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Metal abundances and kinematics of quasar absorbers. I. Absorption systems toward J2233-606
Levshakov, S. A.; Agafonova, I. I.; Centurión, M. +1 more
The metal line profiles of different ions observed in high H I column density systems [N(H I) > 1016 cm-2] in quasar spectra can be used to constrain the ionization structure and kinematic characteristics of the absorbers. For these purposes, a modified Monte Carlo Inversion (MCI) procedure was applied to the study of thre…
Hubble Space Telescope Observations of the Windblown Nebula NGC 7635
Hester, J. Jeff; Dufour, Reginald J.; Scowen, Paul A. +3 more
We present Hubble Space Telescope observations of the northern part of NGC 7635, a circular shell around the O6.5 IIIf star BD +60°2522. The nebula, which lies within the large emission-line region S162, is notable not only for its symmetric shell, but also for a complex of ``cometary'' knots close to the central star. Our observations include spe…
Time variation of SWS spectra of M-type Mira variables and its dust optical properties. I. Z Cyg
Onaka, T.; Yamamura, I.; de Jong, T.
The M-type Mira variable star, Z Cyg, was observed with the Short-Wavelength Spectrometer (SWS) on board the Infrared Space Observatory (ISO) 7 times at roughly 60 day intervals over one and a half period. The infrared spectrum (2.38-45.2 mu m) of Z Cyg shows prominent silicate emission bands at 10 mu m and 18 mu m and displays quite large variati…
Emission of Positron Annihilation Line Radiation by Clusters of Galaxies
Loeb, Abraham; Furlanetto, Steven R.
Clusters of galaxies are enriched with positrons from jets of active galactic nuclei (AGNs) or from the interaction of cosmic rays with the intracluster gas. We follow the cooling of these positrons and show that their eventual annihilation with cluster electrons yields a narrow annihilation line. Unlike annihilation in the interstellar medium of …
XMM-Newton detection of Nova Muscae 1991 in quiescence
Kolb, U.; Casares, J.; Osborne, J. P. +7 more
The soft X-ray transient GU Mus has been detected by XMM-Newton in the quiescent state. The source is very faint, with a 0.5-10.0 keV unabsorbed flux of =~ 1.1 x 10-14 ergs cm-2 s-1. The spectra is well fit by an absorbed powerlaw with a photon index of alpha = 1.6 +/- 0.4, close to the value seen when the source w…
The stellar mass to light ratio in the isolated spiral NGC 4414
Braine, J.; Baudry, A.; Vallejo, O.
We present high resolution CO(1-0) interferometric observations and deep HST B-V-I images of the flocculent isolated Sc type spiral NGC 4414. The goal is to determine the stellar mass-to-light (M/L) ratio in a galactic disk. NGC 4414 is an ideal object for this kind of study, as it is an unperturbed object at high galactic latitude with very exten…
Space Telescope Imaging Spectrograph Ultraviolet Spectroscopy of Early B Supergiants in M31
Bresolin, Fabio; Kudritzki, Rolf-Peter; Urbaneja, Miguel A. +4 more
We analyze Space Telescope Imaging Spectrograph (STIS) spectra in the 1150-1700 Å wavelength range obtained for six early B supergiants in the neighboring galaxy M31. Because of their likely high (nearly solar) abundance, these stars were originally chosen to be directly comparable to their Galactic counterparts and represent a much needed additio…
The host galaxies of Type Ia supernovae at z= 0.6
Farrah, D.; Rowan-Robinson, M.; Mattila, S. +2 more
We examine the host galaxies of high-redshift Type Ia supernovae (SNe Ia) using archival I- and R-band data from the Hubble Space Telescope. The SNe Ia host galaxies show a wide variety of morphologies, including undisturbed ellipticals, spirals and disturbed systems. SNe Ia are also found over a wide range of projected distances from the host gal…
The 12C/13C Ratio in the Planetary Nebula NGC 3242 from Hubble Space Telescope STIS Observations
Marconi, Alessandro; Tosi, Monica; Stanghellini, Letizia +2 more
We present high-resolution Hubble Space Telescope ultraviolet spectroscopy of NGC 3242, the only planetary nebula with a measured abundance of 3He. The Space Telescope Imaging Spectrograph has been used to observe the C III multiplet near 1908 Å. The presence of 12C and 13C lines at these wavelengths allows a direc…
Solar cycle variation of the temperature structure within the cores of coronal streamers
Foley, C. R.; Culhane, J. L.; Patsourakos, S. +1 more
We use the Coronal Diagnostic Spectrometer onboard the Solar and Heliospheric Observatory (SOHO) to analyze conditions in coronal streamer structures observed close to solar minimum (1996 July 8) and near maximum (1999 August 5). We measured the intensities of emission lines from Fe IX-XV ions and found the most intense emission to be from Fe XI a…