A theoretical light-curve model for the 1999 outburst of U Scorpii

Izumi Hachisu, Mariko Kato, Taichi Kato, Katsura Matsumoto

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88 Citations (Scopus)

Abstract

Atheoreticallightcurveforthe1999outburstofUScorpiiispresentedinordertoobtai nvariousphysicalparametersoftherecurrentnova. OurUScomodelconsistsofaverymassivewhitedwarf(WD)withanaccretiondiskandalobe- filling,slightlyevolved,main-sequencestar(MS). Themodelincludesareflectioneffectbythecompanionandtheaccretiondisktogetherwithas hadowingeffectonthecompanionbytheaccretiondisk. Theearlyvisuallightcurve(withalinearphaseoft∼1-15daysaftermaximum) iswellreproducedbyathermonuclearrunawaymodelonaverymassiveWDclosetotheChandrasek harlimit(M WD=1.37±0.01M⊙), inwhichopticallythickwindsblowingfromtheWDplayakeyroleindeterminingthenovadurati on.Theensuingplateauphase(t∼15-30days) isalsoreproducedbythecombinationofaslightlyirradiatedMSandafullyirradiatedflarin g-updiskwitharadius∼1.4timestheRochelobesize.Thecoolingphase(t∼30- 40days)isconsistentwithalow-hydrogencontentofX≈0.05oftheenvelopeforthe1. 37M⊙WD.Thebest-fitparametersaretheWDmassofM WD∼1.37M⊙,thecompanionmassofM MS∼1.5M⊙(0.8-2.0M⊙isacceptable), theinclinationangleoftheorbit(i∼80°),andtheflaring-upedge, theverticalheightofwhichis∼0.30timestheaccretiondiskradius. Thedurationofthestrongwindphase(t∼0-17days) isveryconsistentwiththeBeppoSAXsupersoftX-raydetectionatt∼19- 20daysbecausesupersoftX-raysareself-absorbedbythemassivewind. Theenvelopemassatthepeakisestimatedtobe∼3×10 -6M⊙,whichisindicatesanaveragemassaccretionrateof∼2. 5×10-7M⊙yr -1duringthequiescentphasebetween1987and1999. ThesequantitiesareexactlythesameasthosepredictedinanewprogenitormodelofTypeIasup ernovae.

Original languageEnglish
Pages (from-to)L97-L100
JournalAstrophysical Journal
Volume528
Issue number2 PART 2
Publication statusPublished - 2000 Jan 10

Keywords

  • Accretion, accretion disks
  • Binaries: close
  • Novae, cataclysmic variables
  • Stars: individual (U Scorpii)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Hachisu, I., Kato, M., Kato, T., & Matsumoto, K. (2000). A theoretical light-curve model for the 1999 outburst of U Scorpii. Astrophysical Journal, 528(2 PART 2), L97-L100.