Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey-猫眼课题宝

DOI：

10.1111/j.1365-2966.2008.13729.x

发表时间：

2008-06

期刊：

Monthly Notices of the Royal Astronomical Society

影响因子：

4.8

通讯作者：

中科院分区：

物理与天体物理2区

文献类型：

作者：

D. Pinfield;B. Burningham;M. Tamura;S. Leggett;N. Lodieu;P. Lucas;D. Mortlock;S. Warren;D. Homeier;M. Ishi;N. Deacon;R. McMahon;P. Hewett;M. Z. Osorio;E. Martín;H. Jones;B. Venemans;A. Day-Jones;P. Dobbie;S. Folkes;S. Dye;F. Allard;I. Baraffe;D. B. Navascués;S. Casewell;K. Chiu;G. Chabrier;F. Clarke;S. Hodgkin;A. Magazzú;M. McCaughrean;E. Moraux;T. Nakajima;Y. Pavlenko;C. U. O. Hertfordshire;UK.;N. A. Observatory;Japan.;G. Observatory;Usa;Instituto de Astrof'isica de Canarias-Instituto-de-Astrof'isica-de-Canarias-102997450;Spain.;I. -. London;Georg-August-Universitat;H Germany;Subaru Telescope;R. University;The Netherlands.;C. University;Anglo-Australian Observatory;Australia.;Cardiff University;U. Lyon;France.;C.R.A.L.;Laboratorio de Astrofisica Espacial y Fisica Fundamental-Laboratorio-de-Astrofisica-Espacial-y-Fisica-102686462;U. Leicester;U. Exeter;E. Observatory;Chile.;Fundaci'on Galileo Galilei-INAF;L. D. D. Grenoble-L.-D.-D.-Grenoble-102328384;M. A. Observatory;Ukraine;U. Wales

我们提出了15个新的T2.5-T7.5矮星的发现（估计距离在24- 93 pc之间），在UKIRT红外深空巡天的前三个主要数据发布中确定。这使得大面积巡天（迄今为止）发现的T矮星总数达到28颗。这些发现得到了近红外光谱的证实，从中我们得到了Burgasser等人（2006）统一方案的光谱类型。其中7颗T矮星的光谱类型为T2.5-T4.5，5颗为T5-T5.5，1颗为T6.5p，2颗为T7-7.5。我们评估光谱形态和颜色，以确定我们的样本中可能具有非典型物理特性的T矮星（通过与太阳邻域种群的比较），并发现其中一个新的T矮星可能是金属贫乏的，三个可能具有低表面重力，一个可能具有高表面重力。LAS T矮星的完整样本的颜色显示出一种可能的趋势，随着有效温度的降低，蓝色的Y J，和一些有趣的颜色变化J H和Z J（值得进一步研究）超过T8。来自第一次和第二次主要数据发布的LAS T矮星样本显示了J=19的一致完成水平的良好证据。通过解释不完整性的主要来源（选择、跟踪和空间）以及未解决的双星和Malmquist偏差的影响，我们估计在LAS第二次数据发布的J 619卷中有17±4个>T4矮星。与理论预测相比，亚恒星质量函数指数α在-1.0和0之间是最一致的。这与最新的2 MASS/SDSS约束（基于较低的数字统计）是一致的，并且显著低于L矮星场种群建议的α 1.0，可能是T矮星类探测到的较低质量范围的结果。

We present the discovery of fifteen new T2.5-T7.5 dwarfs (with estimated distances between �24–93pc), identified in the first three main data releases of the UKIRT Infrared Deep Sky Survey. This brings the total number of T dwarfs discovered in the Large Area Survey (to date) to 28. These discoveries are confirmed by near infrared spectroscopy, from which we derive spectral types on the unified scheme of Burgasser et al. (2006). Seven of the new T dwarfs have spectral types of T2.5-T4.5, five have spectral types of T5-T5.5, one is a T6.5p, and two are T7-7.5. We assess spectral morphology and colours to identify T dwarfs in our sample that may have non-typical physical properties (by comparison to solar neighbourhood populations), and find that one of these new T dwarfs may be metal poor, three may have low surface gravity, and one may have high surface gravity. The colours of the full sample of LAS T dwarfs show a possible trend to bluer Y J with decreasing effective temperature, and some interesting colour changes in J H and z J (deserving further investigation) beyond T8. The LAS T dwarf sample from the first and second main data releases show good evidence for a consistent level of completion to J=19. By accounting for the main sources of incompleteness (selection, follow-up and spatial) as well as the effects of unresolved binarity and Malmquist bias, we estimate that there are 17±4 >T4 dwarfs in the J 619 volume of the LAS second data release. Comparing this to theoretical predictions is most consistent with a sub-stellar mass function exponent α between -1.0 and 0. This is consistent with the latest 2MASS/SDSS constraint (which is based on lower number statistics), and is significantly lower than the α � 1.0 suggested by L dwarf field populations, possibly a result of the lower mass range probed by the T dwarf class.

Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey

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