Search Publications

ASCA (and HST) observations of NLS1s

Leighly, Karen M.

The study of NLS1s using ASCA has many advantages. A representative sample can be studied; to date, observations of more than 30 NLS1s have been made. ASCA observations are conducted contiguously, so their X-ray variability properties can be studied systematically. ASCA detectors have a broad band pass and moderate energy resolution, properties wh…

FOS observations of four NLS1s

Goodrich, Robert W.

Ultraviolet through optical spectroscopy of four NLS1s shows strong absorption features in the high-ionization UV resonance lines such as C IV, N V, and Si IV. Mg II is not absorbed. The absorption could originate in the warm absorber.

Chemical enrichment by massive stars

Thuan, T. X.; Izotov, Y. I.

Heavy element abundances derived from high-quality ground-based and Hubble Space Telescope (HST) spectroscopic observations of low-metallicity blue compact galaxies (BCGs) with oxygen abundances 12+log O/H between 7.1 and 8.3 are discussed. None of the heavy element-to-oxygen abundance ratios studied here (C/O, N/O, Ne/O, Si/O, S/O, Ar/O, Fe/O) de…

Extragalactic novae

Shara, Michael M.

Novae are expected to form in all stellar systems with a binary population. Detection of extragalactic novae provides direct evidence of close binary populations and possible spatial variations in those populations. Comparison of extragalactic novae with their local counterparts can yield valuable tests of close binary evolution theory. I report e…

What we learn from quantitative ultraviolet spectroscopy of naked white dwarfs in cataclysmic variables

Long, Knox S.

Using the Hopkins Ultraviolet Telescope and Hubble Space Telescope, observers have now obtained UV spectra with sufficient signal to noise and resolution to allow quantitative spectroscopic analyses of the WDs in several DNe. In the "cleanest" DNe, such as U Gem, the observations are allowing the basic physical parameters of the WD - temperature, …

Molecular gas and star formation in the host galaxy of I Zw 1

Schinnerer, Eva; Eckart, Andreas; Tacconi, Linda

A recent analysis of high angular resolution NIR imaging and spectroscopic data in conjunction with Plateau de Bure interferometric mm-line observations indicate the presence of a circum-nuclear starburst ring of ∼1.5″ (1.5 kpc) diameter in I Zw 1. High angular resolution NIR imaging, using the MPE SHARP camera at the ESO NTT, HST V-band images, a…