A5011292867- Astro and Planetary Science
- Stellar, planetary, and galactic studies
- Space Science and Extraterrestrial Life
- Solar and Space Plasma Dynamics
- Planetary Science and Exploration
- Magnetic confinement fusion research
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Origins and Evolution of Life
- Astronomy and Astrophysical Research
- Earth Systems and Cosmic Evolution
- Paleontology and Stratigraphy of Fossils
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- Fluid Dynamics and Turbulent Flows
- Marine and coastal ecosystems
- Quantum, superfluid, helium dynamics
- Isotope Analysis in Ecology
- Space exploration and regulation
- Spaceflight effects on biology
- Statistical Mechanics and Entropy
- Scientific Research and Discoveries
- Photoreceptor and optogenetics research
- Space Exploration and Technology
- Spacecraft Dynamics and Control
Florida Institute of Technology
2019-2025
The University of Texas at Austin
2013-2024
Harvard University
2016-2021
Center for Astrophysics Harvard & Smithsonian
2016-2019
Harvard University Press
2019
Princeton Plasma Physics Laboratory
2016-2017
Princeton University
2015-2017
Heliophysics
2016
Fusion Academy
2014-2016
Fusion (United States)
2014-2016
Significance The search for exoplanets has rapidly emerged as one of the most important endeavors in astronomy. This field received a major impetus with recent discovery seven temperate Earth-sized orbiting nearby ultracool dwarf star TRAPPIST-1. One crucial requirements conventional (surface-based) planetary habitability is presence an atmosphere over long timescales. We determine atmospheric escape rates numerically and analytically planets TRAPPIST-1 system show that outer are potentially...
Abstract We address the important question of whether newly discovered exoplanet, Proxima Centauri b (PCb), is capable retaining an atmosphere over long periods time. This done by adapting a sophisticated multi-species MHD model originally developed for Venus and Mars computing ion escape losses from PCb. The results suggest that rates are about two orders magnitude higher than terrestrial planets our Solar system if PCb unmagnetized. In contrast, planet does have intrinsic dipole magnetic...
A general theory of the onset and development plasmoid instability is formulated by means a principle least time. The scaling relations for final aspect ratio, transition time to rapid onset, growth rate, number plasmoids are derived shown depend on initial perturbation amplitude (ŵ0), characteristic rate current sheet evolution (1/τ), Lundquist (S). They not simple power laws, proportional Sατβ[ln f(S,τ,ŵ0)]σ. detailed dynamics also elucidated, comprise period quiescence followed sudden...
Waste heat production represents an inevitable consequence of energy conversion as per the laws thermodynamics. Based on this fact, by using simple theoretical models, we analyze constraints habitability Earth-like terrestrial planets hosting putative technological species and technospheres characterized persistent exponential growth consumption waste generation. In particular, quantify deleterious effects rising surface temperature biospheric processes eventual loss liquid water....
The plasmoid instability has revolutionized our understanding of magnetic reconnection in astrophysical environments. By preventing the formation highly elongated layers, it is crucial enabling rapid energy conversion rates that are characteristic many phenomena. Most previous studies have focused on Sweet-Parker current sheets, which, however, unattainable typical systems. Here, we derive a general set scaling laws for resistive and visco-resistive sheets evolve over time. Our method relies...
We present a three-species multi-fluid MHD model (H$^+$, H$_2$O$^+$ and e$^-$), endowed with the requisite atmospheric chemistry, that is capable of accurately quantifying magnitude water ion losses from exoplanets. apply this to world Earth-like parameters orbiting Sun-like star for three cases: (i) current normal solar wind conditions, (ii) ancient (iii) one extreme "Carrington-type" space weather event. demonstrate escape rate (ii), value 6.0$\times$10$^{26}$ s$^{-1}$, about an order...
In this Letter, we make use of sophisticated 3D numerical simulations to assess the extent atmospheric ion and photochemical losses from Mars over time. We demonstrate that escape rates were significantly higher (by more than two orders magnitude) in past at $\sim 4$ Ga compared present-day value owing stronger solar wind ultraviolet fluxes young Sun. found loss atomic hot oxygen dominates total current epoch whilst is likely much important ancient times. briefly discuss ensuing implications...
Abstract The intuition suggested by the Drake equation implies that technology should be less prevalent than biology in galaxy. However, it has been appreciated for decades SETI community technosignatures could more abundant, longer-lived, detectable, and ambiguous biosignatures. We collect arguments against technosignatures’ ubiquity discuss implications of some properties technological life fundamentally differ from nontechnological context modern astrobiology: It can spread among stars to...
