Study of X-ray emission from solar active regions.

A study of the X-ray emission from solar coronal active regions is presented. The observations were made with two instruments: (1) a collimated Bragg crystal spectrometer with high spectral resolution (400 < ?/? ? < 1000) and moderate spatial resolution (about 3 arc min), and (2) a grazing incidence telescope which obtained broad wavelength-band images with high spatial resolution (about 2 arc sec). Chapter 1 gives a brief review of the relevant physics, with particular emphasis on the Sun's soft X-ray emission (i.e. 1 < wavelength,? < 25 A). The plasma and atomic physics required to interpret the X-ray observations are summarised in Chapter 2. The instruments used in this work were the (sounding) rocket-borne Leicester Mk. 3 Bragg spectrometer, and the American Science and Engineering (ASE) X-ray telescope S-054, aboard the Skylab Apollo Telescope mount. The instruments and data analysis techniques are described in Chapter 3. The data are interpreted in terms of thermal emission from an optically thin plasma. In Chapter 4, coronal active region models, are derived, of electron density and emission measure (ne2?v) as a function of electron temperature and spatial location. Abundances are derived for the elements oxygen, neon, sodium, magnesium, aluminium, silicon, iron and nickel in the solar corona. Chapters 5, 6 and 7 describe observations and interpretation of spectra of ions belonging to particular isoelectronic sequences, namely: Chapter 5, the Helium-like ions 0 VII, Ne IX and Mg XI; Chapter 6, the Neon-like ions Fe XVII and Ni XIX, Chapter 7, Fluorine-like Fe XVIII and Oxygen-like Fe XIX

A ROSAT medium-sensitivity Galactic plane survey at 180 degrees <1<280 degrees 180°≲l≲280°

We have performed a moderately deep soft X-ray (0.1–2 keV) survey of the Galactic plane using pointed observations with the ROSAT Position Sensitive Proportional Counter (PSPC). The survey is more than an order of magnitude more sensitive than previous X-ray surveys near the Galactic plane. The data consist of nine fields each of ≈10 ks exposure, pointed at positions on or very close to the Galactic plane (ǀbǀ 0.002 count s[superscript −1]. We present the catalogue of X-ray sources and the number–flux relations (log N–log S). Eighteen sources have possible identifications from the SIMBAD data base. We have searched the Tycho-2 and USNO-A2.0 catalogues to find all possible optical counterparts brighter than ∼ 19th magnitude, and attempt to classify these on the basis of log (f[subscript X]/f[subscript opt]) versus optical colour diagrams and near-infrared photometry from the 2MASS Second Incremental Data Release. Hence, we have found the majority of these sources to be consistent with being late-type main-sequence stars, as previous studies have proposed from incompletely identified surveys. Comparison of the measured number–flux relations with predictions of Galactic (stellar) and extragalactic populations supports the view that the population of young stars in the plane is denser than previously thought

The Mid-Infrared Instrument for the James Webb Space Telescope, II: Design and Build

The Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) provides measurements over the wavelength range 5 to 28.5 μm. MIRI has, within a single “package,” four key scientific functions: photometric imaging, coronagraphy, single-source low-spectral resolving power (R ∼ 100) spectroscopy, and medium-resolving power (R ∼ 1500 to 3500) integral field spectroscopy. An associated cooler system maintains MIRI at its operating temperature of < 6.7 K. This paper describes the driving principles behind the design of MIRI, the primary design parameters, and their realization in terms of the “as-built” instrument. It also describes the test program that led to delivery of the tested and calibrated Flight Model to NASA in 2012, and the confirmation after delivery of the key interface requirements