Search Publications
X-Rays from Radio Millisecond Pulsars: Comptonized Thermal Radiation
Bogdanov, Slavko; Grindlay, Jonathan E.; Rybicki, George B.
X-ray emission from many rotation-powered millisecond pulsars (MSPs) is observed to be of predominantly thermal nature. In PSR J0437-4715, the nearest MSP known, an additional faint power-law tail is observed above 2.5 keV, commonly attributed to nonthermal magnetospheric radiation. We propose that the hard emission in this and other similar MSPs …
Proper Motion of the Crab Pulsar Revisited
Ng, C. -Y.; Romani, Roger W.
It has been suggested that the Crab pulsar's proper motion is aligned with the symmetry axis of the pulsar wind nebula. We have revisited this question, examining >6 years of F547M WFPC2 chip 3 images to obtain a best-fit value of µ*=14.9+/-0.8 mas yr-1 at P.A. 278deg+/-3deg. At 26deg…
Integral Field Spectroscopy of the Extended Emission-Line Region of 3C 249.1
Fu, Hai; Stockton, Alan
We present Gemini Multiobject Spectrograph integral field spectroscopy of the extended emission-line region associated with quasar 3C 249.1. The kinematics of the ionized gas measured from the [O III] λ5007 line is rather complex and cannot be explained globally by a simple dynamical model, but some clouds can be modeled individually as having loc…
A Spectroscopic Observation of a Magnetic Reconnection Site in a Small Flaring Event
Hara, Hirohisa; Ichimoto, Kiyoshi; Delaboudinière, Jean-Pierre +1 more
We have observed two types of coronal bidirectional flows in a flare with a small energy release through a spectroscopic observation of the Fe X emission line at 6374 Å with a ground-based coronagraph at the Norikura Solar Observatory. We find a bidirectional flow of +/-3 km s-1 above the top of a flare loop. Remarkable increases of the…
The Circumstellar Structure of the Class I Protostar TMC-1 (IRAS 04381+2540) from Hubble Space Telescope NICMOS Data
Terebey, Susan; Van Buren, David; Brundage, Michael +1 more
The class I protostar TMC-1 (IRAS 04381+2540) is oriented favorably for determining the properties of its circumstellar envelope and outflow cavity. Deep, high spatial resolution Hubble Space Telescope (HST) NICMOS images at 1.6 µm exhibit both a narrow jet and a wide-angle conical outflow cavity. Model images of the scattered-light distribu…
Mira B Rejuvenated
Wood, Brian E.; Karovska, Margarita
Recent ultraviolet spectra from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) satellites demonstrate that UV line and continuum fluxes observed from Mira B are increasing back toward the levels that the International Ultraviolet Explorer (IUE) observed in 1979-1980 and 1990-1995, after having been found in a ve…
Searching for Annihilation Radiation from SN 1006 with SPI on INTEGRAL
Boggs, S. E.; Kalemci, E.; Milne, P. A. +1 more
Historical Type Ia supernovae are a leading candidate as the source of positrons observed through diffuse annihilation emission in the Galaxy. However, a search for annihilation emission from individual Type Ia supernovae was not possible before the improved sensitivity of INTEGRAL. The total 511 keV annihilation flux from individual SNe Ia, as we…
Extraordinarily Hot X-Ray Emission from the O9 Emission-Line Star HD 119682
Testa, Paola; Wolk, S. J.; Rakowski, Cara E. +1 more
We present new optical and X-ray observations to show that the X-ray source 1WGA J1346.5-6255 previously associated with the SNR G309.2-0.6 can be unequivocally identified with the emission-line star HD 119682 located in the foreground open cluster NGC 5281. Images from Chandra in the X-ray band as well as from Magellan in the narrow optical Hα ba…
A Photoionized Herbig-Haro Object in the Orion Nebula
Martin, P. G.; Blagrave, K. P. M.; Baldwin, J. A.
The spectra of Herbig-Haro objects are usually characteristic of ionization and excitation in shock-heated gas, whether an internal shock in an unsteady outflow or a bow shock interface with the interstellar medium. We examine the easternmost shock-the leading optically visible shock-of a Herbig-Haro outflow (HH 529) seen projected on the face of …
Chlorine in the Galactic Interstellar Medium: Revised f-Values with the Far Ultraviolet Spectroscopic Explorer and the Space Telescope Imaging Spectrograph
York, D. G.; Sonnentrucker, P.; Friedman, S. D.
Cl I is the atomic species most directly coupled to molecular hydrogen due to its chemistry. Its weakest lines are thereby probably the best tracer of optically thick H2 components in diffuse clouds. We report on the empirical determination of the oscillator strengths for four Cl I absorption lines predicted to be weak and often detecte…