Bright spectroscopic binaries: II . A study of five systems with orbital periods of days

Physically quite dissimilar, the BY Dra and RS CVn stars have the common characteristic of extraordinarily high levels of stellar surface activity.The RS CVn group, as defined by Hall, consists of detached binaries both components of types F, G, or K. The orbital periods are from a few days to a few weeks, and the mass ratios are generally near unity. Spectroscopically, the stars are remarkable in that they show very strong Ca II H and K emission outside eclipse. Masses and radii are known for many of these systems; physical parameters indicate these systems contain a moderately evolved subgiant, with mass slightly greater than 1 M⊚. The ages (which may be verified by data on visual companions) are a few 10 years.In contrast, the BY Dra variables are late-type dwarfs, with spectral types ranging from dK5e to dM4e. The e designation indicates the presence of Balmer emission, which is generally visible in moderate strength at Ha and only very weakly present in the blue. The BY Dra stars do exhibit strong emission at H and K, however, and also show UV Ceti-type flares. Approximately 75% of the BY Dra variables are known as double-line spectroscopic binaries.

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Chemically Peculiar Stars Among Spectroscopic Binaries – Revisited

International Astronomical Union Colloquium ◽

10.1017/s025292110002039x ◽

1993 ◽

Vol 138 ◽

pp. 137-142 ◽

Cited By ~ 1

Author(s):

Wilhelm Seggewiss

Keyword(s):

Relative Frequency ◽

Main Sequence ◽

Statistical Investigation ◽

Spectroscopic Binaries ◽

Main Sequence Stars ◽

Eccentric Orbits ◽

Peculiar Stars ◽

Orbital Periods ◽

Chemically Peculiar Stars ◽

The Masses

AbstractThis paper presents a new statistical investigation of peculiar A-type stars (Am, Ap, Hg-Mn) among spectroscopic binary (SB) stars. The relative frequency of Am (CP 1) stars is 55% in the spectral range A1 to A6 of main-sequence stars. The Ap (CP 2) stars amount to 15% in the range B9 to A2. The Hg-Mn stars are concentrated to the spectral types B8 to AO and reach a relative frequency of 23%. The Am SB stars have the shortest orbital periods and the smallest eccentricities (30% circular) whereas the Ap SB stars show a strong tendency to long periods and highly eccentric orbits (only 10% circular). The masses of the Am stars agree with the masses of non-peculiar SB stars of corresponding spectral type.

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Theoretical and Observational Tests for the Mass Transfer Scenario of Ba II stars

International Astronomical Union Colloquium ◽

10.1017/s025292110006293x ◽

1989 ◽

Vol 106 ◽

pp. 223-223

Author(s):

H.M.J. Boffin

Keyword(s):

Mass Transfer ◽

White Dwarf ◽

Mass Function ◽

Spectroscopic Binaries ◽

Red Giants ◽

Orbital Periods ◽

Red Giant ◽

Necessary And Sufficient ◽

Process Elements ◽

Spectral Survey

Ba II stars are red giants showing an enhancement of carbon and s-process elements. The elucidation of their nature seems to require a mass transfer, either by wind or Roche lobe overflow, during their past evolution. Were it really the case, all Ba II stars would be binaries with a white dwarf as companion. To better understand the exact role of their binarity, more orbits are definitely needed. They can be obtained by monitoring the radial velocity variations of those stars. However, a quicker way to find new Ba II stars with orbital elements would be to search for their existence among known spectroscopic binaries. This would also crucially test whether mass transfer is a necessary and sufficient condition to explain Ba II stars. If it is indeed the case, then all spectroscopic binaries, made of a giant and a white dwarf, in a reasonable range of periods, would exhibit the Ba II pecularity. However, the discovery of a peculiar giant+main sequence binary system would imply a revision of our ideas about Ba II stars. To this end have we begun a systematic spectral survey of spectroscopic binaries with orbital periods in the range characteristic of known Ba II stars and containing a red giant. The realization that some stars of the catalogue we compiled were already identified as semibariium stars encourages us to pursue our investigation. Coude spectra were taken with the 152 cm telescope, at a dispersion of 12 Å mm−1 . Until now, 2 stars out of a sample of 31 present a slight enhancement of s-process elements (their anomaly being in the range Ba 0.3 to 0.5), and 2 more appear to be good candidates. The study of a larger sample is currently in progress. A discussion of the nature of the companion to the 2 newly discovered semibarium stars is presented on grounds of their mass function and photometric indices.

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Spectroscopic binaries RV Tauri and DF Cygni

Astronomy and Astrophysics ◽

10.1051/0004-6361/201834956 ◽

2019 ◽

Vol 628 ◽

pp. A40 ◽

Cited By ~ 2

Author(s):

Rajeev Manick ◽

Devika Kamath ◽

Hans Van Winckel ◽

Alain Jorissen ◽

Sanjay Sekaran ◽

...

