TY - JOUR
T1 - A theoretical light-curve model for the 1999 outburst of U Scorpii
AU - Hachisu, Izumi
AU - Kato, Mariko
AU - Kato, Taichi
AU - Matsumoto, Katsura
N1 - Funding Information:
We are very grateful to many amateur astronomers who observed U Sco and sent their valuable data to VS-NET. We also thank the anonymous referee for many critical comments to improve the manuscript. This research has been supported in part by the Grant-in-Aid for Scientific Research (08640321, 09640325, 11640226, and 20283591) of the Japanese Ministry of Education, Science, Culture, and Sports. K. M. has been supported financially as a Research Fellow for Young Scientists by the Japan Society for the Promotion of Science.
PY - 2000/1/10
Y1 - 2000/1/10
N2 - 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.
AB - 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.
KW - Accretion, accretion disks
KW - Binaries: close
KW - Novae, cataclysmic variables
KW - Stars: individual (U Scorpii)
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U2 - 10.1086/312428
DO - 10.1086/312428
M3 - Article
AN - SCOPUS:0034627510
VL - 528
SP - L97-L100
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 PART 2
ER -