Search Publications
An Accurate Age Determination for the Small Magellanic Cloud Star Cluster NGC 121 with the Hubble Space Telescope/Advanced Camera for Surveys
Grebel, Eva K.; Gallagher, John S., III; Sabbi, Elena +8 more
As the first paper of a series devoted to study the old stellar population in clusters and fields in the Small Magellanic Cloud (SMC), we present deep observations of NGC 121 in the F555W and F814W filters, obtained with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope. The resulting color-magnitude diagram reaches ~3.5 mag belo…
Large Einstein radii: a problem for ΛCDM
Barkana, Rennan; Broadhurst, Tom J.
The Einstein radius of a cluster provides a relatively model-independent measure of the mass density of a cluster within a projected radius of ~150kpc, large enough to be relatively unaffected by gas physics. We show that the observed Einstein radii of four well-studied massive clusters, for which reliable virial masses are measured, lie well beyo…
Spitzer Mid-Infrared Spectroscopy of Infrared Luminous Galaxies at z ~ 2. III. Far-IR to Radio Properties and Optical Spectral Diagnostics
Choi, Philip; Helou, George; Lutz, Dieter +7 more
We present the FIR, millimeter, and radio photometry and optical and NIR spectroscopy of a sample of 48 z ~ 1-3 Spitzer-selected ULIRGs with IRS MIR spectra. Our goals are to compute their bolometric emission and to determine both the presence and relative strength of their AGN and starburst components. We find that strong-PAH sources tend to have…
Methane in Martian atmosphere: Average spatial, diurnal, and seasonal behaviour
Geminale, A.; Formisano, V.; Giuranna, M.
A large number of spectra measured by the planetary Fourier spectrometer aboard the European Mars Express mission have been studied to identify the average properties of methane in the Martian atmosphere. Using the line at 3018 cm -1, we have studied the seasonal, diurnal, and spatial variations of methane through the analysis of large …
Large-scale spring deposits on Mars?
van Gasselt, Stephan; Neukum, Gerhard; Hauber, Ernst +5 more
We present a large-scale spring hypothesis for the formation of various enigmatic light-toned deposits (LTDs) on Mars. Layered to massive LTDs occur extensively in Valles Marineris, chaotic terrains, and several large craters, in particular, those located in Arabia Terra. Most of these deposits are not easily explained with either a single process…
Dark Matter and Baryons in the X-Ray Luminous Merging Galaxy Cluster RX J1347.5-1145
Treu, Tommaso; Bradač, Maruša; Schrabback, Tim +12 more
The galaxy cluster RX J1347.5-1145 is one of the most X-ray luminous and most massive clusters known. This makes it a prime target for studying issues addressing cluster formation and cosmology. Despite the naive expectation that mass estimation for this cluster should be straightforward (high mass and favorable redshift make it an efficient lens;…
A New VLA-Hipparcos Distance to Betelgeuse and its Implications
Harper, Graham M.; Brown, Alexander; Guinan, Edward F.
The distance to the M supergiant Betelgeuse is poorly known, with the Hipparcos parallax having a significant uncertainty. For detailed numerical studies of M supergiant atmospheres and winds, accurate distances are a prerequisite to obtaining reliable estimates for many stellar parameters. New high spatial resolution, multiwavelength, NRAO3<…
Helioseismology of Sunspots: Confronting Observations with Three-Dimensional MHD Simulations of Wave Propagation
Duvall, T. L., Jr.; Gizon, L.; Cameron, R.
The propagation of solar waves through the sunspot of AR 9787 is observed by using temporal cross-correlations of SOHO/MDI Dopplergrams. We then use three-dimensional MHD numerical simulations to compute the propagation of wave packets through self-similar magnetohydrostatic sunspot models. The simulations are set up in such a way as to allow a co…
Planetary period oscillations in Saturn's magnetosphere: Phase relation of equatorial magnetic field oscillations and Saturn kilometric radiation modulation
Dougherty, M. K.; Andrews, D. J.; Cowley, S. W. H. +3 more
We examine the planetary-period oscillations in Saturn's magnetic field observed by the Cassini spacecraft on 23 near-equatorial periapsis passes in the inner magnetosphere spanning October 2004 to July 2006. Overall, we find that the phase of the magnetic oscillations is well organized by the long-timescale modulation phase of Saturn kilometric r…
A Comprehensive View of the 2006 December 13 CME: From the Sun to Interplanetary Space
Liu, Y.; Sauvaud, J. -A.; Luhmann, J. G. +7 more
The biggest halo coronal mass ejection (CME) since the Halloween storm in 2003, which occurred on 2006 December 13, is studied in terms of its solar source and heliospheric consequences. The CME was accompanied by an X3.4 flare, EUV dimmings, and coronal waves. It generated significant space weather effects such as an interplanetary shock, radio b…