Erratum: “An Extensive Collection of Stellar Wind X‐Ray Source Region Emission Line Parameters, Temperatures, Velocities, and Their Radial Distributions as Obtained fromChandraObservations of 17 OB Stars” (ApJ, 668, 456 [2007])

AbstractThe stellar winds of hot stars have an important impact on both stellar and galactic evolution, yet their structure and internal processes are not fully understood in detail. One of the best nearby laboratories for studying such massive stellar winds is the O4I(n)fp star ζ Pup. After briefly discussing existing X-ray observations from Chandra and XMM, we present a simulation of X-ray emission line profile measurements for the upcoming 840 kilosecond Chandra HETGS observation. This simulation indicates that the increased S/N of this new observation will allow several major steps forward in the understanding of massive stellar winds. By measuring X-ray emission line strengths and profiles, we should be able to differentiate between various stellar wind models and map the entire wind structure in temperature and density. This legacy X-ray spectrum of ζ Pup will be a useful benchmark for future X-ray missions.

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X-ray observations of central stars of planetary nebulae and their winds

Proceedings of the International Astronomical Union ◽

10.1017/s1743921312010964 ◽

2011 ◽

Vol 7 (S283) ◽

pp. 204-210

Author(s):

Martín A. Guerrero

Keyword(s):

Stellar Wind ◽

Mechanical Energy ◽

Planetary Nebulae ◽

Energy Output ◽

X Rays ◽

Late Type ◽

Coronal Emission ◽

X Ray ◽

Ob Stars ◽

Central Stars

AbstractThe photospheric emission from the hottest central stars of planetary nebulae (CSPNe) is capable to extend into the X-ray domain, with emission peaking at 0.1-0.2 keV and vanishing above 0.4 keV. Unexpected, intriguing hard X-ray emission with energies greater than 0.5 keV has been reported for several CSPNe and for a number of white dwarfs (WDs). Different mechanisms may be responsible for the hard X-ray emission from CSPNe and WDs: coronal emission from a late-type companion, shocks in fast winds as in OB stars, leakage from underneath the star photosphere, or accretion of material from a disk, a companion star, or the circumstellar medium. Therefore, the hard X-ray emission associated with CSPNe may have significant implications for our understanding of the formation of PNe: binary companions, disks, and magnetic fields are thought to play a major role in the shaping of PNe, whereas clumping in the stellar wind may have notable effects in the PN evolution by modifying the stellar mechanical energy output. Here I present the results of different observational efforts to search for hard X-ray emission from CSPNe and discuss the different mechanisms for the production of hard X-rays.

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White-Light Coronal Structures: Streamers and CMEs

International Astronomical Union Colloquium ◽

10.1017/s0252921100025045 ◽

1994 ◽

Vol 144 ◽

pp. 82

Author(s):

E. Hildner

Keyword(s):

Emission Line ◽

Electron Density ◽

White Light ◽

Coronal Mass Ejections ◽

X Rays ◽

Solar Cycles ◽

Temperature Function ◽

X Ray ◽

Eclipse Observations ◽

Coronal Structures

AbstractOver the last twenty years, orbiting coronagraphs have vastly increased the amount of observational material for the whitelight corona. Spanning almost two solar cycles, and augmented by ground-based K-coronameter, emission-line, and eclipse observations, these data allow us to assess,inter alia: the typical and atypical behavior of the corona; how the corona evolves on time scales from minutes to a decade; and (in some respects) the relation between photospheric, coronal, and interplanetary features. This talk will review recent results on these three topics. A remark or two will attempt to relate the whitelight corona between 1.5 and 6 R⊙to the corona seen at lower altitudes in soft X-rays (e.g., with Yohkoh). The whitelight emission depends only on integrated electron density independent of temperature, whereas the soft X-ray emission depends upon the integral of electron density squared times a temperature function. The properties of coronal mass ejections (CMEs) will be reviewed briefly and their relationships to other solar and interplanetary phenomena will be noted.

