Search Publications
Discovery of a Population of Pre-Main-Sequence Stars in NGC 346 from Deep Hubble Space Telescope ACS Images
Tosi, M.; Sabbi, E.; Nota, A. +9 more
We report the discovery of a rich population of low-mass stars in the young, massive NGC 346 star-forming region in the Small Magellanic Cloud from deep V, I, and Hα images taken with the Hubble Space Telescope Advanced Camera for Surveys. These stars have likely formed together with the NGC 346 cluster, ~=3-5 Myr ago. Their magnitudes and colors …
Evolution of the Color-Magnitude Relation in High-Redshift Clusters: Blue Early-Type Galaxies and Red Pairs in RDCS J0910+5422
Demarco, R.; Infante, L.; Zheng, W. +43 more
The color-magnitude relation has been determined for the RDCS J0910+5422 cluster of galaxies at redshift z=1.106. Cluster members were selected from the Hubble Space Telescope Advanced Camera for Surveys (HST ACS) images, combined with ground-based near-IR imaging and optical spectroscopy. The observed early-type color-magnitude relation (CMR) in …
The black hole in NGC 3379: a comparison of gas and stellar dynamical mass measurements with HST and integral-field data
Shapiro, Kristen L.; Gebhardt, Karl; Cappellari, Michele +4 more
We combine Hubble Space Telescope spectroscopy and ground-based integral-field data from the SAURON and OASIS instruments to study the central black hole in the nearby elliptical galaxy NGC 3379. From these data, we obtain kinematics of both the stars and the nuclear gaseous component. Axisymmetric three-integral models of the stellar kinematics f…
A statistical analysis of the location and width of Saturn's southern auroras
Badman, S. V.; Cowley, S. W. H.; Gérard, J. -C. +1 more
A selection of twenty-two Hubble Space Telescope images of Saturn's ultraviolet auroras obtained during 1997-2004 has been analysed to determine the median location and width of the auroral oval, and their variability. Limitations of coverage restrict the analysis to the southern hemisphere, and to local times from the post-midnight sector to just…
A Persistent High-Energy Flux from the Heart of the Milky Way: INTEGRAL's View of the Galactic Center
Terrier, R.; Lund, N.; Bélanger, G. +6 more
Highly sensitive imaging observations of the Galactic center (GC) at high energies with an angular resolution of order 10' is a very recent development in the field of high-energy astrophysics. The IBIS/ISGRI imager on the INTEGRAL observatory detected for the first time a hard X-ray source, IGR J17456-2901, located within 1' of Sagittarius A* (Sg…
Compositional and physical results for Rosetta's new target Comet 67P/Churyumov Gerasimenko from narrowband photometry and imaging
Schleicher, David G.
We present compositional and physical results of Comet 67P/Churyumov-Gerasimenko, the new target of ESA's Rosetta mission. A total of 16 nights of narrowband photometry were obtained at Lowell Observatory during the 1982/83 and 1995/96 apparitions, along with one night of imaging near perihelion in 1996. These data encompass an interval of -61 to …
Molecular Gas Dynamics in NGC 6946: A Bar-driven Nuclear Starburst ``Caught in the Act''
Böker, Torsten; Schinnerer, Eva; Emsellem, Eric +1 more
We present high angular resolution (~1" and 0.6") millimeter interferometric observations of the 12CO(1-0) and 12CO(2-1) line emission in the central 300 pc of the late-type spiral galaxy NGC 6946. The data, obtained with the IRAM Plateau de Bure Interferometer (PdBI), allow the first detection of a molecular gas spiral in th…
M-type giants as optical counterparts of X-ray sources 4U 1700+24 and 4U 1954+319
Palazzi, E.; Frontera, F.; Orlandini, M. +2 more
We observed with Chandra two peculiar galactic X-ray sources, 4U 1700+24 and 4U 1954+319, which are suspected to have a M-type giant star as optical counterpart, in order to get a high-precision astrometric position for both of them. The peculiarity of these sources lies in the fact that these are the only two cases among low-mass X-ray binaries (…
100-metre-diameter moonlets in Saturn's A ring from observations of ‘propeller’ structures
Dones, Luke; Porco, Carolyn C.; Hedman, Matthew M. +5 more
Saturn's main rings are composed predominantly of water-ice particles ranging between about 1centimetre and 10metres in radius. Above this size range, the number of particles drops sharply, according to the interpretation of spacecraft and stellar occultations. Other than the gap moons Pan and Daphnis (the provisional name of S/2005 S1), which hav…
The Magnetic Structure of Coronal Loops Observed by TRACE
López Fuentes, M. C.; Klimchuk, J. A.; Démoulin, P.
Previous studies have found that coronal loops have a nearly uniform thickness, which seems to disagree with the characteristic expansion of active region magnetic fields. This is one of the most intriguing enigmas in solar physics. We here report on the first comprehensive one-to-one comparison of observed loops with corresponding magnetic flux t…