Spectroscopic Binary HD 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.

New Determinations of the Surface Abundances of HD 1909: Paper II: From Calcium to Mercury

New abundances for the elements calcium to mercury are measured for the brightest member of the spectroscopic binary HD 1909 using updated atomic data and spectrum synthesis. Manganese is overabundant by a unusually high factor (80 ⊙). While strontium is underabundant, yttrium and zirconium are very overabundant by factors of 250 and 500 times the solar abundances. Barium is overabundant by a factor of 20. The strongest lines of the twice ionized lanthanides Pr iii and Nd iii are not present which suggests the abundances of these two elements are solar or less. The Hg ii line at 3983.93 Å is unusually strong and reproduced by a mercury overabundance of a factor of 500,000 times the solar mercury abundance.

New Determinations of the Surface Abundances of HD 1909: Paper I: The Light Elements (from Helium to Sulfur)

New abundances for the elements helium to sulfur are derived for the brightest member of the spectroscopic binary HD 1909 using updated atomic data and spectrum synthesis. The majority of these elements are underabundant, the depletion factors appear in parenthesis: helium (0.02 times the solar helium abundance), carbon and oxygen (0.40 ⊙), neon (0.15 ⊙), magnesium (0.45 ⊙), aluminum (0.02 ⊙). silicon (0.50 ⊙) and sulfur (0.35 ⊙). In contrast, phosphorus is overabundant by a factor of 12.5 ⊙ and the silicon–phosphorus–sulfur triad is inverted. The lines of the companion are redshifted by about +122.5 km s−1 with respect to the B9 Hg star in the spectrum analyzed here.

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 26: HD 207857

The analysis of two spectra of the Mn P Ga spectroscopic binary HD 207857 recorded by the SWP camera on board the International Ultraviolet Explorer reveals one instance of variation of the far-ultraviolet flux of this star over a time interval of about 10 months. The orbital period of this spectroscopic binary being 338.2 days, the observed increases of flux below 1800 Å could be due to the presence of a hot 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.

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.

Updated Orbit and Observations of Spectroscopic Binary HD 2019

Binary star system HD 2019 was studied by the David Dunlap Observatory between 1935 and 1947. From the spectroscopic data obtained, the orbital elements of the system were defined. Between then and now, there have been no updated studies of this binary star system. We set out to update the orbit of HD 2019 with new spectroscopic data obtained at Clarkson University's Reynolds Observatory. After finding the radial velocities of the star or stars visible in each spectrum, estimates of the error for each measurement were made. From the radial velocities and error estimates, new orbital elements were fit using the data from David Dunlap Observatory combined with the new data collected at Clarkson. These results lead to further investigation of the eccentricity of the orbit. Using the method of Lucy 2005, we ran a test to check the statistical significance of the eccentric orbit using p-value testing.

Visual Orbits of Spectroscopic Binaries with the CHARA Array. III. HD 8374 and HD 24546

Abstract We present the visual orbits of two long-period spectroscopic binary stars, HD 8374 and HD 24546, using interferometric observations acquired with the CHARA Array and the Palomar Testbed Interferometer. We also obtained new radial velocities from echelle spectra using the APO 3.5 m and Fairborn 2.0 m telescopes. By combining the visual and spectroscopic observations, we solve for the full, three-dimensional orbits and determine the stellar masses and distances to within 3% uncertainty. We then estimate the effective temperature and radius of each component star through Doppler tomography and spectral energy distribution analyses, in order to compare the observed stellar parameters to the predictions of stellar evolution models. For HD 8374, we find masses of M 1 = 1.636 ± 0.050M ⊙ and M 2 = 1.587 ± 0.049M ⊙, radii of R 1 = 1.84 ± 0.05R ⊙ and R 2 = 1.66 ± 0.12R ⊙, temperatures of K and K, and an estimated age of 1.0 Gyr. For HD 24546, we find masses of M 1 = 1.434 ± 0.014M ⊙ and M 2 = 1.409 ± 0.014M ⊙, radii of R 1 = 1.67 ± 0.06R ⊙ and R 2 = 1.60 ± 0.10R ⊙, temperatures of K and K, and an estimated age of 1.4 Gyr. HD 24546 is therefore too old to be a member of the Hyades cluster, despite its physical proximity to the group.

Visual Orbits of Spectroscopic Binaries with the CHARA Array. I. HD 224355

Abstract We present the visual orbit of the double-lined spectroscopic binary HD 224355 from interferometric observations with the CHARA Array, as well as an updated spectroscopic analysis using echelle spectra from the Apache Point Observatory 3.5 m telescope. By combining the visual and spectroscopic orbital solutions, we find the binary components to have masses of M 1 = 1.626 ± 0.005M ⊙ and M 2 = 1.608 ± 0.005M ⊙, and a distance of d = 63.98 ± 0.26 pc. Using the distance and the component angular diameters found by fitting spectrophotometry from the literature to spectral energy distribution models, we estimate the stellar radii to be R 1 = 2.65 ± 0.21R ⊙ and R 2 = 2.47 ± 0.23R ⊙. We then compare these observed fundamental parameters to the predictions of stellar evolution models, finding that both components are evolved toward the end of the main sequence with an estimated age of 1.9 Gyr.

