Binaries among the WN population in the Magellanic Clouds

Symposium - International Astronomical Union ◽

10.1017/s0074180900211911 ◽

2003 ◽

Vol 212 ◽

pp. 180-181

Author(s):

Cédric Foellmi ◽

Anthony F.J. Moffat ◽

Martín A. Guerrero Roncel

Keyword(s):

Radial Velocity ◽

Magellanic Clouds ◽

Photometric Data ◽

Systematic Search ◽

X Ray ◽

Medium Resolution ◽

Velocity Variations

We have undertaken a large and extensive spectroscopic survey of WNE stars both in the SMC and LMC with various 2m and 4m telescopes, reaching a total of 78 nights, spread over three years, and obtaining over 1500 long-slit spectra of medium resolution. The first goal is a systematic search for binaries via periodic radial-velocity variations. We enlarged our dataset with photometric data from the ogle and macho databases, and with archival X-ray data from the ROSAT and Chandra satellites.

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R Coronae Borealis Stars: Long-Term Photometric & Spectroscopic Studies

Highlights of Astronomy ◽

10.1017/s1539299600021298 ◽

1998 ◽

Vol 11 (1) ◽

pp. 379-379

Author(s):

P.L. Cottrell ◽

L. Skuljan ◽

P.M. Kilmartin ◽

C. Gilmore ◽

W.A. Lawson

Keyword(s):

Radial Velocity ◽

Spectroscopic Studies ◽

Photometric Data ◽

Decline Phase ◽

Dust Clouds ◽

Medium Resolution ◽

Formation And Evolution ◽

R Coronae Borealis Stars ◽

Insight Into

For more than a decade we have been able to acquire and analyse a significant amount of photometric data of the highly variable R Coronae Borealis (RCB) stars. This has made been possible by a photometric service observing programme instigated at the Observatory. These photometric data have been combined with less extensive spectroscopic coverage, particularly of the decline phase of these stars. These have been supplemented by observations obtained at Mount Stromlo and Siding Spring Observatories for a radial velocity study. Significantly more spectroscopic observations are now being acquired with the development of a new medium resolution spectrograph at Mount John University Observatory. In this poster we will present recent photometric and spectroscopic results for a number of the RCB stars in our sample. This observational and analysis work can be used to provide further insight into the nature of these stars, their likely progeny and progenitors and the processes that are involved in the formation and evolution of the obscuring dust clouds which cause the decline phase.

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A large systematic search for close supermassive binary and rapidly recoiling black holes – III. Radial velocity variations

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/stx452 ◽

2017 ◽

Vol 468 (2) ◽

pp. 1683-1702 ◽

Cited By ~ 28

Author(s):

Jessie C. Runnoe ◽

Michael Eracleous ◽

Alison Pennell ◽

Gavin Mathes ◽

Todd Boroson ◽

...

Keyword(s):

Black Holes ◽

Radial Velocity ◽

Systematic Search ◽

Velocity Variations

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Revised Wolf-Rayet binary orbits and new binaries

Symposium - International Astronomical Union ◽

10.1017/s0074180900201988 ◽

1995 ◽

Vol 163 ◽

pp. 223-230 ◽

Cited By ~ 1

Author(s):

V.S. Niemela

Keyword(s):

Radial Velocity ◽

Emission Line ◽

Magellanic Clouds ◽

Absorption Lines ◽

Orbital Inclination ◽

Mass Ratios ◽

Velocity Variations

Revised orbits are presented for the double-lined binary WR+O systems HD 63099 (WR9) and HDE 320102 (WR97). The orbit derived for WR9 from OVI emission and HeII absorptions is considerably different from that previously published based on the CIVΛ4658 emission line velocities. WR97 is found to have a period of 12.6 days and small minimum masses, probably due to a low orbital inclination. Two stars in our Galaxy, WR30a and WR70, and two in the Magellanic Clouds, Brey44 and AB7, show radial velocity variations of emission and absorption lines in opposite sense. Although no periods are yet available, preliminary values of the mass ratios can be estimated from the velocity variations.

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The radial velocity variations of WR46 (WN3p)

Symposium - International Astronomical Union ◽

10.1017/s0074180900202040 ◽

1995 ◽

Vol 163 ◽

pp. 245-247

Author(s):

V.S. Niemela ◽

R.H. Barbá ◽

M.M. Shara

Keyword(s):

Binary System ◽

Radial Velocity ◽

Emission Lines ◽

Strong Emission ◽

X Ray ◽

Emission Line Spectrum ◽

Low Mass ◽

Photometric Period ◽

Velocity Variations ◽

X Ray Binaries

Spectral observations of the WN3p star WR46 (HD 104994) obtained during June 1993 and January/February 1994 display large amplitude radial velocity variations of the strong emission lines Nv 4603-19Å and HeII 4686A, on a time scale of a fraction of a day. The most probable period found is 0.311 d, similar to the photometric period found by previous authors. The amplitude of the radial velocity variations of Nv emission is almost twice that of HeII. Noting the similarity of WR46 with low mass X-ray binaries, we suggest that the emission line spectrum corresponds to that of a luminous accretion disk in an evolved binary system.

