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Hintzen, Paul

Publications and source records attributed to Hintzen, Paul.

At least 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1995

Hubble Space Telescope observations of cool white dwarf stars: Detection of new species of heavy elements

Observations of cool white dwarf stars with the Hubble Space Telescope (HST) has uncovered a number of spectral features from previouslly unobserved species. In this paper we present the data on four cool white dwarfs. We present identifications, equivalent width measurements, and brief summaries of the significance of our findings. The four stars observed are GD 40 (DBZ3, G 74-7 (DAZ), L 745-46A (DZ), and LDS 749B (DBA). Many additional species of heavey elements were detected in GD 40 and G 74-7. In L 745-46A, while the detections are limited to Fe 1, Fe II, and Mg II, the quality of the Mg II h and K line profiles should permit a test of the line broadening theories, which are so crucial to abundance determinations. The clear detection of Mg II h and k in LDS 749 B should, once an abundance determination is made, provide a clear test of the hypothesis that the DBA stars are the result of accretion from the interstellar medium. This star contains no other clear features other than a tantalizing hint of C II 1335 with a P Cygni profile, and some expected He 1 lines.

Shipman, Harry↗
NASA NTRS1993

30 Doradus - Ultraviolet and optical stellar photometry

Ultraviolet Imaging Telescope (UIT) UV magnitudes in four bands, together with optical B magnitudes, are presented for up to 314 early-type stars located in a 9.7 x 9.7 arcmin field centered on R136. The magnitudes have an rms uncertainty estimated at 0.10 mag from a comparison between the UIT magnitudes and the IUE spectra. Spectral types and E(B-V) color excesses are estimated. The mean color excesses following the two extinction curves agree well with the predictions of the two-component extinction model of Fitzpatrick and Savage (1984). However, the degree of nebular extinction is found to vary systematically by large amounts over the 30 Dor field. The minimum of nebular extinction in the central parts of the nebula suggests that dust has been expelled from this region by stellar winds. It is suggested that the form of the UV extinction curve can be understood as a consequence of the evolutionary state of the stellar population responsible for making the dust grains.

Hill, Jesse K.↗
NASA NTRS1993

Wide-field direct CCD observations supporting the Astro-1 Space Shuttle mission's Ultraviolet Imaging Telescope

Wide field direct CCD observations are being obtained to support and complement the vacuum-ultraviolet (VUV) images provided by Astro's Ultraviolet Imaging Telescope (UIT) during a Space Shuttle flight in December 1990. Because of the wide variety of projects addressed by UIT, the fields observed include (1) galactic supernova remnants such as the Cygnus Loop and globular clusters such as Omega Cen and M79; (2) the Magellanic Clouds, M33, M81, and other galaxies in the Local Group; and (3) rich clusters of galaxies, principally the Perseus cluster and Abell 1367. Ground-based observations have been obtained for virtually all of the Astro-1 UIT fields. The optical images allow identification of individual UV sources in each field and provide the long baseline in wavelength necessary for accurate analysis of UV-bright sources. To facilitate use of our optical images for analysis of UIT data and other projects, we plan to archive them, with the UIT images, at the National Space Science Data Center (NSSDC), where they will be universally accessible via anonymous FTP. The UIT, one of three telescopes comprising the Astro spacecraft, is a 38-cm f/9 Ritchey-Chretien telescope on which high quantum efficiency, solar-blind image tubes are used to record VUV images on photographic film. Five filters with passbands centered between 1250A and 2500A provide both VUV colors and a measurement of extinction via the 2200A dust feature. The resulting calibrated VUV pictures are 40 arcminutes in diameter at 2.5 arcseconds resolution. The capabilities of UIT, therefore, complement HST's WFPC: the latter has 40 times greater collecting area, while UIT's usable field has 170 times WFPC's field area.

