P. C. Frisch's research while affiliated with University of Chicago and other places
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Publications (201)
On its journey through the Galaxy, the Sun passes through diverse regions of the interstellar medium. High-resolution spectroscopic measurements of interstellar absorption lines in spectra of nearby stars show absorption components from more than a dozen warm partially ionized clouds within 15 pc of the Sun. The two nearest clouds—the Local Interst...
On its journey through the Galaxy, the Sun passes through diverse regions of the interstellar medium. High-resolution spectroscopic measurements of interstellar absorption lines in spectra of nearby stars show absorption components from more than a dozen warm partially ionized clouds within 15 pc of the Sun. The two nearest clouds - the Local Inter...
Measurements of starlight polarized by aligned interstellar dust grains are used to probe the relation between the orientation of the ambient interstellar magnetic field (ISMF) and the ISMF traced by the ribbons of energetic neutral atoms discovered by the Interstellar Boundary Explorer spacecraft. We utilize polarization data, many acquired specif...
We investigate the linear polarization produced by interstellar dust aligned by the magnetic field in the solar neighborhood (d< 50 pc). We also look for intrinsic effects from circumstellar processes, specifically in terms of polarization variability and wavelength dependence. We aim to detect and map dust clouds which give rise to statistically s...
Context. We investigate the linear polarization produced by interstellar dust aligned by the magnetic field in the solar neighborhood ( d < 50 pc). We also look for intrinsic effects from circumstellar processes, specifically in terms of polarization variability and wavelength dependence.
Aims. We aim to detect and map dust clouds which give rise t...
Interstellar neutral gas atoms penetrate the heliopause and reach 1~au, where they are detected by IBEX. The flow of neutral interstellar helium through the perturbed interstellar plasma in the outer heliosheath (OHS) results in creation of the secondary population of interstellar He atoms, the so-called Warm Breeze, due to charge exchange with per...
There is now solid experimental evidence of at least one supernova explosion within 100 pc of Earth within the last few million years, from measurements of the short-lived isotope 60Fe in widespread deep-ocean samples, as well as in the lunar regolith and cosmic rays. This is the first established example of a specific dated astrophysical event out...
The properties of dust in the interstellar medium (ISM) nearest the Sun are poorly understood because the low column densities of dust toward nearby stars induce little photometric reddening, rendering the grains largely undetectable. Stellar polarimetry offers one pathway to deducing the properties of this diffuse material. Here we present multi-w...
The properties of dust in the interstellar medium (ISM) nearest the Sun are poorly understood because the low column densities of dust toward nearby stars induce little photometric reddening, rendering the grains largely undetectable. Stellar polarimetry offers one pathway to deducing the properties of this diffuse material. Here we present multi-w...
Observations from the Interstellar Boundary Explorer (IBEX) of energetic neutral atoms (ENAs) reveal two populations, those emitted from a narrow (~20°–40°) ribbon that is centered on the local interstellar magnetic field, and a globally distributed flux (GDF) that is controlled by processes in the heliosheath. This is a third study utilizing a pre...
The Interstellar Mapping and Acceleration Probe (IMAP) is a revolutionary mission that simultaneously investigates two of the most important overarching issues in Heliophysics today: the acceleration of energetic particles and interaction of the solar wind with the local interstellar medium. While seemingly disparate, these are intimately coupled b...
Light from nearby stars becomes linearly polarized while traversing a dichroic interstellar medium. Polarization data which reveal heliosphere features are summarized. Polarizing dust grains trace a magnetic field direction consistent with the field affecting the warm breeze of secondary interstellar helium found by IBEX. Polarization data also tra...
Starlight that becomes linearly polarized by magnetically aligned dust grains provides a viable diagnostic of the interstellar magnetic field (ISMF). A survey is underway to map the local ISMF using data collected at eight observatories in both hemispheres. Two approaches are used to obtain the magnetic structure: statistically evaluating magnetic...
A range of astronomical data indicates that ancient supernovae created the galactic environment of the Sun and sculpted the physical properties of the interstellar medium near the heliosphere. In this paper we review the characteristics of the local interstellar medium that have been affected by supernovae. The kinematics, magnetic field, elemental...
Starlight linearly polarized by aligned interstellar dust grains provides the necessary data for tracing the structure of the very local interstellar magnetic field (ISMF). Two methods have been developed to recover the ISMF direction from polarized starlight, using data from an ongoing polarization survey. Both methods rely on the probability dist...
The direct measurements of interstellar matter by the Interstellar Boundary Explorer (IBEX) mission have opened a new and important chapter in our study of the interactions that control the boundaries of our heliosphere. Here we derive for the quantitative information about interstellar O flow parameters from IBEX low-energy neutral atom data for t...
