- ID:
- ivo://CDS.VizieR/J/MNRAS/510/1515
- Title:
- Double-lined spectroscopic binaries in M11
- Short Name:
- J/MNRAS/510/1515
- Date:
- 10 Jan 2022 09:23:04
- Publisher:
- CDS
- Description:
- We have developed a new method for spectral analysis of binaries. Our method successfully identifiesSB2 candidates from high-resolution Gaia-ESO spectra. Compared to the commonly used cross-correlation function analysis, it works for binaries with rapidly rotating components. We test our method on synthetic and observational spectra of BAFG-stars with vsin(i) from 1 to 330km/s in the open cluster M11. We confirm five previously detected SB2 candidates and find 19 new ones. For three SB2 candidates we find circular orbits and obtain dynamical mass ratios.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/158/82
- Title:
- DS Andromedae radial velocity & photometric data
- Short Name:
- J/AJ/158/82
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Wilson-Devinney program has been used to analyze well-calibrated photometric and new radial velocity data to determine the properties and distance of DS Andromedae, a 1.01 day period, double-lined, totally eclipsing binary system of early-F spectral type and a likely member of the intermediate-age open cluster NGC 752. The determinations of many of the system elements including the distance are robust against modest changes in model assumptions. Third light is present in all passbands at the 10% level. The weighted means of the best-fitting model yield a distance of 477+/-4+/-12 pc, equivalent to (m-M)_0_=8.390+/-0.018+/-0.060 mag, and masses of 1.655+/-0.003+/-0.030 M_Sun_ and 1.087+/-0.005+/-0.040 M_Sun_, radii of 2.086+/-0.003+/-0.013 and 1.255+/-0.005+/-0.012 R_Sun_, and effective temperatures 7056+/-21+/-140 R_Sun_ and 5971+/-33+/-130 K, for components 1 and 2, respectively, where the formal internal uncertainties are followed by conservatively estimated systematic errors. Possible but less satisfactory semidetached models produce more parameter variations and larger mean residuals. The primary star is seen to be at or very close to the main-sequence turnoff at an age of 1.55+/-0.05 Gyr but appears to be too small for its mass, whereas the secondary appears to be too luminous for its temperature and too large for its mass compared to models of single stars.
- ID:
- ivo://CDS.VizieR/J/AZh/89/674
- Title:
- Dynamical parameters of open clusters
- Short Name:
- J/AZh/89/674
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Presented are the estimates of open cluster dynamical parameters: the cluster core density contrast, the stellar velocity dispersions allowing for influence of Galaxy external field and non-stationarity of the cluster, the oscillation periods of the cluster and the cluster core, the amplitudes of oscillations of a cluster virial factor and a radius of the cluster core. All the values were analytically received as a result solution of the gross dynamical equations for spherical and ellipsoidal cluster models.
- ID:
- ivo://CDS.VizieR/J/A+A/627/A97
- Title:
- Early disc dispersal in close binaries
- Short Name:
- J/A+A/627/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Young (<600Myr) low-mass stars (M<~1M_{sun}_) of equal mass exhibit a distribution of rotation periods. At the very early phases of stellar evolution, this distribution is set by the star-disc locking mechanism, which forces stars to rotate at the same rate as the inner edge of the disc. The primordial disc lifetime and consequently the duration of the disc-locking mechanism, can be significantly shortened by the presence of a close companion, making the rotation period distribution of close binaries different from that of either single stars or wide binaries. We use new data to investigate and better constrain the range of ages, the components separation, and the mass ratio dependence at which the rotation period distribution has been significantly affected by the disc dispersal that is enhanced by close companions. We select a sample of close binaries in the Upper Scorpius association (age~8Myr) whose components have measured the separation and the rotation periods and compare their period distribution with that of coeval stars that are single stars. We find that components of close binaries have, on average, rotation periods that are shorter than those of single stars. More precisely, binaries with approximately equal-mass components (0.9<=M2/M1<=1.0) have rotation periods that are shorter than those of single stars by ~0.4d on average; the primary and secondary components of binaries with smaller mass ratios (0.8<M2/M1<0.9) have rotation periods that are shorter than those of single stars by ~1.9d and ~1.0d on average, respectively. A comparison with the older 25-Myr {beta} Pictoris association shows that whereas in the latter, all close binaries with projected separation {rho}<=80AU rotate faster than single stars, in the Upper Scorpius this is only the case for about 70% of stars. We interpret the enhanced rotation in close binaries with respect to single stars as the consequence of an early disc dispersal induced by the presence of close companions. The enhanced rotation suggests that disc dispersal timescales are longest for single stars and shorter for close binaries.