Hintzen, Paul↗
NASA NTRS1993

Reduction and analysis of VLA maps for 281 radio-loud quasars using the UNLV Cray Y-MP supercomputer

The identification of distorted radio-loud quasars provides a potentially very powerful tool for basic cosmological studies. If large morphological distortions are correlated with membership of the quasars in rich clusters of galaxies, optical observations can be used to identify rich clusters of galaxies at large redshifts. Hintzen, Ulvestad, and Owen (1983, HUO) undertook a VLA A array snapshot survey at 20 cm of 123 radio-loud quasars, and they found that among triple sources in their sample, 17 percent had radio axes which were bent more than 20 deg and 5 percent were bent more than 40 deg. Their subsequent optical observations showed that excess galaxy densities within 30 arcsec of 6 low-redshift distorted quasars were on average 3 times as great as those around undistorted quasars (Hintzen 1984). At least one of the distorted quasars observed, 3C275.1, apparently lies in the first-ranked galaxy at the center of a rich cluster of galaxies (Hintzen and Romanishin, 1986). Although their sample was small, these results indicated that observations of distorted quasars could be used to identify clusters of galaxies at large redshifts. The purpose of this project is to increase the available sample of distorted quasars to allow optical detection of a significant sample of quasar-associated clusters of galaxies at large redshifts.

Ding, Ailian↗
NASA NTRS1992

Ultraviolet Imaging Telescope observations of the Crab Nebula

We obtained ultraviolet images of the Crab Nebula with the Ultraviolet Imaging Telescope during the Astro-1 Space Shuttle mission in 1990 December. The UV continuum morphology of the Crab is generally similar to that in the optical region, but the wispy structures are less conspicuous in the UV and X-ray. UV line emission from the thermal filaments is not strong. UV spectral index maps with a resolution of 10 arcsecs show a significant gradient across the nebula, with the outer parts being redder, as expected from synchrotron losses. The location of the bluest synchrotron continuum does not coincide with the pulsar.

Hennessy, Gregory S.↗
NASA NTRS1992

Astro-1 ultraviolet imaging of the 30 Doradus and SN 1987A fields with the Ultraviolet Imaging Telescope

A preliminary analysis of Ultraviolet Imaging Telescope (UIT) images in the 30 Doradus region is reported. Photometry was obtained for the 30 Doradus cluster and its UV-bright core, R136, in various UIT bandpasses. It is found that about 14 percent of the total FUV light and about 16 percent of the total near-UV light of the 3-arcmin diameter 30 Doradus cluster originates from the region within 5 arcsec of R136. The UV magnitudes and colors of R136 and other known O and Wolf-Rayet WN stars in the same field were measured. The UIT data, combined with published observations at longer wavelengths, indicate that R136a1, the brightest component of R136, is not a supermassive stars. A qualitative comparison between the UIT images, Einstein X-ray data, IRAS HiRes images, and ground-based CCD images in forbidden O III 5007 A, H-alpha, B, R, U, and Stromgren u is performed. The extended diffuse UV feature detected in the UIT images is correlated with the IR structure seen in the IRAS 60-micron HiRes image, which suggests the existence of large amounts of widely distributed dust in this region.

Cheng, Kwang-Ping↗
NASA NTRS1992

Implications of Ultraviolet Imaging Telescope observations for star formation histories in NGC 1275

We discuss UV imagery of NGC 1275 obtained using the Goddard Ultraviolet Imaging Telescope. We are able to study the UV morphology down to mu 249 of about 25 mag/sq arcsec. There are significant nonaxisymmetric structures in the UV continuum associated with the low-velocity filament system. Continuum from the high-velocity system may also be present. The large aperture UV colors indicate that although the mass function extends to about 5 solar masses, more massive objects are not present. This implies either a cessation of star formation during the last 50-100 Myr or a truncated initial mass function.

Smith, Eric P.↗
NASA NTRS1992

Fabry-Perot images of NGC 1275 and its puzzling high-velocity system

The Fabry-Perot imager is used to obtain a velocity sequence of calibrated narrow-band CCD images to cover 3000 km/s velocity space between the redshifted H-alpha emission lines of NGC 1275, its extended associated system of low-velocity (LV) filaments, and the high-velocity (HV) system of knots, projected on the same line of sight in the sky. The lack of intermediate-velocity emission-line gas between the two systems leads to an upper limit of 1.5 x 10 exp -16 ergs/sq cm s sq arcsec (3 sigma) on stripped ionized gas due to the dynamical interaction between NGC 1275 and its HV companion galaxy. It also confirms previous reports that the level of continuum light arising from stellar and nonstellar sources must be very low in otherwise bright, strongly concentrated emission-line knots with unresolved diameters of 425/h pc. The H-alpha luminosities of the emission-line regions of the two systems were measured and star formation rates derived in order to investigate quantitatively the physical relation between the HV galaxy, NGC 1275, and the surrounding cooling flow filaments.

