Double-lined Spectroscopic Binary Research Articles

Determination of the Abundance of Mercury from the Hg ii Line at 5677.10 Å in Late B-type Stars. VII. HD 141556 (χ Lupi)

The weak line of Hg ii located at 5677.10 Å is used to measure the mercury abundance in the most massive component of the double-lined spectroscopic binary HgMn star HD 141556 (χ Lupi). This line is detected at 3σ above the noise in the adjacent continuum. The synthesis of this line confirms a large overabundance of mercury, about +5.30 dex, which is about twice the excess derived from the 3983.93 Å line in earlier studies. Spectrum synthesis yields estimates of the abundance deficiencies/excesses for fourteen other elements which agree well with previous measurements.

A Sample of Compact Object Candidates in Single-lined Spectroscopic Binaries from LAMOST Medium-resolution Survey

The stellar spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) medium-resolution survey can be used to search for compact objects in binaries. The LAMOST Data Release 10 catalog includes >980,000 targets with multiple medium-resolution spectra. We select the targets with large or rapid radial-velocity variation, and obtained an input sample of 1822 sources. We use light curves and spectra to identify and exclude eclipsing binaries and double-lined spectroscopic binaries in the input sample. We finally derive a catalog of 89 candidates with well-folded radial velocity, which are all single-lined spectroscopic binaries, indicating an unseen companion residing in each system. The mass function of each system can be well constrained based on the radial-velocity curve. In our sample, 26 sources have mass function higher than 0.1 M ⊙, among which 18 sources have ellipsoidal-type light curves. In our opinion, compact objects are likely existent in all these 26 binaries, which are worth follow-up identification.

Identifying Quiescent Compact Objects in Massive Galactic Single-lined Spectroscopic Binaries

It is now clearly established that massive stars are predominantly found in multiple systems. While their period and eccentricity distributions are now well established across different metallicity regimes, the mass-ratio distribution has been mostly limited to double-lined spectroscopic binaries. The mass-ratio distribution therefore remains subject to significant uncertainties and open questions encompass the shape and extend of the companion mass-function towards its low-mass end and the nature of undetected companions in single-lined spectroscopic binaries, i.e. low-mass main-sequence stars, binary interaction products, compact objects, etc. We have conducted a large and systematic analysis of a sample of more than 80 single-line O-type spectroscopic binaries in the Milky Way and in the Large Magellanic Cloud using a sophisticated multi-technique, and multi-wavelength approach. We report on the developed methodology, the constraints obtained on the nature of SB1 companions, the distribution of O star mass-ratios at LMC metallicity and the occurrence of quiescent OB+black hole binaries.

Search for spectroscopic binaries using rotational velocities in five open clusters observed by ESO

ABSTRACT In this paper we detect double-lined spectroscopic binaries (SB2) in five open clusters: NGC 2243, NGC 2420, NGC 3532, NGC 6253, and NGC 6705 (M 11) using a method based on high values of the projected rotational velocity when they are fitted with single star spectral model. Observed spectra were obtained from the European Southern Observatory archive. The method was validated on the sets of synthetic spectra for the single and binary stars. It is able to reliably select spectroscopic binaries without confusing them with single stars, if the components in a binary rotate slowly and the radial velocity separation is sufficiently high. We found 60 SB2 candidates: two in NGC 2243, eight each in NGC 2420 and NGC 3532, 17 in NGC 6253, and 25 in NGC 6705. Comparison with literature confirms 18 of them, thus we found 42 new SB2 candidates.

A study of chemical abundances, rotational velocities, and orbital elements in single-lined spectroscopic binary stars in open clusters

