Search Publications
Measurement of T Tauri Binaries Using the Hubble Space Telescope Fine Guidance Sensors
Simon, M.; Taff, L. G.; Holfeltz, S. T.
We report measurements of young star multiples in the Taurus star-forming region using the Fine Guidance Sensors (FGS) of the HST. Of the eight confirmed IR-discovered multiples, the FGS detected six in visible light: DF Tau, ZZ Tau, V928 Tau, Elias 12, HV Tau, and GN Tau. The V-band magnitudes of the components range from 12.1 to 16.4 mag, and th…
Keck Spectroscopy and Hubble Space Telescope Imaging of Field Galaxies at Moderate Redshift
Illingworth, Garth D.; Forbes, Duncan A.; Koo, David C. +1 more
We present 18 spectra, obtained with the Keck 10 m telescope, of faint field galaxies (19 <I < 22, 0.2 < z < 0.84) previously imaged by the Hubble Space Telescope (HST) Wide Field and Planetary Camera 2 (WFPC2). Though small, our sample appears to be representative of field spirals with a magnitude limit of I <= 22. Combining the re…
Are Hubble Deep Field Galaxy Counts Whole Numbers?
Spergel, David N.; Ostriker, Jeremiah P.; Rhoads, James E. +1 more
The Hubble Deep Field (HDF) offers the best view to date of the optical sky at faint magnitudes and small angular scales. Early reports suggested that faint source counts continue to rise to the completeness limit of the data, which implies a very large number of galaxies. In this Letter, we use the two-point angular correlation function and numbe…
Stellar Variability in the Central Populations of 47 Tucanae from WF/PC Observations with the Hubble Space Telescope. II. Binary Systems
Gilliland, Ronald L.; Saha, Abhijit; Shara, Michael M. +3 more
Stars in the core of 47 Tuc have been intensively surveyed for variability, using differential time series photometry, with the Planetary Camera of the Hubble Space Telescope. Some 20,000 stars were surveyed in the U band (F336W) in a 66" x 66" field centered on the core of 47 Tuc, with almost continuous observing over 38.5 hr, and using 1000 s ex…
WFPC2 Observations of the Cooling Flow Elliptical in Abell 1795
Casertano, Stefano; Holtzman, Jon; Ballester, Gilda E. +16 more
We present WFPC2 images of the core of the cooling flow cD galaxy in Abell 1795. An irregular, asymmetric dust lane extends 7 h^{-1}75 kpc in projection to the north-northwest. The dust shares the morphology observed in the H alpha and excess UV emission. We see both diffuse and knotty blue emission around the dust lane, especially at t…
Hubble Space Telescope Imaging and Polarimetry of NGC 5128 (Centaurus A)
Capetti, A.; Sparks, W. B.; Macchetto, F. +2 more
We present imaging and polarimetry of NGC 5128 in the R and I bands obtained using the Hubble Space Telescope (HST) Wide Field Planetary Camera. The morphology and polarization properties of NGC 5128 at these wavelengths are dominated by the presence of the dust lane. The apparent V-band extinction ranges from 0.5 to 7 mag. The overall pattern of …
The Distance to Two Neutral Hydrogen Clouds: The High-Velocity Complex A and the Low-Latitude Intermediate-Velocity Cloud
Danly, Laura; Wakker, Bart; Wilhelm, Ronald +5 more
A lower limit to the distance of the high-velocity cloud (HVC) complex A of 4 kpc (z > 3 kpc) is derived. The HVC is detected toward the Seyfert galaxy Mrk 106 in Mg II λλ2796, 2803 absorption spectra taken with Hubble Space Telescope (HST) proving that Mg^+^ is present in the cloud. It is not detected in the Mg II spectra of two stars, PG 0859…
Hubble Space Telescope Observations of QSO Absorption Lines Associated with Starburst Galaxy Outflows
Bowen, David V.; Danly, Laura; Norman, Colin A. +2 more
In order to study the physical state of outflows from starburst galaxies, we have been obtaining spectra of QSOs located behind possible starburst outflows and searching for UV absorption by low-ionization gas. We have detected strong and probably complex Mg II, Mg I, and Fe II absorption arising from gas in the outer envelope of the starburst gal…
A Two-Wind Interaction Model for Proplyds
Henney, W. J.; Raga, A. C.; Curiel, S. +1 more
Recent HST observations of the Orion Nebula show the presence of compact (∼2") emission-line objects ("proplyds") with bowlike morphologies and tails pointing away from the θ1C Ori star. We model these objects as the result of the interaction between the fast wind from θ1C and slow dense winds from accretion disks around youn…
The Dual Nature of Hard X-Ray Outbursts from the Superluminal X-Ray Transient Source GRO J1655-40
Rupen, M. P.; Zhang, S. N.; Livio, M. +5 more
We report the results of multiwavelength observations of the superluminal X-ray transient GRO J1655-40 during and following the prominent hard X-ray outburst of 1995 March--April. GRO J1655-40 was monitored continuously by BATSE on board the Compton Gamma Ray Observatory and observed repeatedly in the radio and optical bands from the ground. About…