First High‐Contrast Science with an Integral Field Spectrograph: The Substellar Companion to GQ Lupi

Abstract

We present commissioning data from the OSIRIS integral field spectrograph (IFS) on the Keck II 10 m telescope that demonstrate the utility of adaptive optics IFS spectroscopy in studying faint close-in sub-stellar companions in the haloes of bright stars. Our R≈2000 J-and H-band spectra of the sub-stellar companion to the 1-10 Myr-old GQ Lup complement existing K-band spectra and photometry, and improve on the original estimate of its spectral type. We find that GQ Lup B is somewhat hotter (M6-L0) than reported in the discovery paper by Neuhäuser and collaborators (M9-L4), mainly due to the surface-gravity sensitivity of the K-band spectral classification indices used by the discoverers. Spectroscopic features characteristic of low surface gravity objects, such as lack of alkali absorption and a triangular H-band continuum, are indeed prominent in our spectrum of GQ Lup B. The peculiar shape of the H-band continuum and the difference between the two spectral type estimates is well explained in the context of the diminishing strength of H 2 collision induced absorption with decreasing surface gravity, as recently proposed for young ultra-cool dwarfs by Kirkpatrick and collaborators. Using our updated spectroscopic classification of GQ Lup B and a re-evaluation of the age and heliocentric distance of the primary, we perform a comparative analysis of the available sub-stellar evolutionary models to estimate the mass of the companion. We find that the mass of GQ Lup B is 0.010-0.040 M ⊙ . Hence, it is unlikely to be a wide-orbit counterpart to the known radial-velocity extrasolar planets, whose masses are 0.015 M ⊙ . Instead, GQ Lup A/B is probably a member of a growing family of very low mass ratio widely separated binaries discovered through high-contrast imaging.

The Young Substellar Companion ROXs 12 B: Near-infrared Spectrum, System Architecture, and Spin–Orbit Misalignment*

“…There are several caveats about these accreting companions that are worth noting. Paβ emission was not observed in the moderate-resolution spectroscopy of GQ Lup B presented by McElwain et al (2007) and Lavigne et al (2009), which suggests that the emission observed by Seifahrt et al (2007) was variable. Similarly, Wolff et al (2017) also found variable emission for DH Tau B.…”

An ALMA and MagAO Study of the Substellar Companion GQ Lup B∗

“…Figure 9 compares the spectral energy distribution (SED) of GQ Lup B to the 2400 K, log g=4.0 BT-Settl model (Allard et al 2011). The temperature and surface gravity are chosen to be consistent with previous estimates (e.g., Marois et al 2007;McElwain et al 2007;Lavigne et al 2009). The model is normalized at K to minimize the effects from dust emission and extinction.…”

A Substellar Common Proper-Motion Companion to the Pleiad H Ii 1348

“…The data were reduced with the OSIRIS data reduction pipeline (DRP), 6 following the procedure described in McElwain et al (2007). We used the default 7 pixel (0.…”