Search Publications
Simultaneous Velocity-Intensity Spectral and Cross-Spectral Fitting of Helioseismic Data
Hill, F.; Barban, C.; Kras, S.
Solar oscillation parameters, such as the frequency, are usually estimated by fitting the mode profile in the velocity (V) power spectrum. In this paper, the solar oscillation parameters are derived by simultaneously fitting four observational spectra: V and I (intensity) power, I-V phase difference, and I-V coherence using the model of Severino e…
The Ofpe/WN9 Stars in M33
Massey, Philip; Bianchi, Luciana; Bohlin, Ralph
We present Hubble Space Telescope/STIS Ultraviolet spectra of the six known Ofpe/WN9 stars (``slash stars'') in M33. These stars were selected for showing the characteristics of the Ofpe/WN9 class from previous optical ground-based spectroscopy. The UV spectra are rich in wind lines whose strength and terminal velocity vary greatly across our targ…
Detection of Nitrogen and Neon in the X-Ray Spectrum of GP Comae Berenices with XMM/Newton
Strohmayer, Tod E.
We report on X-ray spectroscopic observations with XMM/Newton of the ultracompact, double white dwarf binary GP Com. With the Reflection Grating Spectrometers (RGSs), we detect the Lyα and Lyβ lines of hydrogen-like nitrogen (N VII) and neon (Ne X), as well as the helium-like triplets (N VI and Ne IX) of these same elements. All the emission lines…
A 150 MG Magnetic White Dwarf in the Cataclysmic Variable RX J1554.2+2721
Gänsicke, B. T.; Beuermann, K.; de Martino, D. +4 more
We report the detection of Zeeman-split Lyα absorption π and σ+ lines in the far-ultraviolet Hubble Space Telescope/Space Telescope Imaging Spectrograph (STIS) spectrum of the magnetic cataclysmic variable RX J1554.2+2721. Fitting the STIS data with magnetic white dwarf model spectra, we derive a field strength of B~=144 MG and an effec…
Reanalysis of Copernicus Measurements of Interstellar Carbon Monoxide
Federman, S. R.; Crenny, T.
We used archival data acquired with Copernicus to reexamine CO column densities, as self-consistent oscillator strengths are now available. Our focus is on lines of sight containing modest amounts of molecular species. Our resulting column densities are small enough that self-shielding from photodissociation does not occur in the clouds probed by …
XMM-Newton and Chandra Observations of the Central Region of M31
Kokubun, Motohide; Makishima, Kazuo; Takahashi, Hiromitsu +1 more
Archival XMM-Newton data of the central region of M31 were analyzed for diffuse X-ray emission. Point sources with 0.5-10 keV luminosity exceeding ~4×1035 ergs s-1 were detected. Their summed spectra are reproduced well by a combination of a disk blackbody component and a blackbody component, implying that the emission mainly…
X-Rays from the Mira AB Binary System
Soker, Noam; Kastner, Joel H.
We present the results of XMM-Newton X-ray observations of the Mira AB binary system, which consists of a pulsating, asymptotic giant branch primary and nearby (~0.6" separation) secondary of uncertain nature. The European Photon Imaging Camera (EPIC) CCD (MOS and pn) X-ray spectra of Mira AB are relatively soft, peaking at ~1 keV, with only very …
Stagnated Outflow of O+5 Ions in the Source Region of the Slow Solar Wind at Solar Minimum
Chen, Y.; Strachan, L.; Hu, Y. +1 more
Using recent coordinated UVCS and LASCO measurements by Strachan and coworkers to constrain the heating parameters of a one-dimensional single-fluid minor ion model, we calculate the outflow velocity profile of O+5 ions in the flow tube overlying the helmet streamer, which has been supposed to be the source region of the slow solar wind…
A First XMM-Newton Look at the Relativistic Double Pulsar PSR J0737-3039
Bignami, G. F.; Tiengo, A.; Mereghetti, S. +5 more
We present the results of a 50 ks long X-ray observation of the relativistic double pulsar system PSR J0737-3039 obtained with the XMM-Newton satellite in 2004 March. The source has a soft spectrum (with a power-law photon index of 3.5+0.5-0.3 ) and a 0.2-10 keV luminosity of ~3×1030 ergs s-1 (assuming a…
X-Ray Measurement of Dark Matter ``Temperature'' in A1795
Kitayama, Tetsu; Böhringer, Hans; Ikebe, Yasushi
We present a method from an X-ray observation of a galaxy cluster to measure the radial profile of the dark matter velocity dispersion, σDM, and to compare the dark matter ``temperature'' defined as µmpσ2DM/kB with the gas temperature. The method is applied to the XMM-Newton observation …