A range of astronomical data indicates that ancient supernovae created the galactic environment of the Sun and sculpted the physical properties of the interstellar medium near the heliosphere. In this paper, we review the characteristics of the local interstellar medium that have been affected by supernovae. The kinematics, magnetic field, elementa...
The Interstellar Boundary Explorer (IBEX) samples the interstellar neutral (ISN) gas flow of several species every year from December through late March when the Earth moves into the incoming flow. The first quantitative analyses of these data resulted in a narrow tube in four-dimensional interstellar parameter space, which couples speed, flow lati...
The Interstellar Boundary Explorer (IBEX) has been directly observing neutral atoms from the local interstellar medium for the last six years (2009-2014). This paper ties together the 14 studies in this Astrophysical Journal Supplement Series Special Issue, which collectively describe the IBEX interstellar neutral results from this epoch and provid...
Interstellar He represents a key sample of interstellar matter that, due to its high first ionization potential, survives the journey from beyond our solar system's heliospheric boundaries to Earth. Ongoing analysis of interstellar neutral (ISN) He atoms by the Interstellar Boundary Explorer (IBEX) has resulted in a growing sophistication in our un...
Interstellar dust (ISD) in the solar system was detected in situ for the first time in 1993 by the Ulysses dust detector. The study of ISD is important for understanding its role in star and solar system formation. The goal of this paper is to understand the variability in the ISD observations from the Ulysses mission by using a Monte Carlo simulat...
The interstellar magnetic field (ISMF) near the heliosphere is a basic part
of the solar neighborhood that can only be studied using polarized starlight.
Results of an ongoing survey of polarized starlight are analyzed with the goal
of linking the interstellar magnetic field that shapes the heliosphere to the
nearby field in interstellar space. New...
The Interstellar Boundary Explorer (IBEX) observes enhanced ~ keV energy Energetic Neutral Atoms (ENAs) from a narrow "ribbon" that stretches across the sky and appears to be centered on the direction of the local interstellar magnetic field. The Milagro collaboration, the Asγ collaboration and the IceCube observatory have made global maps of TeV c...
A recently discovered filament of polarized starlight that traces a coherent
magnetic field is shown to have several properties that are consistent with an
origin in the outer heliosheath of the heliosphere: (1) The magnetic field that
provides the best fit to the polarization position angles is directed within
6.7+-11 degrees of the observed upwin...
The journey of the Sun through space carries the solar system through a
dynamic interstellar environment that is presently characterized by Mach 1
motion between the heliosphere and the surrounding interstellar medium (ISM).
The interaction between the heliosphere and ISM is an evolving process due to
the variable solar wind and to interstellar tur...
Interstellar Boundary Explorer (IBEX) measurements from 2009-2010 identified a set of possible solutions with very tight coupling between the interstellar He inflow longitude, latitude, speed, and temperature. The center of this allowable parameter space suggested that the heliosphere could be moving more slowly and in a slightly different directio...
The circular ribbon of enhanced energetic neutral atom (ENA) emission observed by the Interstellar Boundary Explorer (IBEX) mission remains a critical signature for understanding the interaction between the heliosphere and the interstellar medium. We study the symmetry of the ribbon flux and find strong, spectrally dependent reflection symmetry thr...
The Interstellar Boundary Explorer (IBEX) observes enhanced Energetic Neutral Atoms (ENAs) emission in the keV energy range from a narrow (~20° wide) "ribbon" in the sky that appears to be centered on the direction of the local interstellar (LIS) magnetic field. The Milagro collaboration, the Asγ collaboration and the IceCube observatory have recen...
The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (~20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is...
The local interstellar magnetic field affects both the heliosphere and the
surrounding cluster of interstellar clouds (CLIC). Measurements of linearly
polarized starlight provide the only test of the magnetic field threading the
CLIC. Polarization measurements of the CLIC magnetic field show multiple local
magnetic structures, one of which is align...
Recent data on the interstellar magnetic field in the low density nearby interstellar medium suggest a new perspective for understanding interstellar clouds within 40 pc. The directions of the local interstellar magnetic field found from measurements of optically polarized starlight and the very local field found from the Ribbon of energetic neutra...
The Interstellar Boundary Explorer (IBEX) observes enhanced Energetic Neutral Atoms (ENAs) emission in the keV energy range from a narrow (~20° wide) "ribbon" in the sky that appears to be centered on the direction of the local interstellar (LIS) magnetic field. The Milagro collaboration, the Asγ collaboration and the IceCube observatory have recen...
