naa a22 4500 510789862 CHVBK 20180411083316.0 cr unu---uuuuu 180411e20130601xx s 000 0 eng 10.1134/S1063773713060029 doi (NATIONALLICENCE)springer-10.1134/S1063773713060029 On timing and spectral characteristics of the X-ray pulsar 4U 0115+63: Evolution of the pulsation period and the cyclotron line energy [Elektronische Daten] [P. Boldin, S. Tsygankov, A. Lutovinov] An overview of the results of observations for the transient X-ray pulsar 4U 0115+63, amember of a binary system with a Be star, since its discovery to the present day (∼40 years) based on data from more than dozen observatories and instruments is presented. An overall light curve and the history of change in the spin frequency of the neutron star over the entire history of its observations, which also includes the results of recent measurements made by the INTEGRAL observatory during the 2004, 2008, and 2011 outbursts, are provided. The source's energy spectra have also been constructed from the INTEGRAL data obtained during the 2011 outburst for a dynamic range of its luminosities 1037−7 × 1037 erg s−1. We show that apart from the fundamental harmonic of the cyclotron absorption line at energy∼11 keV, its four higher harmonics at energies ≃24, 35.6, 48.8, and 60.7 keV are detected in the spectrum. We have performed a detailed analysis of the source's spectra in the 4-28 keV energy band based on all of the available RXTE archival data obtained during bright outbursts in 1995-2011. We have confirmed that modifying the source's continuum model can lead to the disappearance of the observed anticorrelation between the energy of the fundamental harmonic of the cyclotron absorption line and the source's luminosity. Thus, the question about the evolution of the cyclotron absorption line energy with the luminosity of the X-ray pulsar 4U 0115+63 remains open and a physically justified radiation model for X-ray pulsars is needed to answer it. Pleiades Publishing, Ltd., 2013 X-ray pulsars nationallicence neutron stars nationallicence cyclotron absorption nationallicence Boldin P. Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, 117997, Moscow, Russia aut Tsygankov S. Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500, Piikkiö, Finland aut Lutovinov A. Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, 117997, Moscow, Russia aut Astronomy Letters SP MAIK Nauka/Interperiodica 39/6(2013-06-01), 375-388 1063-7737 39:6<375 2013 39 11443 https://doi.org/10.1134/S1063773713060029 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1134/S1063773713060029 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Boldin P. Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, 117997, Moscow, Russia aut NATIONALLICENCE 700 1- Tsygankov S. Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, FI-21500, Piikkiö, Finland aut NATIONALLICENCE 700 1- Lutovinov A. Space Research Institute, Russian Academy of Sciences, Profsoyuznaya ul. 84/32, 117997, Moscow, Russia aut NATIONALLICENCE 773 0- Astronomy Letters SP MAIK Nauka/Interperiodica 39/6(2013-06-01), 375-388 1063-7737 39:6<375 2013 39 11443 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer