Search Publications

He 2-104: A Link Between Symbiotic Stars and Planetary Nebulae

Shaw, Richard A.; Lutz, Julie H.; Kaler, James B. +2 more

Ultraviolet, optical and infrared observations of He 2-104 are presented, and estimates for some of the physical properties of the nebular shell are made. It is argued that He 2-104 is in transition between the D-type symbiotic star and bipolar planetary nebula phases and, as such, represents a link between subclasses of these two types of objects…

Ultraviolet Observations of the Planetary Nebula NGC 2242

Garnett, Donald R.; Dinerstein, Harriet L.

We present IUE observations of the high-ionization planetary nebula NGC 2242. The ultraviolet spectrum exhibits stong emission lines of C IV, He II, C III], and [Ne IV], plus weaker emission from O IV and N IV. We have also obtained narrow-band imaging of NGC 2242 in the He II 4686 A emission line; comparison of the λ 4686 flux from this image wit…

Systematic Errors in Spectral Features Introduced by Random Noise

Joseph, Charles L.

A common IUE computer routine for measuring equivalent widths is shown to introduce systematic errors in data containing large amounts of noise. During statistical tests using simulations of synthetic spectral features with noise characteristics similar to those of the IUE, the routine was found to overestimate the true strength of an absorption l…