Observations of Diffuse Extreme-Ultraviolet Emission with the<i>Cosmic Hot Interstellar Plasma Spectrometer</i>(<i>CHIPS</i>)

Hurwitz, M.; Sasseen, T. P.; Sirk, Martin M.

doi:10.1086/428446

Cited by 61 publications

(60 citation statements)

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“…40 If this important finding is confirmed, then the contribution of the Local Bubble to the radiation background in the heliosphere at 30.4 nm would be smaller than assumed by us here, with our current estimates thus being conservative.…”

Section: 3mentioning

confidence: 55%

“…Interestingly, the results of the recent CHIPS mission have challenged our current concepts. 40 Main recent astrophysics spectroscopic missions in EUV All these recent low-earth orbit missions operate in the bright geocorona. All the spectrographs are single-slit, with the notable exception of CHIPS, where the clever design collects radiation from six slits and diffraction gratings.…”

Section: 1mentioning

confidence: 99%

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Imaging three-dimensional heliosphere in EUV

Gruntman

Lampton

Edelstein

2005

Solar Physics and Space Weather Instrumentation

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The glow of interstellar plasma and solar wind pickup ions and solar wind emissions at 30.4 nm provide a way of exploring important physical processes in the heliosphere. Imaging the heliosphere at this wavelength with high spectral resolution will map the heliopause, probe pickup ions in the solar wind, and reveal the three-dimensional flow pattern of the solar wind, including in the regions over the sun's poles. The required high-throughput, high-resolution spectrometer for diffuse radiation should be able to measure 1 milli-Rayleigh irradiance in 10000 seconds with a 0.005-nm spectral resolution across pixels subtending a few degrees of celestial arc. The desired performance characteristics can be achieved by combining multiple entrance slits with an optimized spectrometer design. We present a concept of a space experiment to image the heliosphere at 30.4 nm and discuss the scientific rationale and required instrumentation.Keywords: heliosphere, heliopause, extreme ultraviolet, EUV, solar wind, diffuse radiation, spectrometry 1.SOLAR SYSYTEM GALACTIC FRONTIER Global interactionThe interaction of the expanding solar wind plasma with the surrounding galactic medium -Local Interstellar Medium (LISM) -creates the heliosphere.1-4 The heliosphere is a complex phenomenon where the solar wind and interstellar plasmas, interstellar gas, magnetic field, and energetic particles all play important roles. [5][6][7][8] The region where the solar wind meets the galactic medium remains poorly explored, with the present concepts of the heliospheric interface based on scarce and mostly indirect experimental data. The most distant operating spacecraft, Voyager 1, had reached the termination shock region and the spacecraft entered the slowed down solar wind at 94 AU (ecliptic latitude β = 34.8° and ecliptic longitude λ = 253.3°) in December 2004. (The first inconclusive indications of the possible arrival at this region were reported two years ago.9,10 ) This is a major milestone in exploration of the outer heliosphere, although the spacecraft is instrumented for planetary flybys and not optimized for interstellar studies. Voyager 1 will be turned off in 2020-2025 at the distance 150 AU because of the decreasing efficiency of its radioisotope thermoelectric generators.A possible two-shock Sun-LISM interaction scenario 5 illustrates the main features of the heliosphere (Fig. 1). The interstellar wind approaches the heliosphere with a supersonic velocity and forms a bow shock. The dynamic pressure of the expanding, highly supersonic solar wind decreases with the heliocentric distance. At a certain distance from the Sun, this pressure would equal the external LISM pressure of the interstellar wind and magnetic field. The solar wind expansion transitions to a subsonic flow at the termination shock. There the kinetic energy of the supersonic flow is largely converted into thermal energy in the subsonic plasma beyond the shock. The subsonic postshock solar wind plasma (Fig. 1, left) flows in the heliospheric sheath around the ...

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Section: 3mentioning

confidence: 55%

Section: 1mentioning

confidence: 99%

Imaging three-dimensional heliosphere in EUV

Gruntman

Lampton

Edelstein

2005

Solar Physics and Space Weather Instrumentation

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“…Additionally, observations of the diffuse extreme ultraviolet (EUV) sky background spectral emission using both the CHIPS (Hurwitz et al 2005) and EURD (Edelstein et al 2001) satellites are also in contradiction with the predictions of the NEI model. We also note that strong Si III (1206 Å) interstellar absorption has been reported for several sight-lines towards nearby stars (Holberg et al 1999;Nehme et al 2008).…”

