- ID:
- ivo://CDS.VizieR/J/ApJ/701/764
- Title:
- Light curves for five M-dwarf stars
- Short Name:
- J/ApJ/701/764
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have derived masses and radii for both components in five short-period single-lined eclipsing binary stars discovered by the TrES wide-angle photometric survey for transiting planets. All these systems consist of a visible F-star primary and an unseen M-star secondary (M_A_>=0.8M_{sun}_, M_B_<=0.45M_{sun}_). The spectroscopic orbital solution combined with a high-precision transit light curve for each system gives sufficient information to calculate the density of the primary star and the surface gravity of the secondary. The masses of the primary stars were obtained using stellar evolution models, which requires accurate determinations of metallicities and effective temperatures.
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- ID:
- ivo://CDS.VizieR/J/A+A/628/A111
- Title:
- Li in BPS CS22876-032 spectrum
- Short Name:
- J/A+A/628/A111
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present high-resolution and high-quality UVES spectroscopic data of the metal-poor double-lined spectroscopic binary CS 22876-032 ([Fe/H] approximately -3.7dex). Our goal is to derive the ^6^Li/^7^Li isotopic ratio by analysing the LiI 670.8nm doublet. Methods. We co-added all 28 useful spectra normalised and corrected for radial velocity to the rest frame of the primary star. We fitted the Li profile with a grid of the 3D non-local thermodynamic equilibrium (NLTE) synthetic spectra to take into account the line profile asymmetries induced by stellar convection, and performed Monte Carlo simulations to evaluate the uncertainty of the fit of the Li line profile. We checked that the veiling factor does not affect the derived isotopic ratio, ^6^Li/^7^Li, and only modifies the Li abundance, A(Li), by about 0.15dex. The best fit of the Li profile of the primary star provides A(Li)=2.17+/-0.01dex and ^6^Li/^7^Li=8^+2^_-5_% at 68% confidence level. In addition, we improved the Li abundance of the secondary star at A(Li)=1.55+/-0.04dex, which is about 0.6 dex lower than that of the primary star. The analysis of the Li profile of the primary star is consistent with no detection of ^6^Li and provides an upper limit to the isotopic ratio of ^6^Li/^7^Li<10% at this very low metallicity, about 0.5dex lower in metallicity than previous attempts for detection of ^6^Li in extremely metal poor stars. These results do not solve or worsen the cosmological ^7^Li problem, nor do they support the need for non-standard ^6^Li production in the early Universe.
- ID:
- ivo://CDS.VizieR/J/A+A/408/L29
- Title:
- Line identification of HD 34700
- Short Name:
- J/A+A/408/L29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We announce the star HD 34700 to be a double-lined spectroscopic binary, and find it to be a weak-line T Tauri object. The spectra of both components are very similar and both show the Li I feature at 6708{AA}. Strong arguments in favour of the binary nature of the star as opposed to other possibilities are offered. It is very likely that the companion is also a T Tauri star of similar mass. We present, in Table 2, a list of the lines identified and the radial velocities of the two components for three epochs.
- ID:
- ivo://CDS.VizieR/J/A+A/310/164
- Title:
- Line profile variations in eta Ori
- Short Name:
- J/A+A/310/164
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Eta Orionis (HD35411) is a multiple system which consists of at least four early B-type stars. In the present paper we focus on the double-lined spectroscopic eclipsing pair Aab, and in particular on component Ab, which is a remarkable intrinsically variable star. The presence of this variable in an eclipsing system enables us to determine accurately its mass, radius, inclination angle and rotation period.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A7
- Title:
- Li-rich and non-Li-rich K giants RVs
- Short Name:
- J/A+A/639/A7
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The origin of the Li-rich K giants is still highly debated. Here, we investigate the incidence of binarity among this family from a nine-year radial-velocity monitoring of a sample of 11 Li-rich K giants using the HERMES spectrograph attached to the 1.2m Mercator Telescope. A sample of 13 non-Li-rich giants (8 of them being surrounded by dust according to IRAS, WISE, and ISO data) was monitored alongside. When compared to the binary frequency in a reference sample of 190K giants (containing 17.4% of definite spectroscopic binaries - SB - and 6.3% of possible spectroscopic binaries - SB?), the binary frequency appears normal among the Li-rich giants (2/11 definite binaries plus 2 possible binaries, or 18.2% SB + 18.2% SB?), after taking account of the small sample size through the hypergeometric probability distribution. Therefore, there appears to be no causal relationship between Li enrichment and binarity. Moreover, there is no correlation between Li enrichment and the presence of circumstellar dust, and the only correlation that could be found between Li enrichment and rapid rotation is that the most Li-enriched K giants appear to be fast-rotating stars. However, among the dusty K giants, the binary frequency is much higher (4/8 definite binaries plus 1 possible binary). The remaining 3 dusty K giants suffer from a radial-velocity jitter, as is expected for the most luminous K giants, which these are.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/437
- Title:
- LS I +61 303 radial velocities and Halpha EW
- Short Name:
- J/ApJ/656/437
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of an Halpha monitoring campaign on the BeXRB and microquasar system LS I +61 303. We use radial velocity measurements of HeI lines in our spectra to reevaluate the orbital elements and to better establish the time of periastron. We list equivalent widths and other parameters for the Halpha emission line and discuss the orbital phase related variations observed.
