scholarly journals Infrared spectroscopy of Be/X-ray binaries

1994 ◽  
Vol 162 ◽  
pp. 204-205
Author(s):  
C. Everall ◽  
M.J. Coe ◽  
P. Roche ◽  
A. J. Norton ◽  
S. J. Unger
Keyword(s):  
Emission Lines ◽  
Circumstellar Disk ◽  
Density Structure ◽  
X Ray ◽  
Circumstellar Material ◽  
Field Temperature ◽  
Be Star ◽  
Ir Emission ◽  
X Ray Binaries ◽  
Depth Effects

We present infrared spectra of 4 Be/X-ray binaries in the K band, and 4 spectra in the J, H and K bands of 2 more sources. The HI IR emission lines are useful determinators of the conditions in the inner regions of the circumstellar disk about the Be star, due to optical depth effects. These are preliminary results, and hope to be followed up by high resolution echelle spectra, where we wish to estimate the velocity field, temperature and density structure of the circumstellar material.

scholarly journals Multiwavelength observations of the Be-star/X-ray binary EXO2030+375 during outburst

1994 ◽  
Vol 162 ◽  
pp. 206-207
Author(s):  
A.J. Norton ◽  
M.J. Coe ◽  
C. Everall ◽  
P. Roche ◽  
L. Bildsten ◽  
...  
Keyword(s):  
Neutron Star ◽  
Emission Lines ◽  
Be Stars ◽  
Infrared Excess ◽  
X Ray ◽  
Circumstellar Material ◽  
Spin Period ◽  
Be Star ◽  
Star Surface ◽  
X Ray Binaries

EXO2030+375 consists of a neutron star in an eccentric 46 day orbit around a 20th magnitude Be-star companion (Coe et al., 1988; Parmar et al., 1989; Stollberg et al., 1993). The Be-star is thought to be surrounded by a shell/disc of material which is responsible for the infrared excess and Balmer emission lines which are characteristic of Be-stars in general. At periastron, the neutron star passes through this circumstellar material, giving rise to enhanced accretion onto the neutron star surface. As a result of this, the X-ray emission (pulsed at the neutron star spin period of 41.8s) increases dramatically, so producing the transient, outburst behaviour which is commonly seen in Be-star / X-ray binaries.

On the nature of the X-ray outbursts in Be/X-ray binaries

2018 ◽  
Vol 14 (S346) ◽  
pp. 146-148
Author(s):  
Jingzhi Yan ◽  
Wei Liu ◽  
Peng Zhang ◽  
Qingzhong Liu
Keyword(s):  
Neutron Star ◽  
Compact Object ◽  
Optical Emission ◽  
Light Curves ◽  
High Mass ◽  
Circumstellar Disk ◽  
X Ray ◽  
Be Star ◽  
The Relationship ◽  
X Ray Binaries

AbstractBe/X-ray binaries are a major subclass of high mass X-ray binaries. Two different X-ray outbursts are displayed in the X-ray light curves of such systems. It is generally believed that the X-ray outbursts are connected with the neutron star periastron passage of the circumstellar disk around the Be star. The optical emission of the Be star should be very important to understand the X-ray emission of the compact object. We have monitored several Be/X-ray binaries photometrically and spectroscopically in the optical band. The relationship between the optical emission and X-ray activity is described, which is very useful to explain the X-ray outbursts in Be/X-ray binaries.

scholarly journals Multi-wavelength Study of the Be/X-ray Binaries

2012 ◽  
Vol 8 (S290) ◽  
pp. 351-352
Author(s):  
J. Z. Yan ◽  
H. Li ◽  
J. N. Zhou ◽  
Q. Z. Liu
Keyword(s):  
Circumstellar Disk ◽  
Density Region ◽  
X Ray ◽  
Multi Wavelength ◽  
Be Star ◽  
Hα Emission ◽  
Optical Brightness ◽  
Mass Ejection ◽  
X Ray Binaries ◽  
Ejection Event

AbstractAn anti-correlation between the optical brightness and the strength of the Hα emission was observed from two Be/X-ray binaries, A0535+26 and MXB 0656-072: when the optical brightness showed a decrease, the intensity of the Hα emission displayed an obvious increase. This anti-correlation is interpreted as the result of the mass ejection from the Be star. After the mass ejection event, a cavity or low-density region will be developing in the inner parter of the circumstellar disk. The X-ray outbursts of the Be/X-ray binaries might be connected with the mass ejections from the Be star.

scholarly journals The frequency of Kozai–Lidov disc oscillation driven giant outbursts in Be/X-ray binaries

2019 ◽  
Vol 489 (2) ◽  
pp. 1797-1804 ◽  
Author(s):  
Rebecca G Martin ◽  
Alessia Franchini
Keyword(s):  
Orbital Period ◽  
Time Scale ◽  
Orbital Plane ◽  
Material Flows ◽  
X Ray ◽  
System Parameters ◽  
Be Star ◽  
Chaotic Nature ◽  
X Ray Binaries ◽  
Good Agreement