Observations with the Interstellar Boundary Explorer (IBEX) have shown enhanced energetic neutral atom (ENA) emission from
a narrow, circular ribbon likely centered on the direction of the local interstellar medium (LISM) magnetic field. Here, we
show that recent determinations of the local interstellar velocity, based on interstellar atom measurem...
![Figure 2. Schematic of the TOF mass spectrometer (from [29]). Negative...](profile/Lukas-Saul/publication/263026893/figure/fig1/AS:296066424557576@1447599144970/Schematic-of-the-TOF-mass-spectrometer-from-29-Negative-ions-exiting-the-ESA-strike_Q320.jpg)
We report on a comprehensive signal processing procedure for very low signal levels for the measurement of neutral deuterium in the local interstellar medium from a spacecraft in Earth orbit. The deuterium measurements were performed with the IBEX-Lo camera on NASA's Interstellar Boundary Explorer (IBEX) satellite. Our analysis technique for these...
As a sharp feature in the sky, the ribbon of enhanced energetic neutral atom (ENA) flux observed by the Interstellar Boundary Explorer (IBEX) mission is a key signature for understanding the interaction of the heliosphere and the interstellar medium through which we are moving. Over five nominal IBEX energy passbands (0.7, 1.1, 1.7, 2.7, and 4.3 ke...
The properties of interstellar clouds near the Sun are ordered by the Loop I
superbubble and by the interstellar radiation field. Comparisons of the
kinematics and magnetic field of the interstellar gas flowing past the Sun,
including the Local Interstellar Cloud (LIC), indicate a geometric relation
between Loop I as defined by radio synchrotron em...
Neutral hydrogen atoms that travel into the heliosphere from the local interstellar medium (LISM) experience strong effects due to charge exchange and radiation pressure from resonant absorption and re-emission of Lyα. The radiation pressure roughly compensates for the solar gravity. As a result, interstellar hydrogen atoms move along trajectories...
Wind of Change
The flow of interstellar gas and dust through the solar system was thought to be unvarying, but Frisch et al. (p. 1080 ) show that there has been a significant variation of the direction of the flow of interstellar helium through the solar system over the past 40 years. The data, collected by 10 different spacecraft over much of the...
We report the first in situ measurements of neutral deuterium
originating in the local interstellar medium (LISM) in Earth's orbit.
These measurements were performed with the IBEX-Lo camera on NASA's
interstellar boundary explorer (IBEX) satellite. All data from the
spring observation periods of 2009 through 2011 have been analysed. In
the three ye...
Measurements of the velocity of interstellar HeI inside of the heliosphere
have been conducted over the past forty years. These historical data suggest
that the ecliptic longitude of the direction of the interstellar flow has
increased at an average rate of about 0.19 degrees per year over time. Possible
astronomical explanations for these short-te...
The solar wind carves a bubble in the surrounding interstellar medium (ISM),
known as the heliosphere. Charged interstellar dust grains (ISDG) encountering
the heliosphere may be diverted around the heliopause or penetrate it depending
on their charge-to-mass ratio. We present new calculations of trajectories of
ISDG in the heliosphere, and the dus...
A key indicator of the galactic environment of the Sun is provided by the
magnetic field in the interstellar medium (ISM), which influences the shape of
the heliosphere. The direction of the nearby interstellar magnetic field (ISMF)
is determined from starlight polarized in the ISM. The local ISMF direction is
found from the ISMF direction that pro...
The low density interstellar medium (ISM) close to the Sun and inside of the
heliosphere provides a unique laboratory for studying interstellar dust grains.
Grain characteristics in the nearby ISM are obtained from observations of
interstellar gas and dust inside of the heliosphere and the interstellar gas
towards nearby stars. Comparison between t...
The tenuous interstellar medium surrounding the Sun is host to a
magnetic field that distorts the heliosphere and affects the
trajectories of charged interstellar dust grains interacting with the
solar wind. Interstellar dust grains that encounter the heliosphere may
be diverted around heliopause or penetrate it, depending on their
charge-to-mass r...
The ecliptic poles are observed continuously by the Interstellar Boundary Explorer (IBEX); thus, it is possible to discern temporal variations in the energetic neutral atoms (ENAs) from the outer heliosphere on timescales much shorter than the time it takes for IBEX to generate a full sky map (six months). Observations indicate that the ENA flux fr...
We present two new diagnostics of the very local interstellar magnetic
field (ISMF). The Interstellar Boundary Explorer (IBEX) has discovered a
'ribbon' of energetic neutral atoms (ENAs) in the sky. This ribbon forms
a nearly complete arc in the sky and coincides with sightlines that are
perpendicular to the ISMF draping over, and shaping, the heli...
