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Infrared Space Observatory Spectroscopy of Extreme Carbon Stars
Volk, Kevin; Kwok, Sun; Xiong, Guan-Zhu
We present Infrared Space Observatory (ISO) SWS01 (2-43 µm) and LWS01 (43-195 µm) observations of five highly evolved carbon stars with extremely thick circumstellar envelopes. The unidentified 30 µm emission feature is detected in the SWS01 spectra of all five sources. This feature seems to be resolved into two subfeatures at 25…
Ultracompact X-Ray Binaries in Globular Clusters: Variability of the Optical Counterpart of X1832-330 in NGC 6652
Anderson, Scott F.; Margon, Bruce; Deutsch, Eric W.
Evidence is emerging that the luminous X-ray sources in the cores of globular clusters may often consist of, or perhaps even as a class be dominated by, ultracompact (P<~1 hr) binary stars. To the two such systems already known, in NGC 6624 and NGC 6712, we now add evidence for two more. We detect large-amplitude variability in the candidate op…
Hubble Space Telescope Photometry of Hodge 301: An ``Old'' Star Cluster in 30 Doradus
Grebel, Eva K.; Chu, You-Hua
We present Hubble Space Telescope Planetary Camera UVI data for Hodge 301, the little-studied cluster 3' northwest of the central ionizing cluster R136 in 30 Doradus. The average reddening of Hodge 301 is found to be <EB-V>=0.28+/-0.05 mag from published infrared and ultraviolet photometry. Using two different sets of evolutionary…
Near-Infrared Imaging Polarimetry of the GG Tauri Circumbinary Ring
Duchêne, Gaspard; Gledhill, Tim; Ménard, François +1 more
We present 1 µm Hubble Space Telescope/near-infrared camera and multiobject spectrometer resolved imaging polarimetry of the GG Tau circumbinary ring. We find that the ring displays east-west asymmetries in surface brightness as well as several pronounced irregularities but is smoother than suggested by ground-based adaptive optics observati…
Absorption spectra of Mg-rich Mg-Fe and Ca pyroxenes in the mid- and far-infrared regions
Koike, C.; Tsuchiyama, A.; Shibai, H. +6 more
Absorption spectra of the pyroxene group have been measured in mid and far infrared wavelengths. The samples are crystalline pyroxenes (enstatite, diopside, and natural pyroxene) and amorphous pyroxenes (enstatite and diopside glass). Especially, the synthetic pyroxenes such as orthoenstatite, clinoenstatite and diopside are pure and high-quality …
The Resolved Narrow-Line Region in NGC 4151
Gull, T. R.; Kraemer, S. B.; Crenshaw, D. M. +6 more
We present slitless spectra of the narrow-line region (NLR) in NGC 4151 from the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope and investigate the kinematics and physical conditions of the emission-line clouds in this region. Using medium resolution (~0.5 Å) slitless spectra at two roll angles and narrow-band undisperse…
New PAH mode at 16.4 mu m
Schmidt, W.; Léger, A.; Moutou, C. +2 more
The detection of a new 16.4 mu m emission feature in the ISO-SWS spectra of NGC 7023, M17, and the Orion Bar is reported. Previous laboratory experiments measured a mode near this wavelength in spectra of PAHs (Polycyclic Aromatic Hydrocarbons), and so we suggest the new interstellar 16.4 mu m feature could be assigned to low-frequency vibrations …
Origin of Color Gradients in Elliptical Galaxies
Kobayashi, Chiaki; Kodama, Tadayuki; Tamura, Naoyuki +2 more
The origin of color gradients in elliptical galaxies is examined by comparing model gradients with those observed in the Hubble Deep Field. The models are constructed so as to reproduce color gradients in local elliptical galaxies either by a metallicity gradient or by an age gradient. By looking-back a sequence of the color gradient as a function…
The distribution of bright OB stars in the Canis Major-Puppis-Vela region of the Milky Way
Kaltcheva, N. T.; Hilditch, R. W.
The picture of the young stellar groups in the Canis Major-Puppis-Vela (215 deg<l<275 deg) section of the Milky Way is studied and updated utilizing uvbyβ photometry of intrinsically luminous OB stars. We use all data from the literature to create a sample with 98per cent completeness to 9.5mag. The very dense low reddened OB association CMa…
The solar magnetic field and the solar wind: Existence of preferred longitudes
Smith, E. J.; Neugebauer, M.; Feynman, J. +2 more
Direct measurements of the solar wind speed and the radial component of the interplanetary magnetic field acquired over more than three solar cycles are used to search for signatures of a persistent dependence of solar wind properties on solar longitude. Two methods of analysis are used. One finds the rotation period that maximizes the amplitude o…