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arXiv 0709.0465astro-ph
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由SDSS确定的激变变星的轨道周期。II。六个天体的测量,包括两个日食系统

Orbital periods of cataclysmic variables identified by the SDSS. II. Measurements for six objects, including two eclipsing systems

John Southworth, T. R. Marsh, B. T. Gaensicke, A. Aungwerojwit, P. Hakala, D. de Martino, H. Lehto

摘要:

继续我们从论文I(Southworth等人,2006),我们提出了中等分辨率光谱和宽带测光的七个激变变量(CV)发现的SDSS。对于其中六个天体,我们得到了精确的轨道周期,所有这些都是第一次测量。对于SDSS J013132.39+090122.2,它包含一个非径向脉动的白矮星,我们发现一个轨道周期为81.54 +/- 0.13分钟和一个低的径向速度变化幅度指示一个极端的质量比。对于SDSS J205914.87+061220.4,我们发现一个周期为107.52 +/- 0.14分钟。这个物体是一个矮新星,在我们的观测中,它从第一次记录的爆发开始逐渐消失。SDSS J155531.99-001055.0的INT测光表明,该系统经历了1.5等深的日全食,发生在113.54 +/- 0.03分钟的周期内。SDSS J075443.01+500729.2的NOT光变曲线表明,该系统也是食,在205.965 +/- 0.014分钟的周期,但这里的日食是V形的,只有0.5等深。它的低发射线强度,轨道周期和V形日食明确地标志着它是一个新星天体。SDSS J005050.88+000912.6和SDSS J210449.94+010545.8的WHT光度测定分别产生80.3 +/- 2.2和103.62 +/- 0.12 min的周期。第七个也是最后一个系统SDSS J165658.12+212139.3的光度测定仅显示闪烁。我们的研究结果加强了这样一个结论,即SDSS光谱数据库的微弱星等限制意味着它所包含的CV样本与以前研究的这些对象的样本具有完全不同的特征。这里测得的六个轨道周期中有五个比观测到的2-3小时CV周期间隙短。两个系统的周期非常接近富氢CV的最小轨道周期。

英文摘要:

Continuing our work from Paper I (Southworth et al., 2006) we present medium-resolution spectroscopy and broad-band photometry of seven cataclysmic variables (CVs) discovered by the SDSS. For six of these objects we derive accurate orbital periods, all which are measured for the first time. For SDSS J013132.39+090122.2, which contains a non-radially pulsating white dwarf, we find an orbital period of 81.54 +/- 0.13 min and a low radial velocity variation amplitude indicative of an extreme mass ratio. For SDSS J205914.87+061220.4, we find a period of 107.52 +/- 0.14 min. This object is a dwarf nova and was fading from its first recorded outburst throughout our observations. INT photometry of SDSS J155531.99-001055.0 shows that this system undergoes total eclipses which are 1.5 mag deep and occur on a period of 113.54 +/- 0.03 min. A NOT light curve of SDSS J075443.01+500729.2 shows that this system is also eclipsing, on a period of 205.965 +/- 0.014 min, but here the eclipses are V-shaped and only 0.5 mag deep. Its low emission-line strengths, orbital period and V-shaped eclipse unambiguously mark it as a novalike object. WHT photometry of SDSS J005050.88+000912.6 and SDSS J210449.94+010545.8 yields periods of 80.3 +/- 2.2 and 103.62 +/- 0.12 min, respectively. Photometry of the seventh and final system, SDSS J165658.12+212139.3, shows only flickering. Our results strengthen the conclusion that the faint magnitude limit of the SDSS spectroscopic database implies that the sample of CVs contained in it has quite different characteristics to previously studied samples of these objects. Five of the six orbital periods measured here are shorter than the observed 2-3 hr CV period gap. Two systems have periods very close to the minimum orbital period for hydrogen-rich CVs.

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