ABSTRACT Binary interactions play a significant role in stellar evolution. In this study, we present a comprehensive analysis of 17 single-lined spectroscopic binary stars and identify two more as ‘yellow stragglers’, in the context of 15 young open clusters with ages younger than 1.0 Gyr. High-resolution spectroscopy ($R\, \approx \, 48000$) was employed to determine atmospheric parameters and chemical abundances of various elements including Li, C (C2), N (12CN), O, Na, Mg, Al, Ca, Si, Ti, Ni, Cr, Y, Zr, La, Ce, Nd, and Eu, and compared them with the abundances of stars reported in the literature. The projected rotational velocities ($v\, \sin \, \mathrm{ i}$) of 17 stars were determined via the spectral synthesis method. For two stars, we analyse the phenomenon of yellow stragglers based on their spectra and colour–magnitude diagram. Our $v\, \sin \, \mathrm{ i}$ results exhibit excellent agreement with previous studies in the literature for four stars previously analysed. Furthermore, we found a similar set of chemical abundances between thin disc stars and the studied spectroscopic binaries, except for s-process elements, such as La, Ce, and Nd. Also, we confirm that yellow straggler stars are members of binary systems, specifically giant G/K-type stars paired with dwarf A-type stars. Finally, we investigated the relationships between chemical abundances, orbital parameters (obtained from the literature), and $v\, \sin \, \mathrm{ i}$, which can provide insights into the observed anomalies in 7Li abundance in two stars such as NGC 6694-14 and NGC 6709-303. Our findings suggest that the anomalous rotation and lithium enrichment observed in these stars are likely results of interactions within binary companions.

Detection of 12 426 SB2 candidates in the LAMOST-MRS, using a binary spectral model

ABSTRACT We use an updated method for the detection of double-lined spectroscopic binaries (SB2s) using Vsin i values from spectral fits. The method is applied to all spectra from Large sky Area Multi-Object fiber Spectroscopic Telescope Medium Resolution Survey. Using this method, we detect 12 426 SB2 candidates, where 4321 are already known and 8105 are new discoveries. We check their spectra manually to minimize possible false positives. We also detect several cases of contamination of the spectra by solar light. Additionally, for candidates with multiple observations, we compute mass ratios with systemic velocities and determine Keplerian orbits. We present an updated catalogue of all SB2 candidates together with additional information for some of them in separate data tables.

Binary masses and luminosities with Gaia DR3

Context. The recent third data release (DR3) of Gaia has brought some new exciting data about stellar binaries. It provides new opportunities to fully characterize more stellar systems and contributes to enriching our global knowledge of stellar behaviour. Aims. By combining the new Gaia non-single stars catalogue with double-lined spectroscopic binaries (SB2), we can determine the individual masses and luminosities of the components. To fit an empirical mass-luminosity relation in the Gaia G band, lower-mass stars must be added. These masses can be derived using Gaia-resolved wide binaries combined with literature data. Methods. Using the BINARYS tool, we combined the astrometric non-single star solutions in the Gaia DR3 with SB2 data from two other catalogues: the 9th Catalogue of Spectroscopic Binary orbits (SB9), and APOGEE. We also searched for low-mass stars that are resolved in Gaia with direct imaging and HIPPARCOS data or with a literature mass fraction. Results. The combination of Gaia astrometric non-single star solutions with double-lined spectroscopic data enabled us to characterize 43 binary systems with SB9 and 13 systems with APOGEE. We furthermore derived the masses of 6 low-mass binaries that are resolved with Gaia. We then derived an empirical mass-luminosity relation in the Gaia G band down to 0.12 ℳ⊙.

MASS RATIO AND ECCENTRICITY DISTRIBUTIONS OF YOUNG SPECTROSCOPIC BINARY STARS

We collected the information about 83 pre-main sequence double-lined spectroscopic binaries. Among them there are Ae/Be Herbig stars, T Tauri stars and red dwarfs. The eccentricity – period relation, the mass ratio and eccentricity distributions of young spectroscopic binaries are constructed and analyzed. The overwhelming majority of close binaries with \(P {{10}^{d}}\) have eccentricity near to zero, the stars less than 1 million years old are rare among them. The mass ratio distribution of systems with \(P {{10}^{d}}\) has a prominent maximum in a range of \(q = 0.9{\kern 1pt} - {\kern 1pt} 1.0\). The number of young spectroscopic binaries with \(P {{10}^{d}}\) does not decrease with decreasing mass ratio as sharply as in the case of close binary stars, about 12% of these stars have \(q 0.5\). The paper is based on a talk presented at the astrophysical memorial seminar “Novelties in Understanding the Evolution of Binary Stars”, dedicated to the 90th anniversary of Professor M.A. Svechnikov.