Caulet, Adeline↗
NASA NTRS1992

UIT support observations archive

We are in the process of archiving the approximately 1.2Tbytes of imaging data acquired in support of UIT observations. The UIT is one of three telescopes comprising the ASTRO spacecraft and is a 38-cm f/9 Ritchey-Chretien telescope with wavelength coverage 1200 A to 3000 A and a 40 arcminute diameter field-of-view at 4 min FWHM resolution. During the ASTRO shuttle mission, there were 65 different pointings (some with multiple targets) of the UIT and hence 65 fields. Our support data of these fields were obtained with the KPNO and CTIO 0.9m telescopes and several of the 2048x2048 CCD's. Our images are typically about 20 acrminutes on a side and contain the entire UV target except for nearby galaxies, for which mosaiced images were created. All good quality images in the broadband and narrow band filters for every target are being archived. Though all of the UIT targets were well studied astronomical objects, these frames are many of the first large field format images of them and, when combined with the soon to be released UV frames, provide a unique dataset. These data were already used to address a wide variety of astronomical questions. Vacuum ultraviolet (VUV) observations were used to study star formation in a sample of nearby galaxies, since integrated VUV - optical colors provide the most sensitive available measure of the formation rate of massive stars. The blue stages later in stellar evolution are also being studied. These data allow more accurate determination of the helium and metallicities of hothorzontal branch stars. These data are being prepared to release to the public in CD-ROM format through the National Space Science Data Center.

Smith, Eric P.↗
NASA NTRS1991

The physical properties of double degenerate common proper motion binaries

Spectral types and spectrophotometry are presented for 21 double degenerate (DD) common proper motion binaries, along with estimates of their colors, absolute visual and bolometric magnitudes, and cooling ages. The oldest pairs in the sample are 9 x 10 to the 9th yr; the differential cooling ages range from 0.01 to 0.84. The median and mean separations of the DD pairs are 426 and 407 Au, respectively, both apparently smaller than the WD+MS values. The average UVW motions and velocity dispersions are significantly larger than the average velocities and dispersions associated with selected samples of single white dwarfs and MS+WD binaries when the latter are restricted to the same color/Mv range as the DD systems. This may be a result of the dynamical inflation of the velocity dispersion of DD systems due to their extremely ancient total stellar ages.

Sion, Edward M.↗
NASA NTRS1991

The galaxy activity-interaction connection. I - Optical observations

As part of an investigation into the triggering of nuclear radio emission in interacting galaxies, new multicolor, broadband data are presented from a subset of Arp-Madore Catalog galaxies selected on the basis of their optical morphology - systems with loops and/or tails. The CTIO 4 m is used to obtain images in B, V, R, and I for the purpose of performing synthetic aperture photometry. Isophotal ellipse fitting to the more regular objects in the sample is also performed to quantify their isophotal deviation from purely elliptical morphologies. Color index maps for the galaxies are constructed, and the optical morphologies, broadband colors, and detailed photometric properties as well as the IRAS fluxes for the galaxies are discussed. These data are used to obtain a rough measure of the level of activity present in these systems.

Smith, Eric P.↗
NASA NTRS1991

Galaxies clustering around QSOs with z = 0.9-1.5 and the origin of blue field galaxies

Deep CCD images were obtained in Mould-Cousins R and I passbands of 16 radio quasars with z values between 0.9 and 1.5 and absolute values of b above 35 deg, chosen from the Veron-Cetty and Veron (1984) catalog. Results indicate that, in this population of radio quasars, there is a statistically significant excess of galaxies within 15 arcsec of the quasars and brighter than R = 23 and I = 22. However, contrary to the report of Tyson (1986), no excess was found of galaxies with R less than 21 lying within 30 arcsec of quasars in this redshift range. Data were also obtained for very blue galaxies seen among objects in the general field, all of which are bluer in R-I than Magellanic irregulars at any redshift less than 3. It is suggested that this population might be comprised of low-redshift low-luminosity (H II region) galaxies of the type studied by French (1980) and/or higher redshift galaxies with strong cooling flows and forbidden O II lines.

