- ID:
- ivo://CDS.VizieR/J/MNRAS/386/1625
- Title:
- Velocities and photometry in NGC 2112
- Short Name:
- J/MNRAS/386/1625
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on a new, wide-field (20x20arcmin^2^), multicolour (UBVI), photometric campaign in the area of the nearby old open cluster NGC 2112. At the same time, we provide medium-resolution spectroscopy of 35 (and high-resolution of additional 5) red giant and turn-off stars. This material is analysed with the aim to update the fundamental parameters of this traditionally difficult cluster, which is very sparse and suffers from heavy field star contamination. Among the 40 stars with spectra, we identified 21 bona fide radial velocity members which allow us to put more solid constraints on the cluster's metal abundance, long suggested to be as low as the metallicity of globulars. As indicated earlier by us on a purely photometric basis, the cluster [Fe/H] abundance is slightly supersolar ([Fe/H]=0.16+/-0.03) and close to the Hyades value, as inferred from a detailed abundance analysis of three of the five stars with higher resolution spectra. Abundance ratios are also marginally supersolar. Based on this result, we revise the properties of NGC 2112 using stellar models from the Padova and Yale-Yonsei groups.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/561/A94
- Title:
- Velocities and photometry in Trumpler 20
- Short Name:
- J/A+A/561/A94
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Trumpler 20 is an old open cluster (OC) located toward the Galactic centre, at about 3kpc from the Sun and ~7kpc from the Galactic centre. Its position makes this cluster particularly interesting in the framework of the chemical properties of the Galactic disc because very few old OCs reside in the inner part of the disc. For this reason it has been selected as a cluster target of the Gaia-ESO Survey, and spectra of many stars in the main sequence and red clump phases are now available. Moreover, although it has been studied by several authors in the past, no consensus on the evolutionary status of Tr 20 has been reached. The heavy contamination of field stars (the line of sight of Tr 20 crosses the Carina spiral arm) complicates the correct interpretation. Another interesting aspect of the cluster is that it shows a broadened main sequence turn-off and a prominent and extended red clump, characteristics that are not easily explained by classical evolutionary models. Exploiting both spectroscopic information from the Gaia-ESO Survey (and the ESO archive) and literature photometry, we obtain a detailed and accurate analysis of the properties of the cluster. We make use of the first accurate metallicity measurement ever obtained from several spectra of red clump stars, and of cluster membership determination using radial velocities. According to the evolutionary models adopted, we find that Tr 20 has an age in the range 1.35-1.66Gyr, an average reddening E(B-V) in the range 0.31-0.35mag, a distance modulus (m-M)_0_ between 12.64 and 12.72mag. The spectroscopic metallicity is [Fe/H]=+0.17dex. We discuss the structural properties of the object and constrain possible hypotheses for its broadened upper main sequence, by estimating the effect of differential reddening, and its extended red clump.
- ID:
- ivo://CDS.VizieR/J/A+A/485/95
- Title:
- Velocities of F-G-K stars in Blanco 1
- Short Name:
- J/A+A/485/95
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nearby open cluster Blanco 1 is of considerable astrophysical interest for formation and evolution studies of open clusters because it is the third highest Galactic latitude cluster known. It has been observed often, but so far no definitive and comprehensive membership determination is readily available. An observing programme was carried out to study the stellar population of Blanco 1, and especially the membership and binary frequency of the F5-K0 dwarfs. We obtained radial-velocities with the CORAVEL spectrograph in the field of Blanco 1 for a sample of 148 F-G-K candidate stars in the magnitude range 10<V<14. New proper motions and UBVI CCD photometric data from two extensive surveys were obtained independently and are used to establish reliable cluster membership assignments in concert with radial-velocity data. The membership of 68 stars is confirmed on the basis of proper motion, radial velocity, and photometric criteria. Fourteen spectroscopic- and suspected binaries (2 SB2s, 9 SB1s, 3SB?) have been discovered among the confirmed members. Thirteen additional stars are located above the main sequence or close to the binary ridge, with radial velocities and proper motions supporting their membership. These are probable binaries with wide separations. Nine binaries (7 SB1 and 2 SB2) were detected among the field stars. The spectroscopic binary frequency among members is 20% (14/68); however, the overall binary rate reaches 40% (27/68) if one includes the photometric binaries. The cluster mean heliocentric radial velocity is +5.53+/-0.11km/s based on the most reliable 49 members. The Vsini distribution is similar to that of the Pleiades, confirming the age similarities between the two clusters.