The Stardust mission returned cometary, interplanetary and (probably) interstellar dust in 2006 to Earth that have been analysed in Earth laboratories worldwide. Results of this mission have changed our view and knowledge on the early solar nebula. The Rosetta mission is on its way to land on comet 67P/Churyumov-Gerasimenko and will investigate for...
The ecliptic poles are observed continuously by the Interstellar
Boundary Explorer (IBEX); thus, it is possible to discern temporal
variations in the ENAs from the outer heliosphere on time scales much
shorter than the time it takes for IBEX to generate a full sky map (6
months). Observations at all energies indicate that the ENA flux from
the pola...
Unprecedented information on interstellar magnetic fields in low density
interstellar material is provided by the Interstellar Boundary Explorer
(IBEX) discovery of an excess of energetic neutral atoms (ENAs) that
forms a complete arc in the sky. This 'ribbon' traces sightlines that
are perpendicular to the direction of the interstellar magnetic fi...
The Interstellar Boundary Explorer (IBEX) discovered a 'ribbon' of
energetic neutral atoms (ENAs), that forms a complete arc in the sky.
The ribbon coinicides with sightlines that are perpendicular to the
interstellar magnetic field (ISMF) draping over the heliosphere,
according to recent heliosphere models. Starlight that is polarized in
the inter...
Similar directions are obtained for the local interstellar magnetic field
(ISMF) by comparing diverse data and models that sample five orders of magnetic
in spatial scales. These data include the ribbon of energetic neutral atoms
discovered by the Interstellar Boundary Explorer, heliosphere models, the
linear polarization of light from nearby stars...
The combination of the Interstellar Boundary Explorer (IBEX) all-sky maps of the energetic neutral atom (ENA) fluxes with the Voyager in situ measurements provides a unique opportunity to learn about the physics governing the solar wind interaction with the local interstellar medium. The first IBEX results revealed a sky-spanning "ribbon" of unexpe...
The Solar System is embedded in a flow of low-density, warm, and partially ionized interstellar material that has been sampled directly by in situ measurements of interstellar neutral gas and dust in the heliosphere. Absorption line data reveal that this interstellar gas is part of a larger cluster of local interstellar clouds, which is spatially a...
Interstellar dust (ISD) has been directly observed flowing into the Solar System. This dust has an unusual size distribution relative to typical ISD with small grains (a < 0.1 micron) deficient and large grains (about 1 micron) abundant. Such large grains are not expected to be present in warm, low density gas such as the Local Interstellar Cloud (...
The Interstellar Boundary Explorer (IBEX) observes a remarkable feature, the IBEX ribbon, which has energetic neutral atom (ENA) flux over a narrow region ~20° wide, a factor of 2-3 higher than the more globally distributed ENA flux. Here, we separate ENA emissions in the ribbon from the distributed flux by applying a transparency mask over the rib...
The first sky map of energetic neutral atoms (ENAs) from the outer heliosphere measured from the Interstellar Boundary Explorer revealed the ribbon, a remarkable circular arc of enhanced ENA emission [McComas, et al., 2009] narrow in width [Fuselier, et al., 2009] and centered at ecliptic coordinate (lambda,beta)=(221°,39°) [Funsten, et al., 2009]....
The Interstellar Boundary Explorer (IBEX) Mission observes a remarkable feature, the IBEX ribbon. This very narrow ~20° wide feature has energetic neutral atom (ENA) flux ~2-3 times the ENA flux that is globally distributed over other portions of the IBEX maps. Here, we separate ENA emissions in the ribbon from the globally distributed flux by appl...
Spatial variations in the configuration of the interstellar magnetic field (ISMF) near the Sun are constrained by differences in the directions of the interstellar magnetic field found from the Ribbon of emission of energetic neutral atoms (ENA) discovered by the Interstellar Boundary Explorer (IBEX) spacecraft, versus the ISMF direction found from...
The Interstellar Boundary Explorer (IBEX) completes a full sweep of the sky once every six months; thus in general, if we seek evidence for temporal variation in the heliospheric ENA flux, we must wait six months before revisiting the same part of the sky. However, due to the constant sun-pointing orientation of the IBEX spin axis, two points on th...
The Interstellar Boundary Explorer (IBEX) spacecraft is providing the first all-sky maps of the energetic neutral atoms (ENAs) produced by charge-exchange between interstellar neutral \HI\ atoms and heliospheric solar wind and pickup ions in the heliosphere boundary regions. The 'edge' of the interstellar cloud presently surrounding the heliosphere...
