Detection of Superhumps During the Outburst of BC UMA

Kunjaya, Chatief; Katô, Takeo; Hirata, Ryuko

doi:10.1017/s1539299600021389

Cited by 7 publications

(7 citation statements)

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“…Second, during the declining phase, X-Per moved from the lower-right part to the upper-left part in the Stokes normalized plane, and followed the same trace but in opposite direction during the reformation phase. This means that X-Per followed a straight line (Kunjaya & Hirata 1995;Roche et al 1997), indicating that the polarization angle did not change significantly. As shown in Fig.…”

Section: Discussionmentioning

confidence: 94%

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Warped disks during type II outbursts in Be/X-ray binaries: evidence from optical polarimetry

Reig

Blinov

2018

A&A

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Context. Current models that explain giant (type II) X-ray outbursts in Be/X-ray binaries (BeXB), are based on the idea of highly distorted disks. They are believed to occur when a misaligned and warped disk becomes eccentric, allowing the neutron star to capture a large amount of material. The BeXB 4U 0115+63 underwent two major outbursts in 2015 and 2017. Aims. Our aim is to investigate whether the structural changes in the disk expected during type II outbursts can be detected through optical polarimetry. Methods. We present the first optical polarimetric observations and new optical spectra of the BeXB 4U 0115+63 covering the period 2013-2017. We study in detail the shape of the Hα line profile and the polarization parameters before, during, and after the occurrence of a type II X-ray outburst. Results. We find significant changes in polarization degree and polarization angle and highly distorted line profiles during the 2017 X-ray outburst. The degree of polarization decreased by ∼ 1%, while the polarization angle, which is supposed to be related with the disk orientation, first increased by ∼ 10 • in about two months and then decreased by a similar amount and on a similar timescale once the X-ray activity ceased. Conclusions. We interpret the polarimetric and spectroscopic variability as evidence for the presence of a warped disk.

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Section: Discussionmentioning

confidence: 94%

“…Regarding BeXB, the only system for which a detailed polarimetric study has been performed is X-Per (Kunjaya & Hirata 1995;Roche et al 1997). The data covered a declining phase in the evolution of the disk, and the subsequent recovery.…”

Section: Discussionmentioning

confidence: 99%

Warped disks during type II outbursts in Be/X-ray binaries: evidence from optical polarimetry

Reig

Blinov

2018

A&A

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“…If the origin of polarization is the circumstellar disk, then we would expect long-term polarimetric variability, similar to the photometric and spectroscopic variability. A correlation between polarization, Hα emission, and brightness has been reported for the Be/X-ray binary X Per and interpreted in terms of disk development (Kunjaya & Hirata 1995;Roche et al 1997). In contrast, Larionov (1987) suggested that the source of variable polarized radiation measured in the BeXB 1A 0535+262 is an accretion disk around the neutron star.…”

Section: Discussionmentioning

confidence: 89%

The optical counterpart to the Be/X-ray binary SAX J2239.3+6116

Reig

Blay

Blinov

2017

A&A

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Context. Be/X-ray binaries represent the main group of high-mass X-ray binaries. The determination of the astrophysical parameters of the counterparts of these high-energy sources is important for the study of X-ray binary populations in our Galaxy. X-ray observations suggest that SAX J2239.3+6116 is a Be/X-ray binary. However, little is known about the astrophysical parameters of its massive companion. Aims. The main goal of this work is to perform a detailed study of the optical variability of the Be/X-ray binary SAX J2239.3+6116. Methods. We obtained multi-colour BVRI photometry and polarimetry and 4000-7000 Å spectroscopy. The 4000-5000 Å spectra allowed us to determine the spectral type and projected rotational velocity of the optical companion; the 6000-7000 Å spectra, together with the photometric magnitudes, were used to derive the colour excess E(B − V), estimate the distance, and to study the variability of the Hα line. Results. The optical counterpart to SAX J2239.3+6116 is a V = 14.8 B0Ve star located at a distance of ∼4.9 kpc. The interstellar reddening in the direction of the source is E(B − V) = 1.70 ± 0.03 mag. The monitoring of the Hα line reveals a slow long-term decline of its equivalent width since 2001. The line profile is characterized by a stable double-peak profile with no indication of large-scale distortions. We measured intrinsic optical polarization for the first time. Although somewhat higher than predicted by the models, the optical polarization is consistent with electron scattering in the circumstellar disk. Conclusions. We attribute the long-term decrease in the intensity of the Hα line to the dissipation of the circumstellar disk of the Be star. The longer variability timescales observed in SAX J2239.3+6116 compared to other Be/X-ray binaries may be explained by the wide orbit of the system.

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“…In the spectrum of X Per four peaks were observed in HeI6678 emission line in 1994-1995. This is interpreted as due to a double disc structure (Kunjaya & Hirata 1995;Tarasov & Roche 1995). Probably, we have similar situation in March 2019, however the blue peak of the inner disc coincides with the blue peak of the outer disc (on Fig.…”

Section: Discussionmentioning

confidence: 99%

An eccentric wave in the circumstellar disc of the Be/X-ray binary X Persei

Zamanov,

Stoyanov,

Wolter

et al. 2019

Preprint

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We present spectroscopic observations of the Be/X-ray binary X Per obtained during the period December 2017 -March 2019 (MJD 58095 -MJD 58568). In December 2017 the Hα, Hβ, and HeI 6678 emission lines were symmetric with violet-to-red peak ratio V/R ≈ 1. During the first half of the period (MJD 58095 -MJD 58360) the V/R-ratio decreased to 0.5 and the asymmetry developed simultaneously in all three lines. During the second half of the period (MJD 58360 -MJD 58570) the V/R-ratio increased, however with the HeI 6678 line showing a markedly different behaviour than the Balmer lines. A third component with velocity ≥ 250 km s −1 appeared in the red side of HeI line profile. Possibly, during the first half of the period the entire disc become asymmetric and/or elliptical. The third component in HeI can be an indication for inner elliptical disc with eccentricity ∼ 0.4..

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Detection of Superhumps During the Outburst of BC UMA

Abstract: BC UMa was observed during its rare outburst in 1994. The superhumps with period 0.0619 day are clearly apparent, accompanied by secondary superhumps. This confirms the classification of BC UMa as an SU UMa type dwarf nova. The maximum brightness is 12.5 mag, which… Show more

Cited by 7 publications

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Warped disks during type II outbursts in Be/X-ray binaries: evidence from optical polarimetry

Warped disks during type II outbursts in Be/X-ray binaries: evidence from optical polarimetry

The optical counterpart to the Be/X-ray binary SAX J2239.3+6116

An eccentric wave in the circumstellar disc of the Be/X-ray binary X Persei

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