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The kinematical and space structures of IC 2391 open cluster and moving group with Gaia-DR2
Vereshchagin, S. V.; Chupina, N. V.; Postnikova, E. S. +3 more
The kinematical parameters, spatial shape and structure of the open cluster IC 2391 and the associated stellar stream are studied here using Gaia Data Release 2 (GDR2) astrometry data. The apex positions are determined for the open cluster IC 2391 (data taken from Cantat-Gaudin et al.) and for the kinematical stream's stars mentioned in Montes et …
Photometric investigation on the W-subtype contact binary V1197 Her
Soonthornthum, Boonrucksar; Zhou, Xiao
Multi-color light curves of V1197 Her were obtained with the 2.4 meter optical telescope at the Thai National Observatory and the Wilson-Devinney (W-D) program was used to model the observational light curves. The photometric solutions reveal that V1197 Her is a W-subtype shallow contact binary system with a mass ratio of q = 2.61 and a fill-out f…
Eclipsing binary XZ CMi in a hierarchical quadruple system
Zhu, Li-Ying; Wang, Zhi-Hua
The new complete BVRcIc light curves and spectra of the short-period eclipsing binary XZ CMi are presented. The results from the combined analysis based on the photometric and spectroscopic data show that XZ CMi is a near contact binary with the secondary component filling its critical Roche lobe while the primary filling 91%…
Investigation of near-contact semi-detached binary WUMi through observations and evolutionary models
Soydugan, Faruk; Soydugan, Esin; Aliçavuş, Fahri
W UMi is a near contact, semi-detached, double-lined eclipsing binary star with an orbital period of 1.7 d. Simultaneous analysis of new BV R multi-color light curves and radial velocity data yields the main astrophysical parameters of the binary and its component stars. We determined mass and radius to be M1 = 3.22 ± 0.08 M⊙…
Irregular changes in Hα emission line of V423 Aur observed by LAMOST Medium-Resolution Spectrographs
Wu, Hong; Hsia, Chih-Hao; Shi, Jian-Rong +8 more
We obtained seven spectra of the Be star V423 Aur on 2017 Dec. 5 using the LAMOST Medium-Resolution Spectrograph with exposures from 600 to 1200 seconds. These spectra show the irregular Hα emission line profile variations (LPVs). In the seven spectra, from the 4th to 7th, the left part of Hα profile even shows excess. However, no variation can be…
Three new late-type hypervelocity star candidates from Gaia DR2 with refined selection criteria
Kupfer, Thomas; Liu, Chao; Jiang, Deng-Kai +6 more
Several dozen hypervelocity star (HVS) candidates have been reported based on the second data release of Gaia (Gaia DR2). However, it has been proven that the radial velocities of some Gaia HVS candidates are not reliable. In this paper, we employ refined astrometric criteria to re-examine Gaia DR2, arriving at a more reliable sample of HVS and hi…
On the metallicity gradient in the Galactic disk
Loktin, Alexander; Popova, Maria
The problem of the chemical composition gradient in the Galactic disk is studied based on a sample of metallicity estimates of open star clusters, using Gaia DR2-improved distance estimates. A clearly non-monotonic variation was observed in the average metallicity of clusters with increasing Galactocentric distance. One can clearly see the metalli…
Discovery of extended structures around two evolved planetary nebulae M2-55 and Abell 2
Zhang, Yong; Hsia, Chih-Hao; Zhang, Xi-Liang +1 more
We report a multi-wavelength study of two evolved planetary nebulae (PNs)M2-55 and Abell 2. Deep optical narrow-band images ([O III], Hα, and [N II]) of M2-55 reveal two pairs of bipolar lobes and a new faint arc-like structure. This arc-shaped filament around M2-55 appears as a well-defined boundary from southwest to southeast, strongly suggestin…
On the correctness of orbital solutions obtained from a small set of points. Orbit of HIP 53731
Mitrofanova, Arina; Dyachenko, Vladimir; Beskakotov, Anatoly +4 more
HIP 53731 is a binary consisting of stars of the spectral types K0 and K9. The orbit of this object was constructed previously by Cvetković et al. and improved by Tokovinin. It should be noted that there is a 180° ambiguity in the position angles of some published measurements. Speckle interferometric observations were obtained in 2007-2020 (21 me…
The evolutionary status of chemically peculiar eclipsing binary star DV Boo
Aliçavuş, F.; Kahraman Aliçavuş, Filiz
Eclipsing binary systems are unique stellar objects to examine and understand stellar evolution and formation. Thanks to these systems, the fundamental stellar parameters (mass, radius) can be obtained very precisely. The existence of metallic-line (Am) stars in binaries is noticeably common. However, the known number of Am stars in eclipsing bina…