Hintzen, Paul↗
NASA NTRS1990

Multi-color imaging of selected southern interacting galaxies

The authors present preliminary results from a study of selected Arp-Madore Southern Hemisphere peculiar galaxies. Broadband charge coupled device (CCD) images (BVRI) of a subset of these galaxies allow us to study each galaxy's optical morphology, color, and (in a crude manner) degree of nuclear activity, and to compare them with similar data we possess on other active galaxies. Many of these galaxies have optical morphologies closely resembling those of powerful radio galaxies (Smith and Heckman 1989), yet their radio emission is unremarkable. Accurate positions for subsequent spectroscopic studies have been determined along with broad band photometry and morphology studies. Detailed observations of these comparatively bright, low-redshift, well-resolved interacting systems should aid our understanding of the role interactions play in triggering galaxy activity. This work is the initial effort in a long term project to study the role played by the dynamics of the interaction in the production and manifestations of activity in galaxies, and the frequency of galaxy mergers.

Smith, Eric P.↗
NASA NTRS1989

Three very cool degenerate stars in Luyten common proper motion binaries - Implications for the age of the galactic disk

During the course of a spectroscopic study of Luyten common proper motion (CPM) stars, spectrophotometric observations have been obtained of three binaries containing degenerate stars with estimated absolute magnitudes M(V) of about 16. Each of the three pairs consists of a yellow degenerate star primary and a DC 13 + secondary 1.4-2.3 mag fainter. One of the primary stars is spectral class DC 7, another is a sharp-lined DA 8, and the third shows peculiar broad absorption features which we interpret as pressure-shifted C2 Swan bands. The LP 701 - 69/70 system has survived for over 8 billion years without disruption by passing stars, despite its 1500 a.u. orbital major axis. The three cool degenerate companions nearly double the available sample of stars at the low-luminosity terminus of the white dwarf cooling sequence. These findings appear consistent with the conclusion that degenerate stars in the old disk population have not had time to evolve to a luminosity fainter than M(V) about 16.2.

Hintzen, Paul↗
NASA NTRS1989

The structure of host galaxies of radio-loud quasars and possible triggering mechanisms for quasar activity

An image modeling program is used to analyze optical imaging data for a sample of radio-loud quasars with redshifts between 0.2 and 0.7. It is found that the host galaxies of these quasars tend to be more compact than normal ellipticals. The cooling flow cluster elliptical galaxies near these host galaxies are studied. It is suggested that these cooling flow galaxies are also compact due to star formation in their central regions. Two populations of quasars are identified. One, in which activity is triggered by galaxy mergers of interactions has predominately spiral galaxies and are radio quiet. The other, in which activity is triggered by star formation bursts induced by cooling flows, has predominately elliptical hosts and may be radio loud.

Romanishin, W.↗
NASA NTRS1989

A spiral galaxy at z = 0.366 which overlaps the image of the quasar 4C 39.47

Direct CCD images in broad-band R and I were obtained of the radio quasar 1632+391 (4C 39.46). A faint galaxy which overlaps the quasar's image was identified. The galaxy is centered 4.2 arcsecs east of the quasar, corresponding to 28 kpc at the galaxy's redshift. It is found that the galaxy is a disk-dominated late-type spiral with an absolute B magnitue of -21.6. Low-dispersion spectroscopy yielded a redshift of 0.3662 for the galaxy based on Ca II, H, and K absorption and weak forbidden line O II 3727 emission. It is suggested that appreciable interstellar gas is present in the galaxy.

Hintzen, Paul↗
NASA NTRS1988

Peculiar velocities of cD galaxies - MX spectroscopy of Abell 1795

Spectroscopic observations of galaxies in the Abell 1795 field have been obtained using the MX multiple-object spectrograph on the Steward Observatory 2.3 m telescope. Redshifts are presented for 46 galaxies, including 41 cluster members. It is found that the A1795 cD galaxy is not at rest in the cluster gravitational potential well; it has a peculiar radial velocity, cz, of 365 km/s, and the hypothesis that the mean cluster velocity is as large as the cD's velocity can be rejected at the 99.5 percent confidence level. This conclusion is supported by spectroscopic data for the 'cooling flow' gas found in the central region of the cluster; this gas, except for the portion coincident with the cD nucleus, lies at the velocity derived for the cluster mean. It is suggested that current models of the formation of cD galaxies are unlikely to account for the large peculiar velocities of the cD galaxies in A1795 and A2670 unless substantial subclustering is still present. However, the available data show no evidence for velocity subclustering in either A1795 or A2670.

Hill, John M.↗