Section: 1mentioning

confidence: 96%

“…Firstly, it may now be possible for the hot gas in the Local Cavity to be in pressure balance with the embedded warm clouds, especially if the expected downward revisions to the Local Hot Bubble's thermal pressure are severe and if the clouds are somewhat supported by non-thermal pressures such as magnetic pressure and turbulence. Furthermore, the reduction in the Local Hot Bubble X-ray intensity may help to explain the low fluxes of the Fe IX, Fe X, and Fe XI photons observed by in ultra-soft X-ray spectra (McCammon et al 2002;Hurwitz et al 2005). The precise estimates of the expected Fe IX, Fe X, and Fe XI intensities, however, depend on the Local Hot Bubble's (newer lower) temperature, which is not yet known.…”

Section: Ramifications For the 'Accepted Local Hot Bubble Model'mentioning

confidence: 99%

The trouble with the Local Bubble

Welsh

Shelton

2009

Astrophys Space Sci

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The model of a Local Hot Bubble has been widely accepted as providing a framework that can explain the ubiquitous presence of the soft X-ray background diffuse emission. We summarize the current knowledge on this local interstellar region, paying particular reference to observations that sample emission from the presumed local million degree K hot plasma. However, we have listed numerous observations that are seemingly in conflict with the concept of a hot Local Bubble. In particular, the discovery of solar wind charge exchange that can generate an appreciable soft X-ray background signal within the heliosphere, has led to a reassessment of the generally accepted model that requires a hot local plasma.In order to explain the majority of observations of the local plasma, we forward two new speculative models that describe the physical state of the local interstellar gas. One possible scenario is similar to the present widely accepted model of the Local Hot Bubble, except that it accounts for only 50% of the soft X-ray emission currently detected in the galactic plane, has a lower thermal pressure than previously thought, and its hot plasma is not as hot as previously believed. Although such a model can solve several difficulties with the traditional hot Local Bubble model, a heating mechanism for the dimmer and cooler gas remains to be found. The second possible explanation is that of the 'Hot Top' model, in which the Local Cavity is an old su-B.Y. Welsh ( ) Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, USA e-mail: bwelsh@ssl.berkeley.edu R.L. Shelton Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA pernova remnant in which no (or very little) million degree local plasma is presently required. Instead, the cavity is now thought to be filled with partially ionized cloudlets of temperature ∼ 7000 K that are surrounded by lower density envelopes of photo-ionized gas of temperature ∼ 20,000 K. Although this new scenario provides a natural explanation for many of the observations that were in conflict with the Local Hot Bubble model, we cannot (as yet) provide a satisfactory explanation or the emission levels observed in the B and Be ultra-soft X-ray bands.

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“…and found to be around 10' K Al keV). The Cosmic Hot Interstellar Plasma Spectrometer (CHIPS: Hurwitz et al 2005) did not detect the far-ultraviolet (FUV) emission expected from surrounding 106 K gas, and placed the LHB temper-ature rather at 0.086 keV for an emission measure of 4x 104 cm -1 pc.…”

Section: Introductionmentioning

confidence: 99%

XMM-NEWTONOBSERVATIONS OF MBM 12: MORE CONSTRAINTS ON THE SOLAR WIND CHARGE EXCHANGE AND LOCAL BUBBLE EMISSIONS

Koutroumpa

Edgar

Küntz

et al. 2010

ApJ

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We present the first analysis of an XMAI-Newton observation of the nearby molecular cloud MBNI 12. We find that in the direction of MBM 12 the total O VII (0.57 keV) triplet emission is 1.8+0" photons cm -2 s _u sr -1 (or Line Units -LU) while for the O VIII (0.65 keV) line emission we find a 3Q upper limit of <1 LU. We also use a heliospheric model to calculate the O VII and O VIII emission generated by Solar Wind Charge-eXchange (SWCX) which we compare to the XMM-Newton observations. This comparison provides new constraints on the relative heliospheric and Local Bubble contributions to the local diffuse X-ray background. The heliospheric SWCX model predicts 0.82 LU for O VII, which accounts for -,16±15 eic of the observed value, and 0.33 LU for the O VIII line emission consistent with the XMM-Newton observed value. We discuss our results in combination with previous observations of the MBM 12 with CHANDRA and Suzaku.

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Observations of Diffuse Extreme-Ultraviolet Emission with theCosmic Hot Interstellar Plasma Spectrometer(CHIPS)

Cited by 61 publications

References 25 publications

Imaging three-dimensional heliosphere in EUV

Imaging three-dimensional heliosphere in EUV

The trouble with the Local Bubble

XMM-NEWTONOBSERVATIONS OF MBM 12: MORE CONSTRAINTS ON THE SOLAR WIND CHARGE EXCHANGE AND LOCAL BUBBLE EMISSIONS

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