COOL WHITE DWARFS IDENTIFIED IN THE SECOND DATA RELEASE OF THE UKIRT INFRARED DEEP SKY SURVEY
COOL WHITE DWARFS IDENTIFIED IN THE SECOND DATA RELEASE OF THE UKIRT INFRARED DEEP SKY SURVEY
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UKIRT 红外深空调查第二次数据发布中发现的冷白矮星
DOI：
10.1088/0004-637x/692/2/1506
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
A. Nitta
中科院分区：
文献类型：
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作者：
N. Lodieu;S. Leggett;P. Bergeron;A. Nitta
我们已经将UKIRT红外深空巡天大面积巡天的第二次数据发布与斯隆数字巡天的第五次数据发布配对，以确定10个冷白色矮星候选者，从他们的测光和天体测量。在这10颗中，有一颗以前被认为是非常冷的白色矮星。我们已经获得了七个候选者的光谱使用GMOS-N光谱仪在双子座北，并已确认所有七个白色矮星。我们的测光和天体测量表明，剩下的两个物体也是白色矮星。测光和光谱的模型分析表明，7颗新确认的白色矮星和2颗新发现的可能的白色矮星的有效温度在Teff = 5400-6600 K之间。我们对先前已知的白色矮星的分析证实它是冷的，Teff = 3800 K。这颗矮星的冷却年龄为8.7 Gyr，而9颗6000 K的白色矮星的冷却年龄为1.8-3.6 Gyr。我们无法从现有的数据中确定白色矮星的质量，因此我们无法限制白色矮星的总年龄。样本中最冷的白色矮星的冷却年龄很大，加上它的切向速度估计很低，这表明它是薄盘的一个老成员，或者是银河系厚盘的一个成员，年龄为10-11 Gyr。较温暖的白色矮星似乎具有典型的厚盘甚至晕的速度;这些可能是非常古老的低质量恒星的残余物，或者它们可能是相对年轻的薄盘物体，具有异常高的空间运动。
We have paired the second data release of the Large Area Survey of the UKIRT Infrared Deep Sky Survey with the fifth data release of the Sloan Digital Sky Survey to identify 10 cool white dwarf candidates, from their photometry and astrometry. Of these 10, one was previously known to be a very cool white dwarf. We have obtained optical spectroscopy for seven of the candidates using the GMOS-N spectrograph on Gemini North, and have confirmed all seven as white dwarfs. Our photometry and astrometry indicate that the remaining two objects are also white dwarfs. The model analysis of the photometry and available spectroscopy shows that the seven confirmed new white dwarfs, and the two new likely white dwarfs, have effective temperatures in the range of Teff = 5400–6600 K. Our analysis of the previously known white dwarf confirms that it is cool, with Teff = 3800 K. The cooling age for this dwarf is 8.7 Gyr, while that for the nine ∼ 6000 K white dwarfs is 1.8–3.6 Gyr. We are unable to determine the masses of the white dwarfs from the existing data, and therefore we cannot constrain the total ages of the white dwarfs. The large cooling age for the coolest white dwarf in the sample, combined with its low estimated tangential velocity, suggests that it is an old member of the thin disk, or a member of the thick disk of the Galaxy, with an age of 10–11 Gyr. The warmer white dwarfs appear to have velocities typical of the thick disk or even halo; these may be very old remnants of low-mass stars, or they may be relatively young thin-disk objects with unusually high space motion.