WISEA J041451.67–585456.7 and WISEA J181006.18–101000.5: The First Extreme T-type Subdwarfs?
WISEA J041451.67–585456.7 and WISEA J181006.18–101000.5: The First Extreme T-type Subdwarfs?
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DOI：
10.3847/1538-4357/ab9a40
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发表时间：
2020-07
期刊：
影响因子：
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通讯作者：
A. Schneider;A. Burgasser;R. Gerasimov;F. Marocco;J. Gagné;S. Goodman;Paul-André Beaulieu;William Pendrill;A. Rothermich;Arttu Sainio;M. Kuchner;D. Caselden;A. Meisner;J. Faherty;E. Mamajek;C. Hsu;J. Greco;M. Cushing;J. Kirkpatrick;Daniella C. Bardalez-Gagliuffi;S. Logsdon;K. Allers;J. Debes
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文献类型：
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作者：
A. Schneider;A. Burgasser;R. Gerasimov;F. Marocco;J. Gagné;S. Goodman;Paul-André Beaulieu;William Pendrill;A. Rothermich;Arttu Sainio;M. Kuchner;D. Caselden;A. Meisner;J. Faherty;E. Mamajek;C. Hsu;J. Greco;M. Cushing;J. Kirkpatrick;Daniella C. Bardalez-Gagliuffi;S. Logsdon;K. Allers;J. Debes
WISEA J041451.67 - 585456.7和WISEA J181006.18 - 101000.5是两颗低温（1200-1400 K）、高自行的T型次矮星。这两个天体都是通过它们的高自行（>0.“5 yr−1）发现的; WISEA J181006.18−101000.5是NEOWISE自行调查的一部分，WISEA J041451.67−585456.7是公民科学项目后院世界的一部分;行星9。我们已经用后续的近红外光谱证实了两者都是褐矮星。它们的光谱和近红外颜色在已知的棕矮星中是独一无二的，有些颜色与L型棕矮星一致，而其他颜色则类似于最新的T型棕矮星。虽然没有前向模型能一致地再现它们在近红外光谱中看到的特征，但最接近的匹配表明金属丰度非常低（[Fe/H] ≤ −1），使这些物体可能是T光谱类（esdT）极端次矮星的第一个例子。WISEA J041451.67−585456.7和WISEA J181006.18−101000.5被发现是占据“亚恒星过渡区”的小天体群的一部分，并且在这一群中所有天体的质量和有效温度都是最低的。
We present the discoveries of WISEA J041451.67−585456.7 and WISEA J181006.18−101000.5, two low-temperature (1200–1400 K), high proper motion T-type subdwarfs. Both objects were discovered via their high proper motion (>0.″5 yr−1); WISEA J181006.18−101000.5 as part of the NEOWISE proper motion survey and WISEA J041451.67−585456.7 as part of the citizen science project Backyard Worlds; Planet 9. We have confirmed both as brown dwarfs with follow-up near-infrared spectroscopy. Their spectra and near-infrared colors are unique among known brown dwarfs, with some colors consistent with L-type brown dwarfs and other colors resembling those of the latest-type T dwarfs. While no forward model consistently reproduces the features seen in their near-infrared spectra, the closest matches suggest very low metallicities ([Fe/H] ≤ −1), making these objects likely the first examples of extreme subdwarfs of the T spectral class (esdT). WISEA J041451.67−585456.7 and WISEA J181006.18−101000.5 are found to be part of a small population of objects that occupy the “substellar transition zone,” and have the lowest masses and effective temperatures of all objects in this group.