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Variable Star Population in the Open Cluster NGC 6791 Observed by the Kepler Spacecraft
Németh, P.; Sahoo, S. K.; Baran, A. S. +3 more
We present the list of variable stars we found in the Kepler superstamp data covering approximately 9' from the central region of NGC 6791. We classified the variable stars based on the variability type and we established their cluster membership based on the available Gaia Early Data Release 3 astrometry, by means of the Bayesian Gaussian mixture…
The OGLE Collection of Variable Stars. Over 2600 δ Scuti Stars in the Small Magellanic Cloud
Soszyński, I.; Udalski, A.; Szymański, M. K. +11 more
We present the first-ever collection of δ Scuti stars found over the entire area of the Small Magellanic Cloud (SMC). The sample consists of 2810 variables of which over 2600 objects belong to the SMC while the remaining stars are most likely members of the Milky Way's halo. The sample has been divided into 2733 single mode and 77 multimode pulsat…
Studying the Physical Parameters of the Stellar Binary System Hip 42455 (HD 73900)
Abu-Dhaim, A.; Taani, A.; Tanineah, D. +3 more
We present the results of the combined spectrophotometric and dynamic analysis for the close visual binary star Hip 42455 (HD 73900, I 314). A model binary that consists of two main sequence stars with a clear magnitude difference, but completely different estimations of their spectral types, and different parallax measurements given by the four c…
New Short-Period δ Scuti Stars in OGLE-IV Fields toward the Galactic Bulge
Soszyński, I.; Udalski, A.; Szymański, M. K. +12 more
We report the classification of 24 puzzling short-period variable stars located in OGLE-IV Galactic bulge fields. The stars are low-amplitude (<0.05 mag) multi-periodic objects with dominant periods between 22 min and 54 min whose type could not have been unambiguously established based on photometry only. A low-resolution spectroscopic follow-…
Variable Star Population in the Open Cluster NGC 6819 Observed by the Kepler Spacecraft
Németh, P.; Baran, A. S.; Sanjayan, S. +1 more
We present the list of variable stars we found in the Kepler superstamp data covering approximately nine arcminutes from the central region of NGC 6819. This is a continuation of our earlier work. We classified the variable stars based on the variability type and we established their cluster membership based on the available Gaia Data Release 3 as…
TIC 452991707 and TIC 452991693 as a Candidate Sextuple System with Three Eclipsing Binaries
Zasche, P.; Henzl, Z.
We present the discovery of a rare system detected in the TESS data showing three different eclipsing-like signals. TIC 452991707 and TIC 452991693 seem to be the second such system on the sky, whose two components separated about 16" are gravitationally bounded, or comprise a co-moving pair. The three periods detected from the TESS data are: P
Speckle Observations with PISCO in Calern (France): Orbit and Mass Determinations for 22 Visual Binaries
Bendjoya, P.; Rivet, J. -P.; Ling, J. F. +7 more
This paper presents orbits and masses for 22 visual double stars, partly derived using their last observations made with the speckle camera PISCO. For 13 of them we have determined their first-time orbits. Masses were calculated from Hipparcos and Gaia parallaxes when available, and from dynamical parallaxes otherwise. They are compared with masse…
New Photometric and Spectroscopic Observations of the Eclipsing Binary V2080 Cygni
Schwarzenberg-Czerny, A.; Kamiński, K.; Dimitrov, W. +7 more
We present new spectroscopic and photometric measurements of the eclipsing binary V2080 Cyg. It is a detached system with similar components and an orbital period of 4.9 d. We collected spectroscopic data with two instruments, 1.88 m DDO telescope equipped with Cassegrain spectrograph and 0.5 m PST1 connected to a fiber-fed echell\'e spectrograph.…
Classical Cepheids in the Milky Way
Soszyński, I.; Udalski, A.; Pietrukowicz, P.
We share the most up-to-date, carefully verified list of classical Cepheids residing in the Galaxy. Based on long-term OGLE experience in the field of variable stars, we have inspected candidates for Cepheids from surveys such as ASAS, ASAS-SN, ATLAS, Gaia, NSVS, VVV, WISE, ZTF, among others, and also known sources from the General Catalogue of Va…
Measuring the Mass Function of Isolated Stellar Remnants with Gravitational Microlensing I. Revisiting the OGLE-III Dark Lens Candidates
Mróz, P.; Wyrzykowski, Ł.
Gravitational microlensing may detect dark stellar remnants - black holes or neutron stars - even if they are isolated. However, it is challenging to estimate masses of isolated dark stellar remnants using solely photometric data for microlensing events. A recent analysis of OGLE-III long-timescale microlensing events exhibiting the annual paralla…