Search Publications
The Host Galaxies of Narrow-Line Seyfert 1 Galaxies: Nuclear Dust Morphology and Starburst Rings
Kraemer, S. B.; Crenshaw, D. M.; Deo, R. P.
We present a study of the nuclear morphology of a sample of narrow- and broad-line Seyfert 1 galaxies (NLS1s and BLS1s, respectively) based on broadband images in the Hubble Space Telescope archives. In our previous study we found that large-scale stellar bars at >1 kpc from the nucleus are more common in NLS1s than BLS1s. In this paper we find…
Hubble Space Telescope ACS Wide-Field Photometry of the Sombrero Galaxy Globular Cluster System
Spitler, Lee R.; Forbes, Duncan A.; Brodie, Jean P. +3 more
A detailed imaging analysis of the globular cluster (GC) system of the Sombrero galaxy (NGC 4594) has been accomplished using a six-image mosaic from the Hubble Space Telescope Advanced Camera for Surveys. The quality of the data is such that contamination by foreground stars and background galaxies is negligible for all but the faintest 5% of the…
Discovery of an 86 AU Radius Debris Ring around HD 181327
Henning, Thomas; Schneider, Glenn; Hines, Dean C. +11 more
HST NICMOS PSF-subtracted coronagraphic observations of HD 181327 have revealed the presence of a ringlike disk of circumstellar debris seen in 1.1 µm light scattered by the disk grains, surrounded by a diffuse outer region of lower surface brightness. The annular disk appears to be inclined by 31.7d+/-1.6d from face-on, with the disk major-…
Reconstruction of solar irradiance variations in cycles 21-23 based on surface magnetic fields
Solanki, S. K.; Krivova, N. A.; Fröhlich, C. +1 more
Aims.We present a reconstruction of total solar irradiance (TSI) back to 1974, i.e. from the minimum of cycle 21 to the declining phase of cycle 23. We also present a cross-calibration between the magnetograms obtained by the 512 channel magnetograph and the spectromagnetograph at Kitt Peak.
Methods: .The TSI reconstruction is carried out usin…
The Arches Cluster Mass Function
Najarro, F.; Figer, Donald F.; Kim, Sungsoo S. +1 more
We have analyzed H- and Ks-band images of the Arches cluster obtained using the NIRC2 instrument on Keck with the laser guide star adaptive optics (LGS AO) system. With the help of the LGS AO system, we were able to obtain the deepest ever photometry for this cluster and its neighborhood and derive the background-subtracted present-day …
A Survey of Galaxy Kinematics to z~1 in the TKRS/GOODS-N Field. II. Evolution in the Tully-Fisher Relation
Weiner, Benjamin J.; Faber, S. M.; Willmer, Christopher N. A. +7 more
We use kinematic measurements of a large sample of galaxies from the Team Keck Redshift Survey in the GOODS-N field to measure evolution in the optical and near-IR Tully-Fisher (TF) relations to z=1.2. We construct TF relations with integrated line-of-sight velocity widths of ~1000 galaxies in B and ~670 in J; these relations have large scatter, a…
Motion of observed structures calculated from multi-point magnetic field measurements: Application to Cluster
Balogh, A.; Zong, Q. -G.; Lucek, E. +5 more
A new method is described which calculates the velocity of observed, quasi-stationary structures at every moment in time from multi-point magnetic field measurements. Once the magnetic gradient tensor G = $\nabla$$\vec {B and the time variation of the magnetic field have been estimated at every moment, the velocity can then be determined, in princ…
Solar Sources of Impulsive Solar Energetic Particle Events and Their Magnetic Field Connection to the Earth
Liu, Yang; Yashiro, Seiji; Nitta, Nariaki V. +3 more
This paper investigates the solar origin of impulsive solar energetic particle (SEP) events, often referred to as 3He-rich flares, by attempting to locate the source regions of 117 events as observed at ~2-3 MeV amu-1. Given large uncertainties as to when ions at these energies were injected, we use type III radio bursts that…
Detection of Wolf-Rayet stars in host galaxies of gamma-ray bursts (GRBs): are GRBs produced by runaway massive stars ejected from high stellar density regions?
Le Floc'h, E.; Schaerer, D.; Dessauges-Zavadsky, M. +3 more
We have obtained deep spectroscopic observations of several nearby gamma-ray burst (GRB) host galaxies revealing for the first time the presence of Wolf-Rayet (WR) stars and numerous O stars located in rich and compact clusters or star forming regions. Surprisingly, high spatial resolution imaging shows that the GRBs and the associated supernovae …
Subvisible CO 2 ice clouds detected in the mesosphere of Mars
Montmessin, Franck; Bertaux, Jean-Loup; Perrier, Séverine +8 more
The formation of CO 2 ice clouds in the upper atmosphere of Mars has been suggested in the past on the basis of a few temperature profiles exhibiting portions colder than CO 2 frost point. However, the corresponding clouds were never observed. In this paper, we discuss the detection of the highest clouds ever observed on Mars…