Distribution of Young Spectroscopic Binary Stars by Mass Ratio and Eccentricity

Distribution of Young Spectroscopic Binary Stars by Mass Ratio and Eccentricity

Analysis of the possible satellite contamination in LAMOST-MRS spectra

ABSTRACT We present the detection of false positive double-lined spectroscopic binaries candidates using medium-resolution survey spectra from the one time-domain field of Large Sky Area Multi-Object Fibre Spectroscopic Telescope data release 10. The secondary component in all these binaries has near zero radial velocity and solar-like spectral lines. Highly likely this is light from the semitransparent clouds illuminated by the full Moon. However we also suspect that partially this contamination can be caused by a solar light reflected from the surface of low-orbital artificial satellites launched in the beginning of 2022. We found several possible contaminant candidates using archival orbital data. We propose measures to reduce risk of such contamination for the future observations and methods to find it in archived ones.

The value-added catalogue of ASAS-SN eclipsing binaries – III. Masses and radii of Gaia spectroscopic binaries

ABSTRACT Masses and radii of stars can be derived by combining eclipsing binary light curves with spectroscopic orbits. In our previous work, we modelled the All-Sky Automated Survey for Supernovae (ASAS-SN) light curves of more than 30 000 detached eclipsing binaries using phoebe. Here, we combine our results with 128 double-lined spectroscopic orbits from Gaia Data Release 3. We also visually inspect ASAS-SN light curves of the Gaia double-lined spectroscopic binaries on the lower main sequence and the giant branch, adding 11 binaries to our sample. We find that only 50 per cent of systems have Gaia periods and eccentricities consistent with the ASAS-SN values. We use emcee and phoebe to determine masses and radii for a total of 122 stars with median fractional uncertainties of 7.9 per cent and 6.3 per cent, respectively.

A small survey for massive stars in the LMC/SMC: binaries and pulsations

ABSTRACT Binarity and pulsations are two notable properties that frequently appear together in massive stars. To place constraints on how binarity affects stellar evolution, the exact parameters of massive stars in binary systems must be known. Their exact and accurate masses and radii, which were calculated from binary dynamics, present model-independent restrictions and challenge existing theories of stellar evolution. In this investigation, our goal is to determine the atmospheric characteristics of nine double-lined spectroscopic binaries that are located in the Large Magellanic Cloud and Small Magellanic Cloud. Nine newly discovered double-lined eclipsing binaries with B-type massive components have been studied; these binaries were found using the OGLE variable star catalogues. The absolute physical parameters of each component have been measured with an accuracy of less than or equal to 3 per cent. By analysing through Transiting Exoplanet Survey Satellite data of the systems, we were able to identify five candidates for slowly pulsating B stars in massive binary systems with masses ranging from 2 to 25 M⊙. According to the results of the preliminary research, the orbital periods of these binary systems span anywhere from 1.8 to 6.3 d, whereas the pulsating periods range anywhere from 0.3 to 1.5 d. The achievement in identifying a significant number of pulsating eclipsing systems opens the door to the initial sensible approach of constraining the internal physics of a group of massive stars via asteroseismology of eclipsing binaries including such stars.

Searching for Double-line Spectroscopic Binaries in the LAMOST Medium-resolution Spectroscopic Survey with Deep Learning

Double-line spectroscopic binaries (SB2s) are a vital class of spectroscopic binaries for studying star formation and evolution. Searching for SB2s has been a hot topic in astronomy. Although considerable efforts have been made with fruitful outcomes, limitations in automation and accuracy still persist. In this study, we developed a convolutional neural network model to search for SB2 candidates in LAMOST medium-resolution survey (MRS) data release (DR) 9 v1.0 by detecting double peaks in the cross-correlation function (CCF). We first generated a large number of spectra of single stars and binaries using the iSpec spectral synthesis software. The CCFs of these synthesized spectra were then calculated to form our training set. To efficiently detect the peaks of the CCFs, we applied a Softmax function-based noise reduction method. After testing and validation, the model achieved an accuracy of 97.76% in the testing set and was validated for more than 90% of the sample in several published SB2 catalogs. Finally, by applying the model to examine approximately 1.59 million LAMOST-MRS DR9 spectra, we identified 728 candidate SB2s, including 281 newly discovered ones.