Keyword(s):

Orbital Period ◽

Asymptotic Giant Branch ◽

Spectroscopic Binaries ◽

Spectral Energy ◽

Pulsation Frequency ◽

Photometric Variability ◽

Orbital Inclination ◽

Orbital Periods ◽

The Impact

Context. Some RV Tauri stars show a long-term photometric variability in their mean magnitudes. DF Cygni (DF Cyg), the only RV Tauri star in the original Kepler field, and the prototype RV Tauri (RV Tau) are two such stars. Aims. The focus of this paper is on two famous but still poorly understood RV Tauri stars: RV Tau and DF Cyg. We aim to confirm their suspected binary nature and derive their orbital elements to investigate the impact of their orbits on the evolution of these systems. This research is embedded in a wider endeavour to study binary evolution of low- and intermediate-mass stars. Methods. The high amplitude pulsations were cleaned from the radial-velocity data to better constrain the orbital motion, allowing us to obtain accurate orbital parameters. We also analysed the photometric time series of both stars using a Lomb-Scargle periodogram. We used Gaia Data Release 2 (DR2) parallaxes in combination with the spectral energy distributions (SEDs) to compute their luminosities. These luminosities were complemented with the ones we computed using a period-luminosity-colour (PLC) relation for RV Tauri stars. The ratio of the circumstellar infrared (IR) flux to the photospheric flux obtained from the SEDs was used to estimate the orbital inclination of each system. Results. DF Cyg and RV Tau are binaries with spectroscopic orbital periods of 784 ± 16 days and 1198 ± 17 days, respectively. These orbital periods are found to be similar to the long-term periodic variability in the photometry, indicating that binarity indeed explains the long-term photometric variability. The SEDs of these systems indicate the presence of a circumbinary disc. Our line of sight grazes the dusty disc, which causes the photometric flux from the star to extinct periodically with the orbital period. Our derived orbital inclinations enabled us to obtain accurate companion masses for DF Cyg and RV Tau, and these were found to be 0.6 ± 0.1 M⊙ and 0.7 ± 0.1 M⊙, respectively. The derived luminosities suggest that RV Tau is a post asymptotic giant branch (post-AGB) binary, while DF Cyg is likely a post red giant branch (post-RGB) binary. Analysis of the Kepler photometry of DF Cyg revealed a power spectrum with side lobes around the fundamental pulsation frequency. This modulation corresponds to the spectroscopic orbital period and hence to the long-term photometric period. Finally we report on the evidence of high velocity absorption features related to the Hα profile in both objects, indicating outflows launched from around the companion.

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The Gaia-ESO Survey: detection and characterisation of single-line spectroscopic binaries

Astronomy and Astrophysics ◽

10.1051/0004-6361/201935819 ◽

2020 ◽

Vol 635 ◽

pp. A155 ◽

Cited By ~ 7

Author(s):

T. Merle ◽

M. Van der Swaelmen ◽

S. Van Eck ◽

A. Jorissen ◽

R. J. Jackson ◽

...

Keyword(s):