- ID:
- ivo://CDS.VizieR/J/A+A/498/949
- Title:
- Velocities of 1253 F-K dwarfs in open clusters
- Short Name:
- J/A+A/498/949
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A long-term monitoring of solar-type dwarfs in 13 nearby open clusters, d<500pc, was conducted during 19 years, but most individual radial velocities were not published, with the exception of a small number of spectroscopic binaries. The program was designed to study the membership, the duplicity, and to search for new members. We obtained 6070 radial velocities during 19 years at the Haute-Provence Observatory (France) and 1130 during 13 years at ESO La Silla (Chile) for 1253 stars in the field of 13 open clusters. The zero point of the CORAVEL radial velocity system has been improved and the new values supersede those published previously. The membership and binarity of solar-type stars in NGC 1976 (Orion), IC 2602, NGC 7092, and NGC 2682 are briefly discussed. For the whole sample, we confirm the membership of 894 stars and discovered 150 new spectroscopic binaries among them. Added to those already known in the Hyades and Coma Berenices, the number of member spectroscopic binaries amounts to 188. The overall binary frequency is 30% (188/618) for stars with at least 2 measurements. IC 2602 may represent an exception because no spectroscopic binaries were found among the 26 members. New orbital elements were computed with the updated values of the radial velocities for 66 systems, representing 55 members and 11 non-members. This paper is the last one from our team reporting CORAVEL radial velocities of solar-type dwarfs in nearby open clusters. All CORAVEL observations for dwarfs and red giants in open clusters are now available in electronic form.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A127
- Title:
- Velocities of M67 main-sequence and giant stars
- Short Name:
- J/A+A/526/A127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Precise analyses of stellar radial velocities is able to reveal intrinsic causes of the wavelength shifts of spectral lines (other than Doppler shifts due to radial motion), such as gravitational redshifts and convective blueshifts. Aims. Gravitational redshifts in solar-type main-sequence stars are expected to be some 500m/s greater than those in giants. We search for this difference in redshifts among groups of open-cluster stars that share the same average space motion and thus have the same average Doppler shift.
- ID:
- ivo://CDS.VizieR/J/A+A/339/423
- Title:
- Velocities of red giants in NGC 752
- Short Name:
- J/A+A/339/423
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The results of an 18-year radial-velocity survey of 30 red giants in the field of the open cluster NGC 752 are presented. The membership of 15 stars is confirmed. Four spectroscopic binaries have been discovered among the members and three orbits have been determined for H75, 110 and 208, with periods of 3321, 127 and 5276 days respectively. The binary frequency (27%) is normal. A search for additional members in a wide surrounding area (2{deg}) yielded two possible new members: both are clump red giant candidates. The red giant distribution in the colour-magnitude diagram is somewhat unusual, with a clump containing 8 stars and a second, fainter feature extending to the blue, defined by 3 or 4 stars, which is not accounted for by theoretical isochrones.
- ID:
- ivo://CDS.VizieR/J/A+A/307/80
- Title:
- Velocities of red giants in NGC 2099
- Short Name:
- J/A+A/307/80
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 474 radial-velocity observations and new UBV photoelectric data for 55 and 20 red giants respectively, in the field of the intermediate-age open cluster NGC 2099 are presented and analysed for membership and duplicity. The membership of 35 red giants has been confirmed, 16 spectroscopic binaries have been discovered and 11 orbits have been determined. The cluster binary-frequency lower limit is slightly above the average (9/35=26%). The radial distribution of the red giants shows a sharp limit between members and non-members. No mass segregation is observed between the binary and single red giants. The latest isochrones from the Geneva and Padova groups reproduce very well the observed morphology in the colour-magnitude diagram for log t=8.65 and z=0.02, with (m-M)=11.50 and E(B-V)=0.29.
