Query : 2020A&A...636A...1H

2020A&A...636A...1H - Astronomy and Astrophysics, volume 636A, 1-1 (2020/4-1)

Modelling hystereses observed during dwarf nova outbursts.


Abstract (from CDS):

Context. Although the disc instability model is widely accepted as the explanation for dwarf nova outbursts, it is still necessary to compare its predictions to observations because many of the constraints on angular momentum transport in accretion discs are derived from the application of this model to real systems.
Aims. We test the predictions of the model concerning the multicolour time evolution of outbursts for two well-observed systems, SS Cyg and VW Hyi.
Methods. We calculate the multicolour evolution of dwarf nova outbursts using the disc instability model and taking into account the contribution from the irradiated secondary, the white dwarf and the hot spot.
Results. Observations definitely show the existence of a hysteresis in the optical colour-magnitude diagram during the evolution of dwarf nova outbursts. We find that the disc instability model naturally explains the existence and the orientation of this hysteresis. For the specific cases of SS Cyg and VW Hyi, the colour and magnitude ranges covered during the evolution of the system are in reasonable agreement with observations. However, the observed colours are bluer than observed near the peak of the outbursts, as in steady systems, and the amplitude of the hysteresis cycle is smaller than observed. The predicted colours significantly depend on the assumptions made for calculating the disc spectrum during rise, and on the magnitude of the secondary irradiation for the decaying part of the outburst.
Conclusions. Improvements in the spectral disc models are strongly needed if the system evolution in the UV is to be addressed.

Abstract Copyright: © J.-M. Hameury et al. 2020

Journal keyword(s): accretion, accretion disks - stars: dwarf novae - instabilities

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 V* VW Hyi CV* 04 09 11.3967378648 -71 17 41.554528260   12.786 12.543 14.160   ?+L0:e 631 0
2 V* U Gem CV* 07 55 05.2324414746 +22 00 05.044127985   15.3 14.54     DA 1081 0
3 V* Z Cha CV* 08 07 27.7517751528 -76 32 00.665029356           M5.5 601 1
4 V* SU UMa CV* 08 12 28.2695986944 +62 36 22.427676396           B2 486 0
5 V* EX Dra CV* 18 04 14.2485669576 +67 54 12.273781392   14.5 14.7     ~ 121 0
6 V* SS Cyg CV* 21 42 42.8034497592 +43 35 09.867842484 11.07 12.651 12.032 9.326   K5V 1260 1

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