The “Spectroscopy of Plasma Evolution from Astrophysical Radiation” Mission

The "Spectroscopy of Plasma Evolution from Astrophysical Radiation" (SPEAR, also known as the "Far-Ultraviolet Imaging Spectrograph") instruments, flown aboard the STSAT-1 satellite mission, have provided the first large-area spectral mapping of the cosmic far-ultraviolet (FUV; 900-1750 A) background. We describe the mission and its science motivation, the mission data and their processing, and the effects of mission performance on the science data. We present the first map of the cosmic FUV background (1360-1710 A) over most of the sky as an example of the mission results. These SPEAR data reveal diffuse radiation from warm and hot (104-106 K) plasma, molecular hydrogen fluorescence, and dust-scattered starlight. They allow for an unprecedented characterization of the spectral emission from a variety of environments, including the general interstellar medium (ISM), molecular clouds, supernova remnants, and superbubbles.

[1]  D. York,et al.  Far Ultraviolet Spectroscopic Explorer Observations of Diffuse Interstellar Molecular Hydrogen , 2000 .

[2]  Ho Jin,et al.  The SPEAR Instrument and On-Orbit Performance , 2006, astro-ph/0601588.

[3]  P. Shapiro,et al.  NEW RESULTS CONCERNING THE GALACTIC FOUNTAIN , 1991 .

[4]  A. Szalay,et al.  The Galaxy Evolution Explorer: A Space Ultraviolet Survey Mission , 2004, astro-ph/0411302.

[5]  J. Shull,et al.  Highly ionized gas in the Galactic halo , 1994 .

[6]  Paul P. Plucinsky,et al.  Progress on Establishing the Spatial Distribution of Material Responsible for the 1/4 keV Soft X-Ray Diffuse Background Local and Halo Components , 1998 .

[7]  E. B. Jenkins,et al.  Coronal gas in the Galaxy. I - A new survey of interstellar O VI , 1978 .

[8]  A. Davidsen.  Far-Ultraviolet Astronomy on the Astro-1 Space Shuttle Mission , 1993, Science.

[9]  Stuart Bowyer,et al.  The cosmic far ultraviolet background , 1991 .

[10]  R. Henry.  Ultraviolet background radiation , 1991 .

[11]  S. H. Moseley,et al.  A High Spectral Resolution Observation of the Soft X-Ray Diffuse Background with Thermal Detectors , 2000, astro-ph/0205012.

[12]  J. Black,et al.  Fluorescent excitation of interstellar H2 , 1987 .

[13]  D. Schlegel,et al.  Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds , 1998 .

[14]  R. Lallement,et al.  On the contribution of charge-exchange induced X-ray emission in the ISM and ICM , 2004 .

[15]  Jeffrey S. Hull,et al.  The SPEAR science payload , 2003, SPIE Astronomical Telescopes + Instrumentation.

[16]  T. P. Sasseen,et al.  Observations of Diffuse Extreme-Ultraviolet Emission with the Cosmic Hot Interstellar Plasma Spectrometer (CHIPS) , 2004, astro-ph/0411121.

[17]  B. Savage,et al.  Distribution and Kinematics of O VI in the Galactic Halo , 2002, astro-ph/0208140.

[18]  B. Savage,et al.  Observations of Highly Ionized Gas in the Galactic Halo , 1992 .

[19]  D. Schiminovich,et al.  The Narrowband Ultraviolet Imaging Experiment for Wide-Field Surveys. I. Dust-scattered Continuum , 1999, astro-ph/9905362.

[20]  J. Edelstein,et al.  Molecular Hydrogen Fluorescence in the Eridanus Superbubble , 2006, astro-ph/0601590.

[21]  Far-Ultraviolet Observations of a Thermal Interface in the Orion-Eridanus Superbubble , 2006, astro-ph/0601584.

[22]  Dan McCammon,et al.  The soft X-ray diffuse background , 1983 .

[23]  S. Bowyer,et al.  In-Flight Performance and Preliminary Results from the Far Ultraviolet Space Telescope (Faust) Flown on ATLAS-1 , 1993 .

