Spectroscopic Confirmation of Young Planetary-Mass Companions on Wide Orbits

Abstract

We present moderate-resolution (R ∼ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M Jup companions ROXs 42B b and FW Tau b obtained with Keck/OSIRIS and Gemini-North/NIFS. The spectrum of ROXs 42B b exhibits clear signs of low surface gravity common to young L dwarfs, confirming its extreme youth, cool temperature, and low mass. Overall, it closely resembles the free-floating 4-7 M Jup L-type Taurus member 2MASS J04373705+2331080. The companion to FW Tau AB is more enigmatic. Our optical and near-infrared spectra show strong evidence of outflow activity and disk accretion in the form of line emission from, Paβ, and H 2 . The molecular hydrogen emission is spatially resolved as a single lobe that stretches ≈0. 1 (15 AU). Although the extended emission is not kinematically resolved in our data, its morphology resembles shock-excited H 2 jets primarily seen in young Class 0 and Class I sources. The near-infrared continuum of FW Tau b is mostly flat and lacks the deep absorption features expected for a cool, late-type object. This may be a result of accretion-induced veiling, especially in light of its strong and sustained Hα emission (EW(Hα) 290 Å). Alternatively, FW Tau b may be a slightly warmer (M5-M8) accreting low-mass star or brown dwarf (0.03-0.15 M ) with an edge-on disk. Regardless, its young evolutionary stage is in stark contrast to its Class III host FW Tau AB, indicating a more rapid disk clearing timescale for the host binary system than for its wide companion. Finally, we present near-infrared spectra of the young (∼2-10 Myr) low-mass (12-15 M Jup ) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates.

A Search for L/T Transition Dwarfs with Pan-STARRS1 and WISE. III. Young L Dwarf Discoveries and Proper Motion Catalogs in Taurus and Scorpius–Centaurus

“…This table includes the discoveries for which our spectrum has high enough S/N to extract reliable measurements of the AL13 gravity indices, corroborated by visual inspection. Our spectra for PSOJ228.6−29 and PSOJ229.2−26 and the 2MASSJ0437+2331 spectrum from Bowler et al (2014) did not yield reliable gravity scores, but do show visual indications of low gravity (Sections 4.3 and 5.1.5). a Scores in parentheses were determined using the original AL13 classification scheme, in which objects with index values corresponding to INT-G but within s 1 of the FLD-G value are classified with a score of "?."…”

“…We used the SpeX Prism spectrum for 2MASSJ0437+2331 from Bowler et al (2014) to assign a near-infrared spectral type of L1±1, based on a calculated type of L0.9±0.9 using the AL13 indices (Section 4.2). Luhman et al (2009) claimed membership in Taurus for 2MASSJ0437+2331 based on weaker NaI and K I absorption features in its red-optical spectrum, which are recognized signs of youth , along with its central projected location in Taurus.…”

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

“…Regardless of their formation route, the favorable angular separations and contrasts of wide PMCs make them attractive targets for detailed spectroscopic characterization in the nearinfrared (e.g., Bowler et al 2014;Gauza et al 2015). As such, they represent excellent targets to study the atmospheres of young gas giant planets and serve as empirical templates for discoveries with second-generation planet-finding instruments like the Gemini Planet Imager (GPI), Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE), and Subaru Coronagraphic Extreme Adaptive Optics (SCExAO).…”

NEAR-INFRARED SPECTROSCOPY OF 2M0441+2301 AabBab: A QUADRUPLE SYSTEM SPANNING THE STELLAR TO PLANETARY MASS REGIMES

“…An excess of mid-infrared emission was previously identified from both unresolved pairs, indicating that at least one component of each subsystem harbors a circum-(sub)stellar disk (Adame et al 2010;Bulger et al 2014). Spectroscopic validation is essential to confirm the low temperatures, luminosities, and masses of candidate planets at these very young ages when edge-on disks around brown dwarfs or low-mass stars can cause extinction and mimic the photometric properties of faint protoplanets (Bowler et al 2014;Kraus et al 2014;Wu et al 2015).…”