Spectangular: Disentangling variable spectra

Sablowski, D. P.; Järvinen, S. P.; Weber, M.

doi:10.1051/0004-6361/201834836

Cited by 5 publications

(4 citation statements)

References 12 publications

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“…To investigate whether non-degenerate secondaries are present in our sample, we utilise the method of spectral disentangling (Bagnuolo & Gies 1991;Simon & Sturm 1994;Hadrava 1995;Ilijic et al 2004;Sablowski et al 2019). By exploiting the information stored in the spectral-line variability of a spectral time series of a binary, disentangling allows one to separate the component spectra in a binary and derive the orbital parameters.…”

Section: Spectral Disentanglingmentioning

confidence: 99%

The Tarantula Massive Binary Monitoring

Shenar

Sana

Mahy

et al. 2022

A&A

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Context. Massive binaries hosting a black hole (OB+BH) represent a critical phase in the production of BH mergers in the context of binary evolution. In spite of this, such systems have so far largely avoided detection. Single-lined spectroscopic (SB1) O-type binaries are ideal objects to search for elusive BH companions. Moreover, SB1 binaries hosting two main sequence stars probe a regime of more extreme mass ratios and longer periods compared to double-lined binaries (SB2), and are thus valuable for establishing the natal mass ratio distribution of massive stars. Aims. We characterise the hidden companions in 51 SB1 O-type and evolved B-type binaries identified in the Large Magellanic Cloud (LMC) in the framework of the VLT-FLAMES Tarantula Survey (VFTS) and its follow-up, the Tarantula Massive Binary Monitoring (TMBM). The binaries cover periods between few days to years (0 < log P < 3 [d]). Goals are to hunt for BHs and sample the low-mass end of the mass-ratio distribution. Methods. To uncover the hidden companions, we implement the shift-and-add grid disentangling algorithm on 32 epochs of spectroscopy acquired in the framework of TMBM with the FLAMES spectrograph, allowing us to detect companions contributing as little as ≈ 1 − 2% to the visual flux. We further analyse OGLE photometric data for the presence of eclipses or ellipsoidal variations. Results. Out of the 51 SB1 systems, 43 (84%) are found to have non-degenerate stellar companions, of which 28 are confident detections, and 15 are less certain (SB1: or SB2:). Of these 43 targets, one is found to be a triple (VFTS 64), and two are found to be quadruples (VFTS 120, 702). Our sample includes a total of eight eclipsing binaries. The remaining 8 targets (16%) retain an SB1 classification. We model the mass-ratio distribution as f (q) ∝ q κ , and derive κ through a Bayesian approach. We use massratio constraints from previously known SB2 binaries, newly uncovered SB2 binaries, and SB1 binaries, while accounting for binary detection bias. We find κ = 0.2 ± 0.2 for the entire sample and κ = −0.2 ± 0.2 when excluding binaries with periods shorter than 10 d. In contrast, κ = 1.2 ± 0.5 is retrieved for tight binaries (P < 10 d), proposed here to be a consequence of binary interaction. Aside from the unambiguous O+BH binary VFTS 243, analysed in detail in a separate paper, we identify two additional OB+BH candidates: VFTS 514 and 779. Conclusions. Our study firmly establishes a virtually flat natal mass-ratio distribution (κ = 0) for O-type stars at LMC metallicity, covering the entire mass-ratio range (0.05 < q < 1) and periods in the range 0 < log P < 3 [d]. The nature of the OB+BH candidates should be verified through future monitoring, but the frequency of OB+BH candidates is generally in line with recent predictions at LMC metallicity.

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Section: Spectral Disentanglingmentioning

confidence: 99%

The Tarantula Massive Binary Monitoring

Shenar

Sana

Mahy

et al. 2022

A&A

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“…Thanks to spectral disentangling techniques (e.g. Simon & Sturm 1994;Hadrava 1995;Ilijic et al 2001;Sablowski et al 2019), faint components giving rise Based on observations made with the Alfred Jensch Telescope at the Thüringer Landessternwarte Tautenburg and the Mercator Telescope, operated on the island of La Palma by the Flemish Community, at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias.…”

Section: Introductionmentioning

confidence: 99%

“…Thanks to spectral disentangling techniques (e.g. Simon & Sturm 1994;Hadrava 1995;Ilijic et al 2001;Sablowski et al 2019), faint components giving rise stellar evolutionary models. The group of oscillating eclipsing Algol stars (oEAs, hereafter) (Mkrtichian et al 2002) consists of eclipsing Algols with mass transfer where the mass-accreting primary shows δ Sct-like oscillations.…”

