Search Publications
An XMM-Newton Observation of the Luminous Seyfert 1 Galaxy Markarian 509
Reeves, James; Nayakshin, Sergei; O'Brien, Paul +3 more
We present the spectral analysis of an early XMM-Newton observation of the luminous Seyfert 1 galaxy Mrk 509. We find the hard (2-10 keV) continuum slope, including reflection, to be somewhat flatter (Γ=1.75) than that of a typical broad-line Seyfert 1 galaxy. The most obvious feature in the hard X-ray spectrum is a narrow emission line near 6.4 k…
XMM-Newton observation of an unusual iron line in the quasar Markarian 205
Boller, Th.; O'Brien, P. T.; Reeves, J. N. +5 more
XMM-Newton observations of the low luminosity, radio-quiet quasar Markarian 205 have revealed a unique iron K emission line profile. In marked contrast to the broad and redshifted iron K line commonly seen in ASCA observations of Seyfert 1 galaxies, we find that a substantial amount of the line flux in Mrk 205 occurs above the neutral line energy …
A K-band-Selected Photometric Redshift Catalog in the Hubble Deep Field South: Sampling the Rest-Frame V Band to z =3
Franx, Marijn; Labbé, Ivo; van Dokkum, Pieter +7 more
We present the first results from the Faint Infra-Red Extragalactic Survey of the Hubble Deep Field South (HDF-S). Using a combination of deep near-infrared (NIR) data obtained with the Infrared Spectrograph and Array Camera at the VLT and the WFPC2 Hubble Space Telescope data, we construct a K-band-selected sample which is 50% and 90% complete fo…
Multiwavelength analyses of the extraordinary nova LMC 1991*
Della Valle, M.; Baron, E.; Shore, S. N. +3 more
LMC 91 was a very fast, classical nova and the brightest nova ever observed in the Large Magellanic Cloud. It was extensively observed during both its early optically thick and its nebular evolution in the optical and UV wavelength regions. We successfully fit all the optically thick spectra using a grid of spherically symmetric, non-LTE, line-bla…
Spectroscopic Diagnostics of Nanoflare-heated Loops
Klimchuk, J. A.; Cargill, P. J.
To evaluate the usefulness of spectroscopic techniques for diagnosing realistic solar plasmas and to better understand the physical origin of coronal heating, we have simulated observations of model coronal loops that are heated randomly and impulsively by nanoflares. We find that the emission measures, densities, and filling factors that are infe…
Far-Ultraviolet and Hα Imaging of Nearby Spiral Galaxies: The OB Stellar Population in the Diffuse Ionized Gas
Hoopes, Charles G.; Bothun, Gregory D.; Walterbos, René A. M.
We have compared Hα and far-ultraviolet (FUV) images of 10 nearby spirals, with the goal of understanding the contribution of field OB stars to the ionization of the diffuse ionized gas (DIG) in spiral galaxies. The FUV images were obtained by the Ultraviolet Imaging Telescope (UIT), and the Hα images were obtained using various ground-based teles…
XMM-Newton observations of NGC 253 : Resolving the emission components in the disk and nuclear area
Pietsch, W.; Read, A. M.; Ptak, A. +12 more
We describe the first XMM-Newton observations of the starburst galaxy
NGC 1614: A Laboratory for Starburst Evolution
Rieke, G. H.; Alonso-Herrero, A.; Quillen, A. C. +2 more
The modest extinction and reasonably face-on viewing geometry make the luminous infrared galaxy NGC 1614 an ideal laboratory for the study of a powerful starburst. Hubble Space Telescope/near-infrared camera and multiobject spectrometer (NICMOS) observations show (1) deep CO stellar absorption, tracing a starburst nucleus about 45 pc in diameter (…
A two-Type Classification of Lasco Coronal Mass Ejection
Andrews, M. D.; Howard, R. A.
The causes and origins of Coronal Mass Ejections (CMEs) remain among the outstanding questions in Space Physics. The observations of CMEs by the LASCO coronagraphs on SOHO suggest that there are two distinct types of CMEs. The two types of events can be most easily distinguished by examining height-time plots. The Type A (Acceleration) events prod…
Hubble Space Telescope Proper-Motion Measurements of the η Carinae Nebula
Davidson, Kris; Bally, John; Balick, Bruce +3 more
We present proper-motion measurements of the bipolar lobes and equatorial disk features ejected from η Carinae during the last century and deduce their relative ages in order to determine the likelihood of multiple ejection events. Hubble Space Telescope Wide Field Planetary Camera 2 images taken in 1994, 1995, and 1999 were compared, and the moti…