Search Publications
Spectrophotometric Standards from the Far-Ultraviolet to the Near-Infrared: STIS and NICMOS Fluxes
Calzetti, D.; Dickinson, M. E.; Bohlin, R. C.
With photometric repeatability in the 0.2%-0.4% range and wavelength coverage from 1150 to 10,200 Å, the Space Telescope Imaging Spectrograph (STIS) low-dispersion spectrophotometry provides excellent absolute flux standards. STIS observations of 19 stars are used to update the database of Hubble Space Telescope standard stars with absolute fluxes…
The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. II. Basic Parameters of Program Stars and the Role of Microturbulence
Gray, R. O.; Graham, P. W.; Hoyt, S. R.
Paper I of this series presented precise MK spectral types for 372 late A-, F-, and early G-type stars with the aim of understanding the nature of luminosity classification on the MK spectral classification system for this range of spectral types. In this paper, a multidimensional downhill simplex technique is introduced to determine the basic par…
A Detailed Analysis of a Cygnus Loop Shock-Cloud Interaction
Blair, William P.; Danforth, Charles W.; Raymond, John C.
The XA region of the Cygnus Loop is a complex zone of radiative and nonradiatve shocks interacting with interstellar clouds. We combine five far ultraviolet spectral observations from the Hopkins Ultraviolet Telescope (HUT), a grid of 24 IUE spectra, and a high-resolution long-slit Hα spectrum to study the spatial emission line variations across t…
Nuclear Turnoff Times for ONEMG Novae Determined Using Ultraviolet Spectral Evolution
Shore, Steven N.; Starrfield, Sumner; Vanlandingham, Karen M. +1 more
Classical novae go through a phase of constant bolometric luminosity as any remaining hydrogen in the accreted layers on the white dwarf is converted to helium. The length of this phase is dependent on many factors, including the amount of mass left on the white dwarf after the explosive phase of the outburst, the white dwarf's mass, and the effic…
Hubble Space Telescope and Ground-based Spectroscopy of K648 in M15
Ford, Holland; Bianchi, Luciana; Bohlin, Ralph +2 more
We derive some element abundances for the central star of the planetary nebula K648 from analysis of Hubble Space Telescope Faint Object Spectrograph spectra (1200-3300 Å). Carbon is found to be approximately 4 times overabundant with respect to solar values, while oxygen is underabundant and silicon about solar, and He/H=0.6. The stellar continuu…
Ultraviolet Signposts of Resonant Dynamics in the Starburst-ringed SAB Galaxy M94 (NGC 4736)
Madore, Barry F.; Keel, William C.; O'Connell, Robert W. +10 more
The dynamic orchestration of star-birth activity in the starburst-ringed galaxy M94 (NGC 4736) is investigated using images from the Ultraviolet Imaging Telescope (UIT; far-ultraviolet [FUV] band), Hubble Space Telescope (HST; near-ultraviolet [NUV] band), Kitt Peak 0.9 m telescope (Hα, R, and I bands), and Palomar 5 m telescope (B band), along wi…
Abundances in the Planetary Nebula IC 5217
Feibelman, Walter A.; Hyung, Siek; Aller, Lawrence H. +1 more
High-resolution optical wavelength spectroscopic data were secured in the optical wavelengths, 3700-10050 Å, for the planetary nebula IC 5217 with the Hamilton Echelle Spectrograph at Lick Observatory. These optical spectra have been analyzed along with the near-UV and UV archive data. Diagnostic analyses indicate a nebular physical condition with…
An Ultraviolet Study of the Short-Period Binary OO Aquilae
Guinan, Edward F.; Hrivnak, Bruce J.; Ribas, Ignasi +1 more
OO Aql is a rare W UMa-type eclipsing binary in which the two solar-type stars may have only recently evolved into contact. The binary has an unusually high mass ratio (0.84) and a relatively long orbital period (0.506 days) for its spectral type (mid-G). Twelve ultraviolet spectra of OO Aql were obtained in 1988 with the International Ultraviolet…
Infrared Space Observatory Short Wavelength Spectrometer Observations of V1425 Aquilae (Nova Aquila 1995)
Morisset, C.; Humphreys, R. M.; Gehrz, R. D. +19 more
We present observations of the classical nova V1425 Aquilae (Nova Aquila 1995) with the Infrared Space Observatory's (ISO) Short Wavelength Spectrometer, the Isaac Newton Telescope's Intermediate Dispersion Spectrograph, and the International Ultraviolet Explorer's Short-Wavelength Primary Spectrograph. Analysis of He II (1640 Å) development const…
The Accretion Disk and White Dwarf in the U Geminorum type Dwarf Novae UZ Serpentis and SS Aurigae during Quiescence
Sion, Edward M.; Lake, Joshua
We have carried out high-gravity model atmosphere and accretion disk synthetic spectral fits for the U Geminorum type dwarf novae during quiescence. For UZ Ser, we find that the far-UV spectrum is best fitted with a logg=8, Teff=27,000 K photosphere with abundances near solar. The best-fit accretion disk model for UZ Ser has Mwd