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Chandra Observations of Coronal Emission from the Early G Supergiants α and β Aquarii
Ayres, Thomas R.; Harper, Graham M.; Brown, Alexander
We report Chandra detections of coronal X-rays from the early G supergiants α Aquarii (HD 209750: G2 Ib) and β Aquarii (HD 204867: G0 Ib). Previous ROSAT observations of these archetypical ``hybrid chromosphere'' stars were inconclusive, in the case of α Aqr owing to a 38' mispointing, and for β Aqr because of a small positional discrepancy of the…
Dust Extinction in Compact Planetary Nebulae
Kwok, S.; Lee, T. -H.
The effects of dust extinction on the departure from axisymmetry in the morphology of planetary nebulae (PNs) are investigated through a comparison of the radio free-free emission and hydrogen recombination line images. The dust extinction maps from five compact PNs are derived using high-resolution (~0.1") Hα and radio maps of the HST and VLA. Th…
Origin and Acceleration of the Slow Solar Wind
Habbal, Shadia Rifai; Woo, Richard
This Letter uses Doppler dimming measurements by SOHO UVCS to elucidate the origin and acceleration of the slow solar wind. By investigating plasma flow in the corona over an active region during 2000 May 14-16, we confirm what has been suggested by the presence of the imprint of active regions in the solar wind near Earth orbit, that active regio…
Evolution of the Dependence of Rest-Frame Color and Morphology Distribution on Stellar Mass for Galaxies in the Hubble Deep Field-North
Yamada, T.; Kajisawa, M.
Using very deep Subaru K'-band imaging and archival Hubble Space Telescope WFPC2/NICMOS data of the Hubble Deep Field-North, we investigate the evolution of the stellar mass, color, and morphology of galaxies to z~3. We mainly examine the rest-frame U-V color distribution of galaxies as a function of stellar mass. At 0.3<~z<~2, galaxies seem…
Discovery of CH and OH in the -513 km s-1 Ejecta of η Carinae
Gull, T. R.; Nielsen, K. E.; Bruhweiler, F. +3 more
The very massive star η Carinae (η Car) is enshrouded in an unusual complex of stellar ejecta, which is highly depleted in C and O and enriched in He and N. This circumstellar gas gives rise to distinct absorption components corresponding to at least 20 different velocities along the line of sight. The velocity component at -513 km s-1 …
Supersolar N/C in the Narrow-Line Seyfert 1 Galaxy Markarian 1044
Pogge, Richard W.; Nicastro, Fabrizio; Mathur, Smita +2 more
Narrow-line Seyfert 1 galaxies (NLS1s) are known to have extreme values of a number of properties compared to active galactic nuclei (AGNs) as a class. In particular, previous emission-line studies have suggested that NLS1s are unusually metal-rich compared to broad-line AGNs of comparable luminosity. We present low- and medium-resolution spectros…
An XMM-Newton Study of the Coronae of σ2 Coronae Borealis
Güdel, Manuel; Audard, Marc; Suh, Jin A. +1 more
We present results of XMM-Newton Guaranteed Time observations of the RS CVn binary σ2 Coronae Borealis. The spectra obtained with the Reflection Grating Spectrometers and the European Photon Imaging Camera MOS2 were simultaneously fitted with collisional ionization equilibrium plasma models to determine coronal abundances of various ele…
The Prominent Dust Emission Feature near 8.9 µm in Four H II Regions
Hayward, T. L.; Tielens, A. G. G. M.; Boogert, A. C. A. +2 more
We present a mid-infrared study of four H II regions based on the combination of Infrared Space Observatory (ISO) SWS observations with spatial information from SpectroCam-10 images and long-slit spectra. We report a prominent broad emission feature near 8.9 µm. The peak position and width of this feature do not resemble known polycyclic aro…
Molecular Hydrogen in Orion as Observed by the Far Ultraviolet Spectroscopic Explorer
France, K.; McCandliss, S. R.
Diffuse far-ultraviolet stellar emission scattered by dust grains has been observed in a region near the Orion Nebula. In addition to the scattered stellar continuum, emission and absorption features produced by molecular hydrogen have been identified. In this Letter, we present an analysis of this absorption and fluorescent emission from molecula…
A Multiwavelength Study of the X-Ray Sources in NGC 5018
Wu, Kinwah; Tennant, Allyn F.; Swartz, Douglas A. +2 more
The E3 giant elliptical galaxy NGC 5018 was observed with the Chandra X-Ray Observatory's Advanced CCD Imaging Spectrometer for 30 ks on 2001 April 14. Results of the analysis of these X-ray data as well as of complementary optical, infrared, and radio data are reported. Seven X-ray point sources, including the nucleus, were detected. If they are …