L-band spectroscopy is a powerful probe of cool low-gravity atmospheres: the P, Q, and R branch fundamental transitions of methane near 3.3 mu m provide a sensitive probe of carbon chemistry; cloud thickness modifies the spectral slope across the band; and H-3(+) opacity can be used to detect aurorae. Many directly imaged gas-giant companions to nearby young stars exhibit L-band fluxes distinct from the field population of brown dwarfs at the same effective temperature. Here we describe commissioning the L-band spectroscopic mode of Clio2, the 1-5 mu m instrument behind the Magellan adaptive-optics system. We use this system to measure L-band spectra of directly imaged companions. Our spectra are generally consistent with the parameters derived from previous near-infrared spectra for these late M to early L type objects. Therefore, deviations from the field sequence are constrained to occur below 1500 K. This range includes the L-T transition for field objects and suggests that observed discrepancies are due to differences in cloud structure and CO/CH4 chemistry.
| Identifer | oai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/621975 |
| Date | 21 September 2016 |
| Creators | Stone, Jordan M., Eisner, Josh, Skemer, Andy, Morzinski, Katie M., Close, Laird, Males, Jared, Rodigas, Timothy J., Hinz, Phil, Puglisi, Alfio |
| Contributors | Univ Arizona, Steward Observ |
| Publisher | IOP PUBLISHING LTD |
| Source Sets | University of Arizona |
| Language | English |
| Detected Language | English |
| Type | Article |
| Rights | © 2016. The American Astronomical Society. All rights reserved. |
| Relation | http://stacks.iop.org/0004-637X/829/i=1/a=39?key=crossref.366e033367b4bd2b3ca8fe05a5fcc9d3 |
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