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Millimetre-VLBI is an important tool in AGN astrophysics, but it is limited by short atmospheric coherence times and poor receiver and antenna performance. We demonstrate a new kind of phase referencing for the VLBA, enabling us to increase…

天体物理学 · 物理学 2007-05-23 E. Middelberg , A. L. Roy , R. C. Walker , H. Falcke , T. P. Krichbaum

Timing analysis of a ~95 ks long XMM-Newton observation of the Seyfert 1 galaxy MCG-6-30-15 is presented. Model-independent tools have been used with the intent of resolving the different components that produce the observed flux and…

天体物理学 · 物理学 2009-11-10 G. Ponti , M. Cappi , M. Dadina , G. Malaguti

In this paper, we used the database of the university of Michigan Radio Astronomy Observatory (UMRAO) at three (4.8 GHz, 8.0 GHZ, and 14.5 GHz) radio frequency to analyze the radio light curves by the power spectral analysis method in…

天体物理学 · 物理学 2009-11-13 J. H. Fan , Y. Liu , Y. H. Yuan

We present a light curve analysis of fundamental-mode Galactic and Large Magellanic Cloud (LMC) Cepheids based on the Fourier decomposition technique. We have compiled light curve data for Galactic and LMC Cepheids in optical ({\it VI}),…

太阳与恒星天体物理 · 物理学 2015-01-21 Anupam Bhardwaj , Shashi M. Kanbur , Harinder P. Singh , Lucas M. Macri , Chow-Choong Ngeow

The Becklin-Neugebauer (BN) object in the Orion Nebula Cluster (ONC) is a well-studied optically invisible, infrared-bright young stellar object, thought to be an intermediate-mass protostar. We report here that BN exhibited…

天体物理学 · 物理学 2009-10-31 Lynne A. Hillenbrand , John M. Carpenter , M. F. Skrutskie

Using CCD photometry obtained by the EROS collaboration in 1991-1993, we have discovered an LMC variable star with a light curve that is oscillating with a mean period of $\sim 14$ days and an amplitude of $\sim$ 0.3 mag. The oscillations…

天体物理学 · 物理学 2007-05-23 J. P. Beaulieu , R. Buchler , M. J. Goupil , Z. Kollath

The impact of global acoustic modes on the 8B neutrino flux time series is computed for the first time. It is shown that the time fluctuations of the 8B neutrino flux depend on the amplitude of acoustic eigenfunctions in the region where…

太阳与恒星天体物理 · 物理学 2013-10-15 Ilidio Lopes

In this work, I have presented a multi-frequency variability and correlation study of the blazar Ton 599, which was observed first time in flaring state at the end of 2017. Data from \textit{Fermi}-LAT, Swift-XRT/UVOT, Steward Observatory,…

高能天体物理现象 · 物理学 2019-01-30 Raj Prince

The bright blazar Mkn 421 has been observed four times for uninterrupted durations of ~ 9 - 13 hr during the performance verification and calibration phases of the XMM-Newton mission. The source was strongly variable in all epochs, with…

天体物理学 · 物理学 2009-11-07 S. Sembay , R. Edelson , A. Markowitz , R. G. Griffiths , M. J. L. Turner

Radio emissions from RS CVn objects exhibit distinct characteristics at low and high frequencies, widely attributed to differing radiation mechanisms. The disparate processes of high-frequency gyrosynchrotron and low-frequency electron…

太阳与恒星天体物理 · 物理学 2025-09-15 Qichen Huang , Biwei Jiang

Although the continua of radio-loud Active Galactic Nuclei (AGN) are typically dominated by synchrotron radiation over virtually the entire spectrum, it is not clear whether the radio and higher-frequency emission originate in the same or…

星系天体物理 · 物理学 2009-02-06 J. C. Algaba , D. C. Gabuzda , P. S. Smith

The solar activity in the current, that is, the 24-th, sunspot cycle is analyzed. Cyclic variations in the sunspot number (SSN) and radiation fluxes in various spectral ranges have been estimated in comparison with the general level of the…

太阳与恒星天体物理 · 物理学 2018-05-01 E. A. Bruevich , V. V. Bruevich , G. V. Yakunina

Fullerene complexes may play a key role in the design of future molecular electronics and nanostructured devices with potential applications in light harvesting using organic solar cells. Charge and energy flow in these systems is mediated…

We present results of our study of the long-period eclipsing binary star NN Delphini (hereafter NN Del). The results are based on spectral data obtained with the HRS echelle spectrograph of the Southern African Large Telescope (SALT). Our…

太阳与恒星天体物理 · 物理学 2020-11-04 Alexei Kniazev

Context. Quasi-periodic pulsations (QPPs) typically display periodic and regular peaks in the light curves during the flare emissions. Sometimes, QPPs show multiple periods at the same wavelength. However, changing periods in various…

太阳与恒星天体物理 · 物理学 2016-12-28 Dong Li , Qingmin Zhang , Yu Huang , Zongjun Ning , Yingna Su

The NRAO VLA and VLBA were used from 1988 November to 1998 June to monitor the radio continuum counterpart to the optical broad line region (BLR) in the Seyfert galaxy NGC 5548. Photometric and astrometric observations were obtained at 21…

天体物理学 · 物理学 2009-10-31 J. M. Wrobel

We present analysis of the flux and polarization variability of parsec scale radio jets from a dual-frequency, six-epoch, VLBA polarization experiment monitoring 12 blazars. The observations were made at 15 and 22 GHz at bimonthly intervals…

This study presents an analysis of the optical variability of the blazar 1E 1458.8+2249 on diverse timescales using multi-band observations, including observations in the optical BVRI bands carried out with the T60 and T100 telescopes from…

高能天体物理现象 · 物理学 2024-10-25 Aykut Özdönmez , Murat Tekkeşinoğlu

Spectropolarimetric results of Fraunhofer lines between 516.3nm and 532.6nm are presented in local upper solar chromosphere, transition zone and inner corona below a height of about 0.04 solar radius above the solar limb. The data were…

太阳与恒星天体物理 · 物理学 2024-03-26 Z. Q. Qu , L. Chang , G. T. Dun , X. M. Cheng , C. Fang , Z. Xu , D. Yuan , L. H. Deng , X. Y. Zhang