[24]  K. Gorski,et al.  HEALPix: A Framework for High-Resolution Discretization and Fast Analysis of Data Distributed on the Sphere , 2004, astro-ph/0409513.

[25]  R. Shelton.  Simulations of Supernova Remnants in Diffuse Media and Their Application to the Lower Halo of the Milky Way. I. The High-Stage Ions , 1998 .

[26]  J. Edelstein,et al.  Diffuse Far-Ultraviolet Observations of the Taurus Region , 2006, astro-ph/0602010.

[27]  Christopher D. Martin,et al.  Discovery of Molecular Hydrogen Fluorescence in the Diffuse Interstellar Medium , 1990 .

[28]  D-H. Lee,et al.  Far-ultraviolet spectral images of the Vela supernova remnant , 2006 .

[29]  Edward B. Jenkins,et al.  The Distribution of Thermal Pressures in the Interstellar Medium , 2001 .

[30]  O. H. W. Siegmund,et al.  Observations of O VI Emission from the Diffuse Interstellar Medium , 2001, astro-ph/0105278.

[31]  M. Markevitch,et al.  CHANDRA OBSERVATIONS OF THE ''DARK'' MOON AND GEOCORONAL SOLAR WIND CHARGE TRANSFER , 2004, astro-ph/0402247.

[32]  Jeffrey S. Hull,et al.  The microchannel plate detector electronics system for SPEAR , 2003, SPIE Astronomical Telescopes + Instrumentation.

[33]  Richard J. Edgar,et al.  Spectra of the ¼ keV X-Ray Diffuse Background from the Diffuse X-Ray Spectrometer Experiment , 2001 .

[34]  K. Borkowski,et al.  Radiative magnetized thermal conduction fronts , 1990 .

[35]  B. Savage,et al.  Highly Ionized Gas in the Galactic Halo: A FUSE Survey of O VI Absorption toward 22 Halo Stars , 2002, astro-ph/0212196.

[36]  J. Edelstein,et al.  Far-Ultraviolet Spectral Images of the Cygnus Loop , 2005, astro-ph/0601615.

[37]  J. Dickey,et al.  H I in the Galaxy , 1990 .

[38]  Measurements of the Diffuse Ultraviolet Background and the Terrestrial Airglow with the Space Telescope Imaging Spectrograph , 2000, astro-ph/0004147.

[39]  Stuart Bowyer,et al.  Discovery of high-ionization far-ultraviolet line emission from the interstellar medium , 1990 .

[40]  Douglas P. Finkbeiner,et al.  A Full-Sky Hα Template for Microwave Foreground Prediction , 2003, astro-ph/0301558.

[41]  S. Bowyer,et al.  Spectral Observations of Diffuse Far-Ultraviolet Emission from the Hot Phase of the Interstellar Medium with the Diffuse Ultraviolet Experiment , 1997, astro-ph/9709291.

[42]  J. D. Stolarik,et al.  The Ultraviolet Imaging Telescope - Design and performance , 1992 .

[43]  R. Shelton,et al.  Far Ultraviolet Spectroscopic Explorer ($\it FUSE$) observations of emitting and absorbing gas in the Local Interstellar Chimney , 2002 .

[44]  R. Wilson,et al.  A survey of ultraviolet objects , 1983 .

[45]  D. Cox,et al.  Evolution of Supernova Remnant Bubbles in a Warm Diffuse Medium: Survey of Results from One-dimensional Models and Their Impact on Estimates of Interstellar Porosity , 1993 .

[46]  C. Danforth,et al.  A FUSE Survey of Interstellar Molecular Hydrogen toward High-Latitude AGNs , 2005, astro-ph/0507581.

[47]  D. Cox,et al.  Completing the evolution of supernova remnants and their bubbles , 1992 .

[48]  D. Schlegel,et al.  Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds , 1997, astro-ph/9710327.

[49]  Wonyong Han,et al.  Optics development for the SPEAR mission , 2003, SPIE Astronomical Telescopes + Instrumentation.