Hydrodynamic simulations of flares on accretion disks

Glen Williams, Kerri Maletesta

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We have constructed a hydrodynamic simulation of flares on the accretion disks of cataclysmic variable stars. In these flares the disk photosphere is heated by a beam of suprathermal electrons. The beam energy flux, beam duration, position in the accretion disk, and accretion disk temperature were varied in 20 flare simulations. All the flare simulations show that above a site of maximum heating the gas is blown upward from the disk. Below this point the gas is compressed and heated. A non-LTE radiative transfer program calculates the resulting continuous emission and Balmer line radiation from the flare. The temporal development of each flare model is followed by calculating the radiation at 15-20 time steps. The Hβ line flux from accretion disks is estimated for 20 dwarf novae and 12 nova and nova-like systems by using information gathered from the literature. We then use a simple approximation for the rate of flaring across an accretion disk to see whether flares can account for all the Hβ emission. The rate of flickering observed in cataclysmic variables is used as a constraint on this model. Using flickering rates from one study we find that if each observed flicker is one magnetic flare, then flares can account for only l%-2% of the Hβ emission. A much higher flare rate can account for the observed Hβ emission if flickering studies underestimate the true rate of flaring. A flare avalanche model may account for both the observed Hβ flux and the observed flickering.

Original languageEnglish
Pages (from-to)1095-1105
Number of pages11
JournalAstronomical Journal
Issue number2 1754
StatePublished - Feb 2002


  • Novae, cataclysmic variables


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