Magnetic activity and evolution of Algol-type stars

Sarna, MJ
Muslimov, A
Yerli, Sinan Kaan
We examine the possibility of tracing dynamo action in mass-losing stars that are components of Algol-type binaries. Our analysis is based on the calculation of the non-conservative evolution of a system that initially consists of a 1.65-M. star with a small helium core and a 0.99-M. main-sequence companion. We perform our calculations for the evolutionary model of S Cnc in which a more massive companion fills its Roche lobe at the orbital period of the system P(orb)similar to 1.12 d. We show that to maintain the late stages of evolution of this system, which are driven by stellar 'magnetic braking', an efficient mechanism that produces large-scale surface magnetic fields in a donor star is needed. We discuss the relevance of dynamo action in a donor star to the stages of accelerated mass transfer in the evolution of Algol-type systems.


Optical imaging and spectroscopic observation of the galactic supernova remnant G85.9-0.6
GÖK, FATMA; Sezer, A.; Aktekin, E.; Guever, T.; Ercan, N. (Springer Science and Business Media LLC, 2009-11-01)
Optical CCD imaging with H alpha and [SII] filters and spectroscopic observations of the galactic supernova remnant G85.9-0.6 have been performed for the first time. The CCD image data are taken with the 1.5 m Russian-Turkish Telescope (RTT150) at TBA degrees TAK National Observatory (TUG) and spectral data are taken with the Bok 2.3 m telescope on Kitt Peak, AZ.
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...
VERITAS discovery of > 200 GeV gamma-ray emission from the intermediate-frequency-peaked BL Lacertae object W Comae
Acciari, V. A.; et. al. (IOP Publishing, 2008-09-10)
We report the detection of very high energy gamma- ray emission from the intermediate- frequency- peaked BL Lacertae object W Comae (z = 0.102) by VERITAS. The source was observed between 2008 January and April. A strong outburst of gamma-ray emission was measured in the middle of March, lasting for only 4 days. The energy spectrum measured during the two highest flare nights is fit by a power law and is found to be very steep, with a differential photon spectral index of Gamma = 3.81 +/- 0.35(stat) +/- 0.3...
Pulsar braking indices, glitches and energy dissipation in neutron stars
Alpar, M. Ali; Baykal, Altan (Oxford University Press (OUP), 2006-10-11)
Almost all pulsars with anomalous positive Omega measurements (corresponding to anomalous braking indices in the range 5 <vertical bar n vertical bar < 100), including all the pulsars with observed large glitches (Delta Omega/Omega > 10(-7)) as well as post-glitch or interglitch Omega measurements, obey the scaling between Omega and glitch parameters originally noted in the Vela pulsar. Negative second derivative values can be understood in terms of glitches that were missed or remained unresolved. We discu...
Global Site Selection for Astronomy
AKSAKER, NAZIM; Yerli, Sinan Kaan; Erdogan, M. A.; Kurt, Z.; Kaba, K.; Bayazit, M.; YEŞİLYAPRAK, Cahit (Oxford University Press (OUP), 2020-03-01)
A global site selection for astronomy was performed with 1 km spatial resolution (similar to 1 gigapixel in size) using long-term and up-to-date datasets to classify the entire terrestrial surface of the Earth. Satellite instruments are used to get the following datasets of geographical information system (GIS) layers: cloud coverage, digital elevation model, artificial light, precipitable water vapour, aerosol optical depth, wind speed, and land use and land cover. A multi-criteria decision analysis (MCDA)...
Citation Formats
M. Sarna, A. Muslimov, and S. K. Yerli, “Magnetic activity and evolution of Algol-type stars,” MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, pp. 209–214, 1997, Accessed: 00, 2020. [Online]. Available: