L-band Spectroscopy with Magellan-AO/Clio2: First Results on Young Low-mass Companions
Journal
Date Issued
2016
Author(s)
Stone, Jordan M.
•
Eisner, Josh
•
Skemer, Andy
•
Morzinski, Katie M.
•
Close, Laird
•
Males, Jared
•
Rodigas, Timothy J.
•
Hinz, Phil
•
Abstract
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 μm 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 μm 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.
Volume
829
Issue
1
Start page
39
Issn Identifier
0004-637X
Ads BibCode
2016ApJ...829...39S
Rights
open.access
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