Confidence Level ◽

Detection Efficiency ◽

Signal To Noise Ratio ◽

Mass Function ◽

Spectroscopic Binaries ◽

Homogeneous Sample ◽

Giant Stars ◽

Formation And Evolution ◽

Orbital Periods ◽

Red Giant

Context. Multiple stellar systems play a fundamental role in the formation and evolution of stellar populations in galaxies. Recent and ongoing large ground-based multi-object spectroscopic surveys significantly increase the sample of spectroscopic binaries (SBs) allowing analyses of their statistical properties. Aims. We investigate the repeated spectral observations of the Gaia-ESO Survey internal data release 5 (GES iDR5) to identify and characterise SBs with one visible component (SB1s) in fields covering mainly the discs, the bulge, the CoRot fields, and some stellar clusters and associations. Methods. A statistical χ2-test is performed on spectra of the iDR5 subsample of approximately 43 500 stars characterised by at least two observations and a signal-to-noise ratio larger than three. In the GES iDR5, most stars have four observations generally split into two epochs. A careful estimation of the radial velocity (RV) uncertainties is performed. Our sample of RV variables is cleaned from contamination by pulsation- and/or convection-induced variables using Gaia DR2 parallaxes and photometry. Monte-Carlo simulations using the SB9 catalogue of spectroscopic orbits allow to estimate our detection efficiency and to correct the SB1 rate to evaluate the GES SB1 binary fraction and its relation to effective temperature and metallicity. Results. We find 641 (resp., 803) FGK SB1 candidates at the 5σ (resp., 3σ) level. The maximum RV differences range from 2.2 km s−1 at the 5σ confidence level (1.6 km s−1 at 3σ) to 133 km s−1 (in both cases). Among them a quarter of the primaries are giant stars and can be located as far as 10 kpc. The orbital-period distribution is estimated from the RV standard-deviation distribution and reveals that the detected SB1s probe binaries with log P[d] ⪅ 4. We show that SB1s with dwarf primaries tend to have shorter orbital periods than SB1s with giant primaries. This is consistent with binary interactions removing shorter period systems as the primary ascends the red giant branch. For two systems, tentative orbital solutions with periods of 4 and 6 d are provided. After correcting for detection efficiency, selection biases, and the present-day mass function, we estimate the global GES SB1 fraction to be in the range 7–14% with a typical uncertainty of 4%. A small increase of the SB1 frequency is observed from K- towards F-type stars, in agreement with previous studies. The GES SB1 frequency decreases with metallicity at a rate of (−9 ± 3)% dex−1 in the metallicity range −2.7 ≤ [Fe/H] ≤ +0.6. This anticorrelation is obtained with a confidence level higher than 93% on a homogeneous sample covering spectral types FGK and a large range of metallicities. When the present-day mass function is accounted for, this rate turns to (−4 ± 2)% dex−1 with a confidence level higher than 88%. In addition we provide the variation of the SB1 fraction with metallicity separately for F, G, and K spectral types, as well as for dwarf and giant primaries.

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Dynamics of the Open Cluster NGC 188: A Comparison to an N-body Simulation of M67

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308015421 ◽

2007 ◽

Vol 3 (S246) ◽

pp. 111-112

Author(s):

Aaron M. Geller ◽

Robert D. Mathieu ◽

Hugh C. Harris ◽

Robert D. McClure

Keyword(s):

Radial Velocity ◽

Binary Stars ◽

Main Sequence ◽

Open Cluster ◽

Spectroscopic Binaries ◽

Solar Mass ◽

Dynamical Study ◽

Data Set ◽

Spatial Coverage ◽

Orbital Periods

AbstractWe present a detailed dynamical study of the old (7 Gyr) open cluster NGC 188. Our combined radial-velocity data set spans a baseline of 35 years, a magnitude range of 12 ≤ V ≤ 16.5, and a 1° diameter region on the sky. Our magnitude limits include solar-mass main-sequence stars, subgiants, giants, and blue stragglers, and our spatial coverage extends radially to 11.5 core radii. We have measured radial velocities for 1014 stars in the direction of NGC 188 with a precision of 0.4 km s−1, and have calculated radial-velocity membership probabilities for stars with ≥ 3 measurements. We find 420 stars to be high-probability cluster members, including 137 spectroscopic binaries. These detectable binaries all have orbital periods of less than 104 days, and thus are hard. We have derived orbit solutions for 67 member binary stars, and use our 35 main-sequence binaries with orbit solutions to compare the eccentricity and period distributions with simulated observations of the Hurley et al. (2005) model of M67 (4.5 Gyr). We also compare the spatial distributions of cluster member populations.

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Binary Slowly Pulsating B Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100058280 ◽

2000 ◽

Vol 176 ◽

pp. 436-436 ◽

Cited By ~ 1

Author(s):

P. De Cat ◽

C. Aerts

Keyword(s):

Line Profile ◽

Spectroscopic Binaries ◽

High Signal ◽

B Stars ◽

Orbital Frequency ◽

Long Term Follow Up ◽

Order Of Magnitude ◽

Orbital Periods ◽

Photometric Measurements

AbstractThe satellite Hipparcos led to the discovery of 267 new variable B-type stars. Some 100 of them were classified as candidate slowly pulsating B stars (SPBs) by Waelkens et al. (1998). Twelve of the brightest southern candidate SPBs were selected together with 5 confirmed SPBs to start a long-term follow-up study (Aerts et al. 1999). From 1996 up to 1998, numerous high-resolution, high signal-to-noise spectra were taken with the CAT/CES combination at La Silla in order to study the line profile variations of the Si II-doublet centered at 4130 Å.We report our finding that at least 8 of 17 targets turn out to be spectroscopic binaries. We have found a large variety in the obtained orbits. HD 123515 and HD 140873 were known as single-lined spectroscopic binaries, but both turn out to be double-lined. All the others binaries are single-lined. For HD 140873 and HD 177863, we find orbits with large eccentricities of respectively e = 0.731 α 0.006 and e = 0.603 α 0.007. HD 69144, HD 92287 and HD 169978 are three binaries with circular orbits and very short orbital periods (a few days). Since their photometric measurements are dominated by (close to) sinusoidal variations with twice the orbital frequency, these stars are ellipsoidal variables. Their orbital periods are of the same order of magnitude as the expected periods of pulsation.After removing the orbit, we find the same first frequency in the residual radial velocities as in the gathered photometric measurements for 6 stars. For HD 69144 and HD 169978 we did not yet succeed in deriving an intrinsic period, although HD 69144 has prominent line profile variations. For HD 169978, we have serious doubts about the SPB nature.For a detailed description, we refer to De Cat et al. (1999).