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Analysis of the X-ray emission from OB stars III: low-resolution spectra of OB stars

Research in Astronomy and Astrophysics ◽

10.1088/1674-4527/20/7/108 ◽

2020 ◽

Vol 20 (7) ◽

pp. 108

Author(s):

Elizaveta Ryspaeva ◽

Alexander Kholtygin

Keyword(s):

Low Resolution ◽

X Ray ◽

Ob Stars

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Mass outflow of the X-ray emission line gas in NGC 4151

Proceedings of the International Astronomical Union ◽

10.1017/s1743921320001660 ◽

2020 ◽

Vol 15 (S359) ◽

pp. 131-135

Author(s):

S. B. Kraemer ◽

T. J. Turner ◽

D. M. Crenshaw ◽

H. R. Schmitt ◽

M. Revalski ◽

...

Keyword(s):

Emission Line ◽

Total Mass ◽

High Energy ◽

Model Parameters ◽

Zeroth Order ◽

Space Telescope ◽

X Ray ◽

Ngc 4151 ◽

Outflow Rate ◽

Mass Outflow

AbstractWe have analyzed Chandra/High Energy Transmission Grating spectra of the X-ray emission line gas in the Seyfert galaxy NGC 4151. The zeroth-order spectral images show extended H- and He-like O and Ne, up to a distance r ˜ 200 pc from the nucleus. Using the 1st-order spectra, we measure an average line velocity ˜230 km s–1, suggesting significant outflow of X-ray gas. We generated Cloudy photoionization models to fit the 1st-order spectra; the fit required three distinct emission-line components. To estimate the total mass of ionized gas (M) and the mass outflow rates, we applied the model parameters to fit the zeroth-order emission-line profiles of Ne IX and Ne X. We determined an M ≍ 5.4 × 105Mʘ. Assuming the same kinematic profile as that for the [O III] gas, derived from our analysis of Hubble Space Telescope/Space Telescope Imaging Spectrograph spectra, the peak X-ray mass outflow rate is approximately 1.8 Mʘ yr–1, at r ˜ 150 pc. The total mass and mass outflow rates are similar to those determined using [O III], implying that the X-ray gas is a major outflow component. However, unlike the optical outflows, the X-ray emitting mass outflow rate does not drop off at r > 100pc, which suggests that it may have a greater impact on the host galaxy.

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Chemical Abundances of Early Type Stars

Symposium - International Astronomical Union ◽

10.1017/s007418090011486x ◽

1998 ◽

Vol 188 ◽

pp. 224-225

Author(s):

S. Tanaka ◽

S. Kitamoto ◽

T. Suzuki ◽

K. Torii ◽

M.F. Corcoran ◽

...

Keyword(s):

Surface Layer ◽

Stellar Wind ◽

Nuclear Reactions ◽

X Rays ◽

Early Type ◽

Chemical Abundances ◽

X Ray ◽

Low Metallicity ◽

Early Type Stars

X-rays from early-type stars are emitted by the corona or the stellar wind. The materials in the surface layer of early-type stars are not contaminated by nuclear reactions in the stellar inside. Therefore, abundance study of the early-type stars provides us an information of the abundances of the original gas. However, the X-ray observations indicate low-metallicity, which is about 0.3 times of cosmic abundances. This fact raises the problem on the cosmic abundances.

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The May 1985 Superoutburst of OY Carinae: II. Phase-Resolved IUE Spectroscopy and Exosat Observations

International Astronomical Union Colloquium ◽

10.1017/s025292110010510x ◽

1987 ◽

Vol 93 ◽

pp. 371-376 ◽

Cited By ~ 2

Author(s):

B.J.M. Hassall ◽

T. Naylor ◽

G.T. Bath ◽

P.A. Charles ◽

G. Sonneborn ◽

...

Keyword(s):

Emission Line ◽

Line Spectrum ◽

X Ray ◽

Dwarf Nova ◽

Uv Emission ◽

Emission Line Spectrum ◽

Coronal Region

AbstractWe present ultraviolet and X-ray observations of the eclipsing SU UMa dwarf nova OY Car early in the decline from a superoutburst. From the UV emission line spectrum and lack of X-ray eclipse, we deduce the presence of an extended coronal region.

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