- ID:
- ivo://CDS.VizieR/J/other/Sci/337.444
- Title:
- RV curves of Galactic massive O stars
- Short Name:
- J/other/Sci/337.
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The presence of a nearby companion alters the evolution of massive stars in binary systems, leading to phenomena such as stellar mergers, X-ray binaries and gamma-ray bursts. Unambiguous constraints on the fraction of massive stars affected by binary interaction were lacking. We simultaneously measured all relevant binary characteristics in a sample of Galactic massive O stars and quantified the frequency and nature of binary interactions. Over seventy per cent of all massive stars will exchange mass with a companion, leading to a binary merger in one third of the cases. These numbers greatly exceed previous estimates and imply that binary interaction dominates the evolution of massive stars, with implications for populations of massive stars and their supernovae.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/356/1583
- Title:
- RV of Sigma Ori low-mass candidate members
- Short Name:
- J/MNRAS/356/1583
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present radial velocities for 38 low-mass candidate members of the {sigma} Orionis young group. We have measured their radial velocities by cross-correlation of high-resolution (R>>6000) AF2/Wide Field Fibre Optical Spectrograph (WYFFOS) spectra of the gravity-sensitive NaI doublet at 8183,8195{AA}, on the nights of 2003 January 3 and 4. The total sample contained 117 objects, of which 54 have sufficient signal-to-noise ratio to detect NaI at an equivalent width of 3{AA}; however, we only detect NaI in 38 of these. This implies that very low-mass members of this young group display weaker NaI absorption than similarly aged objects in the Upper Scorpius OB association. We develop a technique to assess membership using radial velocities with a range of uncertainties that does not bias the selection when large uncertainties are present. The resulting membership probabilities are used to assess the issue of exclusion in photometric selections, and we find that very few members are likely to be excluded by such techniques. We also assess the level of contamination in the expected pre-main-sequence region of colour-magnitude space brighter than I=17. We find that contamination by non-members in the expected pre-main-sequence region of the colour-magnitude diagram is small. We conclude that although radial velocity alone is insufficient to confirm membership, high signal-to-noise ratio observations of the NaI doublet provide the opportunity to use the strength of NaI absorption in concert with radial velocities to asses membership down to the lowest masses, where lithium absorption no longer distinguishes youth.
- ID:
- ivo://CDS.VizieR/J/A+A/658/A69
- Title:
- RVs of B stars in NGC 6231
- Short Name:
- J/A+A/658/A69
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- It is well known that massive O stars are frequently (if not always) found in binary or higher-order multiple systems, but this fact has been less robustly investigated for the lower mass range of the massive stars, represented by B-type stars. Obtaining the binary fraction and orbital parameter distributions of B-type stars is crucial to understand the impact of multiplicity on the archetypal progenitor of core-collapse supernovae as well as to properly investigate formation channels for gravitational wave progenitors. This work aims to characterise the multiplicity of the B star population of the young open cluster NGC 6231 through multi-epoch optical spectroscopy of 80 B-type stars. We analyse 31 FLAMES/GIRAFFE observations of 80 B-type stars, monitoring their radial velocities (RVs) and performing a least-squares spectral analysis (Lomb-Scargle) to search for periodicity in those stars with statistically significant variability in their RVs. We constrained an observed spectroscopic binary fraction of 33+/-5% for the B-type stars of NGC 6231, with a first order bias correction giving a true spectroscopic binary fraction of 52+/-8%. Out of 27 B-type binary candidates, we obtained orbital solutions for 20 systems: 15 single-lined (SB1) and five double-lined spectroscopic binaries (SB2s). We present these orbital solutions and the orbital parameter distributions associated with them. Our results indicate that Galactic B-type stars are less frequently found in binary systems than their more massive O-type counterparts, but their orbital properties generally resemble those of B- and O-type stars in both the Galaxy and Large Magellanic Cloud.