Significance The search for extraterrestrial life is one of the most exciting frontiers in present-day astronomy. Recently, TRAPPIST-1 star was discovered to host seven rocky planets with masses and radii similar those Earth, which at least three them may be capable supporting life. Our paper addresses possibility that on these can spread others through transfer material. We conclude this process has a high probability being operational, implying planetary system possess multiple...
Recently, many Earth-sized planets have been discovered around stars other than the Sun that might possess appropriate conditions for life. The development of theoretical methods assessing putative habitability these worlds is paramount importance, since it serves dual purpose identifying and quantifying what types biosignatures may exist determining selection optimal target subsequent observations. This Colloquium discusses how a multitude physical factors act in tandem to regulate...
Abstract We examine the possibility that fast radio bursts (FRBs) originate from activity of extragalactic civilizations. Our analysis shows beams used for powering large light sails could yield parameters are consistent with FRBs. The characteristic diameter beam emitter is estimated through a combination energetic and engineering constraints, both approaches intriguingly similar result on scale rocky planet. Moreover, optimal frequency sail shown to be detected FRB frequencies. These...
Abstract We present an analytic model to estimate the total number of rocky or icy objects that could be captured by planetary systems within Milky Way Galaxy and result in panspermia should they harbor life. capture rate ejected from over entire phase space as well time. Our final expression for depends upon velocity dispersion characteristic biological survival time size object. further take into account stars interstellar object traverses, scale height length Way’s disk. The likelihood...
We explore some of the ramifications arising from superflares on evolutionary history Earth, other planets in Solar system, and exoplanets. propose that most powerful can serve as plausible drivers extinction events, their periodicity could correspond to certain patterns terrestrial fossil diversity record. On hand, weaker may play a positive role enabling origin life through formation key organic compounds. Superflares also prove be quite detrimental evolution complex present-day Mars...
We consider the non-dissipative multi-fluid equations, and demonstrate how multi-Beltrami equilibria emerge as natural relaxed states of model, representing an evolution towards minimum energy. General properties these are studied, a wide class solutions is obtained. specialize to cases double triple Beltrami highlight their connections with appropriate physical invariants, viz., generalized helicities In particular, we that different field configurations can give rise distinct or identical...
The general, non-dissipative, two-fluid model in plasma physics is Hamiltonian, but this property sometimes lost or obscured the process of deriving simplified (or reduced) one-fluid models from equations motion. To ensure that reduced are we start with general action functional, and make all approximations, changes variables, expansions directly within context. resulting then mapped to Eulerian fluid variables using a novel nonlocal Lagrange-Euler map. Using method, recover L\"{u}st's...
Abstract We study the prospects for life on planets with subsurface oceans, and find that a wide range of can exist in diverse habitats ice envelopes moderate thickness. quantify energy sources available to these worlds, rate production prebiotic compounds, assess their potential hosting biospheres. Life is likely face challenges, which could be overcome through combination different mechanisms. estimate number such they may outnumber rocky habitable zone stars by few orders magnitude.
The presence of chlorofluorocarbons (CFCs) in Earth's atmosphere is a direct result technology. Ozone-depleting CFCs have been banned by most countries, but some persistent elevated concentrations due to their long stratospheric lifetimes. are effective greenhouse gases and could serve as remotely detectable spectral signature Here we use three-dimensional climate model synthetic spectrum generator assess the detectability CFC-11 CFC-12 technosignature on exoplanets. We consider case...
Large-scale characterization of exoplanetary atmospheres is on the horizon, thereby making it possible in future to extract their statistical properties. In this context, by using a well validated model solar system, we carry out three-dimensional magnetohydrodynamic simulations compute nonthermal atmospheric ion escape rates unmagnetized rocky exoplanets as function radius based fixed stellar radiation and wind conditions. We find that rate is, unexpectedly strikingly, nonmonotonic...
Abstract One of the most fundamental questions in exoplanetology is to determine whether a given planet habitable. We estimate relative likelihood planet's propensity towards habitability by considering key physical characteristics such as role temperature on ecological and evolutionary processes, atmospheric losses via hydrodynamic escape stellar wind erosion. From our analysis, we demonstrate that Earth-sized exoplanets habitable zone around M-dwarfs seemingly display much lower prospects...
There are several plasma models intermediate in complexity between ideal magnetohydrodynamics (MHD) and two-fluid theory, with Hall Extended MHD being two important examples. In this paper, we investigate aspects of these theories, the ultimate goal deriving noncanonical Poisson brackets used their Hamiltonian formulations. We present fully Lagrangian actions for each, as opposed to Eulerian, or mixed Eulerian-Lagrangian, that have appeared previously. As an step process, exhibit each...