2001A&A...373..251D


Query : 2001A&A...373..251D

2001A&A...373..251D - Astronomy and Astrophysics, volume 373, 251-271 (2001/7-1)

The disc instability model for X-ray transients: Evidence for truncation and irradiation.

DUBUS G., HAMEURY J.-M. and LASOTA J.-P.

Abstract (from CDS):

We study the prospect of explaining the outbursts of Soft X-ray Transients (SXTs) by the thermal-viscous instability in a thin disc. This instability is linked to hydrogen ionization and is significantly changed when irradiation of the disc by X-rays from the inner regions is included. We present the first numerically reliable, physically consistent calculations of the outburst cycles which include the effects of accretion disc irradiation. The decay from outburst is governed by irradiation, as pointed out by King & Ritter (1998MNRAS.293L..42K), leading to slow exponential decays. At the end of the outburst, the disc is severely depleted, which lengthens the time needed to rebuild mass to the critical density for an outburst. Despite this, the long recurrence times and quiescent X-ray luminosities of SXTs still require the inner disc to be replaced by another type of flow in quiescence, presumably a hot advection dominated accretion flow (ADAF). We include the effects of such truncation and show that the resulting lightcurves are conclusively similar to those of SXTs like A0620-00. We conclude that the two-α disc instability model provides an adequate description of the outbursts of SXTs when both truncation and irradiation are included. The values for the viscosities in outburst and in quiescence are comparable to those used in CVs. We discuss the model in the context of present observations.

Abstract Copyright:

Journal keyword(s): accretion - accretion discs - instabilities - stars: binaries: close - X-rays: general

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 V* V518 Per HXB 04 21 42.7227473352 +32 54 26.939156184 13.00 13.50 13.2     M4.5V 638 1
2 1A 0620-00 HXB 06 22 44.5423857312 -00 20 44.290460544 10.60 11.40 11.2     K3V-K7V 1073 0
3 V* KV UMa HXB 11 18 10.7930420496 +48 02 12.314730120     12.25     K5V-M1V 768 0
4 V* GU Mus HXB 11 26 26.5961559600 -68 40 32.877752952           K3V-K7V 690 1
5 V* V381 Nor HXB 15 50 58.6637920704 -56 28 35.258385000   17.95 16.6     K3III 1098 0
6 V* V1033 Sco HXB 16 54 00.137 -39 50 44.90   15.20 14.2 16.14   F5IV 1793 1
7 X Aql X-1 LXB 19 11 16.0571313336 +00 35 05.868232692           ~ 1081 1
8 V* WZ Sge CV* 20 07 36.5037622512 +17 42 14.733254952   15.30 15.20     DAepv 918 0

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2022.08.13-23:35:18

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