Search Publications
The Nature of the Ultraluminous Oxygen-Rich Supernova Remnant in NGC 4449
Milisavljevic, Dan; Fesen, Robert A.
Optical images and spectra, both ground based and taken by Hubble Space Telescope (HST), of the young, luminous O-rich supernova remnant in the irregular galaxy NGC 4449 are presented. HST images of the remnant and its local region were obtained with the ACS/WFC using filters F435W, F555W, F814W (B, V, and I, respectively), F502N ([O III]), F658N …
The Fundamental Plane of QSOs and the Relationship between Host and Nucleus
Turnshek, David A.; Casertano, Stefano; Hamilton, Timothy S.
We present results from an archival study of 70 medium-redshift QSOs observed with HST's WFPC2. The QSOs have magnitudes MV <= - 23 (total nuclear plus host light) and redshifts 0.06 <= z <= 0.46. The aim of the present study is to investigate the connections between the nuclear and host properties of QSOs, using high-resolutio…
Isotopic Ratios in Titan's Atmosphere from Cassini CIRS Limb Sounding: CO2 at Low and Midlatitudes
Irwin, P. G. J.; Teanby, N. A.; Flasar, F. M. +8 more
This Letter reports on a search for infrared emissions of isotopologues of CO2 in the atmosphere of Titan using spectral data recorded by the Cassini Composite Infrared Spectrometer (CIRS). We have made a successful 6.5 σ detection of 13CO2 at a fraction CO2/13CO2 = 84 ± 17, consist…
Probing Elemental Abundances in SNR 1987A using XMM-Newton
Haberl, Frank; Heng, Kevin; Hasinger, Günther +1 more
We report on the latest (2007 January) observations of supernova remnant (SNR) 1987A from the XMM-Newton mission. Since the 2003 May observations of Haberl et al., 11 emission lines have experienced increases in flux by factors ~3-10, with the 775 eV line of O VIII showing the greatest increase; we have observed six lines of Fe XVII and Fe XVIII p…
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…