- ID:
- ivo://CDS.VizieR/J/A+A/557/A10
- Title:
- Metallicities of open clusters
- Short Name:
- J/A+A/557/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are a useful tool when investigating several topics connected with stellar evolution; for example the age or distance can be more accurately determined than for field stars. However, one important parameter, the metallicity, is only known for a marginal percentage of open clusters. We aim at a consistent set of parameters for the open clusters investigated in our photometric Delta-a survey of chemically peculiar stars. Special attention is paid to expanding our knowledge of cluster metallicities and verifying their scale. Making use of a previously developed method based on normalised evolutionary grids and photometric data, the distance, age, reddening, and metallicity of open clusters were derived. To transform photometric measurements into effective temperatures to use as input for our method, a set of temperature calibrations for the most commonly used colour indices and photometric systems was compiled. We analysed 58 open clusters in total. Our derived metallicity values were in excellent agreement with about 30 spectroscopically studied targets. The mean value of the absolute deviations was found to be 0.03dex, with no noticeable offset or gradient. The method was also applied using recent evolutionary models based on the currently accepted lower solar abundance value Z~0.014. No significant differences were found compared to grids using the former adopted solar value Z=0.02. Furthermore, some divergent photometric datasets were identified and discussed. The method provides an accurate way of obtaining properly scaled metallicity values for open clusters. In light of present and future homogeneous photometric sky surveys, the sample of stellar clusters can be extended to the outskirts of the Milky Way, where spectroscopic studies are almost impossible. This will help for determining galactic metallicity gradients in more detail.
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Search Results
- ID:
- ivo://CDS.VizieR/J/AJ/130/1916
- Title:
- Metallicity indices in open clusters
- Short Name:
- J/AJ/130/1916
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present metallicity estimates for seven open clusters based on spectrophotometric indices from moderate-resolution spectroscopy. Observations of field giants of known metallicity provide a correlation between the spectroscopic indices and the metallicity of open cluster giants. We use 2 analysis to fit the relation of spectrophotometric indices to metallicity in field giants. The resulting function allows an estimate of the target-cluster giants' metallicities with an error in the method of +/-0.08 dex. We derive the following metallicities for the seven open clusters: NGC 1245, [M/H]=-0.14+/-0.04; NGC 2099, [M/H]=+0.05+/-0.05; NGC 2324, [M/H]=-0.06+/-0.04; NGC 2539, [M/H]=-0.04+/-0.03; NGC 2682 (M67), [M/H]=-0.05+/-0.02; NGC 6705, [M/H]=+0.14+/-0.08; NGC 6819, [M/H]=-0.07+/-0.12. These metallicity estimates will be useful in planning future extrasolar planet transit searches, since planets may form more readily in metal-rich environments.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A55
- Title:
- Metallicity of the {gamma} Vel cluster
- Short Name:
- J/A+A/567/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowledge of the abundance distribution of star forming regions and young clusters is critical to investigate a variety of issues, from triggered star formation and chemical enrichment by nearby supernova explosions to the ability to form planetary systems. In spite of this, detailed abundance studies are currently available for relatively few regions. In this context, we present the analysis of the metallicity of the Gamma Velorum cluster, based on the products distributed in the first internal release of the Gaia-ESO Survey. The Gamma Velorum candidate members have been observed with FLAMES, using both UVES and Giraffe, depending on the target brightness and spectral type. In order to derive a solid metallicity determination for the cluster, membership of the observed stars must be first assessed. To this aim, we use several membership criteria including radial velocities, surface gravity estimates, and the detection of the photospheric lithium line. Out of the 80 targets observed with UVES, we identify 14 high-probability members. We find that the metallicity of the cluster is slightly sub-solar, with a mean [Fe/H]=-0.057+/-0.018dex. Although J08095427-4721419 is one of the high-probability members, its metallicity is significantly larger than the cluster average. We speculate about its origin as the result of recent accretion episodes of rocky bodies of about 60 Msun hydrogen-depleted material from the circumstellar disc.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/50
- Title:
- Mid-IR photometric monitoring of the ONC
- Short Name:
- J/ApJ/733/50