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Surprises in the simultaneous X-ray and optical monitoring of π Aquarii

Astronomy and Astrophysics ◽

10.1051/0004-6361/201936307 ◽

2019 ◽

Vol 632 ◽

pp. A23 ◽

Cited By ~ 1

Author(s):

Yaël Nazé ◽

Gregor Rauw ◽

Myron Smith

Keyword(s):

Radial Velocity ◽

Line Strength ◽

Optical Data ◽

Optical Monitoring ◽

Absorption Component ◽

X Ray ◽

Orbital Cycles ◽

Orbital Phase ◽

Velocity Variations

To help constrain the origin of the peculiar X-ray emission of γ Cas stars, we conducted a simultaneous optical and X-ray monitoring of π Aqr in 2018. At that time, the star appeared optically bright and active, with a very strong Hα emission. Our monitoring covers three 84 d orbital cycles, allowing us to probe phase-locked variations as well as longer-term changes. In the new optical data, the radial velocity variations seem to span a smaller range than previously reported, which might indicate possible biases. The X-ray emission is variable, but without any obvious correlation with orbital phase or Hα line strength. Furthermore, the average X-ray flux and the relative range of flux variations are similar to those recorded in previous data, although the latter data were taken when the star was less bright and its disk had nearly entirely disappeared. Only the local absorption component in the X-ray spectrum appears to have strengthened in the new data. This absence of large changes in X-ray properties despite dramatic disk changes appears at odds with previous observations of other γ Cas stars. It also constrains scenarios proposed to explain the γ Cas phenomenon.

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IUE Studies of Luminous X-Ray Binaries

Highlights of Astronomy ◽

10.1017/s1539299600005736 ◽

1983 ◽

Vol 6 ◽

pp. 648-648

Author(s):

J.B. Hutchings

Keyword(s):

Magellanic Clouds ◽

Thick Shell ◽

High Luminosity ◽

Uv Spectrum ◽

X Ray ◽

Unique Object ◽

The Future ◽

Orbit Inclination ◽

Supercritical Accretion ◽

X Ray Binaries

IUE has been used to study 11 high luminosity X-ray binaries, of which 3 are in the Magellanic Clouds. In the supergiant systems, X-ray ionisation bubbles have been found in most cases, leading to a greater understanding of the winds and accretion processes. Further studies of precessing objects such as LMC X-4 with IUE and ST are clearly of considerable interest, relating to X-ray heating and blanketing. Detailed studies of the Cyg X-l ionisation bubble may resolve the long standing puzzle of its orbit inclination and masses. UV continua have furnished valuable information on extinction, temperatures and luminosities, and the presence of non-stellar (i.e. disk) luminosity. Here too, more detailed studies are clearly indicated for the future. A unique object of interest is the LMC transient 0538-66 whose UV spectrum has quasarlike lines and luminosity which varies oppositely to the visible. This may be a case of supercritical accretion generating an optically thick shell (“disk”) about the pulsar.

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ESA’s X-Ray Astronomy Mission, XMM

International Astronomical Union Colloquium ◽

10.1017/s0252921100076971 ◽

1990 ◽

Vol 123 ◽

pp. 129-140

Author(s):

B.G. Taylor ◽

A. Peacock

Keyword(s):

Resolving Power ◽

Science Program ◽

Eccentric Orbit ◽

Ccd Cameras ◽

Optical Telescope ◽

X Ray ◽

Medium Resolution ◽

Reflection Gratings ◽

Better Than

AbstractESA’s X-ray Astronomy Mission, XMM, scheduled for launch in 1998, is the second of four cornerstones of ESA’s long term science program Horizon 2000. Covering the range from about 0.1 to 10 keV, it will provide a high throughput of 5000 cm2 at 7 keV with three independant telescopes, and have a spatial resolution better than 30 arcsec. Broadband spectrophotometry is provided by CCD cameras while reflection gratings provide medium resolution spectroscopy (resolving power of about 400) in the range 0.3–3 keV. Long uninterrupted observations will be made from the 24 hr period, highly eccentric orbit, reaching a sensitivity approaching 10−15 erg cm−2 s−1 in one orbit. A 30 cm UV/optical telescope is bore-sighted with the x-ray telescopes to provide simultaneous optical counterparts to the numerous serendipitous X-ray sources which will be detected during every observation.

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