Search Publications
Spectral Observations of the Enceladus Plume with Cassini-Vims
Brown, R. H.; Buratti, B. J.; Clark, R. N. +3 more
On 2005 November 27 (day 331), the Visual and Infrared Mapping Spectrometer instrument onboard the Cassini spacecraft obtained high signal-to-noise, spatially resolved measurements of Enceladus' particle plume. These data are processed to obtain spectra of the plume at a range of altitudes between 50 and 300 km from the surface. These spectra show…
The Case of AB Aurigae's Disk in Polarized Light: Is there Truly a Gap?
Schneider, Glenn; Hines, Dean C.; Perrin, Marshall D. +4 more
Using the Near-Infrared Camera and Multi-Object Spectrometer (NICMOS) coronagraph, we have obtained high-contrast 2.0 µm imaging polarimetry and 1.1 µm imaging of the circumstellar disk around AB Aurigae on angular scales of 0.3-3'' (40-550 AU). Unlike previous observations, these data resolve the disk in both total and polarized inten…
Sharpening the Tip of the Red Giant Branch
Madore, Barry F.; Freedman, Wendy L.; Mager, Violet
We introduce a modified detection method for measuring the luminosity of the tip of the red giant branch (TRGB) by introducing the composite magnitude T ≡ I - β[(V - I)xcirc - 1.50], where β is the slope of the tip magnitude as a function of color (or metallicity). The method is specifically designed to account for known systematics due…
Upper Limits on the Masses of 105 Supermassive Black Holes from Hubble Space Telescope/Space Telescope Imaging Spectrograph Archival Data
Beifiori, A.; Dalla Bontà, E.; Corsini, E. M. +4 more
Based on the modeling of the central emission-line width measured over subarcsecond apertures with the Hubble Space Telescope, we present stringent upper bounds on the mass of the central supermassive black hole, M •, for a sample of 105 nearby galaxies (D < 100 Mpc) spanning a wide range of Hubble types (E-Sc) and values of the cent…
Evidence for Quasi-Isotropic Magnetic Fields from Hinode Quiet-Sun Observations
Asensio Ramos, A.
Some recent investigations of spectropolarimetric observations of the Zeeman effect in the Fe I lines at 630 nm carried out with the Hinode solar space telescope have concluded that the strength of the magnetic field vector in the internetwork regions of the quiet Sun is in the hG regime and that its inclination is predominantly horizontal. We cri…
Star Formation in Luminous H II Regions in M33
Relaño, Mónica; Kennicutt, Robert C., Jr.
We present a multiwavelength (ultraviolet, infrared, optical, and CO) study of a set of luminous H II regions in M33: NGC 604, NGC 595, NGC 592, NGC 588, and IC131. We study the emission distribution in the interiors of the H II regions to investigate the relation between the dust emission at 8 µm and 24 µm and the location of the mass…
A Stellar Dynamical Measurement of the Black Hole Mass in the Maser Galaxy NGC 4258
Filippenko, Alexei V.; Ho, Luis C.; Gebhardt, Karl +13 more
We determine the mass of the black hole at the center of the spiral galaxy NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These models are constrained by high spatial resolution imaging and long-slit spectroscopy of the nuclear region obtained with the Hubble Space Telescope, complemented by ground-based observations extendi…
Observations and Nonlinear Force-Free Field Modeling of Active Region 10953
Golub, Leon; van Ballegooijen, Adriaan; Lites, Bruce W. +5 more
We present multiwavelength observations of a simple bipolar active region (NOAA 10953), which produced several small flares (mostly B class and one C8.5 class) and filament activations from April 30 to May 3 in 2007. We also explore nonlinear force-free field (NLFFF) modeling of this region prior to the C8.5 flare on May 2, using magnetograph data…
On the Extended Structure of the Phoenix Dwarf Galaxy
Aparicio, Antonio; Martínez-Delgado, David; Hidalgo, Sebastian L. +1 more
We present the star formation history (SFH) and its variations with galactocentric distance for the Local Group dwarf galaxy of Phoenix. They have been derived from a (F555W, F814W) color-magnitude diagram obtained from WFPC2@HST data, which reaches the oldest main-sequence turnoffs. The IAC-star and IAC-pop codes and the MinnIAC suite have been u…
X-Ray and Infrared Observations of Two Externally Polluted White Dwarfs
Zuckerman, B.; Muno, M. P.; Jura, M. +1 more
With XMM-Newton and the Spitzer Space Telescope, we obtain upper bounds to the X-ray fluxes from G29-38 and GD 362, and the 70 µm flux from G29-38. These data provide indirect evidence that G29-38 is accreting from a tidally disrupted asteroid: it is neither accreting large amounts of hydrogen and helium nor is its surrounding dusty disk bei…