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present initial results from time-series imaging at infrared wavelengths of 0.9deg^2^ in the Orion Nebula Cluster (ONC). During Fall 2009 we obtained 81 epochs of Spitzer 3.6 and 4.5um data over 40 consecutive days. We extracted light curves with ~3% photometric accuracy for ~2000 ONC members ranging from several solar masses down to well below the hydrogen-burning mass limit. For many of the stars, we also have time-series photometry obtained at optical (Ic) and/or near-infrared (JKs) wavelengths. Our data set can be mined to determine stellar rotation periods, identify new pre-main-sequence eclipsing binaries, search for new substellar Orion members, and help better determine the frequency of circumstellar disks as a function of stellar mass in the ONC. Our primary focus is the unique ability of 3.6 and 4.5um variability information to improve our understanding of inner disk processes and structure in the Class I and II young stellar objects (YSOs). In this paper, we provide a brief overview of the YSOVAR Orion data obtained in Fall 2009 and highlight our light curves for AA-Tau analogs -YSOs with narrow dips in flux, most probably due to disk density structures passing through our line of sight. Detailed follow-up observations are needed in order to better quantify the nature of the obscuring bodies and what this implies for the structure of the inner disks of YSOs.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A156
- Title:
- Milky Way global survey of star clusters
- Short Name:
- J/A+A/543/A156
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 650 Milky Way Stellar Clusters (MWSC) in the second quadrant of the Galaxy, found in the 2MAst (2MASS with Astrometry) catalogue. The target list was compiled on the basis of present-day lists of open, globular and candidate clusters. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, proper motion, sometimes radial velocities, distance, reddening, age, tidal parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A53
- Title:
- Milky Way global survey of star clusters. II.
- Short Name:
- J/A+A/558/A53
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 3006 Milky Way Stellar Clusters (MWSC), found in the 2MAst (2MASS with Astrometry) catalogue. The target list was compiled on the basis of present-day lists of open, globular and candidate clusters. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, mean cluster proper motions, distances, reddenings, ages, tidal parameters, and sometimes radial velocities.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A51
- Title:
- Milky Way global survey of star clusters. III.
- Short Name:
- J/A+A/568/A51
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a list of 139 new open clusters at high Galactic latitudes (|b|>18.5{deg}) that are found in the frame of the project Milky Way Star Clusters (MWSC). The target list was compiled as density enhancements using the 2MASS catalogue. For confirmed clusters we determined a homogeneous set of astrophysical parameters such as membership, angular radii of the main morphological parts, proper motion, distance, reddening, age, tidal parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/585/A101
- Title:
- Milky Way global survey of star clusters. V.
- Short Name:
- J/A+A/585/A101
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We determined the integrated magnitudes of 3208 star clusters in the 2MASS near-infrared (JHKs) passbands.
- ID:
- ivo://CDS.VizieR/J/ApJ/672/558
- Title:
- MIPS observations of h and {chi} Persei
- Short Name:
- J/ApJ/672/558
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We describe Spitzer MIPS observations of the double cluster, h and {chi} Persei, covering a ~0.6deg^2^ area surrounding the cores of both clusters. The data are combined with IRAC and 2MASS data to investigate ~616 sources from 1.25-24um. We use the long-baseline Ks-[24] color to identify two populations with IR excess indicative of circumstellar material: Be stars with 24um excess from optically thin free-free emission, and 17 fainter sources (J~14-15) with [24] excess consistent with a circumstellar disk. The frequency of IR excess for the fainter sources increases from 4.5 to 24um. The IR excess is likely due to debris from the planet formation process. The wavelength-dependent behavior is consistent with an inside-out clearing of circumstellar disks. A comparison of the 24um excess population in h and {chi} Per sources with results for other clusters shows that 24um emission from debris disks "rises" from 5 to 10Myr, peaks at ~10-15Myr, and then "falls" from ~15-20Myr to 1Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/463/3513
- Title:
- M67 Kepler/K2-Campaign-5 variable stars
- Short Name:
- J/MNRAS/463/3513
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We revisit the photometric variability of stars in the M67 field using Kepler/K2-Campaign-5 light curves. In our previous work (Gonzalez, 2016, Cat. J/MNRAS/459/1060), we limited the search area around M67 to that of a recent ground-based study. In the present work, we expand the search area and apply a more rigorous period-finding algorithm to determine the rotation periods of 98 main-sequence cluster members from the same data. In addition, we derive periods of 40 stars from the K2SC detrended light curves. We determine the mean period of single sun-like main-sequence cluster members to be 29.6+/-0.6d. Assuming the periods correspond to stellar rotation, the corresponding mean gyrochronological (gyro-) age is 5.4+/-0.2Gyr.
