Related papers: Variability in the Massive Open Cluster NGC 1817 f…
We present a comprehensive photometric analysis of a young open cluster NGC 1960 (M36) along with the long-term variability study of this cluster. Based on the kinematic data of Gaia DR2, the membership probabilities of 3871 stars are…
We have analyzed multi-passband photometric observations, obtained with the {\it Hubble Space Telescope}, of the massive ($1.8 \times 10^5 M_\odot$), intermediate-age (1.8 Gyr-old) Large Magellanic Cloud star cluster NGC 1783. The…
[Abridged] We have studied the optical spectra of 28 O- and early B-type stars in the Large Magellanic Cloud, 22 of which are associated with the young star-forming region N11. Stellar parameters are determined using an automated fitting…
We present a sample of $\sim$ 140,000 primary red clump (RC) stars of spectral signal-to-noise ratios higher than 20 from the LAMOST Galactic spectroscopic surveys, selected based on their positions in the metallicity-dependent effective…
We present wide field photometry of the Galactic Globular Cluster M~22 in the B, V and I passbands for more than 186,000 stars. The study is complemented by the photometry in two narrowband filters centered on H$_{\alpha}$ and the adjacent…
Based on photometric data obtained between 1935 and 2017, $O-C$ diagrams were built for 22 RR Lyrae stars in the globular cluster NGC 6171, leading to the discovery of secular period changes in 4 variables for which we have calculated their…
We have analyzed high-resolution echelle spectra of red giant members for seven open clusters in the Galactic anticentre direction to explore their chemical positions. Cluster membership has been confirmed by radial velocity. The spread in…
We have obtained high-resolution echelle spectra of 18 solar-type stars that an earlier survey showed to have very high levels of Ca II H and K emission. Most of these stars belong to close binary systems, but 5 remain as probable single…
We have analysed high-precision photometry of 77 double-mode RR Lyrae (RRd) stars observed by NASA's Kepler-K2 mission during Campaigns 1-18. Among those stars, we have identified several low-period ratio variables, belonging either to a…
The temperature distribution of field Li-rich red giants suggests the presence of a population of Li-rich red clump (RC) stars. One proposed explanation for this population is that all stars with masses near 2 $M_\odot$ experience a…
Aims. Our main aim with this work was to enlarge the pool of open clusters with determined carbon, nitrogen, and oxygen abundances in evolved giants to further advance chemical clocks in stellar age determinations. Methods. High-resolution…
This study presents the rotational distribution of red giant stars (RGs) in eleven old to intermediate age open clusters. The masses of these stars are all above the Kraft break, so that they lose negligible amounts of their birth angular…
Asteroseismic constraints on K giants make it possible to infer radii, masses and ages of tens of thousands of field stars. Tests against independent estimates of these properties are however scarce, especially in the metal-poor regime.…
We present the results from $VI$ CCD time-series photometry of the globular cluster M13 (NGC 6205). From the Fourier decomposition of the light curves of RRab and RRc stars we found an average metallicity of [Fe/H]zw = -1.58 $\pm$ 0.09. The…
Star clusters are ideal platforms for categorising X-ray emitting stars and to study X-ray emission as a function of stellar age and activity. We present a comprehensive study of an open star cluster, NGC2527, by combining data from…
The Advanced Camera for Surveys on board the Hubble Space Telescope has been used to obtain deep high-resolution images of the giant early-type galaxy NGC 1316 which is an obvious merger remnant. These observations supersede previous,…
We analyze light curves of 284,834 unique K2 targets using a Gaussian process model with a quasi-periodic kernel function. By crossmatching K2 stars to observations from Gaia Data Release 2, we have identified 69,627 likely main-sequence…
We produce light curves for all ~34,000 targets observed with K2 in Campaign 17 (C17), identifying 34 planet candidates, 184 eclipsing binaries, and 222 other periodic variables. The location of the C17 field means follow-up can begin…
We have undertaken a long-term project, Planets in Stellar Clusters Extensive Search (PISCES), to search for transiting planets in open clusters. In this paper we present the results for NGC 2158, an intermediate age, populous cluster. We…
In a sample of six young open clusters we investigated 1753 objects using the narrow band, three filter Delta a photometric system resulting in the detection of eleven bona-fide magnetic chemically peculiar (CP) stars and five Be or…