Search Publications
What causes the absence of pulsations in Central Compact Objects in supernova remnants?
Xiao, Guang-Cheng; Schwope, Axel; Ji, Li +3 more
Most young neutron stars belonging to the class of Central Compact Objects (CCOs) in supernova remnants do not have known periodicities. We investigated seven such CCOs to understand the common reasons for the absence of detected pulsations. Making use of XMM-Newton, Chandra, and NICER observations, we perform a systematic timing and spectral anal…
Searching for the brightest stars in galaxies outside the Local Group
Tikhonov, Nikolay; Galazutdinova, Olga; Sholukhova, Olga +3 more
This paper introduces a technique for searching for bright massive stars in galaxies beyond the Local Group. To search for massive stars, we processed the results of stellar photometry from the Hubble Space Telescope (HST) images using the DAOPHOT and DOLPHOT packages. The results of such searches are demonstrated with examples of the galaxies DDO…
Spectral study of V565 Mon: probable FU Ori-like or chemically peculiar star
Andreasyan, Hasmik
We present a detailed spectroscopic study of pre-main sequence star V565 Mon, which is the illuminating star of the Parsamian 17 cometary nebula. Observations were performed with the 2.6 m telescope in Byurakan Astrophysical Observatory on 2018 February 15. Radial velocities and equivalent widths of the most prominent lines of V565 Mon are present…
Investigation of the shortest period Am type eclipsing binary TYC 6408-989-1
Tian, Xiao-Man
The first BV bands photometric observations and the low-resolution spectrum of the shortest period Am type eclipsing binary TYC 6408-989-1 have been obtained. The stellar atmospheric parameters of the primary star were obtained through the spectral fitting as follows: Teff = 6990 ± 117 K, log g = 4.25 ± 0.26 cm s-2, [Fe/H] = …
Partitioning the Galactic halo with Gaussian Mixture Models
Zhao, Gang; Zhao, Jing-Kun; Liang, Xi-Long +1 more
The Galactic halo is supposed to form from merging with nearby dwarf galaxies. In order to probe different components of the Galactic halo, we have applied the Gaussian Mixture Models method to a selected sample of metal poor stars with [Fe/H] < -0.7 dex in the APOGEE DR16 catalogue based on four-parameters, metallicity, [Mg/Fe] ratio and spati…
Ice lines as the origin for the gap/ring structure in protoplanetary disks: the issue of the assumed temperature profile
Liu, Yao
Gaps and rings are commonly seen in recent high-resolution ALMA observations of protoplanetary disks. Ice lines of volatiles are one of the mechanisms proposed to explain the origin for these substructures. To examine the ice line hypothesis, literature studies usually parameterize the mid-plane temperature with the analytic formula of a passively…
A photometric study of two neglected eclipsing binaries
Fedurco, M.; Parimucha, Š.; Kudak, V. +1 more
We present the first BVR photometry, period variation and photometric light curve analysis of two poorly studied eclipsing binaries, V1321 Cyg and CR Tau. Observations were carried out from November 2017 to January 2020 at the observatory of Uzhhorod National University. Period variations were studied using all available early published as well as…
Search for variable stars in the open cluster NGC 1245
Zhang, Yu; Liu, Jin-Zhong; Zeng, Xiang-Yun +5 more
We used the Nanshan 1m telescope of Xinjiang Astronomical Observatory to investigate variable stars in the region of NGC 1245. We detected 55 variable stars in the field of view, 42 of them are newly discovered: six binaries, 22 pulsating stars, 14 unclassified variables. We discussed the physical properties and classifications of the variable sta…
Chemical abundances of three new Ba stars from the Keck/HIRES spectra
Wang, Liang; Gao, Qi; Yan, Hong-Liang +4 more
Based on high resolution, high signal-to-noise (S/N) ratio spectra from Keck/HIRES, we have determined abundances of 20 elements for 18 Ba candidates. The parameter space of these stars is in the range of 4880 ≤ T eff ≤ 6050 K, $2.56\le \mathrm{log}\,g\le 4.53\,\mathrm{dex}$ and - 0.27 ≤ [Fe/H] ≤ 0.09 dex. It is found that four of them …
Measurement of Hubble constant: were differences in secondary distance indicators apparent as early as the HST Key Project?
Gupta, Shashikant; Thakur, Rahul Kumar; Nigam, Rahul +1 more
Different measurements of the Hubble constant (H0) are not consistent, and a tension between the CMB based methods and cosmic distance ladder based methods has been observed. Measurements from various distance based methods are also inconsistent. To aggravate the problem, the same cosmological probe (Type Ia SNe for instance) calibrated…