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The composite X-ray spectra of radio-loud and radio-quiet SDSS quasars
Gu, Min-Feng; Zhou, Min-Hua
We present a study of the X-ray emission for a sample of radio-detected quasars constructed from the cross-matches between SDSS, FIRST catalogs and XMM-Newton archives. A sample of radio-quiet SDSS quasars without FIRST radio detection is also assembled for comparison. We construct the optical and X-ray composite spectra normalized at rest frame 4…
LAMOST/HRS spectroscopic analysis of two new Li-rich giants
Pan, Kaike; Gao, Qi; Yan, Hong-Liang +9 more
Two Li-rich candidates, TYC 1338-1410-1 and TYC 2825-596-1, were observed by the new high-resolution echelle spectrograph, LAMOST/HRS. Based on their high-resolution and high-signal-to-noise ratio (SNR) spectra, we derived stellar parameters and abundances of 14 important elements for the two candidates. The stellar parameters and lithium abundanc…
Search for age pattern across spiral arms of the Milky Way
Xu, Ye; Hou, Li-Gang; He, Zhi-Hong
The age pattern across spiral arms is one of the key observational features utilised to study the dynamic nature of the Galaxy's spiral structure. With the most updated samples of high-mass star formation region (HMSFR) masers, O stars and open clusters, we investigated their distributions and kinematic properties in the vicinity of the Sun. We fo…
Revisiting pulsar velocities using Gaia Data Release 2
Tsai, Chao-Wei; Li, Di; Zhang, Jie +3 more
Precise measurements of neutron star (NS) velocities provide critical clues in regard to the supernova physics and evolution of binary systems. Based on Gaia Data Release 2 (DR2), we selected a sample of 24 young (< 3 Myr) pulsars with precise parallax measurements and measured the velocity of their local standard of rest (LSR) and the velocity…
Observation of solar coronal heating powered by magneto-acoustic oscillations in a moss region
Ji, Kai-Fan; Hashim, Parida; Hong, Zhen-Xiang +3 more
In this paper, we report the observed temporal correlation between extreme-ultraviolet (EUV) emission and magneto-acoustic oscillations in an EUV moss region, which is the footpoint region only connected by magnetic loops with million-degree plasma. The result is obtained from a detailed multi-wavelength data analysis of the region with the purpos…
BVRI Photometric Observations, Light Curve Solutions and Orbital Period Analysis of BF Pav
Davoudi, Fatemeh; Poro, Atila; Blackford, Mark G. +7 more
A new ephemeris, period change analysis and light curve modeling of the W UMa-type eclipsing binary BF Pav are presented in this study. Light curves of the system taken in BVRI filters from two observatories, in Australia and Argentina, were modeled using the Wilson-Devinney code. The results of this analysis demonstrate that BF Pav is a contact b…
The deep and low-mass-ratio contact binary CSS J022914.4+044340 with a luminous additional companion
Liu, Liang; Li, Xu-Zhi
The first B-, V-, Rc- and Ic-band light curves of CSS J022914.4+044340 are presented and analyzed. It is found that CSS J022914.4+044340 is a low mass ratio (0.198 ± 0.005) deep (63.7 ± 7.9%) contact binary, indicating that it is already at the end evolutionary stage of tidally-locked evolution via magnetized wind. Because of…
The first photometric analysis of the totally eclipsing contact binary V811 Cep
Li, Kai; Gao, Xing; Liu, Yuan +1 more
The first photometric analysis of V811 Cep was carried out. The first complete light curves of V, R and I bands are given. The analysis was carried out by the Wilson-Devinney (W-D) program, and the results show that V811 Cep is a median-contact binary (f = 33.9(±4.9)%) with a mass ratio of 0.285. It is a W-subtype contact binary, that is, the comp…
Variable stars in the 50BiN open cluster survey. II. NGC 869
Li, Cheng-Yuan; Deng, Li-Cai; Wang, Kun +5 more
This work presents a time-series photometric variability survey of the young open cluster NGC 869. More than 13 000 CCD frames in the BV filters were collected on 19 nights between 2014 November 6 and 2014 December 24. In a 20' × 20' field centered on the cluster, we detected a total of 28 stars showing photometric variability, 12 of which are new…
X-ray spectral evolution in an X-ray changing-look AGN NGC 1365 with variable column density
Liu, Hao; Yang, Jun; Wang, Ting-Gui +4 more
X-ray changing-look active galactic nuclei (CL AGNs) are a subpopulation of AGNs, whose line-of-sight column densities increase/decrease within several years. The physical mechanism for the variation of column density is unclear. We reduce the X-ray data from XMM-Newton and NuSTAR observations for a CL AGN NGC 1365 with strong variation of column …