Search Publications
Detection of the Methyl Radical on Neptune
Encrenaz, T.; Feuchtgruber, H.; Bézard, B. +1 more
We report the first detection of the methyl radical (CH3) in the upper atmosphere of Neptune. Observations with the Short-Wavelength Spectrometer of the Infrared Space Observatory (ISO) satellite at a resolving power of 2200 revealed several emission features from the ν2 Q-branch of CH3 around 16.50 µm. The c…
Intrinsic Absorption Lines in the Seyfert 1 Galaxy NGC 5548: Ultraviolet Echelle Spectra from the Space Telescope Imaging Spectrograph
Crenshaw, D. Michael; Kraemer, Steven B.
We present the first observations of a Seyfert galaxy with the echelle gratings on the Space Telescope Imaging Spectrograph (STIS), which provide high-resolution (λ/Δλ~ 40,000) coverage of the intrinsic UV absorption lines in NGC 5548. We confirm the presence of five kinematic components of absorption in Lyα, C IV, and N V at radial velocities of …
The Location of the Nucleus of NGC 1068 and the Three-dimensional Structure of Its Nuclear Region
Kishimoto, Makoto
The Hubble Space Telescope (HST) archival UV imaging polarimetry data of NGC 1068 are reexamined. Through an extensive estimation of the observational errors, we discuss whether the distribution of the position angles (P.A.s) of polarization is simply centrosymmetric or not. Taking into account the effect of a bad focus at the time of the observat…
A Gas-rich Nuclear Bar Fueling a Powerful Central Starburst in NGC 2782
Smith, Beverly J.; Jogee, Shardha; Kenney, Jeffrey D. P.
We present evidence that the peculiar interacting starburst galaxy NGC 2782 (Arp 215) harbors a gas-rich nuclear stellar bar feeding an M82-class powerful central starburst, from a study based on high-resolution interferometric CO (J=1-->0) data and optical BVR and Hα observations, along with available near-infrared (NIR) images, a 5 GHz radio …
Evidence for Non-Maxwellian Electron Energy Distributions in the Solar Transition Region: Si III Line Ratios from SUMER
Wilhelm, K.; Curdt, W.; Mathioudakis, M. +3 more
Recent calculations of Si III emission-line strengths are compared with SUMER observations from a quiet solar region, a coronal hole, and an active region. Diagnostic line ratios are used to derive Te and Ne for the emitting plasma in each region, and good agreement between theory and observations is found. A major enhancemen…
The Distribution of Collisionally Induced Blue Stragglers in the Color-Magnitude Diagram
Sills, Alison; Bailyn, Charles D.
A primary production mechanism for blue stragglers in globular clusters is thought to be collisionally induced mergers, perhaps mediated by dynamical encounters involving binary stars. We model the formation and evolution of such blue stragglers and produce theoretical distributions of them in the color-magnitude diagram. We use a crude representa…
Mercury in the HgMn Stars χ Lupi and HR 7775
Wahlgren, Glenn M.; Brandt, John C.; Proffitt, Charles R. +5 more
Observations of mercury lines in the HgMn stars χ Lupi and HR 7775 made with the Hubble Space Telescope Goddard High Resolution Spectrograph are presented and analyzed. In χ Lupi we find that all observed lines are consistent with the same isotopic mixture (essentially pure 204Hg). Strong ionization anomalies are present, with UV Hg I l…
High-Resolution Infrared Imaging and Spectroscopy of the Pistol Nebula: Evidence for Ejection
Rich, R. Michael; Serabyn, Eugene; Geballe, T. R. +5 more
We present new infrared images, obtained with the Hubble Space Telescope (HST) Near-Infrared Camera and Multiobject Spectrometer (NICMOS), and Brα (4.05 µm) spectroscopy, obtained using CGS4 on UKIRT, of the Pistol Star and its associated nebula. We find strong evidence to support the hypothesis that the Pistol Nebula was ejected from the Pi…
NICMOS Narrowband Images of OMC-1
O'Dell, C. R.; Schultz, A. S. B.; Young, E. T. +5 more
We present images of a 90''×90'' field centered on the Becklin-Neugebauer object (BN) in OMC-1, taken with the Near-Infrared Camera and Multiobject Spectrometer (NICMOS) aboard the Hubble Space Telescope. The observed lines are H2 1-0 S(1), Paα, [Fe II] 1.64 µm, and the adjacent continua. The region is rich i…
First Extragalactic Direct Detection of Large-Scale Molecular Hydrogen in the Disk of NGC 891
van der Werf, Paul P.; Valentijn, Edwin A.
We present direct observations of molecular hydrogen in the disk of the nearby edge-on spiral galaxy NGC 891. With Infrared Space Observatory's Short-Wavelength Spectrometer (SWS) it has been possible, for the first time, to observe the lowest pure rotational lines of H2 [S(0) at 28.2 µm and S(1) at 17.0 µm] at eight positio…