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.
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.
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.
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.
The results of the spectral classification of 1224 O-M stars of different luminosity classes in the region of NGC 2175 and around it are presented. The classification has been carried out on the basis of low dispersion objective prism spectra. Using the B-V and U-B data for 106 stars out of 1224 the MK classification has been done with the photometric Q-method.
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.
In the third paper of this series we continue the exploitation of Kepler/K2 data in dense stellar fields using our PSF-based method. This work is focused on a ~720-arcmin^2^ region centred on the Solar-metallicity and Solar-age open cluster M 67. We extracted light curves for all detectable sources in the Kepler channels 13 and 14, adopting our technique based on the usage of a high-angular-resolution input catalogue and target-neighbour subtraction. We detrended light curves for systematic errors, and searched for variables and exoplanets using several tools. We found 451 variables, of which 299 are new detection. Three planetary candidates were detected by our pipeline in this field. Raw and detrended light curves, catalogues, and K2 stacked images used in this work will be released to the community.
The presence and strength of a stellar magnetic field and activity is rooted in a star's fundamental parameters such as mass and age. Can flares serve as an accurate stellar "clock"? To explore if we can quantify an activity-age relation in the form of a flaring-age relation, we measured trends in the flaring rates and energies for stars with different masses and ages. We investigated the time- domain photometry provided by Kepler's follow-up mission K2 and searched for flares in three solar metallicity open clusters with well-known ages, M45 (0.125Gyr), M44 (0.63Gyr), and M67 (4.3Gyr). We updated and employed the automated flare finding and analysis pipeline Appaloosa, originally designed for Kepler. We introduced a synthetic flare injection and recovery subroutine to ascribe detection and energy recovery rates for flares in a broad energy range for each light curve. We collected a sample of 1761 stars, mostly late-K to mid-M dwarfs and found 751 flare candidates with energies ranging from 4x10^32^erg to 6x10^34^erg, of which 596 belong to M45, 155 to M44, and none to M67. We find that flaring activity depends both on Teff, and age. But all flare frequency distributions have similar slopes with alpha from 2.0 to 2.4, supporting a universal flare generation process. We discuss implications for the physical conditions under which flares occur, and how the sample's metallicity and multiplicity affect our results.
Beijing-Arizona-Taiwan-Connecticut (BATC) multiband photometric data in the field of open cluster M48 are used to determine its membership. By comparing observed spectral energy distributions of M48 stars with theoretical ones, membership probabilities of 750 stars with limiting magnitudes of 15.0 in the BATC c band ({lambda}_eff_=4194{AA}) are determined. We find 323 stars with membership probabilities higher than 30% that are considered to be candidate members of M48. Comparing membership probabilities of 229 stars obtained in common between the present method and proper-motion-based methods, an 80% agreement among these methods is obtained