Search Publications
New Solar Telescope Observations of Magnetic Reconnection Occurring in the Chromosphere of the Quiet Sun
Chae, Jongchul; Goode, P. R.; Ahn, K. +5 more
Magnetic reconnection is a process in which field-line connectivity changes in a magnetized plasma. On the solar surface, it often occurs with the cancellation of two magnetic fragments of opposite polarity. Using the 1.6 m New Solar Telescope, we observed the morphology and dynamics of plasma visible in the Hα line, which is associated with a can…
Toward the General Red Giant Branch Slope-Metallicity-Age Calibration. I. Metallicities, Ages, and Kinematics for Eight Large Magellanic Cloud Clusters
Geisler, D.; Sharma, Saurabh; Borissova, J. +2 more
In this paper, we discuss the properties of color-magnitude diagrams, age, metallicity, and radial velocities of eight massive Large Magellanic Cloud (LMC) clusters using data taken from the FORS2 multiobject spectrograph at the 8.2 m Very Large Telescope/Unit Telescope 1. The strong near-infrared Ca II triplet lines of red giant branch stars obta…
A Novel Approach in Constraining Electron Spectra in Blazar Jets: The Case of Markarian 421
Takahashi, Tadayuki; Tanaka, Takaaki; Kataoka, Jun +7 more
We report results from the observations of the well-studied TeV blazar Mrk 421 with the Swift and the Suzaku satellites in 2008 December. During the observation, Mrk 421 was found in a relatively low activity state, with the corresponding 2-10 keV flux of 3 × 10-10 erg s-1 cm-2. For the purpose of robustly constrai…
Suzaku Observations of the Black Hole H1743-322 in Outburst
Yamaoka, K.; Takahashi, H.; Fabian, A. C. +5 more
We observed the Galactic black hole candidate H1743-322 with Suzaku for approximately 32 ks, while the source was in a low/hard state during its 2008 outburst. We collected and analyzed the data with the HXD/PIN, HXD/GSO, and XIS cameras spanning the energy range 0.7-200 keV. Fits to the spectra with simple models fail to detect narrow Fe XXV and …
Gas kinetics and dust dynamics in low-density comet comae
Kamp, Lucas; Gulkis, Samuel; Lee, Seungwon +4 more
Extensive regions of low-density cometary comae are characterized by important deviations from the Maxwell-Boltzmann velocity distribution, i.e. breakdown of thermodynamic equilibrium. The consequences of this on the shapes of emission and absorption lines, and for the acceleration of solid bodies due to gas drag, have rarely been investigated. Th…
The warm absorber and X-ray variability of the Seyfert 1 galaxy NGC 3516 as seen by the XMM-Newton RGS
Mehdipour, M.; Page, M. J.; Branduardi-Raymont, G.
Aims: We present a new analysis of the soft and medium energy X-ray spectrum of the Seyfert 1 galaxy NGC 3516 taken with the Reflection Grating Spectrometer (RGS) and European Photon Imaging Camera (EPIC) on board the XMM-Newton observatory. We examine four observations made in October 2006. We investigate whether the observed variability is …
Field and Globular Cluster Low-mass X-ray Binaries in NGC 4278
Zezas, A.; Gallagher, J.; King, A. R. +12 more
We report a detailed spectral analysis of the population of low-mass X-ray binaries (LMXBs) detected in the elliptical galaxy NGC 4278 with Chandra. Seven luminous sources were studied individually, four in globular clusters (GCs) and three in the stellar field. The range of (0.3-8 keV) L X for these sources is ~(3-8) × 1038 …
The Discovery of Infrared Rings in the Planetary Nebula NGC 1514 During the WISE All-sky Survey
Hoard, D. W.; Wright, Edward L.; Wachter, Stefanie +3 more
We report the discovery of a pair of infrared, axisymmetric rings in the planetary nebula NGC 1514 during the course of the WISE all-sky mid-infrared survey. Similar structures are seen at visible wavelengths in objects such as the "Engraved Hourglass Nebula" (MyCn 18) and the "Southern Crab Nebula" (Hen 2-104). However, in NGC 1514 we see only a …
Galaxy Clusters at z >= 1: Gas Constraints from the Sunyaev-Zel'dovich Array
Andreon, S.; Carlstrom, J. E.; Leitch, E. M. +20 more
We present gas constraints from Sunyaev-Zel'dovich (SZ) effect measurements in a sample of 11 X-ray and infrared (IR) selected galaxy clusters at z>=1, using data from the Sunyaev-Zel'dovich Array (SZA). The cylindrically integrated Compton-y parameter, Y, is calculated by fitting the data to a two-parameter gas pressure profile. Where possible…
Ground-state ammonia and water in absorption towards Sgr B2
Falgarone, E.; Larsson, B.; Olberg, M. +8 more
Context. Observations of transitions to the ground-state of a molecule are essential to obtain a complete picture of its excitation and chemistry in the interstellar medium, especially in diffuse and/or cold environments. For the important interstellar molecules H2O and NH3, these ground-state transitions are heavily absorbed…