ABSTRACT Giant outbursts of Be/X-ray binaries may occur when a Be-star disc undergoes strong eccentricity growth due to the Kozai–Lidov (KL) mechanism. The KL effect acts on a disc that is highly inclined to the binary orbital plane provided that the disc aspect ratio is sufficiently small. The eccentric disc overflows its Roche lobe and material flows from the Be star disc over to the companion neutron star causing X-ray activity. With N-body simulations and steady state decretion disc models we explore system parameters for which a disc in the Be/X-ray binary 4U 0115+634 is KL unstable and the resulting time-scale for the oscillations. We find good agreement between predictions of the model and the observed giant outburst time-scale provided that the disc is not completely destroyed by the outburst. This allows the outer disc to be replenished between outbursts and a sufficiently short KL oscillation time-scale. An initially eccentric disc has a shorter KL oscillation time-scale compared to an initially circular orbit disc. We suggest that the chaotic nature of the outbursts is caused by the sensitivity of the mechanism to the distribution of material within the disc. The outbursts continue provided that the Be star supplies material that is sufficiently misaligned to the binary orbital plane. We generalize our results to Be/X-ray binaries with varying orbital period and find that if the Be star disc is flared, it is more likely to be unstable to KL oscillations in a smaller orbital period binary, in agreement with observations.

scholarly journals Be stars in X-ray binary systems

2000 ◽  
Vol 175 ◽  
pp. 656-667 ◽  
Author(s):  
M.J. Coe
Keyword(s):  
Neutron Star ◽  
Binary Systems ◽  
Circumstellar Disk ◽  
Be Stars ◽  
X Ray ◽  
The Status ◽  
Be Star

AbstractThis paper will review the status of our observations and understanding of Be stars in X-ray binary systems. In virtually all cases the binary partner to the Be star is a neutron star. The circumstellar disk provides the accretion fuel and hence stimulates the X-ray emission, whilst the neutron star provides a valuable probe of the environment around the Be star. The results coming from studies of such systems are helping in our understanding of the Be phenomenon.

scholarly journals X-Ray Observations of B-Emission Stars (Review Paper)

1987 ◽  
Vol 92 ◽  
pp. 291-308 ◽  
Author(s):  
E.P.J. van den Heuvel ◽  
S. Rappaport
Keyword(s):  
Review Paper ◽  
Circumstellar Disks ◽  
Close Binaries ◽  
Be Stars ◽  
X Ray ◽  
Blue Stragglers ◽  
Galactic Clusters ◽  
Be Star ◽  
Emission Stars ◽  
X Ray Binaries

Most evidence on X-ray emission from the vicinity of Be stars concerns the Be/X-ray binaries. Presently some 20 of these systems are known, making them the most numerous class of massive X-ray binaries. Evidence for the binary nature of these systems comes from (i) Doppler modulation of X-ray pulse periods, (ii) periodic X-ray flaring behavior, and (iii) correlated optical and X-ray variability. The correlation between X-ray pulse period and orbital period found by Corbet (1984) can potentially provide important information on the densities and velocities in the circumstellar disks of Be stars.Evolutionary models indicate that the Be/X-ray binaries represent a later stage in the evolution of normal close binaries with initial primary masses predominantly in the the range 8 to 15 M⊙ . These models indicate that also a class of slightly less massive Be star binaries should exist in which the compact companions are white dwarfs. Be-type blue stragglers in galactic clusters may be such systems.

Soft X-ray emission lines from low-mass X-ray binaries. I - Collision-dominated models

1989 ◽  
Vol 345 ◽  
pp. 498 ◽  
Author(s):  
T. R. Kallman ◽  
S. D. Vrtilek ◽  
S. M. Kahn
Keyword(s):  
Emission Lines ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

Iron K Emission Lines in the Energy Spectra of Low‐Mass X‐Ray Binaries Observed with ASCA

2000 ◽  
Vol 131 (2) ◽  
pp. 571-591 ◽  
Author(s):  
K. Asai ◽  
T. Dotani ◽  
F. Nagase ◽  
K. Mitsuda
Keyword(s):  
Emission Lines ◽  
Energy Spectra ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Observations and Evolutionary Scenario For Be/X-Ray Binaries

1987 ◽  
Vol 92 ◽  
pp. 509-513
Author(s):  
G.M.H.J. Habets
Keyword(s):  
Close Binaries ◽  
Disk Accretion ◽  
Primary Star ◽  
X Ray ◽  
Period Distribution ◽  
Evolutionary Scenario ◽  
M 10 ◽  
Be Star ◽  
Orbital Periods ◽  
X Ray Binaries

Rappaport & Van den Heuvel (1982) suggested the following formation scenario for B emission (Be)/X-ray binaries: the progenitor of the neutron star is the initial primary star with mass M1 = 10-20 M⊙, which during hydrogen-shell burning transfers mass to the companion (with M2 < M1). The secondary is spun up due to disk-accretion (e.g. Packet 1981) and has become a rapidly rotating Be star (M ≃ 10-20 M⊙).With this scenario the observed orbital periods (Porb > 15 d) of the Be/X-ray binaries can be explained. This was shown by van den Heuvel (1983) by adopting an idealized period distribution for unevolved O- and B-type close binaries with Porb, < 30 d (see Fig. 1) and assuming conservative evolution, i.e. that mass and angular momentum are conserved during mass transfer.

scholarly journals Emission Line Variability in the Be Star X-Ray Binaries 4U1258-61 and 4U2206+54

1987 ◽  
Vol 92 ◽  
pp. 311-313
Author(s):  
Robin H.D. Corbet
Keyword(s):  
Emission Line ◽  
Circumstellar Envelope ◽  
X Ray ◽  
Be Star ◽  
X Ray Binaries

AbstractResults of programs to monitor Ha emission line variability in two Be star X-ray binaries are presented. These systems provide a means of investigating the influence of a binary companion on the circumstellar envelope of a Be star.

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