- 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/V/132
- Title:
- SAI Open Clusters Catalog
- Short Name:
- V/132
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The automated search for star clusters of J,H,K_s data from the Two Micron All-Sky Survey (2MASS) was made using a new method based on the convolution with density functions (Koposov et al. 2008A&A...486..771K). In two papers (this one and Koposov et al. 2008A), 168 new clusters were found and verified in the range of galactic latitude |b|<24 degrees. The new method to estimate main physical parameters of clusters was developed, which involves three different techniques: Hess-diagram, color-magnitude diagrams in (J,J-H) and (K_s,J-K_s), and radial density distribution. Color excesses E(B-V), distance moduli and ages were determined for 141 new and 27 known, but poorly studied clusters. We present the Sternberg Astronomical Institute Open Clusters Catalog (SAI OCL Catalog) of coordinates, diameters and main physical parameters of these clusters. The parameters for 9 clusters were determined using J,H,K data from UKIDSS GPS. For 26 new embedded clusters, we publish the coordinates and diameters only. To facilitate the access to these data and its scientific analysis, we have developed a dedicated web-site of the catalog available at http://ocl.sai.msu.ru/
- ID:
- ivo://CDS.VizieR/J/A+A/464/581
- Title:
- Sco OB2 intermediate-mass stars
- Short Name:
- J/A+A/464/581
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present JHK observations of 22 intermediate-mass stars in Sco OB2, obtained with NACO. This survey was performed to determine the status of (sub)stellar candidate companions of Sco OB2 member stars of spectral type A and late-B. The distinction between companions and background stars is made on the basis of a comparison to isochrones and additional statistical arguments. We include in our sample a subset of 9 targets with multi-color ADONIS observations from Kouwenhoven et al. (2005, Cat. <J/A+A/430/137>). We reanalyse the total sample (i.e. NACO and ADONIS) and conclude that of the 176 secondaries, 25 are physical companions, 55 are candidate companions, and 96 are background stars. Although we are sensitive (and complete) to brown dwarf companions as faint as K=14mag in the semi-major axis range 130-520AU, we detect only one, corresponding to a brown dwarf companion fraction of 0.5% (M>30M_Jupiter_). However, the number of brown dwarfs is consistent with an extrapolation of the (stellar) companion mass distribution into the brown dwarf regime. This indicates that the physical mechanism for the formation of brown dwarf companions around intermediate mass stars is similar to that of stellar companions, and that the embryo ejection mechanism does not need to be invoked in order to explain the small number of brown dwarf companions among intermediate mass stars in Sco OB2.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2050
- Title:
- SEGUE stellar parameter pipeline. II.
- Short Name:
- J/AJ/136/2050
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We validate the accuracy and precision of the current SEGUE (Sloan Extension for Galactic Understanding and Exploration) Stellar Parameter Pipeline (SSPP), which determines stellar atmospheric parameters (effective temperature, surface gravity, and metallicity) and radial velocities (RVs), by comparing these estimates for selected members of three globular clusters (M 13, M 15, and M 2) and two open clusters (NGC 2420 and M 67) to the literature values. Spectroscopic and photometric data obtained during the course of the original Sloan Digital Sky Survey (SDSS-I) and its first extension (SDSS-II/SEGUE) are used to determine atmospheric parameter and RV estimates for stars in these clusters.
- ID:
- ivo://CDS.VizieR/J/AJ/136/2070
- Title:
- SEGUE stellar parameter pipeline. III.
- Short Name:
- J/AJ/136/2070
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report high-resolution spectroscopy of 125 field stars previously observed as part of the Sloan Digital Sky Survey and its program for Galactic studies, the Sloan Extension for Galactic Understanding and Exploration (SEGUE). These spectra are used to measure radial velocities and to derive atmospheric parameters, which we compare with those reported by the SEGUE Stellar Parameter Pipeline (SSPP). The SSPP obtains estimates of these quantities based on SDSS ugriz photometry and low-resolution (R~2000) spectroscopy.
- ID:
- ivo://CDS.VizieR/J/AJ/141/89
- Title:
- SEGUE stellar parameter pipeline. IV.
- Short Name:
- J/AJ/141/89
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Spectroscopic and photometric data for likely member stars of five Galactic globular clusters (M3, M53, M71, M92, and NGC 5053) and three open clusters (M35, NGC 2158, and NGC 6791) are processed by the current version of the SEGUE Stellar Parameter Pipeline (SSPP), in order to determine estimates of metallicities and radial velocities (RVs) for the clusters. These results are then compared to values from the literature.
