Detection of Methane in the Closest Extreme Metal-poor T Dwarf WISEA J181006.18-101000.5
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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2025
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| _version_ | 1866913763840491520 |
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| author | Zhang, Jerry Jun-Yan Lodieu, Nicolas Martín, Eduardo L. Tremblin, Pascal Osorio, María Rosa Zapatero Béjar, Víctor J. S. Vitas, Nikola Gauza, Bartosz Pavlenko, Yakiv V. Rebolo, Rafael |
| author_facet | Zhang, Jerry Jun-Yan Lodieu, Nicolas Martín, Eduardo L. Tremblin, Pascal Osorio, María Rosa Zapatero Béjar, Víctor J. S. Vitas, Nikola Gauza, Bartosz Pavlenko, Yakiv V. Rebolo, Rafael |
| contents | WISEA J181006.18-101000.5 (WISE1810) is the nearest metal-poor ultracool dwarf to the Sun. It has a low effective temperature and has been classified as extreme early-T subdwarf. However, methane, the characteristic molecule of the spectral class T, was not seen in the previous low-resolution spectrum. Using the 10.4-m Gran Telescopio Canarias, we collected a high-quality JHK-band intermediate-resolution R~5000 spectrum of WISE1810, in which a 17+/-6 ppm of methane is clearly detected, while carbon monoxide is absent. Based on customly computed ATMO2020++ model, we estimated an effective temperature of 1000+/-100 K, a high surface gravity of log g = 5.5+/-0.5 dex, a carbon abundance [C/H]=-1.5+/-0.2 dex, inferring [Fe/H]=-1.7+/-0.2 dex. Potassium is not seen in our data, and the upper limits of pseudo-equivalent width of J-band atomic lines are at least 25 to 60 times weaker than those measured from solar-metallicity early-T counterparts. We measured a heliocentric radial velocity of -83+/-13 km/s, inferring that WISE1810 is more likely a thick disk member. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2503_22289 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Detection of Methane in the Closest Extreme Metal-poor T Dwarf WISEA J181006.18-101000.5 Zhang, Jerry Jun-Yan Lodieu, Nicolas Martín, Eduardo L. Tremblin, Pascal Osorio, María Rosa Zapatero Béjar, Víctor J. S. Vitas, Nikola Gauza, Bartosz Pavlenko, Yakiv V. Rebolo, Rafael Solar and Stellar Astrophysics Earth and Planetary Astrophysics WISEA J181006.18-101000.5 (WISE1810) is the nearest metal-poor ultracool dwarf to the Sun. It has a low effective temperature and has been classified as extreme early-T subdwarf. However, methane, the characteristic molecule of the spectral class T, was not seen in the previous low-resolution spectrum. Using the 10.4-m Gran Telescopio Canarias, we collected a high-quality JHK-band intermediate-resolution R~5000 spectrum of WISE1810, in which a 17+/-6 ppm of methane is clearly detected, while carbon monoxide is absent. Based on customly computed ATMO2020++ model, we estimated an effective temperature of 1000+/-100 K, a high surface gravity of log g = 5.5+/-0.5 dex, a carbon abundance [C/H]=-1.5+/-0.2 dex, inferring [Fe/H]=-1.7+/-0.2 dex. Potassium is not seen in our data, and the upper limits of pseudo-equivalent width of J-band atomic lines are at least 25 to 60 times weaker than those measured from solar-metallicity early-T counterparts. We measured a heliocentric radial velocity of -83+/-13 km/s, inferring that WISE1810 is more likely a thick disk member. |
| title | Detection of Methane in the Closest Extreme Metal-poor T Dwarf WISEA J181006.18-101000.5 |
| topic | Solar and Stellar Astrophysics Earth and Planetary Astrophysics |
| url | https://arxiv.org/abs/2503.22289 |