NASA Scientific and Technical Aerospace Reports

separation roughly constant. The lines also vary greatly in strength, but with the lower energy line always much stronger than
the higher energy one. The measured equivalent width ranges from approx. 50 to approx. 270 eV for the former, and from
insignificant detection to approx. 140 eV for the latter; the two are reasonably correlated. The correlation between the lines
implies a causal connection; perhaps they share a common origin. Both lines may arise from a single K & alpha; line of
highly ionized iron that is Doppler shifted either in a Keplerian accretion disk or in a bipolar outflow or even both. In both
scenarios, a change in the line energy might simply reflect a change in the ionization state of line-emitting matter. We discuss
the implication of the results and also raise some questions about such interpretations.
Author
X Ray Astronomy; Black Holes (Astronomy); Line Spectra; Iron
20040073166 NASA Marshall Space Flight Center, Huntsville, AL, USA
Spectroscopy of Cyg X-1 the High State with HETG/Chandra
Feng, Y. X.; Tennant, A.; Zhang, S. N.; Bulletin of the American Astronomical Society; 2002; Volume 34, pp. 1206; In
English; 201st AAS Meeting
Contract(s)/Grant(s): NAG5-7927
Report No.(s): AAS-57.02; No Copyright; Avail: Other Sources; Abstract Only
Cyg X-1 was observed in the high state around orbital phase 0 with HETG/Chandra. Significant absorption lines of highly
ionized species were detected, such as Fe XXV, Fe XXIV, Fe XXIII, S XIV, S XVI, Ne X, etc. The observed absorption lines
are found to be blue-shifted (z approx. -0.002) from those observed in the low and transition states. In the high state each
absorption line was composed of a blue-shifted absorption line and a un-shifted absorption line which similar to that observed
in the low state. The broad line feature of Fe K(sub alpha;) at 6.4 keV was detected with a significance of Delta chi(Sup 2)
approx. 40, although precise measurements are hindered by uncertainties in the calibration. The implications of these results
on the configuration of the accretion flow of Cyg X-1 in the high state are discussed.
Author
Spectroscopy; Calibrating; Cygnus Constellation
20040073171 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Three-Layered Atmospheric Structure in Accretion Disks Around Stellar-Mass Black Holes
Zhang, S. N.; Cui, Wei; Chen, Wan; Yao, Yangsen; Zhang, Xiaoling; Sun, Xuejun; Wu, Xue-Bing; Xu, Haiguang; Science;
2000; Volume 287, Issue 5456, pp. 1239-1241; In English
Contract(s)/Grant(s): NAG5-7927; Copyright; Avail: Other Sources; Abstract Only
Modeling of the x-ray spectra of the Galactic superluminal jet sources GRS 1915+105 and GRO J1655-40 reveals a
three-layered atmospheric structure in the inner region of the inner accretion disks. Above the cold and optically thick disk
with a temperature of 0.2 to 0.5 kiloelectron volts, there is a warm layer with a temperature of 1.0 to 1.5 kiloelectron volts
and an optical depth around 10. Sometimes there is also a much hotter, optically thin corona above the warm layer, with a
temperature of 100 kiloelectron volts or higher and an optical depth around unity. The structural similarity between the
accretion disks and the solar atmosphere suggests that similar physical processes may be operating in these different systems.
Author
Accretion Disks; Stellar Mass; Black Holes (Astronomy); X Ray Spectra; Stellar Structure
20040074122 Arizona Univ., Tucson, AZ, USA
Production of Star-Grazing and Star-Impacting Planetestimals via Orbital Migration of Extrasolar Planets
Quillen, A. C.; Holman, M.; The Astronomical Journal; 2000; Volume 119, pp. 397-402; In English
Contract(s)/Grant(s): NAG5-10365; Copyright; Avail: Other Sources; Abstract Only
During the orbital migration of a giant extrasolar planet via ejection of planetesimals (as studied by Murray et al. in 1998),
inner mean-motion resonances can be strong enough to cause planetesimals to graze or impact the star. We integrate
numerically the motions of particles which pass through the 3:1 or 4:1 mean-motion resonances of a migrating Jupiter-mass
planet. We find that many particles can be trapped in the 3:1 or 4:1 resonances and pumped to high enough eccentricities that
they impact the star. This implies that for a planet migrating a substantial fraction of its semimajor axis, a fraction of its mass
in planetesimals could impact the star. This process may be capable of enriching the metallicity of the star at a time when the
star is no longer fully convective. Upon close approaches to the star, the surfaces of these planetesimals will be sublimated.
Orbital migration should cause continuing production of evaporating bodies, suggesting that this process should be detectable
with searches for transient absorption lines in young stars. The remainder of the particles will not impact the star but can be
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