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Hubble Space Telescope Observations of the Wolf-Rayet Nebula NGC 6888
Hester, J. Jeff; Scowen, Paul A.; Moore, Brian D.
We present Hubble Space Telescope Wide Field Planetary Camera 2 images of a portion of the bright northeast rim of NGC 6888, the nebular shell physically associated with the Wolf-Rayet star HD 192163. The exposures are taken in the light of Hα λ6563, [O III] λ5007, and [S II] λλ6717, 6731. The images are used to constrain models of the ionization …
Far infrared extragalactic background radiation --- I. Source counts with ISOPHOT
Juvela, M.; Lemke, D.; Mattila, K.
As a part of the ISOPHOT CIRB (Cosmic Infrared Background Radiation) project we have searched for point-like sources in eight fields mapped at two or three wavelengths between 90 µm and 180 µm. Most of the 55 sources detected are suspected to be extragalactic and cannot be associated with previously known objects. It is probable, also …
Hubble Space Telescope Observations of the Interacting Galaxies NGC 2207 and IC 2163
Bond, Howard E.; Brinks, Elias; Struck, Curtis +11 more
Hubble Space Telescope (HST) images of the galaxies NGC 2207 and IC 2163 show star formation and dust structures in a system that has experienced a recent grazing encounter. Tidal forces from NGC 2207 compressed and elongated the disk of IC 2163, forming an oval ridge of star formation along a caustic where the perturbed gas rebounded after its in…
The Globular Cluster Systems in the Coma Ellipticals. II. Metallicity Distribution and Radial Structure in NGC 4874 and Implications for Galaxy Formation
Kavelaars, J. J.; Harris, William E.; Hesser, James E. +2 more
Deep Hubble Space Telescope WFPC2 images in V and I are used to investigate the globular cluster system (GCS) in NGC 4874, the central cD galaxy of the Coma cluster. Although the luminosity function of the clusters displays its normal Gaussian-like shape and turnover level, other features of the system are surprising. We find the GCS to be (a) spa…
The Temperature and Cooling Age of the White Dwarf Companion to the Millisecond Pulsar PSR B1855+09
Kulkarni, S. R.; van Kerkwijk, M. H.; Kaspi, V. M. +1 more
We report on Keck and Hubble Space Telescope observations of the binary millisecond pulsar PSR B1855+09. We detect its white dwarf companion and measure mF555W=25.90+/-0.12 and mF814W=24.19+/-0.11 (Vega system). From the reddening-corrected color, (mF555W-mF814W)0=1.06+/-0.21, we infer a tempe…
Acoustic Imaging of Solar Active Regions - (Invited Review)
Chou, Dean-Yi
Acoustic imaging is a new method to construct the acoustic signal at a point on the solar surface or in the solar interior with the signals measured at the solar surface. The constructed signals contain both intensity information and phase information. The intensity is computed by summing the squared amplitude of the constructed signal over time. …
Hubble Space Telescope Imaging Spectrograph Observations of the Hot White Dwarf in the Close Binary Feige 24
Vennes, Stéphane; Thorstensen, John R.; Polomski, Elisha F. +3 more
We obtained and analyzed two Hubble Space Telescope Imaging Spectrograph spectra of the white dwarf in the DA plus dMe binary Feige 24. The spectra, obtained at orbital quadratures, provide new estimates of the white dwarf motion and gravitational redshift resulting in revised white dwarf parameters. An analysis of interstellar absorption lines re…
An infrared study of the L1551 star formation region
Liseau, R.; White, G. J.; Ceccarelli, C. +14 more
Spectroscopic observations using the Infrared Space Observatory are reported towards the two well known infrared sources and young stellar objects L1551 IRS 5 and L1551 NE, and at a number of locations in the molecular outflow. The ISO spectrum contains several weak gas-phase lines of O I, C II, [Fe II] and [Si II], along with solid state absorpti…
A photometric and spectroscopic study of the brightest northern Cepheids - III. A high-resolution view of Cepheid atmospheres
Vinkó, József; Kiss, László L.
We present new high-resolution spectroscopic observations (λ/Δλ~40000) of 18 bright northern Cepheids carried out at the David Dunlap Observatory in 1997. The measurements mainly extend those presented in Paper I of this series, adding three more stars (AW Per, SV Vul, T Mon). The spectra were obtained in the yellow-red spectral region in the inte…
Diffraction-limited Near-IR Imaging at Keck Reveals Asymmetric, Time-variable Nebula around Carbon Star CIT 6
Tuthill, P. G.; Monnier, J. D.; Danchi, W. C.
We present multiepoch, diffraction-limited images of the nebula around the carbon star CIT 6 at 2.2 and 3.1 µm from aperture masking on the Keck I Telescope. The near-IR nebula is resolved into two main components, an elongated, bright feature showing time-variable asymmetry and a fainter component about 60 mas away with a cooler color tempe…