11 research outputs found
Rotation of the Mass Donors in High-mass X-ray Binaries and Symbiotic Stars
Our aim is to investigate the tidal interaction in High-mass X-ray Binaries
and Symbiotic stars in order to determine in which objects the rotation of the
mass donors is synchronized or pseudosynchronized with the orbital motion of
the compact companion. We find that the Be/X-ray binaries are not synchronized
and the orbital periods of the systems are greater than the rotational periods
of the mass donors. The giant and supergiant High-mass X-ray binaries and
symbiotic stars are close to synchronization. We compare the rotation of mass
donors in symbiotics with the projected rotational velocities of field giants
and find that the M giants in S-type symbiotics rotate on average 1.5 times
faster than the field M giants. We find that the projected rotational velocity
of the red giant in symbiotic star MWC 560 is v sin i = 8.2 +/- 1.5 km/s, and
estimate its rotational period to be Prot = 144 - 306 days. Using the
theoretical predictions of tidal interaction and pseudosynchronization, we
estimate the orbital eccentricity e = 0.68 - 0.82.Comment: Proceedings of the conference "The Golden Age of Cataclysmic
Variables and Related Objects II", Palermo, 9-14 September 2013. To be
published in Acta Polytechnica. 4 pages, 1 figur
Post-superhumps maximum on intranight time scales of the AM CVn star CR Boo
We present observations of the intranight brightness variability of CR Boo, a
member of the AM CVn stars group. The observational data are obtained with the
2m telescope of the Rozhen National Astronomical Observatory and the 60 cm
telescope of the Belogradchik Observatory, Bulgaria, in BVR bands. We report
the appearance of superhumps, with an amplitude from 0.08 to 0.25 mag, when the
maximum brightness reaches the magnitude 14.08 in the V band, and 14.13 in the
B band. A secondary maximum of each superhump is detected with the same
periodicity as the superhumps: Psh = 24.76 - 24.92 min. In our results, the
post maxima are shifted in time from min to min
in different nights, with an amplitude of mag and an
amplitude difference of mag towards the superhumps' maximum. We
find a correlation of the post maxima with the accretion processes at the outer
side of the disc
Searching For the Physical Drivers of Eigenvector 1: Influence of Black Hole Mass and Eddington Ratio
[Abridged] We compute the virial mass of the central black hole (M) and the
luminosity-to-mass (L/M) ratio of ~ 300 low-z quasars and luminous Seyfert 1
nuclei. We analyze: (1) whether radio-quiet and radio-loud objects show
systematic differences in terms of M and L/M; (2) the influence of M and L/M on
the shape of the H-beta broad component line profile; (3) the significance of
the so-called "blue outliers" i.e., sources showing a significant blueshift of
the [OIII] 4959, 5007 lines with respect to the narrow component of H-beta
which is used as an estimator of the quasar reference frame. We show that M and
L/M distributions for RQ and RL sources are likely different for samples
matched in luminosity and redshift. Line profile comparisons for median spectra
computed over narrow ranges of M and L/M indicate that a Lorentz function
provides a better fit for higher L/M sources and a double Gaussian for lower
L/M values. A second (redshifted) Gaussian component at low L/M appears as a
red asymmetry frequently observed in radio-loud and radio-quiet sources with
broader (FWHM > 4000 km/s) H-beta broad component profiles. This component
becomes stronger in larger mass and lower L/M sources. No specific influence of
radio loudness on the H-beta broad component profile is detected, although
equivalent widths of H-beta broad component and especially of [OIII] 4959,5007
are larger for radio-loud sources. We identify five more "blue outlier"
sources. Since these sources are, on average, one magnitude brighter than other
AGNs with similar mass, they are accreting at an Eddington ratio that is 2-3
times higher. We hint at evolutionary effects that explain some of these
results and reinforce the "Eigenvector 1" correlations.Comment: Accepted for publication in MNRA
For optical flickering in symbiotic star MWC 560
This study is based on observations of MWC560 during the last two
observational seasons (2020/2021 and 2021/2022). Other than looking for
