Search Publications
Cold Dust in Early-Type Galaxies. I. Observations
Brighenti, Fabrizio; Mathews, William G.; Bregman, Jesse D. +1 more
We describe far-infrared observations of early-type galaxies selected from the Infrared Space Observatory (ISO) archive. This rather inhomogeneous sample includes 39 giant elliptical galaxies and 14 S0 (or later) galaxies. These galaxies were observed with the array photometer PHOT on-board the ISO satellite using a variety of different observing …
Puzzling wind properties of young massive stars in SMC-N81
Schaerer, D.; Martins, F.; Hillier, D. J. +1 more
We present a quantitative study of massive stars in the High Excitation Blob N81, a compact star forming region in the SMC. The stellar content was resolved by HST, and STIS was used to obtain medium resolution spectra. The qualitative analysis of the stellar properties presented in Heydari-Malayeri et al. (\cite{papI}) is extended using non-LTE s…
The Discovery of an Anomalous Subgiant Branch in the Color-Magnitude Diagram of ω Centauri
Ferraro, Francesco R.; Origlia, Livia; Cool, Adrienne M. +4 more
Using deep high-resolution multiband images taken with the Very Large Telescope and the Hubble Space Telescope, we discovered a new anomalous sequence in the color-magnitude diagram of ω Cen. This feature appears as a narrow well-defined subgiant branch (SGB-a), which merges into the main sequence of the dominant cluster population at a magnitude …
Organized Subsurface Flows near Active Regions
Thompson, M. J.; Toomre, J.; Hindman, B. W. +1 more
Local helioseismic techniques, such as ring analysis and time-distance helioseismology, have already shown that large-scale flows near the surface converge towards major active regions. Ring analysis has further demonstrated that at greater depths some active regions exhibit strong outflows. A critique leveled at the ring-analysis results is that …
Star cluster formation and evolution in the dwarf starburst galaxy NGC 1569
de Grijs, R.; Anders, P.; Fritze-v. Alvensleben, U. +1 more
We analyse multiwavelength Hubble Space Telescope (HST) observations of a large number of star clusters in the nearby (post-)starburst dwarf galaxy NGC 1569. Their spectral energy distributions (SEDs) cover at least the wavelength range from U to I in equivalent HST filters, in most cases supplemented by near-infrared data. Using our most up-to-da…
Characteristics of active-region sources of solar wind near solar maximum
Neugebauer, M.; Liewer, Paulett C.; Zurbuchen, Thomas
Previous studies of the source regions of solar wind sampled by ACE and Ulysses showed that some solar wind originates from open magnetic flux rooted in active regions. These solar wind sources were labeled active-region sources when the open flux was from a strong field region with no corresponding coronal hole in the NSO He 10830 Å synoptic coro…
Probable intermediate-mass black holes in NGC 4559: XMM-Newton spectral and timing constraints
Cropper, Mark; Soria, Roberto; Wu, Kinwah +3 more
We have examined X-ray and optical observations of two ultraluminous X-ray sources, X7 and X10 in NGC 4559, using XMM-Newton, Chandra and the Hubble Space Telescope (HST). The ultraviolet/X-ray luminosity of X7 exceeds 2.1 × 1040 erg s-1 in the XMM-Newton observation, and that of X10 is > 1.3 × 1040 erg s-1…
Obscuration and Origin of Nuclear X-Ray Emission in FR I Radio Galaxies
Gliozzi, M.; Sambruna, R. M.; Donato, D.
We present X-ray observations of the nuclear region of 25 Fanaroff-Riley type I (FR I) radio galaxies from the 3CRR and B2 catalogs, using data from the Chandra and XMM-Newton archives. We find the presence of a X-ray central compact core (CCCX) in 13/25 sources; in 3/25 sources the detection of a CCCX is uncertain, while in the remaining 9/25 sou…
Field E+A Galaxies at Intermediate Redshifts (0.3 < z < 1)
Franx, Marijn; Kelson, Daniel D.; Illingworth, Garth D. +3 more
We select E+A candidates from a spectroscopic data set of ~800 field galaxies and measure the E+A fraction at 0.3<z<1 to be 2.7%+/-1.1%, a value lower than that in galaxy clusters at comparable redshifts (11%+/-3%). HST WFPC2 imaging for five of our six E+A's shows that they have a heterogeneous parent population: these E+A's span a range in…
Follow-Up Chandra Observations of Three Candidate Tidal Disruption Events
Komossa, S.; Halpern, J. P.; Gezari, S.
Large-amplitude, high-luminosity soft X-ray flares were detected by the ROSAT All-Sky Survey in several galaxies with no evidence of Seyfert activity in their ground-based optical spectra. These flares had the properties predicted for a tidal disruption of a star by a central supermassive black hole. We report Chandra observations of three of thes…