A cyclic bipolar wind in the interacting binary V 393 Scorpii

Graczyk

et al. 2014

A&A

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Aims. In order to better understand the double periodic variable (DPV) phenomenon, we analyse a series of optical spectra of the DPV system DQ Velorum during much of its long-term cycle. In addition, we investigate the evolutionary history of DQ Vel using theoretical evolutionary models to obtain the best representation for the current observed stellar and orbital parameters of the binary. We investigate the evolution of DQ Vel through theoretical evolutionary models to estimate the age and the mass transfer rate which are then compared with those of its twin V393 Scorpii. Methods. We subtracted the donor star contribution from the composite spectra of DQ Vel using a synthetic spectrum as a donor template. Donor-subtracted spectra covering around 60% of the long-term cycle allowed us to investigate time-modulated spectral variations of the gainer star plus the disc. We used Gaussian fits to measure the equivalent widths (EWs) of Balmer and helium lines in the separated spectra during the long-term cycle and thus analyse EW variabilities. We compared the observed stellar parameters of the system with a grid of theoretical evolutionary tracks computed under a conservative and a non-conservative evolution regime. Results. We have found that the EW of Balmer and helium lines in the donor-subtracted spectra are modulated with the long-term cycle. We observe a strengthening in the EWs in all analysed spectral features at the minimum of the long-term cycle which might be related to an extra line emission during the maximum of the long-term variability. Difference spectra obtained at the secondary eclipse support this scenario. We have found that a non-conservative evolutionary model where DQ Vel has lost mass at some stage of its binary history, is a better representation of the current observed properties of the system. The best evolutionary model suggests that DQ Vel has an age of 7.40 × 10 7 yr and is currently in a low mass transfer rate (−9.8 × 10 −9 M /yr) stage, after a mass transfer burst episode. Comparing the evolutionary stages of DQ Vel and V393 Sco we observed that the former is an older system with a lower mass transfer rate. This might explain the differences observed in the physical parameters of their accretion discs.

Section: The O I 7773 Line and Dacsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Exploring the long-term variability and evolutionary stage of the interacting binary DQ Velorum

Barría

Graczyk

et al. 2014

A&A

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“…The short-term variability corresponds to the orbital motion of the binary while the long-term variability A&A 552, A63 (2013) is still not completely understood. DPVs have been interpreted as semi-detached binaries showing cycles of mass loss into the interstellar medium (Mennickent et al 2008(Mennickent et al , 2012b.…”

Section: Introductionmentioning

confidence: 99%

Fundamental stellar and accretion disc parameters of the eclipsing binary DQ Velorum

Barría

Schmidtobreick

et al. 2013

A&A

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Context. To add to the growing collection of well-studied double periodic variables (DPVs) we have carried out the first spectroscopic and photometric analysis of the eclipsing binary DQ Velorum to obtain its main physical stellar and orbital parameters. Aims. Combining spectroscopic and photometric observations that cover several orbital cycles allows us to estimate the stellar properties of the binary components and the orbital parameters. We also searched for circumstellar material around the more massive star. Methods. We separated DQ Velorum composite spectra and measured radial velocities with an iterative method for double spectroscopic binaries. We obtained the radial velocity curves and calculated the spectroscopic mass ratio. We compared our single-lined spectra with a grid of synthetic spectra and estimated the temperature of the stars. We modeled the V-band light curve with a fitting method based on the simplex algorithm, which includes an accretion disc. To constrain the main stellar parameters we fixed the mass ratio and donor temperature to the values obtained by our spectroscopic analysis. Results. We obtain a spectroscopic mass ratio q = 0.31 ± 0.03 together with donor and gainer masses M d = 2.2 ± 0.2 M , M g = 7.3 ± 0.3 M , the radii R d = 8.4 ± 0.2 R , R g = 3.6 ± 0.2 R and temperatures T d = 9400 ± 100 K, T g = 18 500 ± 500 K for the stellar components. We find that DQ Vel is a semi-detached system consisting of a B3V gainer and an A1III donor star plus an extended accretion disc around the gainer. The disc is filling 89% of the gainer Roche lobe with a temperature of 6580 ± 300 K at the outer radius. It has a concave shape that is thicker at its edge (d e = 0.6 ± 0.1 R ) than at its centre (d c = 0.3 ± 0.1 R ). We find a significant sub-orbital frequency of 0.19 d −1 in the residuals of the V-band light curve, which we interpret as a pulsation of an slowly pulsating B-type (SPB) of a gainer star. We also estimate the distance to the binary (d ∼ 3.1 kpc) using the absolute radii, apparent magnitudes, and effective temperatures of the components found in our study.

“…We find that HD 170882 shows spectroscopic properties similar to other DPVs like AU Monocerotis, V 393 Scorpii, DQ Velorum and OGLE 05155332-6925581 (Mennickent et al, 2008, 2012a, 2012b, Barría et al 2013, Garrido et al 2013. These properties include the existence of an optically thick disc surrounding a B-type star and evidence for stream-disc interaction.…”

Section: Discussionmentioning

confidence: 62%

“…The system is characterized by a long photometric cycle of 536 days and is the third longest-period member of the Galactic Double Period Variables (DPVs), after V 495 Cen and V 4142 Sgr (Mennickent & Rosales 2014, Mennickent et al 2012a. DPVs are intermediate mass interacting binaries showing a long photometric cycle lasting about 33 times the orbital pe-riod, which has been interpreted as cyclic episodes of mass loss (Mennickent et al 2003, Mennickent et al 2008, 2012b, Poleski et al 2010). More than 200 DPVs have been found in the Galaxy and the Magellanic Clouds (Mennickent 2013), but very few of them have been studied spectroscopically (e.g.…”

Section: Introductionmentioning

confidence: 99%

Fundamental parameters of the close interacting binary HD 170582 and its luminous accretion disc

Monthly Notices of the Royal Astronomical Society

Djurašević

Cabezas

et al. 2015

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We present a spectroscopic and photometric study of the Double Period Variable HD 170582. Based on the study of the ASAS V-band light curve we determine an improved orbital period of 16.87177 ± 0.02084 days and a long period of 587 days. We disentangled the light curve into an orbital part, determining ephemerides and revealing orbital ellipsoidal variability with unequal maxima, and a long cycle, showing quasi-sinusoidal changes with amplitude ∆V= 0.1 mag. Assuming synchronous rotation for the cool stellar component and semi-detached configuration we find a cool evolved star of M 2 = 1.9 ± 0.1 M , T 2 = 8000 ± 100 K and R 2 = 15.6 ± 0.2 R , and an early B-type dwarf of M 1 = 9.0 ± 0.2 M . The B-type star is surrounded by a geometrically and optically thick accretion disc of radial extension 20.8 ± 0.3 R contributing about 35% to the system luminosity at the V band. Two extended regions located at opposite sides of the disc rim, and hotter than the disc by 67% and 46%, fit the light curve asymmetries. The system is seen under inclination 67.4 ± 0.4 degree and it is found at a distance of 238 ± 10 pc. Specially interesting is the double line nature of He i 5875; two absorption components move in anti-phase during the orbital cycle; they can be associated with the shock regions revealed by the photometry. The radial velocity of one of the He i 5875 components closely follows the donor radial velocity, suggesting that the line is formed in a wind emerging near the stream-disc interacting region.