The Pristine survey – XXI. Exploring the metal-poor boundary with ESPaDoNS

ABSTRACT In this paper, we study high-resolution spectra of 19 stars that have metallicity estimates below –3.5 using at least two metallicity-sensitive photometric indices based on Pristine photometry. The purpose is to understand what kind of stars populate this parameter space, together with extremely metal-poor stars. This because we plan to extensively use the Pristine photometry to provide extremely metal-poor targets to the WEAVE spectroscopic survey and wish to understand the nature of possible contaminants. We find that this extreme sample of stars is heavily contaminated by variable stars, in particular short period eclipsing binaries. We thus found, serendipitously, eight double-lined spectroscopic eclipsing binaries that could be followed-up in future studies to provide reliable masses and distances for these systems. We also found two stars that have metallicity below –3.0, one of which may belong to the Gaia-Sausage-Enceladus structure. The lesson to be learned from this investigation is that to select truly metal-poor stars one should be able to remove all photometrically variable stars, which requires complementary information beyond the Pristine photometry. We show how the Gaia photometry can be used to remove about 85 per cent of the photometrically variable stars. Our investigation also shows that there is a clear potential for Pristine photometry to find double-lined spectroscopic binaries among short period eclipsing binaries.

The IACOB project

Context. The empirical distribution of projected rotational velocities (v sin i) in massive O-type stars is characterised by a dominant slow velocity component and a tail of fast rotators. It has been proposed that binary interaction plays a dominant role in the formation of this tail. Aims. We perform a complete and homogeneous search for empirical signatures of binarity in a sample of 54 fast-rotating stars with the aim of evaluating this hypothesis. This working sample has been extracted from a larger sample of 415 Galactic O-type stars that covers the full range of v sin i values. Methods. We used new and archival multi-epoch spectra in order to detect spectroscopic binary systems. We complemented this information with Gaia proper motions and TESS photometric data to aid in the identification of runaway stars and eclipsing binaries, respectively. We also benefitted from additional published information to provide a more complete overview of the empirical properties of our working sample of fast-rotating O-type stars. Results. The identified fraction of single-lined spectroscopic binary (SB1) systems and apparently single stars among the fast-rotating sample is ∼18% and ∼70%, respectively. The remaining 12% correspond to four secure double-line spectroscopic binaries (SB2) with at least one of the components having a v sin i > 200 km s−1 (∼8%), along with a small sample of 2 stars (∼4%) for which the SB2 classification is doubtful: these could actually be single stars with a remarkable line-profile variability. When comparing these percentages with those corresponding to the slow-rotating sample, we find that our sample of fast rotators is characterised by a slightly larger percentage of SB1 systems (∼18% vs. ∼13%) and a considerably smaller fraction of clearly detected SB2 systems (8% vs. 33%). Overall, there seems to be a clear deficit of spectroscopic binaries (SB1+SB2) among fast-rotating O-type stars (∼26% vs. ∼46%). On the contrary, the fraction of runaway stars is significantly higher in the fast-rotating domain (∼33–50%) than among those stars with v sin i < 200 km s−1. Lastly, almost 65% of the apparently single fast-rotating stars are runaways. As a by-product, we discovered a new over-contact SB2 system (HD 165921) and two fast-rotating SB1 systems (HD 46485 and HD 152200) Also, we propose HD 94024 and HD 12323 (both SB1 systems with a v sin i < 200 km s−1) as candidates for hosting a quiescent stellar-mass black hole. Conclusions. Our empirical results seem to be in good agreement with the assumption that the tail of fast-rotating O-type stars (with v sin i > 200 km s−1) is mostly populated by post-interaction binary products. In particular, we find that the final statistics of identified spectroscopic binaries and apparent single stars are in good agreement with newly computed predictions obtained with the binary population synthesis code BPASS and earlier estimations obtained in previous studies.

The Behavior of HgMn Stars in the Far UV—Paper 27: HD 1909

The analysis of two spectra of the spectroscopic binary B9 Hg star HD 1909 recorded by the SWP camera on board the International Ultraviolet Explorer reveals one instance of variations of the far-ultraviolet flux of this star from 1300 up to 2000 Å. The first TESS lightcurve of HD 1909 on the MAST website is periodic with a period close to 7 days which is very close to an earlier period found for the variations of the Strömgren index u. The FUV variations, which occur over about 5 yr, could be caused by the motion of the lower mass companion.

