Search Publications
RR Lyrae Variables in M32 and the Disk of M31
Monachesi, Antonela; Lauer, Tod R.; Dressler, Alan +7 more
We observed two fields near M32 with the Advanced Camera for Surveys/High Resolution Channel (ACS/HRC) on board the Hubble Space Telescope. The main field, F1, is 1farcm8 from the center of M32; the second field, F2, constrains the M31 background, and is 5farcm4 distant. Each field was observed for 16 orbits in each of the F435W (narrow B) and F55…
Effects of Forsterite Grain Shape on Infrared Spectra
Koike, C.; Tsuchiyama, A.; Suto, H. +5 more
The Infrared Space Observatory (ISO) detected several sharp infrared features around young stars, comets, and evolved stars. These sharp features were identified as Mg-rich crystalline silicates of forsterite and enstatite by comparison with spectra from laboratory data. However, certain infrared emission bands in the observed spectra cannot be id…
On the Origin of the Red Excess in Very Young Super Star Clusters: The Case of SBS 0335-052E
Östlin, G.; Hayes, M.; Adamo, A. +1 more
The spectral energy distribution analysis of very young unresolved star clusters challenges our understanding of the cluster formation process. Studies of resolved massive clusters in the Milky Way and in the nearby Magellanic Clouds show us that the contribution from photoionized gas is very important during the first Myr of cluster evolution. We…
The Minor Role of Gas-Rich Major Mergers in the Rise of Intermediate-Mass Early Types at z <= 1
Barro, Guillermo; Pérez-González, Pablo G.; Balcells, Marc +4 more
We study the evolution of galaxy structure since z ~ 1 to the present. From a Great Observatories Origins Deep Survey South (GOODS-S) multi-band catalog, we define (blue) luminosity- and mass-weighted samples, limited by MB <= -20 and M sstarf >= 1010 M sun, comprising 1122 and 987 galaxies, respec…
Modeling UV and X-ray Emission in a Post-coronal Mass Ejection Current Sheet
Vršnak, Bojan; Raymond, John C.; Ko, Yuan-Kuen +1 more
A post-coronal mass ejection (CME) current sheet (CS) is a common feature developed behind an erupting flux rope in CME models. Observationally, white light observations have recorded many occurrences of a thin ray appearing behind a CME eruption that closely resembles a post-CME CS in its spatial correspondence and morphology. UV and X-ray observ…
Suzaku and BeppoSAX X-ray Spectra of the Persistently Accreting Neutron-star Binary 4U 1705-44
Remillard, Ronald A.; Homan, Jeroen; Lin, Dacheng
We present an analysis of the broadband spectra of 4U 1705-44 obtained with Suzaku in 2006-2008 and by BeppoSAX in 2000. The source exhibits two distinct states: the hard state shows emission from 1 to 150 keV, while the soft state is mostly confined to be <40 keV. We model soft-state continuum spectra with two thermal components, one of which …
Metal Depletion and Warm H2 in the Brown Dwarf 2M1207 Accretion Disk
Brown, Alexander; France, Kevin; Linsky, Jeffrey L. +2 more
We present new far-ultraviolet observations of the young M8 brown dwarf 2MASS J12073346-3932539, which is surrounded by an accretion disk. The data were obtained using the Hubble Space Telescope-Cosmic Origins Spectrograph. Moderate-resolution spectra (R≈ 17,000-18,000) obtained in the 1150-1750 Å and 2770-2830 Å bandpasses reveal H2 em…
A Universal Law for Solar-wind Turbulence at Electron Scales
Galtier, S.; Meyrand, R.
The interplanetary magnetic fluctuation spectrum obeys a Kolmogorovian power law at scales above the proton inertial length and gyroradius which is well regarded as an inertial range. Below these scales, a power-law index around -2.5 is often measured and associated with nonlinear dispersive processes. Recent observations reveal a third region at …
Pre-main-sequence Turn-On as a Chronometer for Young Clusters: NGC 346 as a Benchmark
Prada Moroni, P. G.; Degl'Innocenti, S.; Cignoni, M. +4 more
We present a novel approach to deriving the age of very young star clusters, by using the Turn-On (TOn). The TOn is the point in the color-magnitude diagram (CMD) where the pre-main sequence (PMS) joins the main sequence (MS). In the MS luminosity function (LF) of the cluster, the TOn is identified as a peak followed by a dip. We propose that by c…
Jupiter After the 2009 Impact: Hubble Space Telescope Imaging of the Impact-generated Debris and its Temporal Evolution
Hueso, R.; Sánchez-Lavega, A.; Fletcher, L. N. +9 more
We report Hubble Space Telescope images of Jupiter during the aftermath of an impact by an unknown object in 2009 July. The 2009 impact-created debris field evolved more slowly than those created in 1994 by the collision of the tidally disrupted comet D/Shoemaker-Levy 9 (SL9). The slower evolution, in conjunction with the isolated nature of this s…