A Universal Decline Law of Classical Novae. II. GK Persei 1901 and Novae in 2005
A Universal Decline Law of Classical Novae. II. GK Persei 1901 and Novae in 2005
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DOI：
10.1086/517600
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发表时间：
2007-02
期刊：
影响因子：
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通讯作者：
I. Hachisu;M. Kato
中科院分区：
文献类型：
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作者：
I. Hachisu;M. Kato
经典新星的光学和红外光曲线在不同的白矮星质量和化学成分之间大致相同，当光学薄射出的自由辐射是球形的，并控制着新星的连续通量时。这样的同源模板光曲线被称为“普适衰变定律”。通过引入一个时间尺度因子来拉伸或挤压模板光曲线以与观测结果相匹配，可以从这一普遍定律近似地再现各种新星光曲线。光曲线的时间标度强烈地依赖于WD质量，而弱于化学成分，因此我们能够从光曲线拟合中粗略地估计WD质量。我们已经将宇宙衰变定律应用于旧有的新星GK Persei 1901和2005年爆发的新星。GK Per的WD质量估计为1.15M☉，这与由轨道速度变化确定的WD质量中心值一致。2005年其他10颗新星的WD质量也被估计为1.05M☉(V2361Cyg)，1.15M☉(V382 NOR)，1.2M☉(V5115Sgr)，0.7M☉(V378Ser)，0.9M☉(V5116Sgr)，1.25M☉(V1188Sco)，0.7M☉(V1047Cen)，0.95M☉(V476SCT)，0.95M☉(V1663Aql)和1.30M☉(V477SCT)，在±0.1M☉的粗略精度内。2005年的10颗新星中有4颗(V382 NOR、V5115 SGR、V1188 Sco和V477 SCT)可能是O-Ne-mg WD上的霓虹新星。每个WD质量对化学成分(尤其是氢质量分数X)的依赖性很弱，即6个CO新星的WD质量增加了+0.5(X-0.35)M☉，以上4个霓虹新星的WD质量增加了+0.5(X-0.5 5)M☉。讨论了各种新星参数与其WD质量的关系。
Optical and infrared light curves of classical novae are approximately homologous among various white dwarf (WD) masses and chemical compositions when free-free emission from optically thin ejecta is spherical and dominates the continuum flux of novae. Such a homologous template light curve is called "a universal decline law." Various nova light curves are approximately reproduced from this universal law by introducing a timescaling factor which stretches or squeezes the template light curve to match the observation. The timescale of the light curve depends strongly on the WD mass but weakly on the chemical composition, so we are able to roughly estimate the WD mass from the light-curve fitting. We have applied the universal decline law to the old nova GK Persei 1901 and recent novae that outbursted in 2005. The estimated WD mass is 1.15 M☉ for GK Per, which is consistent with a central value of the WD mass determined from the orbital velocity variations. The other WD masses of 10 novae in 2005 are also estimated to be 1.05 M☉ (V2361 Cyg), 1.15 M☉ (V382 Nor), 1.2 M☉ (V5115 Sgr), 0.7 M☉ (V378 Ser), 0.9 M☉ (V5116 Sgr), 1.25 M☉ (V1188 Sco), 0.7 M☉ (V1047 Cen), 0.95 M☉ (V476 Sct), 0.95 M☉ (V1663 Aql), and 1.30 M☉ (V477 Sct), within a rough accuracy of ±0.1 M☉. Four (V382 Nor, V5115 Sgr, V1188 Sco, and V477 Sct) of 10 novae in the year 2005 are probably neon novae on an O-Ne-Mg WD. Each WD mass depends weakly on the chemical composition (especially the hydrogen content X in mass weight), i.e., the obtained WD masses increase by +0.5(X - 0.35) M☉ for the six CO novae and by +0.5(X - 0.55) M☉ for the four neon novae above. Various nova parameters are discussed in relation to its WD mass.