Shaw, Richard A. | Engineering Papers

DOE OSTI2023

LSE-163: Data Products Definition Document

This document describes the data products and processing services to be delivered by the NSF-DOE Vera C. Rubin Observatory whilst performing the Legacy Survey of Space and Time (LSST). LSST will deliver three levels of data products and services. Prompt data products are computed and released within 24 hours of observation, and include images, difference images, catalogs of sources and objects detected in difference images, and catalogs of Solar System objects. Their primary purpose is to enable rapid follow-up of time-domain events. Data Release data products are computed during annual processing campaigns, and include well-calibrated single-epoch images, deep coadds, and catalogs of objects, sources, and forced sources, enabling static sky and precision time-domain science. The Science Platform will allow for the creation of User Generated data products and will enable science cases that greatly benefit from co-location of user processing and/or data within the Rubin Observatory Data Access Center. LSST will also devote 10% of observing time to programs with special cadence. Their data products will be created using the same software and hardware as Prompt and Data Release products. All data products will be made available using user-friendly databases and web services.

79 ASTRONOMY AND ASTROPHYSICS↗

NASA NTRS1991

PB 6 and its central star

It is found that the hot nucleus of the Type I southern planetary nebula PB 6 is a member of the rare class of O VI stars. The blended O VI 3811 + 3834 emission doublet is one of the strongest seen, with an equivalent width (relative to the stellar continuum) of about 400 A. The helium, nitrogen, and carbon abundances are all very high for the core mass and the relations found by Kaler and Jacoby (1990). The Ne/O ratio, at 0.17, is close to the norm found for planetaries, which supports the high O/H, while the S/O is roughly solar.

Kaler, James B.↗

NASA NTRS1990

Large planetary nebulae and their significance to the late stages of stellar evolution

Spectrophotometry of 75 large PNe with Shklovsky radii greater than 0.15 pc is presented and used to calculate nebular parameters and compositions, stellar Zanstra temperatures and luminosities, and core masses. Nine new Peimbert type I nebulae are identified. About 40 percent of the stars that are on cooling tracks are above 0.7 solar mass, and over 15 percent are above 0.8 solar mass. The large planetaries demonstrate a clear positive correlation between nitrogen enrichment and core mass. N/O is anticorrelated with O/H. The radii of the nebulae whose stars lie along specific cooling tracks increase monotonically with decreasing central star temperature. For a given central temperature, the nebular radii also increase with increasing core mass, showing that in this part of the log L-log T plane the higher mass cores evolve more slowly in agreement with theoretical prediction. However, theoretical evolutionary rates for the large nebulae stars appear to be much too slow.

Kaler, James B.↗

NASA NTRS1990

An accurate registration technique for distorted images

Accurate registration of International Ultraviolet Explorer (IUE) images is crucial because the variability of the geometrical distortions that are introduced by the SEC-Vidicon cameras ensures that raw science images are never perfectly aligned with the Intensity Transfer Functions (ITFs) (i.e., graded floodlamp exposures that are used to linearize and normalize the camera response). A technique for precisely registering IUE images which uses a cross correlation of the fixed pattern that exists in all raw IUE images is described.

Delapena, Michele↗

NASA NTRS1990

A new photometric correction technique for the IUE final archive

A substantial fraction of the noise in reduced International Ultraviolet Explorer data is shown to result from limitations of the image processing methods used. An improved method for photometrically correcting spectral images that will be used in the IUE final archive processing software is described. An image processed with this photometric correction software is shown to have not only lower noise overall, but none of the periodic changes in noise amplitude. The improvement that is realized through the approach not only solves a long standing difficulty with IUE data reduction techniques, but substantially enhances the quality of the IUE archive.

Shaw, Richard A.↗

NASA NTRS1990

Line profiles and the kinematics of the narrow-line region in Seyfert galaxies

High signal-to-noise ratio and long-slit CCD spectra at about 100 km/sec resolution have been obtained for six high-ionization Seyfert galaxies. By subtracting the stellar absorption features with the aid of continuum templates, and using deblending techniques, the asymmetry indices of a number of optical emission-line profiles were measured, spanning a wide range in both ionization potential and critical density in each galaxy. The fundamental problem of the cloud-motion direction in the narrow-line region (NLR) has been studied, using these measurements and on the assumption that the preponderance of blueward profile asymmetries requires radial motion as well as a source of extinction. Simple and spherically symmetric NLR simulations are performed to demonstrate that infall and outflow models can be distinguished by comparing asymmetry indices as a function of ionization potential and critical density.

De Robertis, M. M.↗

NASA NTRS1989

He 2-104 - A link between symbiotic stars and planetary nebulae?

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. The model includes a binary system with a Mira variable and a hot, evolved star. Previous mass loss has resulted in the formation of a disk of gas and dust around the whole system, while the hot star has an accretion disk which produces the observed highly ionized emission line spectrum. Emission lines from cooler, lower density gas is also observed to come from the nebula. In addition, matter is flowing out of the system in a direction perpendicular to the disk with a high velocity and is impacting upon the previously-ejected red giant wind and/or the ambient interstellar medium.

Lutz, Julie H.↗

NASA NTRS1989

He 2-104: A link between symbiotic stars and planetary nebulae

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. The model includes a binary system with a Mira variable and a hot, evolved star. Previous mass loss has resulted in the formation of a disk of gas and dust around the whole system, while the hot star has an accretion disk which produces the observed highly ionized emission line spectrum. Emission lines from cooler, lower density gas is also observed to come from the nebula. In addition, matter is flowing out of the system in a direction perpendicular to the disk with a high velocity and is impacting upon the previously-ejected red giant wind and/or the ambient interstellar medium.

Lutz, Julie H.↗

NASA NTRS1989

A case study of a WC planetary nebula nucleus - Henize 2-99

The WC spectrum of the nucleus of the planetary nebula Henize 2-99. Fluxes are given, emission lines are identified, and blends are described. The most powerful emissions are C III, C II, and C IV. O, H, and Si lines are also observed, but little stellar nitrogen is found except for N V. The interstellar extinction is estimated at c = 0.9 + or - 0.2. Blackbody, Zanstra, and Stoy temperatures are found to be 70,000 K, 26,000 K, and 27,000 K, respectively. It is shown that He 2-99 is binebulous with a prominent enhancement in H-alpha along the minor axis. The structural characteristics of He 2-99 are very similar to BD +30 deg 3639 and NGC 40.

Kaler, James B.↗