Search Publications
A Far Ultraviolet Archival Study of Cataclysmic Variables. I. FUSE and HST STIS Spectra of the Exposed White Dwarf in Dwarf Nova Systems
Szkody, Paula; Sion, Edward M.; Godon, Patrick +3 more
We present a synthetic spectral analysis of Far Ultraviolet Spectroscopic Explorer (FUSE) and Hubble Space Telescope Space Telescope Imaging Spectrograph (HST STIS) spectra of five dwarf novae above and below the period gap during quiescence. We use our synthetic spectral code, including options for the treatment of the hydrogen quasi-molecular sa…
Caught in Formation: The Nuclear-Cluster-to-Be in NGC 2139
Böker, Torsten; Ho, Luis C.; Shields, Joseph C. +4 more
Close to its center, the bulgeless galaxy NGC 2139 hosts a star cluster that is younger and less massive than any nuclear star cluster (NC) studied so far. We have measured the Hα velocity field around the photometric center of this galaxy using the VLT ARGUS integral field unit and the GIRAFFE spectrograph in order to constrain different proposed…
Detailed Atmosphere Model Fits to Disk-dominated ULX Spectra
Krolik, Julian H.; Hui, Yawei
We have chosen six ultraluminous X-ray sources from the XMM-Newton archive whose spectra have high signal-to-noise ratio (S/N) and can be fitted solely with a disk model without requiring any power-law component. To estimate systematic errors in the inferred parameters, we fit every spectrum to two different disk models, one based on local blackbo…
Analysis of a Solar Coronal Bright Point Extreme Ultraviolet Spectrum from the EUNIS Sounding Rocket Instrument
Landi, Enrico; Brosius, Jeffrey W.; Thomas, Roger J. +1 more
We present a well-calibrated EUV spectrum of a solar coronal bright point observed with the Extreme Ultraviolet Normal Incidence Spectrograph (EUNIS) sounding rocket instrument on 2006 April 12. The coronal bright point brightened around 06:30 UT during a period of emerging magnetic flux and remained bright at least until the rocket flight around …
Origins of Coronal Energy and Helicity in NOAA 10030
Alexander, David; Tian, Lirong; Nightingale, Richard
Exploring the origins of coronal helicity and energy, as well as determining the mechanisms that lead to coronal energy release, is a fundamental topic in solar physics. Using MDI 96 minute line-of-sight and HSOS vector magnetograms in conjunction with TRACE white-light and UV (1600 Å) images and BBSO Hα and SOHO EIT (195 Å) images, we find in act…
A Search for Synchrotron X-Ray Emission in Radio Quasars
Giommi, Paolo; Cheung, Chi C.; Landt, Hermine +2 more
This paper presents XMM-Newton and Chandra X-ray spectroscopy of 10 flat-spectrum radio quasars (FSRQ) that are candidates to have an X-ray spectrum dominated by jet synchrotron emission. In all these FSRQ, which are less strongly relativistically beamed than blazars, a considerable contribution from a power-law component similar to that present i…
X-Ray Observations of the Coma Cluster in a Broad Energy Band with the INTEGRAL, RXTE, and ROSAT Observatories
Sunyaev, R. A.; Vikhlinin, A.; Lutovinov, A. A. +2 more
We present results of X-ray observations of the Coma Cluster with multiple instruments over a broad energy band. Using the data from the INTEGRAL, RXTE, and ROSAT observatories, we find that the Coma spectrum in the 0.5-107 keV energy band can be well approximated by a thermal plasma emission model with a temperature of T = 8.2 keV. INTEGRAL was u…
The Evolution of Late-Time Optical Emission from SN 1986J
Kirshner, Robert P.; Leibundgut, Bruno; Milisavljevic, Dan +1 more
We present late-time optical images and spectra of the Type IIn supernova SN 1986J. HST ACS/WFC images obtained in 2003 February show it to be still relatively bright, with mF606W = 21.4 and mF814W = 20.0 mag. Compared to 1994 December HST WFPC2 images, SN 1986J shows a decline of only lesssim1 mag in brightness over 8 years.…
Gemini Spectroscopy and HST Imaging of the Stellar Cluster Population in Region B of M82
Bastian, N.; Smith, L. J.; Gallagher, J. S., III +3 more
We present new spectroscopic observations of the stellar cluster population of region B in the prototype starburst galaxy M82 obtained with the Gemini North 8.1 m telescope. By coupling the spectroscopy with UBVI photometry acquired with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), we derive ages, extinctions, and rad…
The Planetary Nebula NGC 1360: A Test Case of Magnetic Collimation and Evolution after the Fast Wind
López, J. A.; Steffen, W.; García-Segura, G. +2 more
The central star of this nebula has an observed intense magnetic field and the fast wind is no longer present, indicating that a back flow process has probably developed. Long-slit, spatially resolved echelle spectra have been obtained across the main body of NGC 1360 and over its system of bipolar jets. Deep images of the knotty structures of the…