flickering we were interested in following the variability of brightness in the
same period. Looking for similarities in the spectra with other types of stars
is also of great interest to us because it could help clarify the stellar
configuration of such objects. Our observations during the last two
observational seasons of MWC560 confirm the absence of flickering. From the
similarities of the gathered spectra of XX Oph and MWC560 we assume that the
components in XX Oph are a red giant and a white dwarf, which are also
surrounded by a common shell
Magnetic field variability in RZ Ari - an evolved M giant
International audienceRZ Ari is a fast rotating apparently single M giant of 2.2 Msun. It is fairly evolved to tip RGB or early AGB stage. In addition, the star is known as semi-regular variable. We have studied its longitudinal magnetic field variability using spectropolarimetric data obtained with Narval at Telescope Bernard Lyot, Pic du Midi Observatory, France in the period 2008 - 2018. Two periods were identified using the Lomb - Scargle method: 1310 days and 498 days. The second one is very close to the Long Secondary Period of RZ Ari (480 days) and maybe we observe for first time an interplay of the magnetic field and pulsations for a M giant. Taking into account literature data we determined the radius of the star (117.2 Rsun) that is consistent with the AGB phase. Our work hypothesis is that RZ Ari with its fast rotation is an intermediate case of dynamo generated magnetic field and shock wave compression generated fields as we observe in Miras. These stars are the next evolutionary stage, after early-AGB stars. Further study is required to confirm or reject the hypothesis and to understand better the interplay of the magnetic field and pulsation in this fairly evolved giant
Magnetic field variability in RZ ARI – a fairly evolved M giant
https://www.astro.bas.bg/XIBSAC/Proceedings/Proceedings_11BSAC.pdfInternational audienceRZ Ari is a fast rotating apparently single M giant of 2.2 Msun. It is fairly evolved to tip RGB or early AGB stage. In addition, the star is known as semi-regular variable. We have studied its longitudinal magnetic field variability using spectropolarimetric data obtained with Narval at Telescope Bernard Lyot, Pic du Midi Observatory, France in the period 2008 - 2018. Two periods were identified using the Lomb - Scargle method: 1310 days and 498 days. The second one is very close to the Long Secondary Period of RZ Ari (480 days) and maybe we observe for first time an interplay of the magnetic field and pulsations for a M giant. Taking into account literature data we determined the radius of the star (117.2 Rsun) that is consistent with the AGB phase. Our work hypothesis is that RZ Ari with its fast rotation is an intermediate case of dynamo generated magnetic field and shock wave compression generated fields as we observe in Miras. These stars are the next evolutionary stage, after early-AGB stars. Further study is required to confirm or reject the hypothesis and to understand better the interplay of the magnetic field and pulsation in this fairly evolved giant
Magnetic field variability in RZ Ari - an evolved M giant
International audienceRZ Ari is a fast rotating apparently single M giant of 2.2 Msun. It is fairly evolved to tip RGB or early AGB stage. In addition, the star is known as semi-regular variable. We have studied its longitudinal magnetic field variability using spectropolarimetric data obtained with Narval at Telescope Bernard Lyot, Pic du Midi Observatory, France in the period 2008 - 2018. Two periods were identified using the Lomb - Scargle method: 1310 days and 498 days. The second one is very close to the Long Secondary Period of RZ Ari (480 days) and maybe we observe for first time an interplay of the magnetic field and pulsations for a M giant. Taking into account literature data we determined the radius of the star (117.2 Rsun) that is consistent with the AGB phase. Our work hypothesis is that RZ Ari with its fast rotation is an intermediate case of dynamo generated magnetic field and shock wave compression generated fields as we observe in Miras. These stars are the next evolutionary stage, after early-AGB stars. Further study is required to confirm or reject the hypothesis and to understand better the interplay of the magnetic field and pulsation in this fairly evolved giant