Search Publications
A multiwavelength view of a classical T Tauri star CV Cha
Karmakar, Subhajeet; Sharma, Saurabh; Joshi, Arti +3 more
Using long-term optical, ultraviolet (UV) and X-ray data, we present a study of a classical T Tauri star CV Cha. The V -band light curve obtained from the All Sky Automated Survey (ASAS) shows short as well as long-term variability. The short-term variability could be due to rotational modulation of CV Cha. We derive the rotational period of 3.714…
On the weak Lyα emission line of BL Lacertae objects
Bu, Jia; Ma, Ren-Yi; Fang, Tao-Tao +2 more
Recent studies reveal that weak Lyα emission line may be a ubiquitous feature of nearby BL Laceratae objects (BL Lacs). We present a survey of the Lyα emission lines in BL Lacs, with a focus on data obtained by the Cosmic Origins Spectrograph onboard the Hubble Space Telescope. Among the 11 selected targets, seven show a clear detection of the int…
Intra-day variability of three Seyfert galaxies measured with XMM-Newton
Tripathi, Ashutosh; Gu, Min-Feng; Liao, Mai +2 more
We present and analyze the variability of three Seyfert galaxies on intra-day timescales. We have analyzed in a uniform manner the 38 longest (>30 ks) observations made for NGC 4051, MCG-06-30-15 and NGC 4151 by XMM-Newton between 2000 and 2015. The nuclei were quite active during essentially all of these observations and the overall X-ray flux…
Decomposing the host galaxy from high-z QSOs using principal component analysis
Wang, Yi-Ping; He, Wei
High resolution deep imaging from space and adaptive optics techniques with large ground-based facilities have enabled studies examining faint host galaxies of high redshift quasi-stellar objects (QSOs). However, the related image processing techniques, especially for a precise point-spread function (PSF) reconstruction and characterization of the…
The spiral structure of the Milky Way
Xu, Ye; Hou, Li-Gang; Wu, Yuan-Wei
The morphology and kinematics of the spiral structure of the Milky Way are long-standing problems in astrophysics. In this review we firstly summarize various methods with different tracers used to solve this puzzle. The astrometry of Galactic sources is gradually alleviating this difficult situation caused mainly by large distance uncertainties, …
The SAGE photometric survey: technical description
Tan, Ke-Feng; Zhao, Gang; Fan, Zhou +4 more
To investigate a huge sample of data related to the Stellar Abundance and Galactic Evolution (SAGE) survey in more detail, we are performing a northern sky photometric survey named SAGES with the SAGE photometric system. This system consists of eight filters: Strӧmgren-u, SAGE-v, SDSS g, r, i, DDO-51, Hα wide and Hα narrow, i…
Machine learning classification of Gaia Data Release 2
Bai, Yu; Wang, Song; Liu, Ji-Feng
Machine learning has increasingly gained more popularity with its incredibly powerful ability to make predictions or calculate suggestions for large amounts of data. We apply machine learning classification to 85 613 922 objects in the Gaia Data Release 2, based on a combination of Pan-STARRS 1 and AllWISE data. The classification results are cros…
Physical and geometrical parameters of VCBS XIII: HIP 105947
Masda, Suhail Gumaan; Al-Wardat, Mashhoor Ahmed; Pathan, Jiyaulla Khan Moula Khan
The best physical and geometrical parameters of the main sequence close visual binary system (CVBS), HIP 105947, are presented. These parameters have been constructed conclusively using Al-Wardat’s complex method for analyzing CVBSs, which is a method for constructing a synthetic spectral energy distribution (SED) for the entire binary system usin…
The simplest way to get a cluster’s parameters in the Gaia era (Dolidze 41)
Tadross, Ashraf Latif
The astro-photometric parameters of the open star cluster Dolidze 41, which is located in the constellation Cygnus, have been investigated using the Gaia DR2 large survey that is merged with the near infrared Two Micron All Sky Survey (2MASS) database. The radial density distribution (limited, core and tidal radii), color-magnitude diagrams, galac…
High amplitude δ Scuti star BO Lyn with evidence of a late A-type companion in an elliptical orbit
Li, Lin-Jia; Qian, Sheng-Bang; Zhu, Li-Ying +2 more
We present 145 times of light maximum for high amplitude δ Scuti star BO Lyn based on several sky surveys (CRTS, DASCH, NSVS, OMC and SuperWASP) and our photometric observations. Combining with the data in literature, a total of 179 times of light maximum are used to analyze the O - C diagram of BO Lyn. We find that it can be described by an upwar…