Search Publications
An Unexpected Discovery in the Rich Open Cluster NGC 6819 Using XMM-Newton
Ramirez-Ruiz, Enrico; Pooley, David; Kalirai, Jason +4 more
We present the first study of the X-ray population of the intermediate-age rich open cluster NGC 6819 using the XMM-Newton Observatory. In the past decade, Chandra X-ray observations have shown a relationship between the X-ray population of globular clusters and their internal dynamics and encounter frequency. We investigate the role dynamics poss…
Shocked and Scorched: The Tail of a Tadpole in an Interstellar Pond
Sahai, R.; Morris, M. R.; Claussen, M. J.
We report multi-wavelength observations of the far-infrared source IRAS 20324+4057, including high-resolution optical imaging with the Hubble Space Telescope, and ground-based near-infrared, millimeter-wave and radio observations. These data show an extended, limb-brightened, tadpole-shaped nebula with a bright, compact, cometary nebula located in…
The Central Region of the Barred Spiral Galaxy NGC 1097 Probed by AKARI Near-infrared Spectroscopy
Oyabu, Shinki; Onaka, Takashi; Yamagishi, Mitsuyoshi +6 more
With the Infrared Camera on board AKARI, we carried out near-infrared (2.5-5.0 µm) spectroscopy of the central kiloparsec region of the barred spiral galaxy, NGC 1097, categorized as Seyfert 1 with a circumnuclear starburst ring. Our observations mapped the area of ~50'' × 10'' with the resolution of ~5'', covering about a half of the ring a…
Multipolar Planetary Nebulae: Not as Geometrically Diversified as Thought
Kwok, Sun; Tafoya, D.; Imai, H. +2 more
Planetary nebulae (PNe) have diverse morphological shapes, including point-symmetric and multipolar structures. Many PNe also have complicated internal structures such as tori, lobes, knots, and ansae. A complete accounting of all the morphological structures through physical models is difficult. A first step toward such an understanding is to der…
Modeling the Accretion Structure of AU Mon
Peters, Geraldine J.; Miller, Brendan P.; Budaj, Ján +2 more
AU Mon is a long-period (11.113 days) Algol-type binary system with a persistent accretion disk that is apparent as double-peaked Hα emission. We present previously unpublished optical spectra of AU Mon which were obtained over 20 years from 1991-2011 with dense orbital phase coverage. We utilize these data, along with archival UV spectra, to mode…
Coronal Cells
Warren, H. P.; Sheeley, N. R., Jr.
We have recently noticed cellular features in Fe XII 193 Å images of the 1.2 MK corona. They occur in regions bounded by a coronal hole and a filament channel, and are centered on flux elements of the photospheric magnetic network. Like their neighboring coronal holes, these regions have minority-polarity flux that is ~0.1-0.3 times their flux of …
Hubble Space Telescope Observations of the Stellar Distribution near Sgr A*
Yusef-Zadeh, F.; Wardle, M.; Bushouse, H.
Sgr A* is embedded within the nuclear cluster, which consists of a mixture of evolved and young populations of stars dominating the light over a wide range of angular scales. Here we present Hubble Space Telescope/NICMOS data to study the surface brightness distribution of stellar light within the inner 10'' of Sgr A* at 1.45 µm, 1.7 µ…
The Resolved Stellar Population in 50 Regions of M83 from HST/WFC3 Early Release Science Observations
Mutchler, Max; McCarthy, Patrick J.; Calzetti, Daniela +22 more
We present a multi-wavelength photometric study of ~15,000 resolved stars in the nearby spiral galaxy M83 (NGC 5236, D = 4.61 Mpc) based on Hubble Space Telescope Wide Field Camera 3 observations using four filters: F336W, F438W, F555W, and F814W. We select 50 regions (an average size of 260 pc by 280 pc) in the spiral arm and inter-arm areas of M…
Power Spectra of Velocities and Magnetic Fields on the Solar Surface and their Dependence on the Unsigned Magnetic Flux Density
Katsukawa, Y.; Orozco Suárez, D.
We have performed power spectral analysis of surface temperatures, velocities, and magnetic fields, using spectropolarimetric data taken with the Hinode Solar Optical Telescope. When we make power spectra in a field of view covering the supergranular scale, kinetic and thermal power spectra have a prominent peak at the granular scale while the mag…
Suzaku X-Ray Imaging of the Extended Lobe in the Giant Radio Galaxy NGC 6251 Associated with the Fermi-LAT Source 2FGL J1629.4+8236
Cheung, C. C.; Kataoka, J.; Stawarz, Ł. +7 more
We report the results of a Suzaku X-ray imaging study of NGC 6251, a nearby giant radio galaxy with intermediate FR I/II radio properties. Our pointing direction was centered on the γ-ray emission peak recently discovered with the Fermi Large Area Telescope (LAT) around the position of the northwest (NW) radio lobe 15 arcmin offset from the nucleu…