- ID:
- ivo://CDS.VizieR/J/A+A/610/A17
- Title:
- RV of candidate hybrid variable stars
- Short Name:
- J/A+A/610/A17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Hundreds of candidate hybrid pulsators of intermediate type A-F were revealed by recent space missions. Hybrid pulsators allow us to study the full stellar interiors, where both low-order p- and high-order g-modes are simultaneously excited. The true hybrid stars must be identified since other processes, related to stellar multiplicity or rotation, might explain the presence of (some) low frequencies observed in their periodograms. We measured the radial velocities of 50 candidate delta Scuti - gamma Doradus hybrid stars from the Kepler mission with the Hermes and Ace spectrographs over a time span of months to years. We aim to derive the fraction of binary and multiple systems and to provide an independent and homogeneous determination of the atmospheric properties and v.sini for all targets. The long(er)-term objective is to identify the (probable) physical cause of the low frequencies. We computed one-dimensional cross-correlation functions (CCFs) in order to find the best set of parameters in terms of number of components, spectral type(s), and v.sini for each target. Fundamental parameters were determined by fitting (composite) synthetic spectra to the normalised median spectra corrected for the appropriate Doppler shifts. We report on the analysis of 478 high-resolution Hermes and 41 Ace spectra of A/F-type candidate hybrid pulsators from the Kepler field. We determined their radial velocities, projected rotational velocities, and atmospheric properties and classified our targets based on the shape of the CCFs and the temporal behaviour of the radial velocities. We derived orbital solutions for seven new systems. Three preliminary long-period orbital solutions are confirmed by a photometric time-delay analysis. Finally, we determined a global multiplicity fraction of 27 percent in our sample of candidate hybrid stars.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AN/341/99
- Title:
- RV of 11 spectroscopic binaries
- Short Name:
- J/AN/341/99
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results of our second radial velocity (RV) monitoring campaign, carried out with the Echelle spectrograph FLECHAS at the University Observatory Jena in the course of the Grosschwabhausen binary survey between December 2016 and June 2018. The aim of this project is to obtain precise RV measurements for spectroscopic binary stars in order to redetermine, verify, improve, and constrain their Keplerian orbital solutions. In this paper, we describe the observations, data reduction, and analysis and present the results of this project. In total, we have taken 721 RV measurements of 11 stars and derived well-determined orbital solutions for nine systems (seven single- and two double-lined spectroscopic binaries) with periods in the range between 2 and 70 days. In addition, we could rule out the orbital solutions for the previously classified spectroscopic binary systems HIP 107136 and HIP 107533, whose radial velocities are found to be constant on the km/s-level over a span of time of more than 500 days. In the case of HIP 2225, a significant change of its systematic velocity is detected between our individual observing epochs, indicating the presence of an additional companion, which is located on a wider orbit in this system.
- ID:
- ivo://CDS.VizieR/J/AJ/157/136
- Title:
- RVs of RGs with suspected massive companions
- Short Name:
- J/AJ/157/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Motivated by the existence of binary systems where a stellar-mass black hole is bound to a normal star, we selected four red giants with large radial velocity (RV) variation from the survey of Space Interferometry Mission (SIM) grid stars and monitored their RVs for several months. None turned out to contain a massive companion above 2.5 solar masses. The red giant TYC 9299-1080-1 with a large RV and a large proper motion is a single-lined spectroscopic binary with a period of 81 days. It is an extreme halo object moving at 350 km/s almost directly toward the Galactic center. HD 206092 is a double-lined binary with a short period of 4.37 days. It belongs to the rare class of active RS CVn-type binaries with evolved primary components, apparently undergoing mass transfer. The X-ray luminosity of HD 206092 is about twice as high as the most luminous coronal X-ray emitters observed by ROSAT, including II Peg and the prototype star RS CVn. HD 318347 has a variable double-peaked emission-line spectrum (not a giant), while HD 324668 has a constant RV. Despite the overall good quality of the SIM survey data confirmed by a comparison with Gaia Data Release 2 (DR2, Cat. I/345) mean RVs, the few large RV variations are explained, mostly, by erroneous data. We discuss the significance of the non-detection of massive companions in the SIM grid sample and the associated work.
