper solar atmosphere. We will also directly study the detailed evolution and heating of coronal loops. The EIS instrument incorporates a unique two element, normal incidence design. The optics are coated with optimized multilayer coatings. We have selected highly efficient, backside-illuminated, thinned CCDs. These design features result in an instrument that has significantly greater effective area than previous orbiting EUV spectrographs with typical active region 2 – 5 s exposure times in the brightest lines. EIS can scan a field of 6×8.5 arc min with spatial and velocity scales of 1 arc sec and 25 km s−1 per pixel. The instrument design, its absolute calibration, and performance are described in detail in this paper. EIS will be used along with the Solar Optical Telescope (SOT) and the X-ray Telescope (XRT) for a wide range of studies of the solar atmosphere.

http://www.rxollc.com/windt/papers/2007_SolPhys_243_19.pdf

The EUV Imaging Spectrometer for Hinode

Coronal jets are transient, collimated eruptions that occur in regions of predominantly open magnetic field in the solar corona. Our understanding of these events has greatly evolved in recent years but several open questions, such as the contribution of coronal jets to the solar wind, remain. Here we present an overview of the observations and numerical modeling of coronal jets, followed by a brief description of "next-generation" simulations that include an advanced description of the energy transfer in the corona ("thermodynamic MHD"), large spherical computational domains, and the solar wind. These new models will allow us to address some of the open questions.

Modeling Jets in the Corona and Solar Wind

Prediction of the Solar Corona for the 2017 August 21 Total Solar Eclipse

aim of this paper is to brieﬂy summarize some of the outstanding gaps in the observations and modeling of stellar ﬂares, CMEs, and exoplanetary space weather, and to discuss how the theoretical and computational tools and methods that have been developed in heliophysics can play a critical role in meeting these challenges. The maturity of data-inspired and data-constrained modeling of the Sun-to-Earth space weather chain provides a natural starting point for the development of new, multidisciplinary research and applications to other stars and their exoplanetary systems. Here we present recommendations for future solar CME research to further advance stellar ﬂare and CME studies. These recommendations will require institutional and funding agency support for both fundamental research (e.g. theoretical consid-erations and idealized eruptive ﬂare / CME numerical modeling) and applied research (e.g. data inspired / constrained modeling and estimating exoplanetary space weather impacts). In short, we recommend continued and expanded support for: (1.) Theoretical and numerical studies of CME initiation and low coronal evolution, including conﬁnement of “failed” eruptions; (2.) Systematic analyses of Sun-as-a-star observations to develop and improve stellar CME detection techniques and alternatives; (3.) Improvements in data-inspired and data-constrained MHD modeling of solar CMEs and their application to stellar systems; and (4.) Encouraging comprehensive solar–stellar research collaborations and conferences through new interdisciplinary and multi-agency / division funding mechanisms.

Connecting Solar and Stellar Flares/CMEs: Expanding Heliophysics to Encompass Exoplanetary Space Weather

Writhing and rotation of erupting prominences and CMEs

We investigate the plasma flows resulting from the interaction between a mature active region (AR) and a surrounding equatorial coronal hole (CH) observed by Hinode’s EIS and XRT from 15 to 18 October 2007. For 3 days, EIS velocity maps showed upflows at the AR’s eastern and western edges that were consistently between 5 and 10 km s^-1, whereas downflows of up to 30 km s^-1 were seen in AR loops. However, on 18 October, velocity profiles of hotter coronal lines revealed intensification in upflow velocities of up to 18 km s^-1 at the AR’s western footpoints 4.5 hours prior to a CME. We compare the AR’s plasma flows with 2.5D MHD numerical simulations of the magnetic configuration, which show that expansion of the mature AR’s loops drives upflows along the neighboring CH field. Further, the intensification of upflows observed on the AR’s western side prior to a CME is interpreted to be the result of the expansion of a flux rope containing a filament further compressing the neighboring CH field.

Tibor Torok

Papers

Modeling Jets in the Corona and Solar Wind

Prediction of the Solar Corona for the 2017 August 21 Total Solar Eclipse

Connecting Solar and Stellar Flares/CMEs: Expanding Heliophysics to Encompass Exoplanetary Space Weather

Writhing and rotation of erupting prominences and CMEs

Intensification of Plasma Upflows in an Active Region-Coronal Hole Complex: A CME Precursor