Search Publications
Simulation of Nonlinear Waves in a Magnetic Flux Tube near the Quiet Solar Photospheric Network
Sakai, J. I.; Mizuhata, Y.; Kawata, T. +1 more
Recent high-resolution observations from photospheric magnetograms made with the SOHO/Michelson Doppler Imager instrument and Swedish Vacuum Solar Telescope on La Palma showed that magnetic flux tubes in the quiet photospheric network of the solar photosphere are highly dynamic objects with small-scale substructures. We investigate nonlinear waves…
A Photometric and Kinematic Study of the Stars and Interstellar Medium in the Central 2 Kiloparsecs of NGC 3379
Winge, Cláudia; Ferrari, Fabricio; Macchetto, F. Duccio +2 more
Hubble Space Telescope images of NGC 3379 show that the V and I luminosity profiles in the inner 13" of this E1 galaxy are represented by two different components: a stellar bulge following a Sérsic law with exponent n=2.36 and a central core (r<0.7") with a characteristic ``cuspy'' profile. Subtraction of the underlying stellar component repre…
Wavelengths of Forbidden Transitions Arising from Levels Within the Fe+19 2S22P3 Ground Configuration
Curdt, W.; Feldman, U.; Kucera, T. A. +1 more
In this paper we report the identification of all remaining unidentified forbidden lines arising from transitions within levels of the Fe+19 ground configuration. These lines were identified using data from the SOHO/SUMER spectrograph and Skylab. Adjusted wavelength values are also given for some previously observed lines. Forbidden lin…
Hubble Space Telescope Observations of the Associated Absorption-Line Systems in Q0122+0338
Papovich, Casey; Koekemoer, Anton M.; Bowen, David V. +4 more
We have studied a spectrum of Q0122+0338 (ze~1.202) obtained by the Faint Object Spectrograph (FOS) on board the Hubble Space Telescope (HST). We present the analysis of three associated (za~ze) absorption systems at z=1.207, 1.199, and 1.166. The most complex of these, at za~1.207, shows strong absorpti…
Random-Lag Singular Cross-Spectrum Analysis
Henney, C. J.; Ulrich, R. K.; Bertello, L. +1 more
In a previous paper (Varadi et al.), random-lag singular spectrum analysis was introduced for finding oscillations in very noisy and long time series. This work presents a generalization of the technique to search for common oscillations in two or more time series.
Model Photospheres for Late-Type Stars from the Inversion of High-Resolution Spectroscopic Observations: Groombridge 1830 and ɛ Eridani
Lambert, David L.; Allende Prieto, Carlos; García López, Ramón J. +1 more
An inversion technique to recover LTE one-dimensional model photospheres for late-type stars, which was previously applied to the Sun by Allende Prieto et al. in 1998, is now employed to reconstruct, semiempirically, the photospheres of cooler dwarfs: the metal-poor Groombridge 1830 and the active star of solar metallicity ɛ Eridani. The model atm…
Far-Ultraviolet Absolute Flux of α Virginis
Bowyer, Stuart; Edelstein, Jerry; Cobb, Jeff +7 more
We present the far-ultraviolet spectrum of α Virginis taken with Espectrógrafo Ultravioleta extremo para la Radiación Difusa (EURD) spectrograph on board MINISAT-01. The spectral range covered is from ~900 to 1080 Å with 5 Å spectral resolution. We have fitted Kurucz models to IUE spectra of α Vir and compared the extension of the model to our wav…
Nonequilibrium Ionization and First Ionization Potential Effect Diagnostics
Esser, Ruth; Edgar, Richard J.
We examine the accuracy of a common first ionization potential effect diagnostic, the ratio of Ne VI to Mg VI lines in the solar transition region. Since the two ions have quite similar contribution functions near their maxima in equilibrium, the ratio of these two ions is often taken to be the abundance ratio of Ne and Mg. First we compute nonequ…
Age Difference between the Populations of Binary and Single F Stars Revealed from Hipparcos Data
Suchkov, A. A.
We have compared the kinematics and metallicity of the main-sequence binary and single uvby F stars from the Hipparcos catalog to see if the populations of these stars originate from the same statistical ensemble. The velocity dispersions of the known unresolved binary F stars have been found to be dramatically smaller than those of the single F s…
Resolving SNR 0540-6944 from LMC X-1 with Chandra
Petre, Robert; Chu, You-Hua; Chen, C. -H. Rosie +1 more
We examine the supernova remnant SNR 0540-697 in the Large Magellanic Cloud (LMC) using data from the Chandra Advanced CCD Imaging Spectrometer. The X-ray emission from this supernova remnant (SNR) had previously been hidden in the bright emission of the nearby X-ray binary LMC X-1 however, new observations with Chandra can finally reveal the SNR'…