Search Publications
Central Stars of Planetary Nebulae in the Large Magellanic Cloud: A Far-Ultraviolet Spectroscopic Analysis
Bianchi, L.; Herald, J. E.
We observed seven central stars of planetary nebulae (PNe) in the Large Magellanic Cloud (LMC) with the Far Ultraviolet Spectroscopic Explorer and performed a model-based analysis of these spectra in conjunction with Hubble Space Telescope spectra in the UV and optical range to determine the stellar and nebular parameters. Most of the objects show…
Resolving the Nature of the Large Magellanic Cloud Microlensing Event MACHO-LMC-5
Cook, K. H.; Drake, A. J.; Keller, S. C.
We present the results from an analysis of Hubble Space Telescope high-resolution camera data for the Large Magellanic Cloud microlensing event MACHO-LMC-5. By determining the parallax and proper motion of this object, we find that the lens is an M dwarf star at a distance of 578+65-53 pc with a proper motion of 21.39+/-0.04 …
Effects of Metallicity on the Rotational Velocities of Massive Stars
Gies, Douglas R.; Penny, Laura R.; Sprague, Amanda J. +1 more
Recent theoretical predictions for low-metallicity massive stars predict that these stars should have drastically reduced equatorial winds (mass loss) while on the main sequence, and so should retain most of their angular momentum. Observations of both the Be/(B+Be) ratio and the blue-to-red supergiant ratio appear to have a metallicity dependence…
The Galactic Inner Halo: Searching for White Dwarfs and Measuring the Fundamental Galactic Constant, Θ0/R0
Rich, R. Michael; Gibson, Brad K.; Stetson, Peter B. +9 more
We establish an extragalactic, zero-motion frame of reference within the deepest optical image of a globular star cluster, a Hubble Space Telescope (HST) 123 orbit exposure of M4 (GO 8679, Cycle 9). The line of sight beyond M4 (l,b=351deg,16deg) intersects the inner halo (spheroid) of our Galaxy at a tangent-point distance of…
An Erupting Classical Nova in a Globular Cluster of M87
Zurek, David R.; Lauer, Tod R.; Shara, Michael M. +2 more
Only one certain classical nova eruption has ever been detected inside a globular cluster-nova T Sco (observed in A.D. 1860) in M80. During a survey of M87 we have detected an erupting star coincident (to within 0.08 pixels) with a globular cluster of that giant elliptical galaxy. We are able to discount variables in the foreground or background o…
Strong Gravitational Lens Candidates in the GOODS ACS Fields
Ferguson, H. C.; Moustakas, L. A.; Lucas, R. A. +3 more
We present results from a systematic search for strong gravitational lenses in the Great Observatories Origins Deep Survey (GOODS) Advanced Camera for Surveys (ACS) data. The search technique involves creating a sample of likely lensing galaxies, which we define as massive early-type galaxies in a redshift range 0.3<z<1.3. The target galaxie…
On the Formation of Extreme-Ultraviolet Helium Lines in the Sun: Analysis of SOHO Data
Judge, Philip G.; Pietarila, Anna
The resonance lines of helium in the Sun are several times stronger than expected, relative to lines of other ions. To explore the origins of this ``helium enhancement,'' we have studied data from the SUMER, CDS, MDI, and EIT instruments on the Solar and Heliospheric Observatory (SOHO). Time series data obtained in a quiet region and a coronal hol…
The Magnetic Structure of Hα Macrospicules in Solar Coronal Holes
Wang, H.; Moore, R. L.; Suess, S. T. +2 more
Measurements by Ulysses in the high-speed polar solar wind have shown the wind to carry some fine-scale structures in which the magnetic field reverses direction by having a switchback fold in it. The lateral span of these magnetic switchbacks, translated back to the Sun, is of the scale of the lanes and cells of the magnetic network in which the …
Magnetostatic Structures of the Solar Corona. III. Normal and Inverse Quiescent Prominences
Zhang, M.; Low, B. C.
Analytical solutions describing equilibrium magnetic fields in the solar corona, deformed by prominence-like plasma condensations in the Cartesian plane, are treated in this paper. The equilibrium equations for this class of problems usually take different forms in distinct subdomains, separated by free boundaries to be solved as one of the unknow…
Methane Abundance Variations toward the Massive Protostar NGC 7538 IRS 9
Blake, G. A.; Boogert, A. C. A.; Öberg, K.
Absorption and emission lines originating from the ν3 CH stretching manifold of gas-phase CH4 were discovered in the high-resolution (R=25,000) infrared L-band spectrum along the line of sight toward NGC 7538 IRS 9. These observations provide a diagnostic of the complex dynamics and chemistry in a massive star-forming region.…