The He II lambda1640 angstrom emission feature on the IUE spectra of II Peg has been compared with the observed X-ray flux. The atmospheric activity level is determined by comparing the several diagnostic line intensities with the solar case.


X-ray outburst of 4U 0115+634 and ROTSE observations of its optical counterpart V635 Cas
Baykal, Altan; Kiziloglu, N; Balman, S; Inam, SC (EDP Sciences, 2005-09-01)
ROTSE IIId ( The Robotic Optical Transient Experiment) observations of the X-ray binary system 4U 0115+634/V635 Cas obtained during 2004 June and 2005 January make it possible, for the first time, to study the correlation between optical and type II X-ray outbursts. The X-ray outburst sharply enhanced after periastron passage where the optical brightness was reduced by 0.3 mag for a few days. We interpret the sharp reduction of optical brightness as a sign of mass ejection from the outer parts of the disc o...
Frequency-resolved spectroscopy of XB1323-619 using XMM-Newton data: detection of a reflection region in the disc
Balman, Şölen (Oxford University Press (OUP), 2010-09-21)
We present the frequency-resolved energy spectra (FRS) of the low-mass X-ray binary dipper XB1323-619 during persistent emission in four different frequency bands using an archival XMM-Newton observation. FRS method helps to probe the inner zones of an accretion disc. XB1323-619 is an Atoll source and a type-I burster. We find that the FRS is well described by a single blackbody component with kT in a range 1.0-1.4 keV responsible for the source variability in the frequency ranges of 0.002-0.04 and 0.07-0.3...
X-ray spectral evolution of Her X-1 in a low state and the following short high state
Inam, SC; Baykal, Altan (Oxford University Press (OUP), 2005-08-21)
We analysed spectral variations of similar to 8.5-d long Rossi X-ray Timing Explorer (RXTE) monitoring observations of Her X-1 in 2001 December. This set of observations enables, for the first time, frequent continuous monitoring (111 pointings in similar to 8.5 d) of the source with RXTE including a similar to 1.7-d-long low state part and the following similar to 6.8-d-long short high state part. We used an absorbed power-law model with an iron line energy complex modelled as a Gaussian to fit both the 3-...
X-ray flux related timing and spectral features of 2S 1417-62
Inam, SC; Baykal, Altan; Scott, DM; Finger, M; Swank, J (Oxford University Press (OUP), 2004-03-21)
Rossi X-ray Timing Explorer (RXTE) observations of the X-ray transient pulsar 2S 1417-62 between 1999 November and 2000 August with a total exposure of similar to394 ks have been analysed. Observations include a main outburst followed by a series of mini outbursts. Changes in pulse morphology and pulse fraction were found to be related to the changes in X-ray flux. Particularly low X-ray flux regions were found to have significantly lower pulse fractions with different pulse morphologies. The 3-60 keV Propo...
Avdan, H.; Avdan, S.; AKYÜZ, AYSUN; Balman, Şölen; AKSAKER, NAZIM; AKKAYA ORALHAN, Inci (American Astronomical Society, 2016-09-10)
We study the X-ray and optical properties of the ultraluminous X-ray source (ULX) X-6 in the nearby galaxy NGC 4258 (M106) based on the archival XMM-Newton, Chandra, Swift, and Hubble Space Telescope (HST) observations. The source has a peak luminosity of L-X similar to 2 x 10(39) erg s(-1) in the XMM-Newton observation of 2004 June. Consideration of the hardness ratios and the spectral model parameters shows that the source seems to exhibit possible spectral variations throughout the X-ray observations. In...
Citation Formats
A. ESENDEMIR and H. ALEV, “X-RAY VS HE-II LAMBDA-1640 A CORRELATION OF II-PEG,” ASTROPHYSICS AND SPACE SCIENCE, pp. 35–41, 1992, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/64721.