• Z.-Q. Shen

      Articles written in Journal of Astrophysics and Astronomy

    • Peculiar Physical Properties of HST-1 in M87

      Y. J. Chen G.-Y. Zhao Z.-Q. Shen

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      We report on VLA observations of HST-1 in M87 at 8 GHz from 2003–2007, during which a long major outburst occurs from radio to X-ray wave bands. At the VLA resolution, the flux density of HST-1 rises rapidly from 2003, peaks at the end of 2004, and then falls slowly in subsequent stages, which is similar to that in optical and X-ray wave bands. It appears that HST-1 moves with an apparent speed of 1.23𝑐 ± 0.91𝑐, and the fractional polarization keeps rising through the whole major outburst. The persistent increase in polarization level may mainly be attributed to the formation of a couple of new `subcomponents’ of relatively high degree of polarization within HST-1, and the weakening depolarization due to Faraday rotation and/or opacity through the whole major outburst.

    • Position Measurements of the Core in 3C 66B

      G.-Y. Zhao Y.-J. Chen Z.-Q. Shen H. Sudou S. Iguchi Y. Murata Y. Taniguchi

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      It was argued that 3C 66B, a nearby radio galaxy, harbors a supermassive black hole binary (SMBHB). To investigate this, a 4-epoch VLBA phase referencing imaging observation was performed in 2004–2005. Here we present some preliminary results of this project. We found a large position difference compared to previous results.

    • Pumping Mechanisms for SiO Masers around VX Sgr

      J. B. Su Z.-Q. Shen X. Chen Jiyune Yi D. R. Jiang Y. J. Yun

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      VX Sgr, a semi-regular variable, is a red giant star with intense SiO maser emission at 43 GHz. The pumping mechanism of the circumstellar SiO masers has been controversial for decades since its discovery. In order to pursue this long-standing problem further, we have carried out simultaneous VLBA observations of two 7 mm SiO masers at five epochs in about two years. We present relatively aligned 𝑣 = 1 and 𝑣 = 2, 𝐽 = 1-0 SiO maser maps and discuss the dominant pumping mechanism, which may be epoch dependent or a combination of both mechanisms.

    • Multi-Frequency VLBA Studies of the Parsec-Scale Jets in 3C 66A and 3C 66B

      G.-Y. Zhao Y.-J. Chen Z.-Q. Shen H. Sudou S. Iguchi F. Gao Y. Murata Y. Taniguchi

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      We report multi-frequency VLBA phase-referencing observation results of 3C 66A and 3C 66B, including high resolution maps and relative position measurements. The resulting images show similar morphology with that presented in previous works. We find core shift variations in both sources, indicating some physical condition changes in the jets.

    • Helical Magnetic Fields in AGN Jets

      Y. J. Chen G.-Y. Zhao Z.-Q. Shen

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      We establish a simple model to describe the helical magnetic fields in AGN jets projected on the sky plane and the line-of-sight. This kind of profile has been detected in the polarimetric VLBI observation of many blazar objects, suggesting the existence of helical magnetic fields in these sources.

    • Outward Motions of SiO Masers around VX Sgr

      J. B. Su Z.-Q. Shen X. Chen D. R. Jiang

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      We report the proper motions of SiO maser features around VX Sgr from the two-epoch VLBA observations (2006 December 15 and 2007 August 19). The majority of maser feature activities show a trend of outward motions. It is consistent with our previous finding that the outflow may play an important role for SiO maser pumping.

  • Journal of Astrophysics and Astronomy | News

    • Continuous Article Publication

      Posted on January 27, 2016

      Since January 2016, the Journal of Astrophysics and Astronomy has moved to Continuous Article Publishing (CAP) mode. This means that each accepted article is being published immediately online with DOI and article citation ID with starting page number 1. Articles are also visible in Web of Science immediately. All these have helped shorten the publication time and have improved the visibility of the articles.

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