Search Publications
Hubble Space Telescope Spectrum of SN 1987A at an Age of 8 Years: Radioactive Luminescence of Cool Gas
Challis, Peter M.; Chevalier, Roger A.; Kirshner, Robert P. +1 more
The Hubble Space Telescope 2000-8000 Å spectrum of SN 1987A observed on 1995 January 7 (7.87 yr after the explosion) is dominated by Hα and UV lines, including Mg II-Mg I λ2825 (equal to Hα in luminosity), Fe II UV 2 (two-thirds the intensity of Hα), Fe II UV 3 (one-half the intensity of Hα), and a 3730 Å emission feature identified with a blend o…
Spectroscopy of Close Companions to Quasi-Stellar Objects and the Ages of Interaction-Induced Starbursts
Stockton, Alan; Canalizo, Gabriela
We present low-resolution absorption-line spectra of three candidate close (<3") companions to the low-redshift QSOs 3CR 323.1, PG 1700+518, and PKS 2135-147. The spectra were obtained with the Low-Resolution Imaging Spectrometer (LRIS) on the Keck telescopes and with the Faint Object Spectrograph on the University of Hawaii 2.2 m telescope. Fo…
The Extragalactic Distance Scale Key Project. VIII. The Discovery of Cepheids and a New Distance to NGC 3621 Using the Hubble Space Telescope
Illingworth, Garth D.; Huchra, John P.; Kennicutt, Robert C. +18 more
We report on the discovery of Cepheids in the field spiral galaxy NGC 3621, based on observations made with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope (HST). NGC 3621 is one of 18 galaxies observed as a part of the HST Key Project on the Extragalactic Distance Scale, which aims to measure the Hubble constant to 10% accur…
On Calibrating Brightest Asymptotic Giant Branch Stars as Age Indicators: The Bulge Globular Cluster NGC 6553 and the Age of M32
Renzini, Alvio; Ortolani, Sergio; Guarnieri, Maria Donata
Bright asymptotic giant branch (AGB) stars can be used as an age indicator for stellar populations that are too far away for their main-sequence turnoffs to be reachable. However, the method requires an empirical calibration, as the brightness of the AGB termination depends on both age and metallicity in ways that cannot be predicted from first pr…
Hubble Space Telescope Imaging of the Central 1 Kiloparsec of M81
Ford, Holland; Devereux, Nick; Jacoby, George
M81 is the closest example of a galaxy that exhibits both LINER and Seyfert 1 characteristics. New, postrepair (cycle 5), Hubble Space Telescope imaging observations of the central kpc of M81 are presented, specifically, WFPC2 Hα and continuum images, a WFPC2 UV continuum (1500 Å) image, and a V-band faint object camera (FOC) image. The continuum …
Interferometric Angular Diameters of Mira Variables with the Hubble Space Telescope
Munari, Ulisse; Whitelock, Patricia A.; Feast, Michael W. +1 more
This paper presents the first successful interferometric observations of angular diameters with the astrometer Fine Guidance Sensor (FGS) aboard the Hubble Space Telescope, the only optical interferometer operating in space. We report single-epoch angular diameters in visible light for the two Mira-type variables, R Leonis and W Hydrae, along two …
Solar Coronal Heating: AC versus DC
Martens, Petrus C. H.; Milano, Leonardo J.; Gómez, Daniel O.
The heating of the plasma confined in active regions of the solar corona is caused by the dissipation of magnetic stresses induced by the photospheric motions of the loop footpoints. The aim of the present paper is to analyze whether solar coronal heating is dominated by slow (DC) or rapid (AC) photospheric driving motions. We describe the dynamic…
The Narrow-Line Region of NGC 4151: A Turbulent Cauldron
Axon, David J.; Macchetto, F. D.; Capetti, A. +1 more
We present the first results of the Hubble Space Telescope/Faint Object Camera long-slit spectroscopy of the inner 8" of the narrow-line region (NLR) of NGC 4151 at a spatial resolution of 0.029". The emission gas is characterized by an underlying general orderly behavior, consistent with galactic rotation, over which are superposed kinematically …
Hubble Space Telescope Discovers Optical Emission from the Radio Pulsar PSR 1055-52
Caraveo, P. A.; Bignami, G. F.; Mignani, R.
Optical/UV emission from isolated neutron stars, if detected, represents a valuable indicator of the pulsar's emission mechanisms, and more so for those objects of ``intermediate'' age, where thermal and nonthermal processes are known to coexist. PSR 1055-52 is a middle-aged pulsar and a strong γ-ray emitter. As such, it represents a logical targe…
Resolved Structure in the Nuclear Region of the Ultraluminous Infrared Galaxy Markarian 273
Knapen, J. H.; Laine, S.; Doyon, R. +4 more
We have studied the core morphology of the ultraluminous infrared galaxy Mrk 273 by combining a high-resolution adaptive optics near-infrared image with an optical image from the Hubble Space Telescope and interferometric radio continuum data, all at spatial resolutions of 150 mas or better. The near-infrared image reveals that the nucleus has two…