Search Publications
Triggered Star Formation and the Creation of the Supergiant H I Shell in IC 2574
Cannon, John M.; Dolphin, Andrew E.; Skillman, Evan D. +4 more
Based on deep imaging from the Advanced Camera for Surveys aboard the Hubble Space Telescope (HST), we present new evidence that stellar feedback created a ~1 kpc supergiant H I shell (SGS) and triggered star formation (SF) around its rim in the M81 Group dwarf irregular galaxy IC 2574. Using photometry of the resolved stars from the HST images, w…
Evidence of Chromospheric Evaporation in the 2004 December 1 Solar Flare
Cao, Wenda; Ning, Zongjun; Yan, Yihua +3 more
In this paper, we present the radio and hard X-ray evidence of chromospheric evaporation during an M1.0 flare which occurred on 2004 December 1. The radio emission was observed by the Solar Broadband Radio Dynamic Spectrometer in China, which yielded dynamic spectra of decimetric emission. The hard X-ray emission was observed by RHESSI. In the rad…
Solar-like Oscillations in a Metal-poor Globular Cluster with the Hubble Space Telescope
Stello, Dennis; Gilliland, Ronald L.
We present analyses of variability in the red giant stars in the metal-poor globular cluster NGC 6397, based on data obtained with the Hubble Space Telescope. We use a nonstandard data reduction approach to turn a 23 day observing run originally aimed at imaging the white dwarf population, into time-series photometry of the cluster's highly satura…
Physical Conditions in the Inner Narrow-Line Region of the Seyfert 2 Galaxy Markarian 573
Kraemer, S. B.; Crenshaw, D. M.; Schmitt, H. R. +3 more
We have examined the physical conditions within a bright emission-line knot in the inner narrow-line region (NLR) of the Seyfert 2 galaxy Mrk 573 using optical spectra and photoionization models. The spectra were obtained with the Hubble Space Telescope/Space Telescope Imaging Spectrograph, through the 0farcs2 × 52farcs0 slit, at a position angle …
Statistical analysis of earthward flow bursts in the inner plasma sheet during substorms
Zhang, T. L.; Dandouras, I.; Lucek, E. +5 more
In this article, we study the velocity distribution, density, duration, and energy transport of earthward flow bursts in the inner plasma sheet (IPS) during three substorm phases using the data of Cluster in 2001 and 2002. The mean peak velocity of earthward flow bursts in recovery phases (390 km/s) is smaller than those in growth and expansion ph…
Transient auroral features at Saturn: Signatures of energetic particle injections in the magnetosphere
Krupp, N.; Roussos, E.; Mitchell, D. G. +7 more
We report for the first time transient isolated auroral spots at Saturn's southern polar region, based on Hubble Space Telescope (HST) FUV images. The spots last several minutes and appear distinct from the rest of the auroral emissions. We study two sets of HST and Cassini observations during which Cassini instrumentation detected signatures of e…
Suzaku Observation of Group of Galaxies NGC 507: Temperature and Metal Distributions in the Intra-Cluster Medium
Ishida, Manabu; Sato, Kosuke; Ohashi, Takaya +3 more
The temperature and abundance distributions of the intra-cluster medium (ICM) in the NGC 507 group of galaxies were studied with Suzaku. The observed concentric annular spectra were well-represented by a two-temperature model for ICM, and steeper abundance gradients were found for Mg, Si, S, and Fe compared with O in the central region. The abunda…
Pulsations in the late-type Be star HD 50 209 detected by CoRoT
Auvergne, M.; Poretti, E.; Michel, E. +22 more
Context: The presence of pulsations in late-type Be stars is still a matter of controversy. It constitutes an important issue to establish the relationship between non-radial pulsations and the mass-loss mechanism in Be stars.
Aims: To contribute to this discussion, we analyse the photometric time series of the B8IVe star HD 50 209 observed by…
X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
Fabian, Andrew C.; Takahashi, Tadayuki; Yamauchi, Makoto +13 more
We report on results from a Suzaku observation of the narrow-line Seyfert 1 NGC 4051. During our observation, large-amplitude rapid variability was seen, and the averaged 2--10keV flux was 8.1×10-12erg s-1cm-2, which is several times lower than the historical average. The X-ray spectrum hardens when the source flux…
HST/ACS Emission Line Imaging of Low-redshift 3CR Radio Galaxies. I. The Data
Baum, Stefi A.; O'Dea, Christopher P.; Axon, David J. +11 more
We present 19 nearby (z < 0.3) 3CR radio galaxies imaged at low and high excitation as part of a Cycle 15 Hubble Space Telescope (HST) snapshot survey with the Advanced Camera for Surveys (ACS). These images consist of exposures of the Hα (6563 Å, plus [N II] contamination) and [O III]λ5007 emission lines using narrowband linear ramp filters ad…