- ID:
- ivo://CDS.VizieR/J/ApJ/899/121
- Title:
- 127 early type and pre-main-sequence stars in W4
- Short Name:
- J/ApJ/899/121
- Date:
- 15 Mar 2022 03:47:36
- Publisher:
- CDS
- Description:
- Stellar kinematics provides the key to understanding the formation process and dynamical evolution of stellar systems. Here, we present a kinematic study of the massive star-forming region (SFR) W4 in the Cassiopeia OB6 association using the Gaia Data Release 2 and high-resolution optical spectra. This SFR is composed of a core cluster (IC1805) and a stellar population distributed over 20pc, which is a typical structural feature found in many OB associations. According to a classical model, this structural feature can be understood in the context of the dynamical evolution of a star cluster. The core-extended structure exhibits internally different kinematic properties. Stars in the core have an almost isotropic motion, and they appear to reach virial equilibrium given their velocity dispersion (0.9{+/-}0.3km/s) comparable to that in a virial state (~0.8km/s). On the other hand, the distributed population shows a clear pattern of radial expansion. From the N-body simulation for the dynamical evolution of a model cluster in subvirial state, we reproduce the observed structure and kinematics of stars. This model cluster experiences collapse for the first 2Myr. Some members begin to radially escape from the cluster after the initial collapse, eventually forming a distributed population. The internal structure and kinematics of the model cluster appear similar to those of W4. Our results support the idea that the stellar population distributed over 20pc in W4 originate from the dynamical evolution of IC1805.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2220
- Title:
- Early-type Sco-Cen members with literature RVs
- Short Name:
- J/MNRAS/453/2220
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the serendipitous discovery of several young mid-M stars found during a search for new members of the 30-40Myr-old Octans Association. Only one of the stars may be considered a possible Octans(-Near) member. However, two stars have proper motions, kinematic distances, radial velocities, photometry and LII {lambda}6708 measurements consistent with membership in the 8-10Myr-old TW Hydrae Association. Another may be an outlying member of TW Hydrae but has a velocity similar to that predicted by membership in Octans. We also identify two new lithium-rich members of the neighbouring Scorpius-Centaurus OB Association (Sco-Cen). Both exhibit large 12 and 22{mu}m excesses and strong, variable H{alpha} emission which we attribute to accretion from circumstellar discs. Such stars are thought to be incredibly rare at the ~16Myr median age of Sco-Cen and they join only one other confirmed M-type and three higher mass accretors outside of Upper Scorpius. The serendipitous discovery of two accreting stars hosting large quantities of circumstellar material may be indicative of a sizeable age spread in Sco-Cen, or further evidence that disc dispersal and planet formation time-scales are longer around lower mass stars. To aid future studies of Sco-Cen, we also provide a newly compiled catalogue of 305 early-type Hipparcos members with spectroscopic radial velocities sourced from the literature.