- ID:
- ivo://CDS.VizieR/J/AJ/159/290
- Title:
- RVs of 12 spectroscopic binaries M-dwarfs
- Short Name:
- J/AJ/159/290
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the spectroscopic orbits of 11 nearby, mid-to-late M dwarf binary systems in a variety of configurations: 2 single-lined binaries (SB1s), 7 double-lined binaries (SB2s), 1 double-lined triple (ST2), and 1 triple-lined triple (ST3). Eight of these orbits are the first published for these systems, while five are newly identified multiples. We obtained multi-epoch, high-resolution spectra with the TRES instrument on the 1.5m Tillinghast Reflector at the Fred Lawrence Whipple Observatory located on Mt. Hopkins in AZ. Using the TiO molecular bands at 7065-7165{AA}, we calculated radial velocities for these systems, from which we derived their orbits. We find LHS 1817 to have in a 7hr period a companion that is likely a white dwarf, due to the ellipsoidal modulation we see in our MEarth-North light-curve data. We find G123-45 and LTT11586 to host companions with minimum masses of 41MJup and 44MJup with orbital periods of 35 and 15days, respectively. We find 2MA0930+0227 to have a rapidly rotating stellar companion in a 917 day orbital period. GJ268, GJ1029, LP734-34, GJ1182, G258-17, and LTT7077are SB2s with stellar companions with orbital periods of 10, 96, 34, 154, 5, and 84days; LP655-43 is an ST3 with one companion in an 18day orbital period and an outer component in a longer undetermined period. In addition, we present radial velocities for both components of L870-44AB and for the outer components of LTT11586 and LP655-43.
- ID:
- ivo://CDS.VizieR/J/ApJ/811/85
- Title:
- RVs & V-band LCs of probable members of Cyg OB2
- Short Name:
- J/ApJ/811/85
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Cygnus OB2 Association is one of the nearest and largest collections of massive stars in the Galaxy. Situated at the heart of the "Cygnus X" complex of star-forming regions and molecular clouds, its distance has proven elusive owing to the ambiguous nature of kinematic distances along this l~=80{deg} sightline and the heavy, patchy extinction. In an effort to refine the three-dimensional geometry of key Cygnus X constituents, we have measured distances to four eclipsing double-lined OB-type spectroscopic binaries that are probable members of Cyg OB2. We find distances of 1.33+/-0.17, 1.32+/-0.07, 1.44+/-0.18, and 1.32+/-0.13kpc toward MT91 372, MT91 696, CPR2002 A36, and Schulte 3, respectively. We adopt a weighted average distance of 1.33+/-0.06kpc. This agrees well with spectrophotometric estimates for the Association as a whole and with parallax measurements of protostellar masers in the surrounding interstellar clouds, thereby linking the ongoing star formation in these clouds with Cyg OB2. We also identify Schulte 3C (O9.5V), a 4" visual companion to the 4.75 day binary Schulte 3(A+B), as a previously unrecognized Association member.
- ID:
- ivo://CDS.VizieR/J/MNRAS/475/1609
- Title:
- RV variability in NGC 2516 and NGC 2422
- Short Name:
- J/MNRAS/475/1609
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present multi-epoch, high-dispersion, optical spectra obtained with the Michigan/Magellan Fiber System of 126 and 125 Sun-like stars in the young clusters NGC 2516 (141Myr) and NGC 2422 (73Myr). We determine stellar properties including radial velocity (RV), Teff, [Fe/H], [{alpha}/Fe], and the line-of-sight rotation rate, v_r_sin(i), from these spectra. Our median RV precision of 80m/s on individual epochs that span a temporal baseline of 1.1yr enables us to investigate membership, stellar binarity, and search for sub-stellar companions. We determine membership probabilities and RV variability probabilities for our sample along with candidate companion orbital periods for a select subset of stars. We identify 81 RV members in NGC 2516, 27 spectroscopic binaries (17 previously identified as photometric binaries), and 16 other stars that show significant RV variability after accounting for average stellar jitter found to be at the 74m/s level. In NGC 2422 we identify 57 members, 11 spectroscopic binaries, and 3 other stars that show significant RV variability after accounting for an average jitter of 138m/s. We use Monte Carlo simulations to verify our stellar jitter measurements, determine the proportion of exoplanets and stellar companions to which we are sensitive, and estimate companion mass limits for our targets. We also report mean cluster metallicity, velocity, and velocity dispersion based on our member targets and identify 58 non-member stars as RV variables - 24 of which have RV amplitudes that imply stellar or brown-dwarf mass companions. Finally, we note the discovery of a separate RV clustering of stars in our NGC 2422 sample.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A26
- Title:
- SACY. V. Multiple systems
- Short Name:
- J/A+A/568/A26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dynamically undisrupted, young populations of stars are crucial in studying the role of multiplicity in relation to star formation. Loose nearby associations provide us with a great sample of close (<150pc) pre-main sequence (PMS) stars across the very important age range (~5-70Myr) to conduct such research. We characterize the short period multiplicity fraction of the search for associations containing young stars (SACY) sample, accounting for any identifiable bias in our techniques and present the role of multiplicity fractions of the SACY sample in the context of star formation. Using the cross-correlation technique we identified double-lined and triple-lined spectroscopic systems (SB2/SB3s), in addition to this we computed radial velocity (RV) values for our subsample of SACY targets using several epochs of fiber-fed extended range optical spectrograph (FEROS) and ultraviolet and visual echelle spectrograph (UVES) data. These values were used to revise the membership of each association that was then combined with archival data to determine significant RV variations across different data epochs characteristic of multiplicity; single-lined multiple systems (SB1). Results: We identified seven new multiple systems (SB1s: 5, SB2s: 2). We find no significant difference between the short period multiplicity fraction (F_m_) of the SACY sample and that of close star-forming regions (~-2Myr) and the field (F_m_<=10%). These are seen both as a function of age and as a function of primary mass, M_1_, in the ranges P [1:200day] and M_2_ [0.08M_{sun}_-M_1_], respectively. Our results are consistent with the picture of universal star formation, when compared to the field and close star-forming regions (SFRs). We comment on the implications of the relationship between increasing multiplicity fraction with the primary mass within the close companion range in relation to star formation.
