Search Publications
``Comets'' orbiting a black hole
Maiolino, R.; Elvis, M.; Fabbiano, G. +6 more
We use a long (300 ks), continuous Suzaku X-ray observation of the active nucleus in NGC 1365 to investigate the structure of the circumnuclear broad line region (BLR) clouds through their occultation of the X-ray source. The variations of the absorbing column density and of the covering factor indicate that the clouds surrounding the black hole a…
Identifications and Photometric Redshifts of the 2 Ms Chandra Deep Field-South Sources
Lehmer, B. D.; Alexander, D. M.; Silverman, J. D. +11 more
We present reliable multiwavelength identifications and high-quality photometric redshifts for the 462 X-ray sources in the ≈2 Ms Chandra Deep Field-South (CDF-S) survey. Source identifications are carried out using deep optical-to-radio multiwavelength catalogs, and are then combined to create lists of primary and secondary counterparts for the X…
A new form of Saturn's magnetopause using a dynamic pressure balance model, based on in situ, multi-instrument Cassini measurements
Coates, A. J.; Krupp, N.; Dougherty, M. K. +9 more
The shape and location of a planetary magnetopause can be determined by balancing the solar wind dynamic pressure with the magnetic and thermal pressures found inside the boundary. Previous studies have found the kronian magnetosphere to show rigidity (like that of Earth) as well as compressibility (like that of Jupiter) in terms of its dynamics. …
Ultradeep Infrared Array Camera Observations of Sub-L* z ~ 7 and z ~ 8 Galaxies in the Hubble Ultra Deep Field: the Contribution of Low-Luminosity Galaxies to the Stellar Mass Density and Reionization
Trenti, M.; Oesch, P. A.; Carollo, C. M. +9 more
We study the Spitzer Infrared Array Camera (IRAC) mid-infrared (rest-frame optical) fluxes of 14 newly WFC3/IR-detected z ~ 7 z 850-dropout galaxies and 5z ~ 8 Y 105-dropout galaxies. The WFC3/IR depth and spatial resolution allow accurate removal of contaminating foreground light, enabling reliable flux measurements at 3.6 &…
Methane absorption coefficients for the jovian planets from laboratory, Huygens, and HST data
Karkoschka, Erich; Tomasko, Martin G.
We use 11 data sets of methane transmission measurements within 0.4-5.5 µm wavelength to model the methane transmission for temperature and pressure conditions in the jovian planets. Eight data sets are based on published laboratory measurements. Another two data sets come from two spectrometers onboard the Huygens probe that measured methan…
Initial results for the north pole of the Moon from Mini-SAR, Chandrayaan-1 mission
Kirk, R. L.; Neish, C. D.; Butler, B. J. +27 more
We present new polarimetric radar data for the surface of the north pole of the Moon acquired with the Mini-SAR experiment onboard India's Chandrayaan-1 spacecraft. Between mid-February and mid-April, 2009, Mini-SAR mapped more than 95% of the areas polewards of 80° latitude at a resolution of 150 meters. The north polar region displays backscatte…
The Sun's Supergranulation
Rieutord, Michel; Rincon, François
The Sun's supergranulation refers to a physical pattern covering the surface of the quiet Sun with a typical horizontal scale of approximately 30,000 km and a lifetime of around 1.8 d. Its most noticeable observable signature is as a fluctuating velocity field of 360 m st-1 rms whose components are mostly horizontal. Supergranulation wa…
Magnetic Turbulence in the Geospace Environment
Perri, S.; Alexandrova, O.; Sorriso-Valvo, L. +5 more
Magnetic turbulence is found in most space plasmas, including the Earth's magnetosphere, and the interaction region between the magnetosphere and the solar wind. Recent spacecraft observations of magnetic turbulence in the ion foreshock, in the magnetosheath, in the polar cusp regions, in the magnetotail, and in the high latitude ionosphere are re…
Solar Meridional Circulation from Doppler Shifts of the Fe I Line at 5250 Å as Measured by the 150-foot Solar Tower Telescope at the Mt. Wilson Observatory
Ulrich, Roger K.
Doppler shifts of the Fe I spectral line at 5250 Å from the full solar disk obtained over the period 1986 to 2009 are analyzed to determine the circulation velocity of the solar surface along meridional planes. Simultaneous measurements of the Zeeman splitting of this line are used to obtain measurements of the solar magnetic field that are used t…
The Luminosity, Mass, and Age Distributions of Compact Star Clusters in M83 Based on Hubble Space Telescope/Wide Field Camera 3 Observations
Mutchler, Max; Calzetti, Daniela; Whitmore, Bradley C. +21 more
The newly installed Wide Field Camera 3 (WFC3) on the Hubble Space Telescope has been used to obtain multi-band images of the nearby spiral galaxy M83. These new observations are the deepest and highest resolution images ever taken of a grand-design spiral, particularly in the near-ultraviolet, and allow us to better differentiate compact star clu…