Search Publications
The Surprising Emission Distribution within the Helix Nebula Cometary Knots
O'Dell, C. R.; Henney, W. J.; Burkert, A.
We compare the morphology of the cometary knots in the Helix Nebula in different emission lines using Hubble Space Telescope Wide Field Planetary Camera 2 and Space Telescope Imaging Spectrograph observations. We find that the [N II] 6658 Å line emission from the cometary heads is displaced with respect to Hα, peaking at a position that is closer …
Optical and Infrared Images and Spectroscopy of the HH 168 Bubble in Cepheus A
Hartigan, Patrick; Bally, John; Morse, Jon
We present new optical emission-line and continuum images taken with the Hubble Space Telescope of the shocked bubble HH 168 (GGD 37) associated with the massive star formation region Cepheus A. The new images clearly resolve the interface between the molecular flow, defined by near-IR images of H2, and the shocked, optically emitting g…
A Close-Separation Double Quasar Lensed by a Gas-rich Galaxy
White, Richard L.; Wisotzki, Lutz; Gregg, Michael D. +5 more
In the course of a Cycle 8 snapshot imaging survey with the Space Telescope Imaging Spectrograph (STIS), we have discovered that the z=1.565 quasar HE 0512-3329 is a double with image separation 0.644", differing in brightness by only 0.4 mag. This system is almost certainly gravitationally lensed. Although separate spectra for the two images have…
Interferometric Astrometry of the Detached White Dwarf-M Dwarf Binary Feige 24 Using HST Fine Guidance Sensor 3: White Dwarf Radius and Component Mass Estimates
Hemenway, P. D.; Jefferys, W. H.; Nelan, E. +14 more
With Hubble Space Telescope Fine Guidance Sensor 3 we have determined a parallax for the white dwarf-M dwarf interacting binary, Feige 24. The white dwarf (DA) component has an effective temperature Teff~56,000 K. A weighted average with past parallax determinations (πabs=14.6+/-0.4 mas) narrows the range of possible radius v…
The Asymmetric Coma of Comets. I. Asymmetric Outgassing from the Nucleus of Comet 2P/Encke
Festou, M. C.; Barale, O.
Very little is known about how outgassing regions are distributed over the nucleus of comets. In periodic comets, active regions are believed to be few and of small extent. Since periodic comets are notorious for their lack of (small) solid particles that efficiently scatter sunlight, we try to find traces of the existence of production sites by e…
V1334 Cygni: A Triple System Containing a Classical Cepheid
Evans, Nancy Remage
We have observed the small-amplitude Cepheid V1334 Cyg A (pulsation period 3.3 days) for nearly 30 years. From these radial velocity data we have derived an orbit with a period of 5 years. From this orbit we have derived limits on the mass of the companion (V1334 Cyg C) of 3.1 to 4.4 Msolar. The system is also a marginally resolved visu…
Globular Clusters in the DE,N Galaxy NGC 3115 DW1: New Insights from Spectroscopy and Hubble Space Telescope Photometry
Brodie, Jean P.; Kissler-Patig, Markus; Puzia, Thomas H. +1 more
The properties of globular clusters in dwarf galaxies are key to understanding the formation of globular cluster systems and in particular in verifying scenarios in which globular cluster systems of larger galaxies formed (at least partly) from the accretion of dwarf galaxies. Here, we revisit the globular cluster system of the dE,N galaxy NGC 311…
The Stellar Content of the Halo of NGC 5907 from Deep Hubble Space Telescope NICMOS Imaging
Zepf, Stephen E.; Graham, James R.; Sackett, Penny D. +2 more
We present H-band images obtained with the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) of a field 75" (5 kpc) above the plane of the disk of the edge-on spiral galaxy NGC 5907. Ground-based observations have shown that NGC 5907 has a luminous halo with a shallow radial profile between 4 and 8 kpc that roughly traces the dark matter…
Hubble Space Telescope Imaging of Central Stars of High-Excitation Planetary Nebulae with WFC and WFPC2
Groth, Edward J.; Wolff, Michael J.; Code, Arthur D.
We present observations of four high excitation planetary nebulae (IC 2165, Me 2-1, NGC 2440, NGC 7027) taken with the Wide Field Camera and the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. The high angular resolution of the instruments allows for the unambiguous identification of the central star, which was not found to be t…
Supernova Remnants in the Fossil Starburst in M82
Chevalier, Roger A.; de Grijs, Richard; O'Connell, Robert W. +2 more
We report the discovery of 10 compact Hα-bright sources in the poststarburst region northeast of the center of M82, called M82 B. These objects have Hα luminosities and sizes consistent with Type II supernova remnants (SNRs). They fall on the same Hα surface brightness-diameter relation (Σ-D) defined by SNRs in other nearby star-forming galaxies, …