- ID:
- ivo://CDS.VizieR/J/MNRAS/451/4346
- Title:
- Early-type stars in SMC and LMC
- Short Name:
- J/MNRAS/451/4346
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We employ CaII K and NaI D interstellar absorption-line spectroscopy of early-type stars in the Large and Small Magellanic Clouds (LMC, SMC) to investigate the large- and small-scale structure in foreground intermediate- and high-velocity clouds (I/HVCs). Data include FLAMES-GIRAFFE CaII K observations of 403 stars in four open clusters, plus FEROS or UVES spectra of 156 stars in the LMC and SMC. The FLAMES observations are amongst the most extensive probes to date of CaII structures on ~20-arcsec scales in Magellanic I/HVCs. From the FLAMES data within a 0.5{deg} field of view, the CaII K equivalent width in the I/HVC components towards three clusters varies by factors of >=10. There are no detections of molecular gas in absorption at intermediate or high velocities, although molecular absorption is present at LMC and Galactic velocities towards some sightlines. The FEROS/UVES data show CaII K I/HVC absorption in ~60 per cent of sightlines. The range in the CaII/NaI ratio in I/HVCs is from -0.45 to +1.5dex, similar to previous measurements for I/HVCs. In 10 sightlines we find CaII/Oi ratios in I/HVC gas ranging from 0.2 to 1.5dex below the solar value, indicating either dust or ionization effects. In nine sightlines I/HVC gas is detected in both Hi and CaII at similar velocities, implying that the two elements form part of the same structure.
- ID:
- ivo://CDS.VizieR/J/ApJ/887/109
- Title:
- EBs in Ruprecht 147. II. EPIC 219568666 LC & RVs
- Short Name:
- J/ApJ/887/109
- Date:
- 30 Nov 2021
- Publisher:
- CDS
- Description:
- We report our spectroscopic monitoring of the detached, grazing, and slightly eccentric 12 day double-lined eclipsing binary EPIC 219568666 in the old nearby open cluster Ruprecht 147. This is the second eclipsing system to be analyzed in this cluster, following our earlier study of EPIC 219394517. Our analysis of the radial velocities combined with the light curve from the K2 mission yields absolute masses and radii for EPIC 219568666 of M_1_=1.121+/-0.013M_{sun}_ and R_1_=1.1779+/-0.0070R_{sun}_ for the F8 primary and M_2_=0.7334+/-0.0050M_{sun}_ and R_2_=0.640+/-0.017R_{sun}_ for the faint secondary. Comparison with current stellar evolution models calculated for the known metallicity of the cluster points to a primary star that is oversized, as is often seen in active M dwarfs, but this seems rather unlikely for a star of its mass and with a low level of activity. Instead, we suspect a subtle bias in the radius ratio inferred from the photometry, despite our best efforts to avoid it, which may be related to the presence of spots on one or both stars. The radius sum for the binary, which bypasses this possible problem, indicates an age of 2.76+/-0.61Gyr, which is in good agreement with a similar estimate from the binary in our earlier study.
- ID:
- ivo://CDS.VizieR/J/A+A/525/A2
- Title:
- Eclipsing binaries in NGC6791
- Short Name:
- J/A+A/525/A2
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present photometric and spectroscopic observations of eclipsing binaries and single stars, which are members of the open cluster NGC6791. These were used to measure precise and accurate masses, radii and metallicity of the stars along with reddening and distance modulus to the cluster.
- ID:
- ivo://CDS.VizieR/J/ApJ/325/798
- Title:
- Einstein survey of stars in the Hyades
- Short Name:
- J/ApJ/325/798
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The paper reports the results of an extensive X-ray study of the Hyades region and improves on previous studies by using refined X-ray source detection algorithms and the complete set of Einstein Observatory IPC exposures covering the Hyades cluster region (a total of 63 1 x 1 deg images). Maximum likelihood integral X-ray luminosity functions were computed for the Hyades stars for given color index (B-V) ranges. The present results agree substantially with a previous survey about the ubiquity of the stellar activity in the Hyades cluster, especially among solar-type stars. The result of Stern et al. (1981ApJ...249..647S) that stellar X-ray emission is dependent on stellar age is confirmed.