Variations in the spatial configuration of the interstellar magnetic field (ISMF) near the Sun can be constrained by comparing the ISMF direction at the heliosphere found from the Interstellar Boundary Explorer (IBEX) spacecraft observations of a "Ribbon" of energetic neutral atoms (ENAs), with the ISMF direction derived from optical polarization d...
During the solar journey through galactic space, variations in the physical
properties of the surrounding interstellar medium (ISM) modify the heliosphere
and modulate the flux of galactic cosmic rays (GCR) at the surface of the
Earth, with consequences for the terrestrial record of cosmogenic
radionuclides. One phenomenon that needs studying is th...
The Interstellar Boundary Explorer (IBEX) has obtained all-sky images of energetic neutral atoms (ENAs) emitted from the heliosheath, located between the termination shock of the solar wind and the local interstellar medium (LISM). The spectral variations over the energy range 0.3-6 keV in the ENA all-sky maps reveal an unexpected new picture of th...
1] The first all‐sky maps of Energetic Neutral Atoms (ENAs) from the Interstellar Boundary Explorer (IBEX) exhibited smoothly varying, globally distributed flux and a narrow "ribbon" of enhanced ENA emissions. In this study we compare the second set of sky maps to the first in order to assess the possibility of temporal changes over the 6 months be...
The Interstellar Boundary Explorer (IBEX) mission is exploring the frontiers of the heliosphere where energetic neutral atoms (ENAs) are formed from charge exchange between interstellar neutral hydrogen atoms and solar wind ions and pickup ions. The geography of this frontier is dominated by an unexpected nearly complete arc of ENA emission, now kn...
Many studies of the Loop I magnetic superbubble place the Sun at the edges of the bubble. One recent study models the polarized radio continuum of Loop I as two magnetic shells with the Sun embedded in the rim of the "S1" shell. If the Sun is in such a shell, it should be apparent in both the local interstellar magnetic field and the distribution o...
Due to an error at the publisher, the affiliation for author N. A. Schwadron was listed incorrectly. The correct affiliation appears above. Also, the interstellar magnetic field orientation was reversed. Specifically, in the first sentence of Section 3, the phrase "pointed toward ecliptic coordinate (224, 41)" should correctly read "pointing from e...
The distribution of interstellar dust grains (ISDG) observed in the Solar System depends on the physical properties of the interstellar medium interacting with the heliosphere. Small grains couple tightly to the magnetic field in the outer heliosheath, while large grains enter the heliosphere. These grain distributions provide a new tool for unders...
First data from NASA's Interstellar Boundary EXplorer (IBEX) mission show a striking "ribbon" feature of enhanced energetic neutral atom (ENA) emission. The enhancement in flux is between 2 and 3 times greater than adjacent regions of the sky. Yet the spectral index of ENAs appears to be the same both inside and outside the ribbon. While the ribbon...
IBEX is returning observations of energetic neutral atoms (ENAs) created in the boundary regions separating the supersonic solar wind and the pristine local interstellar medium. Underlying the interpretation of the IBEX results is the character of the proton distribution function in the inner and outer heliosheath. In particular, the proton distrib...
IBEX observations of energetic neutral atoms (ENAs) are providing the
first all-sky maps of the remote interaction regions between the solar
wind and interstellar gas. These ENAs are byproducts of the interaction
between interstellar neutral atoms and the solar wind, and as such
provide information on the physical conditions of the interstellar clo...
Interstellar Boundary Explorer (IBEX) mission gives us a unique opportunity to analyze global, three-dimensional and time-dependent, structure of the outer heliosphere. Charge exchange between interstellar neutral atoms and ions and interstellar magnetic field, through the heliopause draping, can significantly affect the topology of the heliospheri...
Modern models of the interaction between solar wind and the local interstellar medium solve a large coupled system of equations for ions, neutrals and magnetic fields that reproduce much of the gross features observed in spacecraft data. However, unlike the limited in situ observations of the outer heliosphere currently available, first data from t...
The Interstellar Boundary Explorer (IBEX) completes a full sweep of the sky once every six months; thus in general, if we seek evidence for temporal variation in the heliospheric ENA flux, we must wait six months before revisiting the same part of the sky [see McComas, et al., ``Time variations of the ENA flux observed by IBEX: Is the outer heliosp...
The distribution of interstellar dust grains (ISDG) observed in the Solar System depends on the nature of the interstellar medium‐solar wind interaction. The charge of the grains couples them to the interstellar magnetic field (ISMF) resulting in some fraction of grains being excluded from the heliosphere while grains on the larger end of the size...
