Physical properties of IP Pegasi: an eclipsing dwarf nova with an unusually cool white dwarf
Physical properties of IP Pegasi: an eclipsing dwarf nova with an unusually cool white dwarf
复制标题
DOI：
10.1111/j.1365-2966.2009.16010.x
复制
发表时间：
2009-11
影响因子：
4.8
通讯作者：
C. Copperwheat;T. Marsh;V. Dhillon;S. Littlefair;R. Hickman;B. Gaensicke;J. S. U. O. Warwick;U. Sheffield;Keele University
中科院分区：
文献类型：
--
作者：
C. Copperwheat;T. Marsh;V. Dhillon;S. Littlefair;R. Hickman;B. Gaensicke;J. S. U. O. Warwick;U. Sheffield;Keele University
我们提出了高速光度观测的食矮新星飞马座IP（IP Peg）采取的三光束相机ULTRACAM安装在威廉赫歇尔望远镜。在2004年，该系统中的主日食被观测到两次，然后在2005年的3周内又观测到16次。我们的观测是在斯隆u '、g'和r'波段同时进行的。通过相位折叠和平均我们的数据，我们在这个系统中首次发现了白色矮星的进入，并发现白色矮星食的相位宽度为0.0935 +/- 0.0003，明显高于之前的最佳值0.0863 < phi < 0.0918。发现质量比为q = M-2/M-1 = 0.48 +/- 0.01，与先前的测量结果一致，但我们发现倾斜度为83 °.8 +/- 0 °.5，显著高于先前报道的。我们发现白色矮星的半径为0.0063 +/- 0.0003 R圆点，这意味着白色矮星的质量为1.16 +/- 0.02 M圆点。供体质量为0.55 +/- 0.02 M-圆点。白色矮星的温度更难确定，因为白色矮星的流量变化很大，即使在连续的日食之间。这在u'波段尤其明显，可能是光盘材料吸收的结果。我们对温度的最佳估计是10 000-15 000 K，这比具有这一周期的激变变星星星的预期温度低得多，意味着平均吸积速率< 5 x 10（-11）M（圆点）yr（-1），比预期速率低40倍以上。
We present high-speed photometric observations of the eclipsing dwarf nova IP Pegasi (IP Peg) taken with the triple-beam camera ULTRACAM mounted on the William Herschel Telescope. The primary eclipse in this system was observed twice in 2004, and then a further 16 times over a 3 week period in 2005. Our observations were simultaneous in the Sloan u', g' and r' bands. By phase-folding and averaging our data, we make the first significant detection of the white dwarf ingress in this system and find the phase width phi of the white dwarf eclipse to be 0.0935 +/- 0.0003, significantly higher than the previous best value of 0.0863 < phi < 0.0918. The mass ratio is found to be q = M-2/M-1 = 0.48 +/- 0.01, consistent with previous measurements, but we find the inclination to be 83 degrees.8 +/- 0 degrees.5, significantly higher than previously reported. We find the radius of the white dwarf to be 0.0063 +/- 0.0003 R-circle dot, implying a white dwarf mass of 1.16 +/- 0.02 M-circle dot. The donor mass is 0.55 +/- 0.02 M-circle dot. The white dwarf temperature is more difficult to determine, since the white dwarf is seen to vary significantly in flux, even between consecutive eclipses. This is seen particularly in the u' band, and is probably the result of absorption by disc material. Our best estimate of the temperature is 10 000-15 000 K, which is much lower than would be expected for a cataclysmic variable star with this period, and implies a mean accretion rate of < 5 x 10(-11) M(circle dot)yr(-1), more than 40 times lower than the expected rate.