The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs
The Field Substellar Mass Function Based on the Full-sky 20 pc Census of 525 L, T, and Y Dwarfs
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DOI：
10.3847/1538-4365/abd107
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发表时间：
2020-11
期刊：
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通讯作者：
J. Kirkpatrick;C. Gelino;J. Faherty;A. Meisner;D. Caselden;A. Schneider;F. Marocco;Alfred J. Cayago;R. Smart;P. Eisenhardt;M. Kuchner;E. Wright;M. Cushing;K. Allers;D. B. Gagliuffi;A. Burgasser;J. Gagné;S. Logsdon;E. Martin;J. Ingalls;P. Lowrance;E. Abrahams;C. Aganze;R. Gerasimov;Eileen C. Gonzales;C. Hsu;N. Kamraj;Rocio Kiman;J. Rees;C. Theissen;Kareem Ammar;Nikolaj Stevnbak Andersen;Paul-André Beaulieu;G. Colin;C. Elachi;S. Goodman;Léopold Gramaize;Leslie K. Hamlet;Justin Hong;A. Jonkeren;Mohammed M. Khalil;David W. Martin;William Pendrill;Benjamin Pumphrey;A. Rothermich;Arttu Sainio;A. Stenner;Christopher Tanner;M. Thévenot;N. V. Voloshin;Jim Walla;Zbigniew Wędracki
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文献类型：
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作者：
J. Kirkpatrick;C. Gelino;J. Faherty;A. Meisner;D. Caselden;A. Schneider;F. Marocco;Alfred J. Cayago;R. Smart;P. Eisenhardt;M. Kuchner;E. Wright;M. Cushing;K. Allers;D. B. Gagliuffi;A. Burgasser;J. Gagné;S. Logsdon;E. Martin;J. Ingalls;P. Lowrance;E. Abrahams;C. Aganze;R. Gerasimov;Eileen C. Gonzales;C. Hsu;N. Kamraj;Rocio Kiman;J. Rees;C. Theissen;Kareem Ammar;Nikolaj Stevnbak Andersen;Paul-André Beaulieu;G. Colin;C. Elachi;S. Goodman;Léopold Gramaize;Leslie K. Hamlet;Justin Hong;A. Jonkeren;Mohammed M. Khalil;David W. Martin;William Pendrill;Benjamin Pumphrey;A. Rothermich;Arttu Sainio;A. Stenner;Christopher Tanner;M. Thévenot;N. V. Voloshin;Jim Walla;Zbigniew Wędracki
最后，我们提出了361 L，T和Y矮星的斯皮策三角视差。我们将这些联合收割机与先前的研究相结合，建立了一个525个已知的L，T和Y矮星的列表，其中38个是第一次出现在这里。使用已发表的光度学和光谱学以及我们自己的后续行动，我们提出了一系列的颜色幅度和颜色颜色图，以进一步表征普查成员，我们提供多项式拟合的批量趋势。使用这些特征，我们为每个对象分配一个T eff值，并判断T eff和频谱类型的bin上的样本完整性。除了≥T8和T eff < 600 K的类型外，我们的普查在统计上完全达到20 pc的极限。我们将我们测量的空间密度与模拟的密度分布进行比较，发现最佳拟合是α = 0.6 ± 0.1的幂律（）。我们发现，Saumon和Marley的演化模型正确地预测了在1200 K < T eff < 1350 K时观察到的空间密度尖峰的大小，认为这是由L/T转变的冷却时间尺度增加引起的。使用该样品定义低质量末端需要一个统计学上更稳健和完整的矮星样品≥ Y 0.5且T eff < 400 K。我们的结论是，这种寒冷的对象必须存在大量的，尽管事实上，很少有到目前为止已被确定，我们讨论了可能的原因，为什么他们在很大程度上逃避检测。
We present final Spitzer trigonometric parallaxes for 361 L, T, and Y dwarfs. We combine these with prior studies to build a list of 525 known L, T, and Y dwarfs within 20 pc of the Sun, 38 of which are presented here for the first time. Using published photometry and spectroscopy as well as our own follow-up, we present an array of color–magnitude and color–color diagrams to further characterize census members, and we provide polynomial fits to the bulk trends. Using these characterizations, we assign each object a T eff value and judge sample completeness over bins of T eff and spectral type. Except for types ≥T8 and T eff < 600 K, our census is statistically complete to the 20 pc limit. We compare our measured space densities to simulated density distributions and find that the best fit is a power law ( ) with α = 0.6 ± 0.1. We find that the evolutionary models of Saumon & Marley correctly predict the observed magnitude of the space density spike seen at 1200 K < T eff < 1350 K, believed to be caused by an increase in the cooling timescale across the L/T transition. Defining the low-mass terminus using this sample requires a more statistically robust and complete sample of dwarfs ≥Y0.5 and with T eff < 400 K. We conclude that such frigid objects must exist in substantial numbers, despite the fact that few have so far been identified, and we discuss possible reasons why they have largely eluded detection.