News

Publication: High-resolution Observations of Pickup-ion-mediated Shocks to 60 au
April 21, 2025

This study provides a detailed analysis of 14 distant interplanetary shocks observed by the Solar Wind Around Pluto instrument on board New Horizons. These shocks were observed with a pickup ion data cadence of approximately 30 minutes, covering a heliocentric distance range of ∼52–60 au. All the shocks observed within this distance range are…

Publication: Correlations and Kappa Distributions: Numerical Experiment and Physical Understanding
April 2, 2025

Kappa distributions, their statistical framework, and their thermodynamic origin describe systems with correlations among their particle energies, residing in stationary states out of classical thermal equilibrium/space plasmas, from solar wind to the outer heliosphere, are such systems. We show how correlations from long-range interactions…

Publication: Comparing Methods for Calculating Solar Energetic Particle Intensities: Re-binning versus Spectral Binning
Feb. 19, 2025

Solar energetic particle (SEP) events have been observed for decades in the interplanetary medium by spacecraft measuring the intensity of energetic ions and electrons. These intensities provide valuable information about particle acceleration, the effects of bulk plasma dynamics on particle transport, and the anisotropy of particle…

AAMG Faculty Voice - David McComas Professor of Astrophysical Sciences
Feb. 11, 2025

Professor David McComas was recently invited to give a brief “voice of the faculty” talk to the close Princeton's Academic and Administrative Managers Group (AAMG) meeting on February 5th, titled "Space Physics at Princeton and the Interstellar Mapping and Acceleration Probe (IMAP) NASA Mission.

The AAMG is comprised of managerial…

Publication: Size Distribution of Small Grains in the Inner Zodiacal Cloud
Dec. 6, 2024

The Parker Solar Probe (PSP) spacecraft has transited the innermost regions of the zodiacal cloud and detects impacts to the spacecraft body via its electric field instrument. Multiple dust populations have been proposed to explain the PSP dust impact rates. PSP’s unique orbit allows us to identify a region where the impact rates are likely…

Publication: Theory of Thermodynamic Relativity
Oct. 9, 2024

This a novel and broadened theoretical framework of special relativity, which is unified for describing entropies and velocities, and consistent with both thermodynamics and kinematics. The new theory is not to be confused with some relativistic adaptation of thermodynamics; instead, it is a unification of the physical disciplines of…

Publication: Observations of Kappa Distributions in Solar Energetic Protons and Derived Thermodynamic Properties
Sept. 20, 2024

In this paper we model the high-energy tail of observed solar energetic proton energy distributions with a kappa distribution function. We employ a technique for deriving the thermodynamic parameters of solar energetic proton populations measured by the Parker Solar Probe (PSP) Integrated Science Investigation of the Sun (IS⊙IS) EPI-Hi high…

Publication: Kappa-tail Technique: Modeling and Application to SEPs
Sept. 11, 2024

We develop the kappa-tail fitting technique, which analyzes observations of power-law tails of distributions and energy flux spectra, and connects them to theoretical modeling of kappa distributions, to determine the thermodynamics of the examined space plasma. In particular, we (i) construct the associated mathematical formulation; (ii) prove…

Publication: Thermodynamics of Pickup Ions in the Heliosphere
Sept. 11, 2024

The paper shows the thermodynamic nature of the evolution of the pickup ion (PUI) distributions through their incorporation and subsequent expansion as the solar wind moves outward through the heliosphere. In particular, the PUI expansive cooling is connected to thermodynamic polytropic processes and the thermodynamic kappa parameter…

Professor McComas concludes service as vice president for PPPL as NASA mission nears launch
Aug. 30, 2024

David McComas, Princeton University’s vice president for the Princeton Plasma Physics Laboratory (PPPL), will conclude his PPPL leadership role to focus on the successful completion and launch of NASA’s Interstellar Mapping and Acceleration Probe (IMAP). McComas is the principal investigator for the IMAP mission, which is scheduled to launch…