The Three-dimensional Orbit, Orbital Parallax, and Individual Masses of the Double-lined Spectroscopic Binaries HD 183255, HD 114882, and HD 30712

Abstract Recent speckle observations performed at the Discovery Channel Telescope, the Gemini North Telescope, and the Special Astrophysical Observatory 6 m Telescope have permitted us to calculate the visual orbit of SB2 HD 114882 for the first time and to improve the visual orbits of two other SB2 systems, HD 30712 and HD 183255, using algorithms published by the authors of this research. Recently, new high-quality spectroscopic orbits have been obtained for these binaries by other authors. We determine their 3D orbits, individual masses, and orbital parallaxes, and present them in this paper. The parallaxes are compared with those available from the Gaia mission, and a comparison between the values confirms the precision of the results obtained here.

Magnetic field detections in Herbig Ae SB2 systems

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.

Orbital parameters and evolutionary status of the highly peculiar binary system HD 66051

Context. The spectroscopic binary system HD 66051 (V414 Pup) consists of a highly peculiar CP3 (HgMn) star and an A-type component. It also shows out-of-eclipse variability that is due to chemical spots. This combination allows the derivation of tight constraints for the testing of time-dependent diffusion models. Aims. We aim at deriving astrophysical parameters, information on age, and an orbital solution of the system. Methods. We analysed radial velocity and photometric data using two different methods to determine astrophysical parameters and the orbit of the system. Appropriate isochrones were used to derive the age of the system. Results. The orbital solution and the estimates from the isochrones are in excellent agreement with the estimates from a prior spectroscopic study. The system is very close to the zero-age main sequence and younger than 120 Myr. Conclusions. HD 66051 is a most important spectroscopic binary system that can be used to test the predictions of the diffusion theory explaining the peculiar surface abundances of CP3 stars.

Weak Magnetic Fields in Two Herbig Ae Systems: The SB2 AK Sco and the Presumed Binary HD 95881

Abstract We report the detection of weak mean longitudinal magnetic fields in the Herbig Ae double-lined spectroscopic binary AK Sco and in the presumed spectroscopic Herbig Ae binary HD 95881 using observations with the High Accuracy Radial velocity Planet Searcher polarimeter (HARPSpol) attached to the European Southern Observatory’s (ESO’s) 3.6 m telescope. Employing a multi-line singular value decomposition method, we detect a mean longitudinal magnetic field G in the secondary component of AK Sco on one occasion. For HD 95881, we measure G and G at two different observing epochs. For all the detections the false alarm probability is smaller than 10−5. For AK Sco system, we discover that accretion diagnostic Na i doublet lines and photospheric lines show intensity variations over the observing nights. The double-lined spectral appearance of HD 95881 is presented here for the first time.

The magnetic field of the double-lined spectroscopic binary system HD 5550

(Abridged) In the framework of the BinaMicS project, we have begun a study of the magnetic properties of a sample of intermediate-mass and massive short-period binary systems, as a function of binarity properties. We report in this paper the characterisation of the magnetic field of HD 5550, a double-lined spectroscopic binary system of intermediate-mass, using high-resolution spectropolarimetric Narval observations of HD 5550. We first fit the intensity spectra using Zeeman/ATLAS9 LTE synthetic spectra to estimate the effective temperatures, microturbulent velocities, and the abundances of some elements of both components, as well as the light-ratio of the system. We then fit the least-square deconvolved $I$ profiles to determine the radial and projected rotational velocities of both stars. We then analysed the shape and evolution of the LSD $V$ profiles using the oblique rotator model to characterise the magnetic fields of both stars. We confirm the Ap nature of the primary, previously reported in the literature, and find that the secondary displays spectral characteristics typical of an Am star. While a magnetic field is clearly detected in the lines of the primary, no magnetic field is detected in the secondary, in any of our observation. If a dipolar field were present at the surface of the Am star, its polar strength must be below 40 G. The faint variability observed in the Stokes $V$ profiles of the Ap star allowed us to propose a rotation period of $6.84_{-0.39}^{+0.61}$ d, close to the orbital period ($\sim$6.82 d), suggesting that the star is synchronised with its orbit. By fitting the variability of the $V$ profiles, we propose that the Ap component hosts a dipolar field inclined with the rotation axis at an angle $\beta=156\pm17$ $^{\circ}$ and a polar strength $B_{\rm d}=65 \pm 20$ G. The field strength is the weakest known for an Ap star.

