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The solar transition region: a time-varying interface between the chromosphere and corona?
Doyle, J. G.; Keenan, F. P.; O'Shea, E.
Using joint observations taken with the CDS and SUMER instruments onboard SOHO, we re-examine the solar transition region in an attempt to determine whether it is de-coupled from the over-lying coronal region. Line ratios calculated from temporal series observations of O iv and Fe xiii spectral lines were converted to electron density, and hence e…
Serendipitous Discovery of a Broad Absorption Line QSO at Z = 2.169
Roth, Katherine C.; Stockton, Alan; Canalizo, Gabriela
We report the serendipitous discovery of a broad absorption line (BAL) QSO at z = 2.169, located 41" southwest of 3C 48. We present Keck Low Resolution Imaging Spectrometer spectroscopy covering rest-frame wavelengths 1500-2300 Å. The C iv BAL has three components, and it extends to outflow velocities of at least 12,000 km s^-1. The BAL QSO has an…
A New Technique for Performing Two-Dimensional Spectroscopy of Objects of Large Dynamic Range: The Binary System HD 167605 A+B
Arribas, S.; Mediavilla, E.; Fuensalida, J. J.
We present a new technique for performing two-dimensional (integral-field) spectroscopy of objects with a large range in intensity. It is based on the capability of optical fibers to discretize the intensity distribution at the telescope focal plane. This allows not only reformatting but also the equalization of fiber output intensities, matching …
The Complex IUE Spectrum of the ``O VI Sequence'' Planetary Nebula NGC 2867
Feibelman, Walter A.
The IUE spectrum of the planetary nebula NGC 2867 and its central star displays a rich variety of emission lines that has not been reported before. Fluxes for more than 80 UV features were determined from low- and high-dispersion spectra. Electron densities of log Ne = 3.4 +/- 0.1 cm-3 from C III], log Ne = 3.9 +/-…
HST photometry of the stars near the center of PN NGC 650
Pottasch, S. R.; Koornneef, J.
Colours and magnitudes of the central star of NGC 650 and its two companions have been obtained from HST images. The spectral types of the companions, which have been deduced from the colours, suggest a probable distance to the companions of between 5 and 6 kpc. Using the spectral and photometric characteristics of the central star, which are very…
A Search for an Emission-Line Region in the Hydrogen-deficient Carbon Star HD 182040
Clayton, Geoffrey C.; Ayres, T. R.; Brunner, Andrew R.
A long-exposure short-wavelength IUE spectrum of the hydrogen-deficient carbon (HdC) star HD 182040 does not show any detectable emission in the C II lambda1335 line. It is not certain whether this absence of emission is intrinsic or due to the large uncertainties in the distance, absolute luminosity, and reddening toward HD 182040. If intrinsic, …
Cassini as a heliospheric probe - the potential of pick-up ion measurements during its cruise phase
Fichtner, H.; Mall, U.; Hamilton, D. C. +2 more
Measurements of the spatial distributions of pick-up ions can be utilized to infer important information about the structure of the heliosphere. First, a determination of the symmetry axis of flux distributions of pick-up ions not experiencing any significant filtration of their neutral parent atoms in the heliospheric interface represents a new m…
Hubble Space Telescope Observations of Chromospheric Emission from the Population II Red Giant HD 216143
Smith, Graeme H.; Dupree, A. K.
Spectra of the Hα and Ca ii K line of Population II red giants exhibit evidence for chromospheric mass outflows only among stars brighter than M_V = -1.7. In order to determine whether this phenomenon is indicative of a true physical onset in mass outflow, spectra of the 2800 Å Mg ii lines of the metal-poor halo red giant HD 216143 have been obtai…
Latitudinal structure within Jovian hectometric radiation
Higgins, Charles A.; Thieman, James R.; Fung, Shing F. +2 more
Jovian hectometric radio emission (HOM: 300-3000 kHz) has a number of persistent structural features associated with it as observed by the Voyager 1, Voyager 2, Ulysses, and Galileo spacecraft for specific jovigraphic latitudes (-4° to +7.1°) and local times (0.3 to 10.5 hours). Most notable are the presence of HOM emission between 270° and 120° c…
The Variable Central Star of PN G243.8-37.1
Peña, Miriam; Ruiz, María Teresa
Spectroscopic and photometric variations of the central star of the planetary nebula PRTM 1 (PN G243.8-37.1) have been detected from optical spectrophotometric data. The photometric variations can be as large as ΔV~1 mag, but most of the time they are within 0.2 mag. The phenomenon seems to be cyclic. These optical changes confirm the UV variation…