An ellipsoidal modulation in X-ray Nova Vela 1993 ( = GRS 1009 — 45)

Shahbaz, T.; Hooft, F. van der; Charles, P. A.; Casares, J.; Paradijs, J.A. van

doi:10.1093/mnras/282.4.l47

Cited by 35 publications

(58 citation statements)

References 2 publications

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“…As mentioned above, these recent values are a factor v sin i of ∼2 lower than the previously reported value of Shahbaz et al (1999). Shahbaz & Watson (2007) conclude that the dominant absorption blend near 6495 may have biased the 1999 A determination, which used data with relatively low S/N, v sin i as well as low spectral resolution.…”

Section: Discussionmentioning

confidence: 62%

“…We paired up the individual spectra with our five templates and found that in all cases, the optimal rotational broadening was found to be close to 32 km s , a value that is significantly Ϫ1 lower than the km s reported by Shahbaz et al (1999).…”

Section: Discussionmentioning

confidence: 88%

“…These previous studies suggested the presence of a rather massive compact object with a mass between ∼2 and 4 . In the case of V395 Car the main source of error in the M , mass of the compact object is the large error on the rotational velocity (Jonker et al 2005), which was derived from relatively low resolution data (Shahbaz et al 1999). …”

Section: Introductionmentioning

confidence: 99%

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On the Mass of the Neutron Star in V395 Carinae/2S 0921-630

Steeghs

Jonker

2007

ApJ

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We report high-resolution optical spectroscopy of the low-mass X-ray binary V395 Car/2S 0921Ϫ630 obtained with the MIKE echelle spectrograph on the Magellan-Clay telescope. Our spectra are obtained near the inferior conjunction of the mass donor star, and we exploit the absorption lines originating from the back side of the Ktype object to accurately derive its rotational velocity. Using K0-K1 III templates, we find v sin i p 32.9 ‫ע‬ km s . We show that the choice of template star and the assumed limb-darkening coefficient has little impact Ϫ1 0.8 on the derived rotational velocity. This value is a significant revision downward compared to previously published values. We derive new system parameter constraints in light of our much lower rotational velocity. We find , , and , where the errors have been estimated M p 1.44 ‫ע‬ 0.10 M M p 0.35 ‫ע‬ 0.03 M qp 0.24 ‫ע‬ 0.02 1 , 2 ,through a Monte Carlo simulation. A possible remaining systematic effect is the fact that we may be overestimating the orbital velocity of the mass donor due to irradiation effects. However, any correction for this effect will only reduce the compact object mass further, down to a minimum mass of . There is thus M p 1.05 ‫ע‬ 0.08 M 1 , strong evidence that the compact object in this binary is a neutron star of rather typical mass and that the previously reported mass values of 2-4 were too high due to an overestimate of the rotational broadening. M ,

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Section: Discussionmentioning

confidence: 62%

Section: Discussionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

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On the Mass of the Neutron Star in V395 Carinae/2S 0921-630

Steeghs

Jonker

2007

ApJ

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“…a * [ 0.85, NOTE ADDED IN MANUSCRIPT.ÈAs we were completing the revision of this manuscript, Shahbaz et al (1999) presented additional radial velocities of GRO J1655[40 obtained during quiescence. They derive an optical mass function of f (M) \ 2.73^0.09 (compared to 3.24 M _ 0.09 reported by .…”

Section: Discussionmentioning

confidence: 99%

RXTESpectral Observations of the 1996–1997 Outburst of the Microquasar GRO J1655−40

Sobczak

McClintock

Remillard³

et al. 1999

ApJ

103

123

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Excellent coverage of the entire 16 month 1996È1997 outburst cycle of GRO J1655[40 was provided by the Rossi X-Ray T iming Explorer (RXT E). We present a full spectral analysis of these data, which includes 52 Proportional Counter Array spectra from 2.5 to 20 keV and High Energy X-Ray Timing Experiment spectra above 20 keV. We also include a nearly continuous All-Sky Monitor light curve with several intensity measurements per day. The data are interpreted in the context of the multicolor blackbody disk/power-law model. The source exhibits two principal outburst states which we associate with the very high and the high/soft states. During the very high state, the spectrum is often dominated by a power-law component with photon index (!) D 2.3È2.7. The source exhibits intense hard Ñares on timescales of hours to days which are correlated with changes in both the Ðtted temperature and radius of the inner accretion disk. During the high/soft state, the spectrum is dominated by the soft thermal emission from the accretion disk with spectral parameters that suggest approximately constant inner disk radius and temperature. The power-law component is relatively weak with ! D 2È3. During the last few observations, the source undergoes a transition to the low/hard state. We Ðnd that a tight relationship exists between the observed inner radius of the disk and the Ñux in the power-law component. During intense hard Ñares, the inner disk radius is observed to decrease by as much as a factor of 3 on a timescale of days. The apparent decrease of the inner disk radius observed during the Ñares may be due to the failure of the multicolor disk model caused by a steepening of the radial temperature proÐle in the disk coupled with increased spectral hardening and not physical changes of the inner disk radius. The distortion of the inner disk spectrum by the power-law Ñares indicates that the physical mechanism responsible for producing the power-law emission is linked to the inner disk region. Assuming that our spectral model is valid during periods of weak power-law emission, our most likely value for the inner disk radius implies Such a low value for the black hole angular momentum is inconsistent with a * \ 0.7. the relativistic frame dragging and the "" diskoseismic ÏÏ models as interpretations for the 300 Hz X-ray QPO seen during some of these RXT E observations.

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“…Several attempts have been made to constrain the system parameters of V395 Car using the photospheric absorption lines from the companion star, which are detectable in spite of the large contamination by disc flux (Shahbaz et al 1999, 2004; Jonker et al 2005; Shahbaz & Watson 2007; Steeghs & Jonker 2007). From measurements of the radial velocity curve and rotational broadening, and assuming an appropriate inclination for an eclipsing system, it is possible to solve for the masses of both objects.…”

Section: Introductionmentioning

confidence: 99%

Optical and infrared light curves of the eclipsing X-ray binary V395 Car = 2S 0921−630

Ashcraft

Hynes

Robinson

2012

Monthly Notices of the Royal Astronomical Society

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We present results of optical and infrared photometric monitoring of the eclipsing low‐mass X‐ray binary V395 Car (2S 0921−630). Our observations reveal a clear, repeating orbital modulation with an amplitude of about 1 mag in B and V, and a little less in J. Combining our data with archival observations spanning about 20 years, we derive an updated ephemeris with orbital period 9.0026 ± 0.0001 d. We attribute the modulation to a combination of the changing aspect of the irradiated face of the companion star and eclipses of the accretion disc around the neutron star. Both appear to be necessary as a secondary eclipse of the companion star is clearly seen. We model the B, V and J light curves using a simple model of an accretion disc and companion star and find a good fit is possible for binary inclinations of 82.°2 ± 1.°0. We estimate the irradiating luminosity to be about 8 × 1035 erg s−1, in good agreement with X‐ray constraints.

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An ellipsoidal modulation in X-ray Nova Vela 1993 ( = GRS 1009 — 45)

Cited by 35 publications

References 2 publications

On the Mass of the Neutron Star in V395 Carinae/2S 0921-630

On the Mass of the Neutron Star in V395 Carinae/2S 0921-630

RXTESpectral Observations of the 1996–1997 Outburst of the Microquasar GRO J1655−40

Optical and infrared light curves of the eclipsing X-ray binary V395 Car = 2S 0921−630

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