Spectroscopic and photometric analysis of the early-type spectroscopic binary HD 161853 in the centre of an H ii region

We study the O-type star HD 161853, which has been noted as a probable double-lined spectroscopic binary system. We secured high-resolution spectra of HD 161853 during the past nine years. We separated the two components in the system and measured their respective radial velocities for the first time. We confirm that HD 161853 is an $\sim$1 Ma old binary system consisting of an O8 V star ($M_{\rm A,RV} \geq 22$ M$_\odot$) and a B1--3 V star ($M_{\rm B,RV} \geq 7.2$ M$_\odot$) at about 1.3 kpc. From the radial velocity curve, we measure an orbital period $P$ = 2.66765$\pm$0.00001 d and an eccentricity $e$ = 0.121$\pm$0.007. Its $V$-band light curve is constant within 0.014 mag and does not display eclipses, from which we impose a maximum orbital inclination $i=54$ deg. HD 161853 is probably associated with an H II region and a poorly investigated very young open cluster. In addition, we detect a compact emission region at 50 arcsec to HD 161853 in 22$\mu$m-WISE and 24$\mu$m-Spitzer images, which may be identified as a dust wave piled up by the radiation pressure of the massive binary system.

Tachoastrometry: astrometry with radial velocities

Spectra of composite systems (e.g., spectroscopic binaries) contain spatial information that can be retrieved by measuring the radial velocities (i.e., Doppler shifts) of the components in four observations with the slit rotated by 90 degrees in the sky. By using basic concepts of slit spectroscopy we show that the geometry of composite systems can be reliably retrieved by measuring only radial velocity differences taken with different slit angles. The spatial resolution is determined by the precision with which differential radial velocities can be measured. We use the UVES spectrograph at the VLT to observe the known spectroscopic binary star HD 188088 (HIP 97944), which has a maximum expected separation of 23 milli-arcseconds. We measure an astrometric signal in radial velocity of 276 \ms, which corresponds to a separation between the two components at the time of the observations of 18 $\pm2$ milli-arcseconds. The stars were aligned east-west. We describe a simple optical device to simultaneously record pairs of spectra rotated by 180 degrees, thus reducing systematic effects. We compute and provide the function expressing the shift of the centroid of a seeing-limited image in the presence of a narrow slit.The proposed technique is simple to use and our test shows that it is amenable for deriving astrometry with milli-arcsecond accuracy or better, beyond the diffraction limit of the telescope. The technique can be further improved by using simple devices to simultaneously record the spectra with 180 degrees angles.With tachoastrometry, radial velocities and astrometric positions can be measured simultaneously for many double line system binaries in an easy way. The method is not limited to binary stars, but can be applied to any astrophysical configuration in which spectral lines are generated by separate (non-rotational symmetric) regions.

HD 50975: a yellow supergiant in a spectroscopic binary system

Context. Recent detection of a yellow supergiant star as a possible progenitor of a supernova has posed serious questions about our understanding of the evolution of massive stars. Aims. The spectroscopic binary star HD 50975 with an unseen hot secondary was studied in detail with the main goal of estimating fundamental parameters of both components and the binary system. Methods. A comprehensive analysis and modeling of collected long-term radial velocity measurements, photometric data, and spectra was performed to calculate orbital elements, atmospheric parameters, abundances, and luminosities. The spectrum in an ultraviolet region was studied to clarify the nature of an unseen companion star. Results. The orbital period was found to be 190:22 0:01 days. The primary star (hereafter HD 50975A) is a yellow supergiant with an e ective temperature Te = 5900 150 K and a surface gravity of log(g) = 1:4 0:3 (cgs). The atmosphere of HD 50975 A is slightly metal deficient relative to solar, [Fe=H] = 0:26 0:06 dex. Abundances of Si and Ca are close to the scaled solar composition. The r-process element europium is enhanced, [Eu=H] = +0:61 0:07. The bolometric magnitude of the primary was estimated to be Mbol = 5:5 0:3 mag and its mass to be 10:7 2:0 M . The secondary (hereafter HD 50975B) is a hot star of spectral type B2 near ZAMS with an e ective temperature of Te ’ 21 000 K and a mass M’ 8:6 M . The distance between HD 50975A and B is about 370R : The binary star is near a semi-detached configuration with a radius, RA’ 107R , and a radius of Roche lobe of about 120R for the primary star.

New Radial Velocity Studies and Curve Analysis of Spectroscopic Binary Systems CS22964-161, LV Her, RW Lac and HD 34700

Using measured radial velocity data of four double-lined spectroscopic binary systems CS22964-161, LV Her, RW Lac and HD 34700, we find corresponding orbital and spectroscopic elements via a Probabilistic Neural Network (PNN). Our numerical results are in good agreement with those obtained by others using more traditional methods.

New Radial Velocity Studies and Curve Analysis of Spectroscopic Binary Systems CS22964-161, LV Her, RW Lac and HD 34700

Using measured radial velocity data of four double-lined spectroscopic binary systems CS22964-161, LV Her, RW Lac and HD 34700, we find corresponding orbital and spectroscopic elements via a Probabilistic Neural Network (PNN). Our numerical results are in good agreement with those obtained by others using more traditional methods.