- ID:
- ivo://CDS.VizieR/J/ApJ/676/1109
- Title:
- Velocities of stars in the Orion Nebula Cluster
- Short Name:
- J/ApJ/676/1109
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present results from 1351 high-resolution spectra of 1215 stars in the Orion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtained with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We confirmed 1111 stars as members, based on their radial velocity and/or H{alpha} emission. The radial velocity distribution of members shows a dispersion of {sigma}=3.1km/s. We found a substantial north-south velocity gradient and spatially coherent structure in the radial velocity distribution, similar to that seen in the molecular gas in the region. We also identified several binary and high velocity stars, a region exhibiting signs of triggered star formation, and a possible foreground population of stars somewhat older than the ONC.
- ID:
- ivo://CDS.VizieR/J/AJ/151/66
- Title:
- Velocities of WOCS 24009 and WOCS 40007 in NGC 6819
- Short Name:
- J/AJ/151/66
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As part of our study of the old (~2.5Gyr) open cluster NGC 6819 in the Kepler field, we present photometric (Kepler and ground-based BVR_C_I_C_) and spectroscopic observations of the detached eclipsing binary WOCS 24009 (Auner 665; KIC5023948) with a short orbital period of 3.6 days. WOCS 24009 is a triple-lined system, and we verify that the brightest star is physically orbiting the eclipsing binary using radial velocities and eclipse timing variations. The eclipsing binary components have masses M_B_=1.090+/-0.010M_{sun}_ and M_C_=1.075+/-0.013M_{sun}_, and radii R_B_=1.099+/-0.006+/-0.005R_{sun}_and R_C_=1.069+/-0.006+/-0.013R_{sun}_. The bright non-eclipsing star resides at the cluster turnoff, and ultimately its mass will directly constrain the turnoff mass: our preliminary determination is M_A_=1.251+/-0.057M_{sun}_. A careful examination of the light curves indicates that the fainter star in the eclipsing binary undergoes a very brief period of total eclipse, which enables us to precisely decompose the light of the three stars and place them in the color-magnitude diagram (CMD). We also present improved analysis of two previously discussed detached eclipsing stars in NGC6819 (WOCS40007 and WOCS23009) en route to a combined determination of the cluster's distance modulus (m-M)_V_=12.38+/-0.04. Because this paper significantly increases the number of measured stars in the cluster, we can better constrain the age of the CMD to be 2.21+/-0.10+/-0.20Gyr. Additionally, using all measured eclipsing binary star masses and radii, we constrain the age to 2.38+/-0.05+/-0.22Gyr. The quoted uncertainties are estimates of measurement and systematic uncertainties (due to model physics differences and metal content), respectively.
- ID:
- ivo://CDS.VizieR/J/MNRAS/400/518
- Title:
- Velocity and proper motion of OB associations
- Short Name:
- J/MNRAS/400/518
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The proper motions of OB-associations computed using the old (1997, Cat. <I/239>) and new (2008, Cat. <I/311>) reductions of the Hipparcos data are in a good agreement with each other. The Galactic rotation curve derived from the analysis of line-of-sight velocities and proper motions of OB-associations is almost flat in the 3-kpc neighborhood of the Sun. The angular rotation velocity at the solar distance is Omega_0_=31(+/-1)km/s/kpc. The standard deviation of the velocities of OB-associations from the rotation curve is sigma=7.2km/s. The distance scale for OB associations by Blaha and Humpreys (1989AJ.....98.1598B) should be shortened by 10-20%. The residual velocities of OB-associations calculated for the new and old reductions differ, on average, by 3.5km/s. The mean residual velocities of OB-associations in the stellar-gas complexes depend slightly on the data reduction employed.
