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The Pleiades apex and its kinematical structure
Yadav, R. K. S.; Vereshchagin, S. V.; Chupina, N. V. +4 more
A study of cluster characteristics and internal kinematical structure of the middle-aged Pleiades open star cluster is presented. The individual star apexes and various cluster kinematical parameters including the velocity ellipsoid parameters are determined using both Hipparcos and Gaia data. Modern astrometric parameters were taken from the Gaia…
A study of pulsation & rotation in a sample of A-K type stars in the Kepler field
Paul, K. T.; Engelbrecht, Chris A.; Joshi, Santosh +3 more
We present the results of time-series photometric analysis of 15106 A-K type stars observed by the Kepler space mission. We identified 513 new rotational variables and measured their starspot rotation periods as a function of spectral type and discuss the distribution of their amplitudes. We examined the well-established period-color relationship …
Memberships, distance and proper-motion of the open cluster NGC 188 based on a machine learning method
Gao, Xin-Hua
In this paper, we present an investigation of the memberships, distance and proper motion for the old open cluster NGC 188 using a machine-learning-based method. This method combines two widely used algorithms: spectral clustering (SC) and random forest (RF). The former one is used to construct a reliable training set, the membership probabilities…
Using GALEX-SDSS-PanSTARRS-HST-Gaia to understand post-AGB evolution
Bianchi, Luciana; Casewell, Sarah; Bohlin, Ralph +2 more
Hot WDs in binary systems with a less evolved star are particularly invaluable astrophysical probes, the unevolved companion enabling better derivation of distance and age than is usually possible for post-AGB objects, and therefore also of their radius and luminosity. But hot white dwarfs (WD) are elusive at all wavelengths except the UV (Bianchi…
GALEX far-ultraviolet observations of metal-poor subdwarfs
Smith, Graeme H.
Far-ultraviolet photometry derived from the GALEX satellite observatory has been compiled for a sample of metal-poor subdwarfs with
The astrometric signal of microlensing events caused by free floating planets
Nucita, Achille A.; De Paolis, Francesco; Hamolli, Lindita +1 more
Astrometric observations of microlensing events can be used to obtain important information about lenses. During these events, the shift of the position of the multiple image centroid with respect to the source star location can be measured. This effect, which is expected to occur on scales from micro-arcseconds to milli-arcseconds, depends on the…