Search Publications
Chandra Exposes the Core-collapsed Globular Cluster NGC 6397
Heinke, C. O.; Cool, A. M.; Grindlay, J. E. +2 more
We report results of the Chandra deep-imaging observation of the closest post-core-collapse globular cluster, NGC 6397. Some 25 sources are detected within 2' of the cluster center, of which ~20 are likely cluster members, with LX>~3×1029 ergs s-1. The X-ray spectra suggest identifications with one quiescent low…
Soft X-ray emission lines from a relativistic accretion disk in MCG -6-30-15 and Mrk 766
Kaastra, J. S.; Sako, M.; Page, M. J. +3 more
XMM-Newton Reflection Grating Spectrometer (RGS) spectra of the Narrow Line Seyfert 1 galaxies
The Fossil Starburst in M82
de Grijs, Richard; O'Connell, Robert W.; Gallagher, John S., III
We present high-resolution HST imaging in the optical (WFPC2) and near-infrared (NICMOS) of a disk region 1 kpc northeast of the starburst core in the nearby galaxy M82. This region, M82 ``B,'' has been suspected to be a fossil starburst site in which an intense episode of star formation occurred over 100 Myr ago, and our new observations confirm …
Improvements to the HAF solar wind model for space weather predictions
Dryer, M.; Smith, Z.; Fry, C. D. +5 more
We have assembled and tested, in real time, a space weather modeling system that starts at the Sun and extends to the Earth through a set of coupled, modular components. We describe recent efforts to improve the Hakamada-Akasofu-Fry (HAF) solar wind model that is presently used in our geomagnetic storm prediction system. We also present some resul…
Chromospheric activity, lithium and radial velocities of single late-type stars possible members of young moving groups
Montes, D.; López-Santiago, J.; Fernández-Figueroa, M. J. +1 more
We present here high resolution echelle spectra taken during three observing runs of 14 single late-type stars identified in our previous studies (Montes et al. \cite{M_etal01b}, hereafter Paper I) as possible members of different young stellar kinematic groups (Local Association (20-150 Myr), Ursa Major group (300 Myr), Hyades supercluster (600 M…
Chandra Limits on X-Ray Emission Associated with the Supermassive Black Holes in Three Giant Elliptical Galaxies
Angelini, Lorella; Loewenstein, Michael; Mushotzky, Richard F. +2 more
Elliptical galaxy nuclei are the sites of the largest black holes known but typically show little or no nuclear activity. We investigate this extreme quiescence using Chandra X-Ray Observatory observations of the giant elliptical galaxies NGC 1399, NGC 4472, and NGC 4636. The unique Chandra imaging power enables us to place upper limits of 7.3, 15…
Dusty Nuclear Disks and Filaments in Early-Type Galaxies
Jaffe, W.; Ford, H. C.; van den Bosch, F. C. +4 more
We examine the dust properties of a nearby distance-limited sample of early-type galaxies using WFPC2 of the Hubble Space Telescope. Dust is detected in 29 out of 67 galaxies (43%), including 12 with small nuclear dusty disks. In a separate sample of 40 galaxies biased for the detection of dust by virtue of their detection in IRAS 100 µm ban…
The magnetic field and wind confinement of β Cephei: new clues for interpreting the Be phenomenon?
Donati, J. -F.; Babel, J.; Harries, T. J. +3 more
In this paper, we use the very recent spectropolarimetric observations of β Cep collected by Henrichs et al. and propose for this star a consistent model of the large-scale magnetic field and of the associated magnetically confined wind and circumstellar environment. A re-examination of the fundamental parameters of β Cep in the light of the Hippa…
Slow magnetoacoustic waves in coronal loops: EIT and TRACE
Berghmans, D.; Poedts, S.; Hochedez, J. F. +3 more
On May 13, 1998 the EIT (Extreme ultraviolet Imaging Telescope) on board of SoHO (Solar and Heliospheric Observatory) and TRACE (Transition Region And Coronal Explorer) instruments produced simultaneous high cadence image sequences of the same active region (AR 8218). TRACE achieved a 25 s cadence in the Fe Ix (171 Å) bandpass while EIT achieved a…
Bipolar outflows in OH/IR stars
Norris, R. P.; Molster, F. J.; Comeron, F. +5 more
We investigate the development of bipolar outflows during the early post-AGB evolution. A sample of 10 OH/IR stars with irregular OH spectra and unusually large expansion velocities is observed at high angular resolution. The sample includes bipolar nebulae (e.g., OH231.8+4.2), bright post-AGB stars (HD 101584) and reflection nebulae (e.g., Robert…