Search Publications
A 2 Hour Quasi Period in an Ultraluminous X-Ray Source in NGC 628
Bregman, Joel N.; Seitzer, Patrick; Espaillat, Catherine +3 more
Quasi-periodic oscillations and X-ray spectroscopy are powerful probes of black hole masses and accretion disks, and here we apply these diagnostics to an ultraluminous X-ray source (ULX) in the spiral galaxy NGC 628 (M74). This object was observed four times over 2 years with the Chandra X-Ray Observatory and XMM-Newton, with three long observati…
Flare-associated Coronal Disturbances Observed with the Norikura Green-Line Imaging System. I. A Coronal Mass Ejection Onset
Ichimoto, K.; Sakurai, T.; Hori, K. +2 more
We present the first detection of an onset of a coronal mass ejection (CME) in the coronal green-line emission (Fe XIV λ5303, 2 MK) by the two-dimensional Doppler coronagraph NOGIS (Norikura Green-Line Imaging System) at the Norikura Solar Observatory, National Astronomical Observatory of Japan. On 2003 June 1-2, NOGIS continuously observed the bi…
Discovery of Ne VII in the Winds of Hot Evolved Stars
Hillier, D. J.; Bianchi, L.; Herald, J. E.
We show that a strong P Cygni feature seen in the far-UV spectra of some very hot (Teff>~85 kK) central stars of planetary nebulae (CSPN), which has been previously identified as C III λ977, actually originates from Ne VII λ973. Using stellar atmosphere models, we reproduce this feature seen in the spectra of two [WR] PG 1159-type CS…
Extragalactic Source Counts in the Spitzer 24 Micron Band: What Do We Expect from ISOCAM 15 Micron Data and Models?
Pozzi, F.; Rodighiero, G.; Gruppioni, C. +2 more
The comparison between the new Spitzer data at 24 µm and the previous ISOCAM data at 15 µm is a key tool to understand galaxy properties and evolution in the infrared and to interpret the observed number counts, since the combination of Spitzer with the Infrared Space Observatory cosmological surveys provides for the first time the dir…
Probing Halos of Galaxies at Very Large Radii Using Background QSOs
Freeman, K. C.; Wyse, R. F. G.; Broadhurst, T. +2 more
Gaseous halos of nine nearby galaxies (with redshifts cz<6000 km s-1) were probed at large galactocentric radii using background quasars observed with the Hubble Space Telescope Goddard High Resolution Spectrograph and the Space Telescope Imaging Spectrograph. The projected quasar-galaxy separations range from 55 to 387 h-1
The Initial Mass Function toward the Low-Mass End in the Large Magellanic Cloud with Hubble Space Telescope WFPC2 Observations
Henning, Th.; Brandner, W.; Gouliermis, D.
We present V- and I-equivalent Hubble Space Telescope (HST) WFPC2 photometry of two areas in the Large Magellanic Cloud: the southern part of the stellar association LH 52, located on the western edge of the supershell LMC 4, and a field between two associations, which is located on the southwestern edge of the shell and accounts for the general b…
Modeling the Shock Aftermath Source of Energetic Particles in the Solar Corona
Vainio, Rami; Kocharov, Leon; Torsti, Jarmo +2 more
Recent observations on board the Solar and Heliospheric Observatory (SOHO) indicate that acceleration of solar energetic particles (SEPs) at intermediate scales in the solar corona, between flare acceleration and interplanetary CME-driven shock acceleration, significantly contributes to the production of >10 MeV protons. Coronal shocks seem to …
The Discovery of Extended Thermal X-Ray Emission from PKS 2152-699: Evidence for a ``Jet-Cloud'' Interaction
Bechtold, Jill; Ly, Chun; De Young, David S.
A Chandra ACIS-S observation of PKS 2152-699 reveals thermal emission from a diffuse region around the core and a hotspot located 10" northeast from the core. This is the first detection of thermal X-ray radiation on kiloparsec scales from an extragalactic radio source. Two other hotspots located 47" north-northeast and 26" southwest from the core…
X-Rays from Hybrid Stars
Ayres, Thomas R.
The late-type giants and supergiants of the ``hybrid chromosphere'' class display signatures of cool (T<~2×104 K) winds together with hot emission lines from species like C IV (T~105 K). A survey of such stars by Reimers et al. using ROSAT reported numerous X-ray detections (T~106 K), strengthening the (then her…
Galaxy Evolution Explorer Ultraviolet Spectroscopy and Deep Imaging of Luminous Infrared Galaxies in the European Large-Area ISO Survey S1 Field
Buat, Véronique; Burgarella, Denis; Heckman, Timothy M. +23 more
The European Large-Area ISO Survey (ELAIS) S1 field was observed by the Galaxy Evolution Explorer (GALEX) in both its Wide Spectroscopic and Deep Imaging Survey modes. This field was previously observed by the Infrared Space Observatory, and we made use of the catalog of multiwavelength data published by the ELAIS consortium to select galaxies com…