arXiv subjects

Maciej Mikolajewski

Publications and source records attributed to Maciej Mikolajewski.

3 recordsLinked to original sources

arXiv2002

Possible pulsations of the M giant in MWC560

MWC 560 and other peculiar symbiotic binary, CH Cyg, have been classified as the prototypes of the new subclass of symbiotic systems - propellers, with accretion onto a magnetic white dwarf being the source of activity. The companion of the hot component in this model should demonstrate stellar wind with relatively high mass-loss. It can be expected rather a late AGB, Mira or semiregular variable (SR) than any normal red giant.Our analysis performed for the I band shows that the M giant probably belongs to such kind of stars and pulsates with a period of about 5 months.

astro-ph↗

arXiv2002

HP Lyr - possibly the hottest RV Tau type object

We report Johnson's UBVRI photometric and optical spectroscopic observations of a long period variable HP Lyr which up to now has been considered an eclipsing binary with a period of 140 days. The spectral type changes continually from A2-3 at maxima to A7-F2 at minima. We propose that the brightness changes are caused by the pulsation of the star with two periods: P1=69.35, and P2=2xP1=138.7 days. These periods decreased by more than 1% between 1960 and 1980. The spectral luminosity class determination gives an A type supergiant Iab. HP Lyr is also the optical counterpart of the infrared source IRAS 19199+3950. Relatively high galactic latitude (b=+11.7 degr) and high radial velocity (-113 km/s) indicate that HP Lyr is an evolved, most likely post-AGB star. All presented features argue that this star is an RV Tau type object.

astro-ph↗

arXiv2000

Magnetic propeller in symbiotic stars

Rapidly spinning magnetic white dwarfs in symbiotic stars may pass through the propeller stage. It is believed that a magnetic propeller acts in two such stars CH Cyg and MWC 560. We review a diversity of manifestations of the propeller there. In these systems in a quiescent state the accretion onto a white dwarf from the strong enough wind of a companion star is suppressed by the magnetic field, and the hot component luminosity is low. Since the gas stored in the envelope eventually settles to the corotation radius the star-propeller reveals itself by long-time outbursts, short-time brightness dips, strong amplitude flickering, ejection of a powerful wind and jets. The envelope appears to be stratified and inhomogeneous because of the shock pumping of the propeller. At this stage, at which catastrophic transitions to the accretion stage and back are possible, the release of energy and angular momentum of the white dwarf is maximum. Using this property, we estimate the magnetic field strength of the white dwarfs in CH Cyg and MWC 560 to be of order $10^8$ G. The most spectacular property of these stars - jets - is inherently connected with the propeller. This suggests hydromagnetic models of jet acceleration.

astro-ph↗