Search Publications
High-Resolution Imaging of Proto-Planetary Nebulae: The Effects of Orientation
Kwok, Sun; Hrivnak, Bruce J.; Su, Kate Y. L.
Deep Hubble Space Telescope (HST) F814W images were obtained of six proto-planetary nebulae (PPNs), each of which shows a bipolar morphology but with a difference in orientation. Two of these (IRAS 17245-3951 and IRAS 22574+6609) show a dark lane separating bipolar lobes and appear to be seen approximately edge-on. The other four (IRAS 16594-4656,…
Preliminary Astrometric Masses for Proposed Extrasolar Planetary Companions
Han, Inwoo; Gatewood, George; Black, David C.
As a first step in the implementation of an astrometric survey, we have reduced the Hipparcos intermediate astrometric data (IAD) for 30 stars that currently exhibit small-amplitude periodic radial velocity variations. We consider only systems with periods longer than 10 days, where the motion is attributed to the presence of an ``extrasolar plane…
Quasi-periodic Oscillation in Seyfert Galaxies: Significance Levels. The Case of Markarian 766
Yaqoob, Tahir; Staubert, Rüdiger; Wilms, Jörn +2 more
We discuss methods to compute significance levels for the existence of quasi-periodic oscillations (QPOs) in active galactic nuclei (AGNs) that take the red-noise character of the X-ray light curves of these objects into account. Applying epoch folding and periodogram analysis to the XMM-Newton observation of the Seyfert galaxy Mrk 766, a possible…
Chromospheric Heating in the Late Phase of Two-Ribbon Flares
De Pontieu, B.; Czaykowska, A.; Alexander, D.
Fast upflows observed in the late gradual phase of an M6.8 two-ribbon flare by the Solar and Heliospheric Observatory/Coronal Diagnostic Spectrometer have provided evidence for the presence of chromospheric evaporation more than an hour after the impulsive phase of the flare. The chromospheric heating necessary to generate these upflows requires t…
Imaging and Photometry of Comet C/1999 S4 (LINEAR) Before Perihelion and After Breakup
Woodney, Laura M.; Schleicher, David G.; Farnham, Tony L. +3 more
We analyzed photometric measurements and images of comet C/LINEAR before perihelion and after its breakup. Results from our photometry data include a lower limit of 0.44 kilometer for the radius of the nucleus before breakup, and a determination that it was depleted in carbon-chain molecules relative to most other comets. Our imaging and modeling …
The host galaxy and optical light curve of the gamma-ray burst GRB 980703
Tanvir, N.; Pedersen, H.; Fynbo, J. P. U. +10 more
We present deep HST/STIS and ground-based photometry of the host galaxy of the gamma-ray burst
Ultraluminous Infrared Galaxies: Mergers of Sub-L* Galaxies?
Lucas, Ray A.; Colina, Luis; Bushouse, Howard +6 more
A sample of 27 low-redshift, mostly cool, ultraluminous infrared galaxies (ULIRGs) has been imaged at 1.6 µm with the Hubble Space Telescope (HST) Near-Infrared Camera and Multi-Object Spectrometer (NICMOS). The majority (67%) of the sample's galaxies are multiple-nucleus galaxies with projected separations of up to 17 kpc, and the rest of t…
Star clusters in M 33. IV. A new survey from deep HST images
Ford, H. C.; Bianchi, L.; Chandar, R.
We have detected 102 star clusters in M 33, from 35 deep Hubble Space Telescope (HST) WFPC2 fields taken from our program and from the HST archive. Twenty-eight fields have V and I band imaging, and an additional seven fields are imaged in a single V filter. Eighty-two of the clusters were previously unknown. Integrated photometry reveals that 25 …
Hubble Space Telescope Observations of Dust and Star-forming Regions in the Ocular Galaxy IC 2163 and Its Spiral Companion NGC 2207
Brinks, Elias; Struck, Curtis; Elmegreen, Bruce G. +4 more
Hubble Space Telescope observations in U, B, V, and I passbands of the interacting spiral galaxies IC 2163 and NGC 2207 are used to measure extinctions in the cloud and intercloud regions and ages and luminosities of the star-forming regions. The extinction in the part of NGC 2207 seen in projection against IC 2163 was determined by using the meth…
ISOCAM Imaging of Comets 103P/Hartley 2 and 2P/Encke
Fulle, M.; Brucato, J. R.; Mennella, V. +7 more
We present the results of ISOCAM observations performed on Comets 2P/Encke and 103P/Hartley 2, on 31 October 1997 and 1 January 1998, respectively. Images were obtained in the broadband filters LW3 (centered at 15.00 µm) and LW10 (centered at 11.50 µm). Tail models have been applied to the images to analyze the evolution of the dust co…