将加拿大-法国褐矮星巡天扩展到近红外:来自CFBDSIR的第一颗超冷褐矮星
Extending the Canada-France brown Dwarfs Survey to the near-infrared: first ultracool brown dwarfs from CFBDSIR
摘要:
我们目前正在进行的加拿大-法国褐矮星巡天-红,以下CFBDSIR,近红扩展到光学宽视场调查CFBDS的第一个结果。我们的最终目标是通过找到一个统计上显着的样本的对象冷却器低于650 K,并探索建立在一个定义良好的样本,这样的对象的超冷褐矮星质量函数约束超冷大气物理。使用优化的psf拟合在CFHT/WIRCam J和CFHT/MegaCam z'图像中识别候选者,并且我们在NTT使用SOFI进行指向近红外成像。我们最终获得了最冷候选者的低分辨率光谱,以验证他们的大气物理学。到目前为止,我们已分析和跟进了335平方度调查中首66平方度的所有候选人。我们确定了55个z '-J > 3:5的T矮星候选者,并根据它们的远红和近红外颜色确认了其中6个是T矮星,包括3个强晚于T8的候选者。我们还在这里介绍了这些超冷矮星之一CFBDSIR 1458 +1013的近红外光谱,这证实了它是已知最冷的褐矮星之一,可能在550- 600 K温度范围内。从完成的调查中,我们预计会发现10到15颗晚于T8的矮星,这是已知数量的两倍多。这将有助于详细研究它们的极端大气特性,并为研究它们的光度函数提供更强的统计基础。
英文摘要:
We present the first results of the ongoing Canada-France Brown Dwarfs Survey-InfraRed, hereafter CFBDSIR, a Near InfraRed extension to the optical wide-field survey CFBDS. Our final objectives are to constrain ultracool atmosphere physics by finding a statistically significant sample of objects cooler than 650K and to explore the ultracool brown dwarf mass function building on a well defined sample of such objects. Candidates are identified in CFHT/WIRCam J and CFHT/MegaCam z' images using optimised psf-fitting, and we follow them up with pointed near infrared imaging with SOFI at NTT. We finally obtain low resolution spectroscopy of the coolest candidates to characterise their atmospheric physics. We have so far analysed and followed up all candidates on the first 66 square degrees of the 335 square degrees survey. We identified 55 T-dwarfs candidates with z'-J > 3:5 and have confirmed six of them as T-dwarfs, including 3 that are strong later-than-T8 candidates, based on their far-red and NIR colours. We also present here the NIR spectra of one of these ultracool dwarfs, CFBDSIR1458+1013 which confirms it as one of the coolest brown dwarf known, possibly in the 550-600K temperature range. From the completed survey we expect to discover 10 to 15 dwarfs later than T8, more than doubling the known number of such objects. This will enable detailed studies of their extreme atmospheric properties and provide a stronger statistical base for studies of their luminosity function.
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