The Behavior of HgMn Stars in the Far UV—Paper 25: HD 77350

The analysis of five spectra of the Hg Mn spectroscopic binary star HD 77350 recorded by the SWP camera on board the International Ultraviolet Explorer reveals one instance of variation of the far-ultraviolet flux of this star shortwards of 1800 Å. The analysis of the coadded SWP spectrum built from the high resolution SWP spectra obtained through the small aperture shows the importance of low excitation and resonance Si ii lines shortwards of 1540 Å, of the Ga ii and Ga iii resonance lines at 1414 and 1495 Å and of the Al ii resonance line at 1670 Å. A very rough estimate of a period from the currently available Transiting Exoplanet Survey Satellite lightcurves yields a value of 9.63 ± 0.18 days which could be the rotation period but this needs confirmation.

The Physical Parameters, Stability, and Habitability of some Double-lined Spectroscopic Binaries

Large ground telescopes can now resolve most double-lined binaries optically at some point in their orbit due to the improvement of imaging techniques in recent decades. Using additional information about these systems, such as astrometric parallax, even a single precise visual observation can provide a 3D orbit and the primary physical parameters. Furthermore, both the visual and spectroscopic orbits can be determined. We combine the Edward method with the visual solution and the spectroscopic orbit parameters: period (P), periastron epoch (T), eccentricity (e), semimajor axis (a1,2) and inclination (i), we also know the mass ratio of the system. The developed method allows us to select doublelined spectroscopic systems with recently calculated orbits. We calculate the individual masses, orbital parallax, and other fundamental astrophysical parameters. The purpose of these parameters is to verify the reliability of the data received from space missions and to calculate the stability and habitability, which is the primary goal of this study. Astronomical information can be obtained from binary stars. By observing short period binaries using both spectroscopy and interferometry, we can determine the individual masses and orbital parallaxes of the objects based on their corresponding orbits. Spectroscopic binaries with double-lines are therefore fundamentally important to optically resolve. To determine the required telescope aperture for the resolution of a spectroscopic binary, we developed a specific algorithm. Wedetermined the most probable maximum and minimum separations between each spectroscopic binary based on photometric and spectroscopic information. Thus, we also determined the different physical parameters of each system by using the calibrations we obtained in our study. Based on optically resolved spectroscopic binaries with both spectroscopic and visual orbits, the methodology presented here was successfully tested.

Sub-percent binary star masses and distances from interferometric observations

AbstractOur knowledge of stellar evolution relies on constraints provided by measurements of the physical stellar properties such as the mass, effective temperature, and radii. The most fundamental parameter, the stellar mass, is rarely available or has a low accuracy, providing poor constraints on the stellar structure and evolution. Observing binary stars combining astrometry and spectroscopy offers the unique opportunity to measure very precise masses. In addition, double-lined spectroscopic binaries provide independent distance measurements with an extreme accuracy, allowing to test the Gaia parallaxes and the period-luminosity (P-L) relations. I will show that masses and distances with an accuracy level as high as 0.05% can be obtained by combining interferometric and spectroscopic observations for different types of binary systems, i.e. binary Cepheids, eclipsing and non-eclipsing binaries.

Visual Orbits of Spectroscopic Binaries with the CHARA Array. IV. HD 61859, HD 89822, HD 109510, and HD 191692

We present the visual orbits of four spectroscopic binary stars, HD 61859, HD 89822, HD 109510, and HD 191692, using long baseline interferometry with the CHARA Array. We also obtained new radial velocities from echelle spectra using the APO 3.5 m, CTIO 1.5 m, and Fairborn Observatory 2.0 m telescopes. By combining the astrometric and spectroscopic observations, we solve for the full, three-dimensional orbits and determine the stellar masses to 1%–12% uncertainty and distances to 0.4%–6% uncertainty. We then estimate the effective temperature and radius of each component star through Doppler tomography and spectral energy distribution analyses. We found masses of 1.4–3.5 M ⊙, radii of 1.5–4.7 R ⊙, and temperatures of 6400–10,300 K. We then compare the observed stellar parameters to the predictions of the stellar evolution models, but found that only one of our systems fits well with the evolutionary models.