Section: Introductionmentioning

confidence: 99%

Spectroscopic long-term monitoring of RZ Cas

Lehmann

Dervişoğlu

Mkrtichian

et al. 2020

A&A

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Context. RZ Cas is a short-period Algol-type system showing episodes of mass transfer and δ Sct-like oscillations of its massgaining primary component. This system exhibits temporal changes in orbital period, v sin i, and the oscillation pattern of the primary component. Aims. We analyse high-resolution spectra of RZ Cas that we obtained during a spectroscopic long-term monitoring lasting from 2001 to 2017. In this first part we investigate the atmospheric parameters of the stellar components and the time variation of orbital period, v sin i, and radial velocities (RVs), searching for seasonal changes that could be related to episodes of mass exchange and to a possible activity cycle of the system triggered by the magnetic cycle of the cool companion. Methods. We used spectrum synthesis to analyse the spectra of both components of RZ Cas. The study of variations of the orbital period is based on published times of primary minima. We used the LSDbinary program to derive separated RVs and least-squares deconvolved (LSD) profiles of the components. From the LSD profiles of the primary we determined its v sin i. Using Markov Chain Monte Carlo simulations with the PHOEBE program, we modelled the RV variations of both components. Results. Spectrum analysis resulted in precise atmospheric parameters of both components, in particular in surface abundances below solar values. We find that the variation of orbital period is semi-regular and derive different characteristic timescales for different epochs of observation. We show that the RV variations with orbital phase can be modelled when including two cool spots on the surface of the secondary component. The modelling leads to very precise masses and separation of the components. The seasonal variation of several parameters, such as v sin i, rotation-orbit synchronisation factor, strength of the spots on the cool companion, and orbital period, can be characterised by a common timescale of the order of nine years. Conclusions. We interpret the timescale of nine years as the magnetic activity cycle of the cool companion. In particular the behaviour of the dark spots on the cool companion leads us to the interpretation that this timescale is based on an 18-year magnetic dynamo cycle. We conclude that the mass-transfer rate is controlled by the variable depth of the Wilson depression in the magnetic spot around the Lagrangian point L1. In the result, based on available data, we observe a damped activity cycle of the star, starting with a high mass-transfer episode around 2001 with a calculated mass-transfer rate of 1.5 × 10 −6 M yr −1 , followed by quiet periods in 2006 and 2009, slightly higher activity around 2013 and 2014, and again followed by quiet periods in 2015 and 2016. However, owing to missing data for years 2010 and 2011, we cannot exclude that a second high mass-transfer episode occurred within this time span.

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“…G+K). While there have been advances in 'disentangling' SB2 spectra (Sablowski & Weber 2017;Sablowski et al 2019), these methods have generally relied on high resolution, high S/N, and multi-epoch spectra. These high quality spectra require significant dedicated telescope time.…”

Section: Introductionmentioning

confidence: 99%

Classifying Single Stars and Spectroscopic Binaries Using Optical Stellar Templates

Roulston,

Green,

Kesseli

2020

Preprint

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Stellar spectral classification is a fundamental tool of modern astronomy, providing insight into physical characteristics such as effective temperature, surface gravity, and metallicity. Accurate and fast spectral typing is an integral need for large all-sky spectroscopic surveys like the SDSS and LAMOST. Here, we present the next version of PyHammer, stellar spectral classification software that uses optical spectral templates and spectral line index measurements. PyHammer v2.0 extends the classification power to include dwarf carbon (dC) stars, DA white dwarf (WD) stars, and also double-lined spectroscopic binaries (SB2). This release also includes a new empirical library of luminosity-normalized spectra that can be used to flux calibrate observed spectra, or to create synthetic SB2 spectra. We have generated physically reasonable SB2 combinations as templates, adding to PyHammer the ability to spectrally type SB2s. We test classification success rates on SB2 spectra, generated from the SDSS, across a wide range of spectral types and signal-to-noise ratios. Within the defined range of pairings described, more than 95% of SB2s are correctly classified.

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Spectangular: Disentangling variable spectra

Cited by 5 publications

References 12 publications

The Tarantula Massive Binary Monitoring

The Tarantula Massive Binary Monitoring

Spectroscopic long-term monitoring of RZ Cas

Classifying Single Stars and Spectroscopic Binaries Using Optical Stellar Templates

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