- ID:
- ivo://CDS.VizieR/J/AJ/158/155
- Title:
- SB candidates from the RAVE & Gaia DR2 surveys
- Short Name:
- J/AJ/158/155
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The combination of the final version of the Radial Velocity Experiment (RAVE) spectroscopic survey data release 6 with radial velocities (RVs) and astrometry from Gaia DR2 (Cat. I/345) allows us to identify and create a catalog of single-lined binary star candidates (SB1), their inferred orbital parameters, and to inspect possible double-lined binary stars (SB2). A probability function for the detection of RV variations is used for identifying SB1 candidates. The estimation of orbital parameters for main-sequence dwarfs is performed by matching the measured RVs with theoretical velocity curves sampling the orbital parameter space. The method is verified by studying a mock sample from the SB 9 catalog (Cat. B/sb9). Studying the boxiness and asymmetry of the spectral lines allows us to identify possible SB2 candidates, while matching their spectra to a synthetic library indicates probable properties of their components. From the RAVE catalog we select 37664 stars with multiple RV measurements and identify 3838 stars as SB1 candidates. Joining RAVE and Gaia DR2 yields 450646 stars with RVs measured by both surveys and 27716 of them turn out to be SB1 candidates, which is an increase by an order of magnitude over previous studies. For main-sequence dwarf candidates we calculate their most probable orbital parameters: orbital periods are not longer than a few years and primary components have masses similar to the solar mass. All our results are available in the electronic version.
- ID:
- ivo://CDS.VizieR/B/sb9
- Title:
- SB9: 9th Catalogue of Spectroscopic Binary Orbits
- Short Name:
- B/sb9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Ninth Catalogue of Spectroscopic Binary Orbits continues the series of compilations of spectroscopic orbits carried out over the past 35 years by Batten and collaborators (see e.g. Cat. V/64). The catalogue is continuously updated, see http://sb9.astro.ulb.ac.be/ This version is dated 02-May-2011. Previous versions may be found in subdirectories "v00" (April 2005), "v01" (September 2005), etc...
- ID:
- ivo://CDS.VizieR/J/A+A/645/A30
- Title:
- SB updated census in SACY sample
- Short Name:
- J/A+A/645/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Nearby young associations offer one of the best opportunities for a detailed study of the properties of young stellar and substellar objects thanks to their proximity (<200pc) and age (~5-150Myr). Previous works have identified spectroscopic (<5au) binaries, close (5-1000au) visual binaries, and wide or extremely wide (1000-100000au) binaries in the young associations. Inmost of the previous analyses, single-lined spectroscopic binaries (SB1) were identified based on radial velocities variations. However, this apparent variation may also be caused by mechanisms unrelated to multiplicity. We seek to update the spectroscopy binary fraction of the Search for Associations Containing Young stars (SACY) sample, taking into consideration all possible biases in our identification of binary candidates, such as activity and rotation. Using high-resolution spectroscopic observations, we produced ~1300 cross-correlation functions (CCFs) to disentangle the previously mentioned sources of contamination. The radial velocity values we obtained were cross-matched with the literature and then used to revise and update the spectroscopic binary (SB) fraction in each object of the SACY association. In order to better describe the CCF profile, we calculated a set of high-order cross-correlation features to determine the origin of the variations in radial velocities. We identified 68 SB candidates from our sample of 410 objects. Our results hint that at the possibility that the youngest associations have a higher SB fraction. Specifically, we found sensitivity-corrected SB fractions of 22^+15^_-11_% for {epsilon} Cha, 31^+16^_-14_% for TW Hya and 32^+9^_-8_% for {beta} Pictoris, in contrast to the five oldest associations we have sampled (~35-125Myr) which are ~10% or lower. This result seems independent of the methodology used to asses membership to the associations. The new CCF analysis, radial velocity estimates, and SB candidates are particularly relevant for membership revision of targets in young stellar associations. These targets would be ideal candidates for follow-up campaigns using high-resolution techniques to confirm binarity, resolve orbits, and, ideally, calculate dynamical masses. Additionally, if the results on the SB fraction in the youngest associations were confirmed, it could hint at a non-universal multiplicity among SACY associations.
