TY - JOUR
T1 - A model for the quiescent phase of the recurrent nova U Scorpii
AU - Hachisu, Izumi
AU - Kato, Mariko
AU - Kato, Taichi
AU - Matsumoto, Katsura
AU - Nomoto, Ken'ichi
N1 - Funding Information:
We thank the anonymous referee for many critical comments that helped to improve the manuscript. This research has been supported in part by the Grants-in-Aid for Scientific Research (07CE200, 08640321, 09640325, 11640226, and 20283591) of the Japanese Ministry of Education, Science, Culture, and Sports. K. M. has been financially supported as a Research Fellow for Young Scientists by the Japan Society for the Promotion of Science.
PY - 2000/5/10
Y1 - 2000/5/10
N2 - A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d ∼ 6 kpc) and the quiescences (d ∼ 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M⊙ WD + 1.5 M⊙ MS (0.8-2.0 M⊙ MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i ∼ 80°. The calculated color is rather blue (B-V ∼ 0.0) for a suggested mass accretion rate of 2.5 × 10-7 M⊙ yr-1, thus indicating a large color excess of E(B-V) ∼ 0.56 with the observational color of B-V = 0.56 in quiescence. Such a large color excess corresponds to an absorption of Av ∼ 1.8 and AB11 ∼ 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of ∼3 × 10-7 M⊙ yr-1 through the outer Lagrangian points in quiescence.
AB - A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d ∼ 6 kpc) and the quiescences (d ∼ 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M⊙ WD + 1.5 M⊙ MS (0.8-2.0 M⊙ MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i ∼ 80°. The calculated color is rather blue (B-V ∼ 0.0) for a suggested mass accretion rate of 2.5 × 10-7 M⊙ yr-1, thus indicating a large color excess of E(B-V) ∼ 0.56 with the observational color of B-V = 0.56 in quiescence. Such a large color excess corresponds to an absorption of Av ∼ 1.8 and AB11 ∼ 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of ∼3 × 10-7 M⊙ yr-1 through the outer Lagrangian points in quiescence.
KW - Accretion, accretion disks
KW - Binaries: close
KW - Novae, cataclysmic variables
KW - Stars: individual (U scorpii)
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U2 - 10.1086/312684
DO - 10.1086/312684
M3 - Article
AN - SCOPUS:0034630555
VL - 534
SP - L189-L192
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2 PART 2
ER -