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Magnetic field detections in Herbig Ae SB2 systems

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319003776 ◽

2018 ◽

Vol 14 (A30) ◽

pp. 124-124

Author(s):

S. P. Järvinen ◽

S. Hubrig ◽

T. A. Carroll ◽

M. Schöller ◽

I. Ilyin

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Binary Systems ◽

Spectroscopic Binaries ◽

Close Binary ◽

Be Stars ◽

Magnetic Field Generation ◽

Orbital Periods ◽

Low Incidence ◽

Herbig Ae Stars

AbstractStudies of the presence of magnetic fields in Herbig Ae/Be stars are extremely important because they enable us to improve our insight into how the magnetic fields of these stars are generated and how they interact with their environment, including their impact on the planet formation process and the planet-disk interaction. We report new detections of weak mean longitudinal magnetic fields in the close Herbig Ae double-lined spectroscopic binary AK Sco and in the presumed spectroscopic Herbig Ae binary HD 95881 (Järvinen et al. 2018) based on observations obtained with HARPSpol attached to ESO’s 3.6 m telescope. Such studies are important because only very few close spectroscopic binaries with orbital periods below 20 d are known among Herbig Ae stars. Our detections favour the conclusion that the previously suggested low incidence (5-10%) of magnetic Herbig Ae stars can be explained by the weakness of these fields and the limited accuracy of the published measurements. The search for magnetic fields and the determination of their geometries in close binary systems will play an important role for understanding the mechanisms that are responsible for the magnetic field generation.

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The effect of tides on near-core rotation: analysis of 35 Kepler γ Doradus stars in eclipsing and spectroscopic binaries

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2266 ◽

2020 ◽

Vol 497 (4) ◽

pp. 4363-4375

Author(s):

Gang Li ◽

Zhao Guo ◽

Jim Fuller ◽

Timothy R Bedding ◽

Simon J Murphy ◽

...

Keyword(s):

Angular Momentum ◽

Eclipsing Binaries ◽

Momentum Transport ◽

Spectroscopic Binaries ◽

Angular Momentum Transport ◽

Rotation Rates ◽

Rotation Periods ◽

Spectroscopic Binary ◽

Orbital Periods ◽

Core Rotation

ABSTRACT We systematically searched for gravity- and Rossby-mode period spacing patterns in Kepler eclipsing binaries with γ Doradus pulsators. These stars provide an excellent opportunity to test the theory of tidal synchronization and angular momentum transport in F- and A-type stars. We discovered 35 systems that show clear patterns, including the spectroscopic binary KIC 10080943. Combined with 45 non-eclipsing binaries with γ Dor components that have been found using pulsation timing, we measured their near-core rotation rates and asymptotic period spacings. We find that many stars are tidally locked if the orbital periods are shorter than 10 d, in which the near-core rotation periods given by the traditional approximation of rotation are consistent with the orbital period. Compared to the single stars, γ Dor stars in binaries tend to have slower near-core rotation rates, likely a consequence of tidal spin-down. We also find three stars that have extremely slow near-core rotation rates. To explain these, we hypothesize that unstable tidally excited oscillations can transfer angular momentum from the star to the orbit, and slow the star below synchronism, a process we refer to as ‘inverse tides’.

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Spectroscopic Binaries in Young Open Clusters

Symposium - International Astronomical Union ◽

10.1017/s0074180900225217 ◽

2001 ◽

Vol 200 ◽

pp. 191-198 ◽

Cited By ~ 2

Author(s):

Jean-Claude Mermilliod ◽

Beatriz García

Keyword(s):

Open Clusters ◽

Spectroscopic Binaries ◽

Cluster Center ◽

Multiple Systems ◽

Multiple Stars ◽

Cluster Area ◽

Orbital Periods ◽

The Rich

We have analysed the binarity and multiplicity characteristics of 120 O-type stars in 22 very young open clusters and found marked differences between the “rich” (N ≥ 6 O-type stars and primaries) and “poor” (N = 1) clusters. In the rich clusters, the binary frequencies vary between 14% (1 SB among 7 stars) and 80% (8 SBs among 10 stars). Multiple systems seem not to be frequent and stars are spread all over the cluster area. In poor clusters, the binary frequency of the O-type objects is nearly 100%, with orbital periods around 3 days. Several binaries are also eclipsing. Additional companions are always present. They form either hierarchical multiple stars or trapezium systems. These massive multiple systems are generally found close to the cluster center, although there are exceptions.

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