Science Archives Publication System

Identification of a Dynamic Atmosphere at Enceladus with the Cassini Magnetometer

DOI: 10.1126/science.1120985 Bibcode: 2006Sci...311.1406D

Russell, C. T.; Dougherty, M. K.; Khurana, K. K. +4 more

The Cassini magnetometer has detected the interaction of the magnetospheric plasma of Saturn with an atmospheric plume at the icy moon Enceladus. This unanticipated finding, made on a distant flyby, was subsequently confirmed during two follow-on flybys, one very close to Enceladus. The magnetometer data are consistent with local outgassing activi…

2006 • Science

Cassini 308

The Proper Motion of the Large Magellanic Cloud Using HST

DOI: 10.1086/498972 Bibcode: 2006ApJ...638..772K

Drake, A. J.; Geha, M.; van der Marel, Roeland P. +4 more

We present a measurement of the systemic proper motion of the Large Magellanic Cloud (LMC) from astrometry with the High Resolution Camera (HRC) of the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST). We observed LMC fields centered on 21 background QSOs that were discovered from their optical variability in the MACHO databas…

2006 • The Astrophysical Journal

eHST 307

Dry Mergers in GEMS: The Dynamical Evolution of Massive Early-Type Galaxies

DOI: 10.1086/499931 Bibcode: 2006ApJ...640..241B

Bell, Eric F.; Somerville, Rachel S.; Wisotzki, Lutz +16 more

We have used the 28^'×28^' Hubble Space Telescope image mosaic from the GEMS (Galaxy Evolution from Morphology and SEDs) survey in conjunction with the COMBO-17 photometric redshift survey to constrain the incidence of major mergers between spheroid-dominated galaxies with little cold gas (dry mergers) since z=0.7. A set of N-b…

2006 • The Astrophysical Journal

eHST 300

On the X-ray, optical emission line and black hole mass properties of local Seyfert galaxies

DOI: 10.1051/0004-6361:20064894 Bibcode: 2006A&A...455..173P

Cappi, M.; Iwasawa, K.; Barcons, X. +5 more

We investigate the relation between X-ray nuclear emission, optical emission line luminosities and black hole masses for a sample of 47 Seyfert galaxies. The sample, which has been selected from the Palomar optical spectroscopic survey of nearby galaxies (Ho et al. 1997a, ApJS, 112, 315), covers a wide range of nuclear powers, from L_{2-10 keV<…}

2006 • Astronomy and Astrophysics

XMM-Newton 298

The Direct Detection of Lyman Continuum Emission from Star-forming Galaxies at z~3

DOI: 10.1086/507511 Bibcode: 2006ApJ...651..688S

Pettini, Max; Erb, Dawn K.; Shapley, Alice E. +2 more

We present the results of rest-frame UV spectroscopic observations of a sample of 14 z~3 star-forming galaxies in the SSA 22a field. These spectra are characterized by unprecedented depth in the Lyman continuum region. For the first time, we have detected escaping ionizing radiation from individual galaxies at high redshift, with 2 of the 14 objec…

2006 • The Astrophysical Journal

eHST 298

ISM properties in low-metallicity environments

DOI: 10.1051/0004-6361:20053890 Bibcode: 2006A&A...446..877M

Madden, S. C.; Galliano, F.; Sauvage, M. +1 more

We present new ISOCAM mid-infrared spectra of three starbursting nearby dwarf galaxies, NGC 1569, NGC 1140 and II Zw 40 and the 30 Dor region of the LMC and explore the properties of the ISM in low-metallicity environments, also using additional sources from the literature. We analyse the various components of the ISM probed by the mid-infrared ob…

2006 • Astronomy and Astrophysics

ISO 296

Strong and Weak Lensing United. III. Measuring the Mass Distribution of the Merging Galaxy Cluster 1ES 0657-558

DOI: 10.1086/508601 Bibcode: 2006ApJ...652..937B

Bradač, Maruša; Schrabback, Tim; Jones, Christine +7 more

The galaxy cluster 1ES 0657-558 (z=0.296) is remarkably well suited for addressing outstanding issues in both galaxy evolution and fundamental physics. We present a reconstruction of the mass distribution from both strong and weak gravitational lensing data. Multicolor, high-resolution HST ACS images allow detection of many more arc candidates tha…

2006 • The Astrophysical Journal

eHST 293

Physical parameters and wind properties of galactic early B supergiants

DOI: 10.1051/0004-6361:20053685 Bibcode: 2006A&A...446..279C

Crowther, P. A.; Lennon, D. J.; Walborn, N. R.

We present optical studies of the physical and wind properties, plus CNO chemical abundances, of 25 O9.5-B3 Galactic supergiants. We employ non-LTE, line blanketed, extended model atmospheres, which provide a modest downward revision in the effective temperature scale of early B supergiants of up to 1-2 kK relative to previous non-blanketed result…

2006 • Astronomy and Astrophysics

IUE 293

The Expansion Asymmetry and Age of the Cassiopeia A Supernova Remnant

DOI: 10.1086/504254 Bibcode: 2006ApJ...645..283F

Chevalier, Roger A.; Raymond, John C.; Dopita, Michael A. +7 more

HST images of the young supernova remnant Cas A are used to explore the expansion and spatial distribution of its highest velocity debris. ACS WFC images taken in 2004 March and December with Sloan F625W, F775W, and F850LP filters were used to identify 1825 high-velocity, outlying ejecta knots through measured proper motions of 0.35"-0.90" yr^…

2006 • The Astrophysical Journal

eHST 278

The Evolution of the Star Formation Activity in Galaxies and Its Dependence on Environment

DOI: 10.1086/500666 Bibcode: 2006ApJ...642..188P

Aragón-Salamanca, Alfonso; White, Simon D. M.; Milvang-Jensen, Bo +16 more

We study how the proportion of star-forming galaxies evolves between z=0.8 and 0 as a function of galaxy environment, using the O II line in emission as a signature of ongoing star formation. Our high-z data set comprises 16 clusters, 10 groups, and another 250 galaxies in poorer groups and the field at z=0.4-0.8 from the ESO Distant Cluster Surve…

2006 • The Astrophysical Journal

eHST 274