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How Common can the Origin of Clusters Cha I, Cha II, ϵ Cha and η Cha be?
Bobylev, V. V.; Bajkova, A. T.
The trajectories of the groupings η Cha, ϵ Cha and Cha I, Cha II, constructed backward in time, have been studied. We concluded that the hypothesis about the joint formation of all four of these clusters from one molecular cloud cannot be completely excluded. However, 10–15 Myr ago, all these four clusters were located at approximately the same he…
Long Term X-Ray Spectral Variations of the Seyfert-1 Galaxy Mrk 279
Jeena, K.; Misra, Ranjeev; Akhila, K. +1 more
We present the results from a long term X-ray analysis of Mrk 279 during the period 2018–2020. We use data from multiple missions – AstroSat, NuSTAR and XMM-Newton, for the purpose. The X-ray spectrum can be modeled as a double Comptonization along with the presence of neutral Fe Kα line emission, at all epochs. We determined the source's X-ray fl…
Isochrone Fitting of Galactic Globular Clusters—VI. High-latitude Clusters NGC 5024 (M53), NGC 5053, NGC 5272 (M3), NGC 5466, and NGC 7099 (M30)
Savchenko, S. S.; Gontcharov, G. A.; Il'in, V. B. +7 more
We fit various color–magnitude diagrams (CMDs) of the high-latitude Galactic globular clusters NGC 5024 (M53), NGC 5053, NGC 5272 (M3), NGC 5466, and NGC 7099 (M30) by isochrones from the Dartmouth Stellar Evolution Database and Bag of Stellar Tracks and Isochrones for α–enrichment [α/Fe] = +0.4. For the CMDs, we use data sets from Hubble Space Te…
Astronomical Test with CMOS on the 60 cm Telescope at the Xinglong Observatory, NAOC
Fan, Zhou; Zhang, Yu; Wu, Hong +2 more
This work shows details of an evaluation of an observational system comprising a complementary metal-oxide-semiconductor detector, 60 cm telescope and filter complement. The system's photometric precision and differential photometric precision, and extinction coefficients were assessed through observations of Supersky flat fields, open clusters, s…
JWST Observations Constrain the Time Evolution of Fine Structure Constants and Dark Energy-electromagnetic Coupling
Feng, Lei; Lei, Lei; Fan, Yi-Zhong +1 more
It was hypothesized in the literature that some physical parameters may be time-evolving and the astrophysical data can serve as a probe. Recently, the James Webb Space Telescope (JWST) released its early observations. In this work, we select the JWST spectroscopic observations of the high redshift (z > 7.1) galaxies with strong [O III] (λ = 49…
BSN: The First Light Curve Analysis of the Total Eclipse Binary System EL Tuc
Poro, Atila; Sarvari, Elham; Fernández Lajús, Eduardo
We conducted the first light curve study of the binary star EL Tuc within the Binary Systems of South and North project's framework. The photometric observations were made using standard multiband BVR c I c filters at an observatory in Argentina. We presented a new ephemeris for EL Tuc and a linear fit to the O – C diagra…
Long-term Variation of the Solar Polar Magnetic Fields at Different Latitudes
Hou, Yijun; Li, Ting; Yang, Shuhong +10 more
The polar magnetic fields of the Sun play an important role in governing solar activity and powering fast solar wind. However, because our view of the Sun is limited in the ecliptic plane, the polar regions remain largely uncharted. Using the high spatial resolution and polarimetric precision vector magnetograms observed by Hinode from 2012 to 202…
The Astrometric Performance of the China Space Station Telescope (CSST) Sky Survey in Extending the Gaia Celestial Reference Frame
Zhu, Zi; Yao, Jun; Liu, Niu +2 more
The multi-color imaging sky survey conducted by the China Space Station Telescope (CSST) holds significant promise for advancing the development of the celestial reference frame. In this study, we focus on assessing the astrometric performance of the CSST celestial reference frame (CSST-CRF) in extending the Gaia Celestial Reference Frame 3 (Gaia-…
Investigation of WZ Sge-type Dwarf Nova ASASSN-19oc: Optical Spectroscopy and Multicolor Light Curve Analysis
Krushevska, Viktoriia; Shugarov, Sergey; Ochner, Paolo +3 more
In this study, we present an investigation of the newly discovered dwarf nova ASASSN-19oc during its superoutburst on 2019 June 2. We carried out detailed UBVR c I c -photometric observations and also obtained a spectrum on day 7 of the outburst, which shows the presence of hydrogen absorption lines commonly found in dwarf…
A Preliminary Comparative Study on the Centering Algorithms for Cassini-ISS NAC Images
Zhang, Q. -F.; Liang, T.; Liu, G. -M. +2 more
Obtaining high precision is an important consideration for astrometric studies using images from the Narrow Angle Camera (NAC) of the Cassini Imaging Science Subsystem (ISS). Selecting the best centering algorithm is key to enhancing astrometric accuracy. In this study, we compared the accuracy of five centering algorithms: Gaussian fitting, the m…