SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS
We present medium-resolution optical (λ/Δλ ~ 4000) and near-infrared (λ/Δλ ~ 8000) spectral data for components of the newly discovered WISE J104915.57-531906.1AB (Luhman 16AB) brown dwarf binary. The optical spectra reveal strong 6708 Å Li I absorption in both Luhman 16A (8.0 ± 0.4 Å) and Luhman 16...
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| Format: | Article |
| Language: | en_US |
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Institute of Physics/American Astronomical Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/94628 https://orcid.org/0000-0003-3769-9559 |
| _version_ | 1826217823477694464 |
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| author | Faherty, Jacqueline K. Beletsky, Yuri Burgasser, Adam J. Tinney, Chris Osip, David J. Filippazzo, Joseph C. Simcoe, Robert A. |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Faherty, Jacqueline K. Beletsky, Yuri Burgasser, Adam J. Tinney, Chris Osip, David J. Filippazzo, Joseph C. Simcoe, Robert A. |
| author_sort | Faherty, Jacqueline K. |
| collection | MIT |
| description | We present medium-resolution optical (λ/Δλ ~ 4000) and near-infrared (λ/Δλ ~ 8000) spectral data for components of the newly discovered WISE J104915.57-531906.1AB (Luhman 16AB) brown dwarf binary. The optical spectra reveal strong 6708 Å Li I absorption in both Luhman 16A (8.0 ± 0.4 Å) and Luhman 16B (3.8 ± 0.4 Å) confirming their substellar mass. Interestingly, this is the first detection of Li I absorption in a T dwarf. In the near-infrared data, we find strong K I absorption at 1.168, 1.177, 1.243, and 1.254 μm in both components. Neither the optical nor the near-infrared alkali lines show low surface gravity signatures. Along with the Li I absorption detection, we can broadly constrain the system age to 0.1-3 Gyr or the mass to 20-65 M [subscript Jup] for each component. Compared to the strength of K I line absorption in equivalent spectral subtype brown dwarfs, Luhman 16A is weaker while Luhman 16B is stronger. Analyzing the spectral region around each doublet in distance scaled flux units and comparing the two sources, we confirm the J-band flux reversal and find that Luhman 16B has a brighter continuum in the 1.17 μm and 1.25 μm regions than Luhman 16A. Converting flux units to a brightness temperature we interpret this to mean that the secondary is ~50 K warmer than the primary in regions dominated by condensate grain scattering. One plausible explanation for this difference is that Luhman 16B has thinner clouds or patchy holes in its atmosphere allowing us to see to deeper, hotter regions. We also detect comparably strong FeH in the 0.9896 μm Wing-Ford band for both components. Traditionally, a signpost of changing atmosphere conditions from late-type L to early T, the persistence and similarity of FeH at 0.9896 μm in both Luhman 16A and Luhman 16B is an indication of homogenous atmosphere conditions. We calculate bolometric luminosities from observed data supplemented with best fit models for longer wavelengths and find the components are consistent within 1σ with resultant T [subscript effs] of 1310 ± 30 K and 1280 ± 75 K for Luhman 16AB respectively. |
| first_indexed | 2024-09-23T17:09:43Z |
| format | Article |
| id | mit-1721.1/94628 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T17:09:43Z |
| publishDate | 2015 |
| publisher | Institute of Physics/American Astronomical Society |
| record_format | dspace |
| spelling | mit-1721.1/946282022-10-03T10:49:56Z SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS Faherty, Jacqueline K. Beletsky, Yuri Burgasser, Adam J. Tinney, Chris Osip, David J. Filippazzo, Joseph C. Simcoe, Robert A. Massachusetts Institute of Technology. Department of Physics MIT Kavli Institute for Astrophysics and Space Research Simcoe, Robert A. We present medium-resolution optical (λ/Δλ ~ 4000) and near-infrared (λ/Δλ ~ 8000) spectral data for components of the newly discovered WISE J104915.57-531906.1AB (Luhman 16AB) brown dwarf binary. The optical spectra reveal strong 6708 Å Li I absorption in both Luhman 16A (8.0 ± 0.4 Å) and Luhman 16B (3.8 ± 0.4 Å) confirming their substellar mass. Interestingly, this is the first detection of Li I absorption in a T dwarf. In the near-infrared data, we find strong K I absorption at 1.168, 1.177, 1.243, and 1.254 μm in both components. Neither the optical nor the near-infrared alkali lines show low surface gravity signatures. Along with the Li I absorption detection, we can broadly constrain the system age to 0.1-3 Gyr or the mass to 20-65 M [subscript Jup] for each component. Compared to the strength of K I line absorption in equivalent spectral subtype brown dwarfs, Luhman 16A is weaker while Luhman 16B is stronger. Analyzing the spectral region around each doublet in distance scaled flux units and comparing the two sources, we confirm the J-band flux reversal and find that Luhman 16B has a brighter continuum in the 1.17 μm and 1.25 μm regions than Luhman 16A. Converting flux units to a brightness temperature we interpret this to mean that the secondary is ~50 K warmer than the primary in regions dominated by condensate grain scattering. One plausible explanation for this difference is that Luhman 16B has thinner clouds or patchy holes in its atmosphere allowing us to see to deeper, hotter regions. We also detect comparably strong FeH in the 0.9896 μm Wing-Ford band for both components. Traditionally, a signpost of changing atmosphere conditions from late-type L to early T, the persistence and similarity of FeH at 0.9896 μm in both Luhman 16A and Luhman 16B is an indication of homogenous atmosphere conditions. We calculate bolometric luminosities from observed data supplemented with best fit models for longer wavelengths and find the components are consistent within 1σ with resultant T [subscript effs] of 1310 ± 30 K and 1280 ± 75 K for Luhman 16AB respectively. National Science Foundation (U.S.) (NSF IRFP award No. 0965192) United States. National Aeronautics and Space Administration (NASA ADAP grant 11-ADAP11-0169) 2015-02-19T15:10:44Z 2015-02-19T15:10:44Z 2014-08 2013-12 Article http://purl.org/eprint/type/JournalArticle 0004-637X 1538-4357 http://hdl.handle.net/1721.1/94628 Faherty, Jacqueline K., Yuri Beletsky, Adam J. Burgasser, Chris Tinney, David J. Osip, Joseph C. Filippazzo, and Robert A. Simcoe. “SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS.” The Astrophysical Journal 790, no. 2 (July 8, 2014): 90.© 2014 American Astronomical Society. https://orcid.org/0000-0003-3769-9559 en_US http://dx.doi.org/10.1088/0004-637X/790/2/90 Astrophysical Journal Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. application/pdf Institute of Physics/American Astronomical Society American Astronomical Society |
| spellingShingle | Faherty, Jacqueline K. Beletsky, Yuri Burgasser, Adam J. Tinney, Chris Osip, David J. Filippazzo, Joseph C. Simcoe, Robert A. SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title | SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title_full | SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title_fullStr | SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title_full_unstemmed | SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title_short | SIGNATURES OF CLOUD, TEMPERATURE, AND GRAVITY FROM SPECTRA OF THE CLOSEST BROWN DWARFS |
| title_sort | signatures of cloud temperature and gravity from spectra of the closest brown dwarfs |
| url | http://hdl.handle.net/1721.1/94628 https://orcid.org/0000-0003-3769-9559 |
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