Search Publications
Distant Red Galaxies in the Hubble Ultra Deep Field
Toft, S.; van Dokkum, P.; Bouwens, R. J. +4 more
We take advantage of the Hubble Ultra Deep Field data to study the rest-frame optical and UV morphologies of the novel population of distant red galaxies (DRGs). Six galaxies with J-Ks>2.3 are found to Ks=21.5, five of which have photometric redshifts zphot>~2, corresponding to a surface density of 0.9 arcmin…
A New View of the Circumstellar Environment of SN 1987A
Crotts, Arlin P. S.; Lawrence, Stephen S.; Sugerman, Ben E. K. +2 more
We summarize the analysis of a uniform set of both previously known and newly discovered scattered-light echoes, detected within 30" of SN 1987A in 10 years of optical imaging, and with which we have constructed the most complete three-dimensional model of the progenitor's circumstellar environment. Surrounding the SN is a richly structured bipola…
Multiwavelength Observations of Radio Galaxy 3C 120 with XMM-Newton
Malkan, M. A.; Page, M. J.; Tornikoski, M. +5 more
We present XMM-Newton observations of the radio galaxy 3C 120. Contemporaneous radio, millimeter-wave, and optical data provide additional constraints on the spectral energy distribution and physical state of the active galactic nucleus. The hard X-ray spectrum contains a marginally resolved Fe I Kα emission line with FWHM=9000+/-3000 km s-1<…
Improved Laboratory Transition Probabilities for Pt I and Application to the Platinum Abundances of BD +17°3248 and the Sun
Sneden, C.; Beers, T. C.; Lawler, J. E. +3 more
Radiative lifetimes, accurate to +/-5%, have been measured for 58 odd-parity levels of Pt I using laser-induced fluorescence. The lifetimes were combined with branching fractions measured using grating and Fourier transform spectrometry to determine transition probabilities for 127 lines of Pt I. The new Pt lifetime measurements were found to be i…
MV Lyrae in Low, Intermediate, and High States
Szkody, Paula; Sion, Edward M.; Hoard, D. W. +4 more
Archival IUE spectra of the VY Sculptoris system MV Lyrae, taken during an intermediate state, can be best fit by an isothermal accretion disk extending half-way to the tidal cutoff radius. In contrast, a recent HST spectrum, while MV Lyr was in a high state, can be best fit with a standard T(R) profile for an accretion disk extending from an inne…
Chandra Observations of NGC 4261 (3C 270): Revealing the Jet and Hidden Active Galactic Nucleus in a Type 2 LINER
Zezas, A.; Fabbiano, G.; Birkinshaw, M. +2 more
We present results from a Chandra ACIS-S observation of the type 2 low-ionization nuclear emission-line region (LINER) radio galaxy NGC 4261 (3C 270). The X-ray data show that this galaxy hosts a heavily obscured (NH~8×1022 cm-2) active galactic nucleus (AGN) with an intrinsic luminosity of 2.4×1041 ergs…
Do Young Galaxies Exist in the Local Universe? Red Giant Branch Detection in the Metal-poor Dwarf Galaxy SBS 1415+437
Leitherer, C.; Tosi, M.; van der Marel, R. P. +3 more
We present results from an HST/ACS imaging study of the metal-poor blue compact dwarf galaxy SBS 1415+437. It has been argued previously that this is a very young galaxy that started to form stars only <~100 Myr ago. However, we find that the optical color-magnitude diagram prominently reveals asymptotic giant branch and red giant branch (RGB) …
New Elemental Abundances for V1974 Cygni
Shore, S. N.; Starrfield, S.; Wagner, R. M. +2 more
We present a new analysis of existing optical and ultraviolet spectra of the ONeMg nova V1974 Cygni 1992. Using these data and the photoionization code Cloudy, we have determined the physical parameters and elemental abundances for this nova. Many of the previous studies of this nova have made use of incorrect analyses, and hence a new study was r…
Constraining the Distribution of L and T Dwarfs in the Galaxy
Hathi, N. P.; Ryan, R. E., Jr.; Windhorst, R. A. +1 more
We estimate the thin-disk scale height of the Galactic population of L and T dwarfs based on star counts from 15 deep parallel fields from the Hubble Space Telescope. From these observations, we have identified 28 candidate L and T dwarfs based on their i'-z' color and morphology. By comparing these star counts with a simple Galactic model, we est…
XTE J1550-564: INTEGRAL Observations of a Failed Outburst
Shrader, C. R.; Sturner, S. J.
The well-known black hole X-ray binary transient XTE J1550-564 underwent an outburst during the spring of 2003, which was substantially underluminous in comparison to previous periods of peak activity in that source. In addition, our analysis shows that it apparently remained in the hard spectral state over the duration of that outburst. This is a…