153 research outputs found
The supercritical accretion disk in SS433 and ultraluminous X-ray sources
SS433 is the only known persistent supercritical accretor, it may be very
important for understanding ultraluminous X-ray sources (ULXs) located in
external galaxies. We describe main properties of the SS433 supercritical
accretion disk and jets. Basing on observational data of SS433 and published 2D
simulations of supercritical accretion disks we estimate parameters of the
funnel in the disk/wind of SS 433. We argue that the UV radiation of the SS433
disk (~50000 K, ~10^{40}erg/s) is roughly isotropic, but X-ray radiation (~10^7
K, ~10^{40}erg/s) of the funnel is midly anisotropic. A face-on SS433 object
has to be ultraluminous in X-rays (10^{40-41}erg/s). Typical time-scales of the
funnel flux variability are estimated. Shallow and very broad (0.1-0.3c) and
blue-shifted absorption lines are expected in the funnel X-ray spectrum.Comment: 4 pages, 2 figures; Proceedings of IAUS23
Search for LBV Candidates in the M33 Galaxy
A total of 185 luminous blue variable (LBV) candidates with V < 18.5 and B-V
< 0.35 are selected based on the photometrical Survey of Local Group Galaxies
made by P. Massey et al. 2006. The candidates were selected using aperture
photometry of H-alpha images. The primary selection criterion is that the
prospective candidate should be a blue star with H-aplha emission. In order not
to miss appreciably reddened LBV candidates, we compose an additional list of
25 presumably reddened (0.35 < B-V < 1.2, V < 18.5) emission star candidates. A
comparison with the list of known variables in the M33 galaxy showed 29% of our
selected candidates to be photometrically variable. We also find our list to
agree well with the lists of emission-line objects obtained in earlier papers
using different methods.Comment: 6 figure
Superbroad Component in Emission Lines of SS 433
We have detected new components in stationary emission lines of SS 433; these
are the superbroad components that are low-contrast substrates with a width of
2000--2500 km s-1 in He I and H and 4000--5000 km s-1 in
He II . Based on 44 spectra taken during four years of
observations from 2003 to 2007, we have found that these components in the He
II and He I lines are eclipsed by the donor star; their behavior with
precessional and orbital phases is regular and similar to the behavior of the
optical brightness of SS 433. The same component in H shows neither
eclipses nor precessional variability. We conclude that the superbroad
components in the helium and hydrogen lines are different in origin. Electron
scattering is shown to reproduce well the superbroad component of H at a
gas temperature of 20--35 kK and an optical depth for Thomson scattering 0.25--0.35. The superbroad components of the helium lines are probably
formed in the wind from the supercritical accretion disk. We have computed a
wind model based on the concept of Shakura-Sunyaev supercritical disk
accretion. The main patterns of the He II line profiles are well reproduced in
this model: not only the appearance of the superbroad component but also the
evolution of the central two-component part of the profile of this line during
its eclipse by the donor star can be explained.Comment: 17 pages, 13 figures, 2 tables, published in Astronomy Letters, 2013,
vol. 39, N 12, pp. 826 - 84
Identification of the Mass Donor Star's Spectrum in SS 433
We present spectroscopy of the microquasar SS 433 obtained near primary
eclipse and disk precessional phase Psi = 0.0, when the accretion disk is
expected to be most ``face-on''. The likelihood of observing the spectrum of
the mass donor is maximized at this combination of orbital and precessional
phases since the donor is in the foreground and above the extended disk
believed to be present in the system. The spectra were obtained over four
different runs centered on these special phases. The blue spectra show clear
evidence of absorption features consistent with a classification of A3-7 I. The
behavior of the observed lines indicates an origin in the mass donor. The
observed radial velocity variations are in anti-phase to the disk, the
absorption lines strengthen at mid-eclipse when the donor star is expected to
contribute its maximum percentage of the total flux, and the line widths are
consistent with lines created in an A supergiant photosphere. We discuss and
cast doubt on the possibility that these lines represent a shell spectrum
rather than the mass donor itself. We re-evaluate the mass ratio of the system
and derive masses of 10.9 +/- 3.1 Msun and 2.9 +/- 0.7 Msun for the mass donor
and compact object plus disk, respectively. We suggest that the compact object
is a low mass black hole.
In addition, we review the behavior of the observed emission lines from both
the disk/wind and high velocity jets.Comment: submitted to ApJ, 24 pages, 7 figure
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