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Fully relativistic calculations of radiative rates and electron impact excitation cross sections for Fe X are used to derive theoretical emission-line ratios involving transitions in the 174-366 A wavelength range. A comparison of these…

天体物理学 · 物理学 2009-11-13 F P Keenan , D B Jess , K M Aggarwal , R J Thomas , J W Brosius , J M Davila

Milliarcsecond resolution Very Long Baseline Array (VLBA) observations of the archetype WR+O star colliding-wind binary (CWB) system WR140 have been obtained at 23 epochs between orbital phases 0.74 to 0.97. The emission in the…

天体物理学 · 物理学 2007-05-23 S. M. Dougherty , A. J. Beasley , M. J. Claussen , B. A. Zauderer , N. J. Bolingbroke

The X-ray emission from the wind-wind collision in short-period massive O+O-star binaries is investigated. The emission is calculated from three-dimensional hydrodynamical models which incorporate gravity, the driving of the winds, orbital…

太阳与恒星天体物理 · 物理学 2015-05-14 J. M. Pittard , E. R. Parkin

Archival X-ray spectra of the four prominent single, non-magnetic O stars Zeta Pup, Zeta Ori, Ksi Per and Zeta Oph, obtained in high resolution with Chandra HETGS/MEG have been studied. The resolved X-ray emission line profiles provide…

天体物理学 · 物理学 2008-11-26 L. M. Oskinova , A. Feldmeier , W. -R. Hamann

Wisconsin H-Alpha Mapper (WHAM) observations reveal high-velocity and [NII]$\lambda6584$ emission lines in the same direction and velocity as ultraviolet absorption-line features that have been previously associated with the biconical…

星系天体物理 · 物理学 2020-08-19 Dhanesh Krishnarao , Robert A. Benjamin , L. Matthew Haffner

We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M supergiants using TEXES on the IRTF. These low opacity emission lines are resolved at R = 50, 000 and provide new diagnostics of the dynamics and thermodynamics of…

太阳与恒星天体物理 · 物理学 2011-02-11 G. M. Harper , M. J. Richter , N. Ryde , A. Brown , J. Brown , T. K. Greathouse , S. Strong

We present deep XMM-Newton EPIC observations of the Wolf-Rayet (WR) bubble NGC6888 around the star WR136. The complete X-ray mapping of the nebula confirms the distribution of the hot gas in three maxima spatially associated with the caps…

太阳与恒星天体物理 · 物理学 2016-01-20 J. A. Toalá , M. A. Guerrero , Y. -H. Chu , S. J. Arthur , D. Tafoya , R. A. Gruendl

We present a cold-fluid analysis of the purely transverse Weibel (current-filamentation) instability across four regimes: non-relativistic (NR) single-species, NR multi-species, relativistic single-species, and relativistic multi-species…

等离子体物理 · 物理学 2026-03-16 Vivek Shrivastav , Mani K Chettri , Hemam D Singh , Britan Singh , Rupak Mukherjee

We find line emission from the hydrogen- and/or helium-like ions of Ne, O, N and C in the low and short-on states of Her X-1, using the XMM-Newton Reflection Grating Spectrometer. The emission line velocity broadening is 200 < sigma < 500…

天体物理学 · 物理学 2007-05-23 M. A. Jimenez-Garate , C. J. Hailey , J. W. den Herder , S. Zane , G. Ramsay

One of the main properties of Wolf-Rayet (WR) stars is a very intense outflow of gas. No less than 40\% \ of WR stars belong to binary systems. Young massive O and B stars are the secondary components of such systems. OB stars also have an…

天体物理学 · 物理学 2007-05-23 Vladimir V. Usov

(Abridged) We use optical spectroscopy to investigate the disk, wind, and accretion during the 2008 ZCMa NW outburst. Over 1000 optical emission lines reveal accretion, a variable, multi-component wind, and double-peaked lines of disk…

太阳与恒星天体物理 · 物理学 2020-10-28 A. Sicilia-Aguilar , J. Bouvier , C. Dougados , K. Grankin , J. -F. Donati

We present the first radio--continuum detection of the circumstellar shell around the well-known WN8 type Wolf-Rayet star WR16 at 943.5\,MHz using the \ac{ASKAP} \ac{EMU} survey. At this frequency, the shell has a measured flux density of…

Large wind kinetic power of Wolf-Rayet (WR) stars make them ideal targets in low radio frequencies to search for non-thermal emission due to relativistic particle acceleration. In this paper, we present observations of two WR stars, WR 114…

We present the soft X-ray spectrum of the LINER galaxy M81 derived from a long observation with the XMM RGS. The spectrum is dominated by continuum emission from the active nucleus, but also contains emission lines from Fe L, and H-like and…

天体物理学 · 物理学 2009-11-07 M. J. Page , A. A. Breeveld , R. Soria , K. Wu , G. Branduardi-Raymont , K. O. Mason , R. L. C. Starling , S. Zane

The eccentric WR+O binary system WR 140 produces dust for a few months at intervals of 7.94 yrs coincident with periastron passage. We present the first resolved images of this dust shell, at binary phases ~0.039 and ~0.055, using aperture…

天体物理学 · 物理学 2009-11-07 J. D. Monnier , P. G. Tuthill , W. C. Danchi

A campaign of 35 epochs of milli-arcsec resolution VLBA observations of the archetype collidingwind WR+O star binary system WR140 show the wind-collision region (WCR) as a bow-shaped arc of emission that rotates as the highly eccentric…

太阳与恒星天体物理 · 物理学 2011-01-06 S. M. Dougherty , V. Trenton , A. J. Beasley

This paper presents calculations for forbidden emission line profile shapes arising from colliding wind binaries. The main application is for systems involving a Wolf-Rayet (WR) star and an OB star companion. The WR wind is assumed to…

太阳与恒星天体物理 · 物理学 2009-11-13 R Ignace , R Bessey , C S Price

We present the results of Chandra X-ray Observatory (CXO) observations of the planetary nebulae (PNs) NGC 40 and Hen 2-99. Both PNs feature late-type Wolf-Rayet central stars that are presently driving fast ~1000 km/s, massive winds into…

天体物理学 · 物理学 2009-11-13 Rodolfo Montez , Joel H. Kastner , Orsola De Marco , Noam Soker

Line ratio of O IV 1407.3 \AA/1401.1 \AA\- is calculated using mostly our own atomic and collisional data. Energy levels and oscillator strengths needed for this calculation have been calculated using a Hartree-Fock relativistic (HFR)…

太阳与恒星天体物理 · 物理学 2015-06-17 Nabil Ben Nessib , Norah Alonizan , Rabia Qindeel , Sylvie Sahal-Bréchot , Milan S. Dimitrijević

Massive star winds are known to be responsible for X-ray emission arising from wind plasma heated by the strong shocks up to the temperature of 10$^6$--10$^7$ K in case of colliding wind binaries. We have investigated thermal and…

太阳与恒星天体物理 · 物理学 2024-04-04 Bharti Arora , M. De Becker , Jeewan C. Pandey