102 research outputs found
Connection between orbital modulation of H-alpha and gamma-rays in the Be/X-ray binary LSI+61303
We studied the average orbital modulation of various parameters (gamma-ray
flux, H-alpha emission line, optical V band brightness) of the radio- and
gamma-ray emitting Be/X-ray binary LSI+61303. Using the Spearman rank
correlation test, we found highly significant correlations between the orbital
variability of the equivalent width of the blue hump of the H-alpha and
Fermi-LAT flux with a Spearman p-value 2e-5, and the equivalent widths ratio
EW_B/EW_R and Fermi-LAT flux with p-value 9e-5. We also found a significant
anti-correlation between Fermi-LAT flux and V band magnitude with p-value
7.10^{-4}.
All these correlations refer to the average orbital variability, and we
conclude that the H-alpha and gamma-ray emission processes in LSI+61303 are
connected. The possible physical scenario is briefly discussed.Comment: accepted as a Letter in Astronomy and Astrophysic
Spectral observations of X Persei: Connection between H-alpha and X-ray emission
We present spectroscopic observations of the Be/X-ray binary X Per obtained
during the period 1999 - 2018. Using new and published data, we found that
during "disc-rise" the expansion velocity of the circumstellar disc is 0.4 -
0.7 km/s. Our results suggest that the disc radius in recent decades show
evidence of resonant truncation of the disc by resonances 10:1, 3:1, and 2:1,
while the maximum disc size is larger than the Roche lobe of the primary and
smaller than the closest approach of the neutron star. We find correlation
between equivalent width of H-alpha emission line () and the X-ray
flux, which is visible when . The
correlation is probably due to wind Roche lobe overflow.Comment: Accepted for publication in Astronomy & Astrophysic
Rotational velocities of the giants in symbiotic stars: III. Evidence of fast rotation in S-type symbiotics
We have measured the projected rotational velocities (vsini) in a number of
symbiotic stars and M giants using high resolution spectroscopic observations.
On the basis of our measurements and data from the literature, we compare the
rotation of mass-donors in symbiotics with vsini of field giants and find that:
(1) the K giants in S-type symbiotics rotate at vsini>4.5 km/s, which is 2-4
times faster than the field K giants;
(2) the M giants in S-type symbiotics rotate on average 1.5 times faster than
the field M giants. Statistical tests show that these differences are highly
significant: p-value < 0.001 in the spectral type bins K2III-K5III,
M0III-M6III, and M2III-M5III;
(3) our new observations of D'-type symbiotics also confirm that they are
fast rotators.
As a result of the rapid rotation, the cool giants in symbiotics should have
3-30 times larger mass loss rates. Our results suggest also that bipolar
ejections in symbiotics seem to happen in objects where the mass donors rotate
faster than the orbital period.
All spectra used in our series of papers can be obtained upon request from
the authors.Comment: MNRAS (accepted), 7 pages, 5 figure
The hidden symbiotic star SU Lyn -- detection of flickering in U band
We report photometric observations of the hidden symbiotic star SU Lyn in the optical bands. In five nights we detect a weak flickering in U band with amplitude of about 0.05 magnitudes. No intranight variations are found in B, V, g' and r' bands. This is one more indication that the secondary component is a white dwarf accreting at low accretion rate. We also searched for intranight variability of a dozen related object (RR Boo, RT Boo, AM Cyg, AG Peg, BF Cyg, NQ Gem, StHa190, V627 Cas, XX Oph, FS Cet and Y Gem) in which no variability above the observational errors is detected.This work is part of the project KP-06-H28/2 08.12.2018 ”Binary
stars with compact object” (Bulgarian National Science Fund). DM and BB acknowledge
project RD-08-100/2022. JM and PLE acknowledge support from Programa Operativo
FEDER 2014-2020 and Consejer´ıa de Econom´ıa y Conocimiento of Junta de Andaluc´ıa (Ref.
1380270)
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