Search Publications
A new photometric study of Herbig Ae/Be stars in the infrared
Zhang, P.; Chen, P. S.; Shan, H. G.
In this paper we collected almost all HAeBe stars known so far (253 sources in total) to photometrically study their infrared properties. The 2MASS, WISE, IRAS and AKARI data are employed to make analyses. It is shown from several two-color diagrams that from 1 µm to 60 µm infrared radiations from circumstellar disks with the power law…
The curious temporal behavior of the frequency of different class flares
Zhong, J.; Gao, P. X.
We investigate the frequency of all (X-ray flare events higher than class B1.0), B, C, M and X-class flares, respectively, derived from the National Geophysical Data Center (NGDC) list of solar flares between May 1983 and September 2014, which corresponds to the two complete solar cycles (SCs) 22 and 23 as well as the rise and maximum phases of SC…
Flux and spectral variability of the blazar PKS 2155 -304 with XMM-Newton: Evidence of particle acceleration and synchrotron cooling
Bhagwan, Jai; Papadakis, I. E.; Wiita, Paul J. +1 more
We have analyzed XMM-Newton observations of the high energy peaked blazar, PKS 2155 -304, made on 24 May 2002 in the 0.3-10 keV X-ray band. These observations display a mini-flare, a nearly constant flux period and a strong flux increase. We performed a time-resolved spectral study of the data, by dividing the data into eight segments. We fitted t…
Detection of coronal mass ejections using AdaBoost on grayscale statistic features
Guo, Juan; Zhang, Ling; Yin, Jian-qin +2 more
We present an automatic algorithm to detect coronal mass ejections (CMEs) in Large Angle Spectrometric Coronagraph (LASCO) C2 running difference images. The algorithm includes 3 steps: (1) split the running difference images into blocks according to slice size and analyze the grayscale statistics of the blocks from a set of images with and without…
V421 Pegasi: a detached eclipsing binary with a possible γ Doradus component
Akan, C.; Çakırlı, Ö.; Özdarcan, O.
We present spectroscopic and photometric study of V421 Peg. This eclipsing binary displays lines from both components that are well separated. This allowed us to classify the primary and secondary component as F(1 ± 0.5) V and F(2 ± 0.5) V, respectively. We use our radial velocity measurements together with Hipparcos and ASAS photometry and apply …
Abundance analysis of the supergiant stars HD 80057 and HD 80404 based on their UVES Spectra
Baştürk, Ö.; Tanrıverdi, T.
This study presents elemental abundances of the early A-type supergiant HD 80057 and the late A-type supergiant HD 80404. High resolution and high signal-to-noise ratio spectra published by the UVES Paranal Observatory Project (Bagnulo et al., 2003) were analyzed to compute their elemental abundances using ATLAS9 (Kurucz, 1993; 2005; Sbordone et a…
First analysis of eight Algol-type binaries: EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri
Zasche, P.
The available photometry from the online databases were used for the first light curve analysis of eight eclipsing binary systems EI Aur, XY Dra, BP Dra, DD Her, VX Lac, WX Lib, RZ Lyn, and TY Tri. All these stars are of Algol-type, having the detached components and the orbital periods from 0.92 to 6.8 days. For the systems EI Aur and BP Dra the …
Multiwavelength modelling the SED of supersoft X-ray sources I. The method and examples
Skopal, A.
Radiation of supersoft X-ray sources (SSS) dominates both the supersof X-ray and the far-UV domain. A fraction of their radiation can be reprocessed into the thermal nebular emission, seen in the spectrum from the near-UV to longer wavelengths. In the case of symbiotic X-ray binaries (SyXBs) a strong contribution from their cool giants is indicate…
Multiwavelength modeling the SED of supersoft X-ray sources. II. RS Ophiuchi: From the explosion to the SSS phase
Skopal, A.
RS Oph is a recurrent symbiotic nova that undergoes nova-like outbursts on a time scale of 20 yr. Its two last eruptions (1985 and 2006) were subject of intensive multiwavelengths observational campaign from the X-rays to the radio. This contribution aims to determine physical parameters and the ionization structure of the nova from its explosion …
Multiwavelength modeling the SED of supersoft X-ray sources III. RS Ophiuchi: The supersoft X-ray phase and beyond
Skopal, A.
I modeled the 14 Å-37 µm SED of the recurrent symbiotic nova RS Oph during its supersoft source (SSS) phase and the following quiescent phase. During the SSS phase, the model SEDs revealed the presence of a strong stellar and nebular component of radiation in the spectrum. The former was emitted by the burning WD at highly super-Eddington ra…