Search Publications
M84: A Warp Caused by Jet-induced Pressure Gradients?
Bower, Gary A.; Quillen, A. C.
In radio galaxies such as M84 dust features tend to be nearly perpendicular to radio jets yet are not aligned with the galaxy isophotes. The timescale for precession in the galaxy is short (~107 yr at 100 pc), suggesting that an alternative mechanism causes the gas disk to be misaligned with the galaxy. In M84 we estimate the pressure o…
The Extended Narrow-Line Region of 3C 299
McCarthy, Patrick J.; Sparks, William B.; Macchetto, F. Duccio +2 more
We present results of Hubble Space Telescope (HST) observations of the radio galaxy 3C 299. The broadband F702W (R) and F555W (V) images (WFPC2/PC) show an elliptical galaxy with a comet-like structure extending to the northeast in the radio jet direction. The [O III] λ5007 emission-line map shows a biconical structure centered on the nucleus, whi…
A Possible Gravitational Lens in the Hubble Deep Field South
Hogg, David W.; Blandford, Roger; Barkana, Rennan
We model an apparent gravitational lens system HDFS 2232509-603243 in the Hubble Deep Field South. The system consists of a blue V=25 mag arc separated by 0.9" from a red V=22 mag elliptical galaxy. A mass distribution that follows the observed light distribution with a constant mass-to-light ratio can fit the arc component positions if external s…
Searching for Signal in Noise by Random-Lag Singular Spectrum Analysis
Henney, C. J.; Ulrich, R. K.; Bertello, L. +2 more
Singular spectrum analysis, a technique to detect oscillations in short and noisy time series, was first developed for geophysical applications. This work offers a generalization for long and noisy time series in astrophysical applications. The motivating problem is the detection of low-amplitude solar oscillations.
Increasing the Visibility of Solar Oscillations
Toutain, T.; Jefferies, S. M.; Toner, C. G.
Recent calculations by Toutain, Berthomieu, & Provost predict that low-degree p- and g-modes should produce large continuum intensity perturbations close to the solar limb. Analysis of 72 hr of spatially resolved, full-disk, continuum intensity images of the Sun--obtained with the Solar Oscillations Investigation/Michelson Doppler Imager instr…
Can Streamer Blobs Prevent the Buildup of the Interplanetary Magnetic Field?
Martens, P. C. H.; van Aalst, M. K.; Beliën, A. J. C.
Coronal mass ejections continuously drag closed magnetic field lines away from the Sun, adding new flux to the interplanetary magnetic field (IMF). We propose that the outward-moving blobs that have been observed in helmet streamers are evidence of ongoing, small-scale reconnection in streamer current sheets, which may play an important role in th…
Analyzing the Energetics of Explosive Events Observed by SUMER on SOHO
Winebarger, Amy R.; Warren, Harry P.; Mariska, John T. +1 more
The SUMER spectrometer on SOHO has obtained numerous observations of optically thin chromosphere-corona transition-region line profiles with high spatial, spectral, and temporal resolution. Many of these profiles exhibit asymmetries and broadenings associated with impulsive mass motions (explosive events) in the solar atmosphere. We present here a…
Evidence for a Population of Numerous Binaries with Comparably Bright Components among HIPPARCOS ``Single'' F Stars
McMaster, M.; Suchkov, A. A.
We find evidence for the presence of a population of numerous binaries with comparably bright components (C binaries) among Hipparcos F stars that are flagged in the Hipparcos catalog as single. We propose a criterion that identifies such binaries. The criterion is based on comparison of absolute magnitude MV obtained from the Hipparcos…
Galactic Extinction from Colors and Counts of Field Galaxies in WFPC2 Frames: An Application to GRB 970228
Fruchter, Andrew S.; González, Rosa A.; Dirsch, Boris
We develop the ``simulated extinction method'' to measure average foreground Galactic extinction from field galaxy number counts and colors. The method comprises simulating extinction in suitable reference fields by changing the isophotal detection limit. This procedure takes into account selection effects; in particular, the change in the isophot…
Plasma and Warm Dust in the Collisional Ring Galaxy VII ZW 466 from VLA and ISO Observations
Appleton, P. N.; Charmandaris, V.; Ghigo, F. +4 more
We present the first mid-infrared (mid-IR) (5-15 µm) and radio continuum (λ=20, 6, and 3.6 cm) observations of the star-forming collisional ring galaxy VII Zw 466 and its host group made with the Infrared Space Observatory (ISO) and the NRAO Very Large Array. A search was also made for CO line emission in two of the galaxies with the Onsala …