- ID:
- ivo://CDS.VizieR/J/ApJ/656/431
- Title:
- LS I +65 010 radial velocities and Halpha EW
- Short Name:
- J/ApJ/656/431
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a 3yr spectroscopic monitoring program of the Halpha emission in the massive X-ray binary LS I +65 010 = 2S 0114+650, which consists of a B supergiant and a slowly rotating X-ray pulsar. We present revised orbital elements that yield a period of P=11.5983+/-0.0006days and confirm that the orbit has a nonzero eccentricity e=0.18+/-0.05. The Halpha emission profile is formed in the base of the wind of the B supergiant primary, and we show how this spectral feature varies on timescales that are probably related to the rotational period of the B supergiant. We also examine the X-ray fluxes from the Rossi X-ray Timing Explorer All-Sky Monitor instrument, and we show that the X-ray orbital light curve has a maximum at periastron and a minimum at the inferior conjunction of the B supergiant. We also show that the wind emission strength and the high-energy X-ray flux appear to vary in tandem on timescales of approximately 1yr.
- ID:
- ivo://CDS.VizieR/J/A+A/626/A128
- Title:
- Main-sequence and subgiant Barium stars
- Short Name:
- J/A+A/626/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Barium (Ba) dwarfs and CH subgiants are the less evolved analogues of Ba and CH giants. They are F- to G-type main-sequence stars polluted with heavy elements by their binary companions when the companion was on the asymptotic giant branch (AGB). This companion is now a white dwarf that in most cases cannot be directly detected. We present a large systematic study of 60 objects classified as Ba dwarfs or CH subgiants. Combining radial-velocity measurements from HERMES and SALT high-resolution spectra with radial-velocity data from CORAVEL and CORALIE, we determine the orbital parameters of 27 systems. We also derive their masses by comparing their location in the Hertzsprung-Russell diagram with evolutionary models. We confirm that Ba dwarfs and CH subgiants are not at different evolutionary stages, and that they have similar metallicities, despite their different names. Additionally, Ba giants appear significantly more massive than their main-sequence analogues. This is likely due to observational biases against the detection of hotter main- sequence post-mass-transfer objects. Combining our spectroscopic orbits with the Hipparcos astrometric data, we derive the orbital inclination and the mass of the WD companion for four systems. Since this cannot be done for all systems in our sample yet (but should be possible with upcoming Gaia data releases), we also analyse the mass-function distribution of our binaries. We can model this distribution with very narrow mass distributions for the two components and random orbital orientations on the sky. Finally, based on BINSTAR evolutionary models, we suggest that the orbital evolution of low-mass Ba systems can be affected by a second phase of interactions along the red giant branch of the Ba star, which impact the eccentricities and periods of the giants.
- ID:
- ivo://CDS.VizieR/J/AJ/131/1015
- Title:
- MAP observations of the position of Procyon
- Short Name:
- J/AJ/131/1015
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the analysis of observations of Procyon obtained with the Multichannel Astrometric Photometer during the years 1986-2004. While the results significantly increase the precision of the estimated characteristics of the components of the system, they are generally in good agreement with the most recent studies.
- ID:
- ivo://CDS.VizieR/J/ApJ/490/328
- Title:
- "Mass Discrepancy" for Massive Stars
- Short Name:
- J/ApJ/490/328
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar evolutionary models are often used to infer a star's mass via its luminosity, but empirical checks on the accuracy of the theoretical mass-luminosity relation for very massive stars have been lacking. This is of particular concern given that modern atmosphere models yield systematically smaller masses for massive stars than do evolutionary models, with the discrepancy a factor of two for Of stars. We attempt to resolve this mass discrepancy by obtaining new, high-resolution optical data on seven early-type spectroscopic binaries: V453 Cyg, HD 191201, V382 Cyg, Y Cyg, HD 206267, DH Cep, and AH Cep. Our study produces improved spectral subtypes for the components of these systems, crucial for evaluating their luminosities and locations in the H-R diagram. Our radial velocity study utilizes a measuring method which explicitly accounts for the effects of pair-blending. We combine our new orbit solutions with existing data on inclinations and distances when available to compare the orbital masses with evolutionary models, and we find good agreement in all cases where the stars are non-interacting. (The components of V382 Cyg and DH Cep fill their Roche lobes, and in both cases we find masses substantially lower than the masses inferred from evolutionary tracks, suggesting that significant material has been lost rather than transferred. We confirm that this same trend exists for other systems drawn from the literature.) Our own data extends to only 15 M_{sun}_, although photometric inclination determinations for HD 191201 and HD 206267 should prove possible, and will provide examples of higher mass systems. We briefly discuss suitable systems from the literature, and conclude that orbit solutions provide good agreement with the evolutionary models to 25 M_{sun}_. Beyond this, most known binaries either fill their Roche lobes or have other complications. We also discuss five systems for which our improved data and analysis failed to yield acceptable orbit solutions: EO Aur, IU Aur, V640 Mon (Plaskett's star), LY Aur, and 29 UW CMa all remained intractable, despite improved data.
