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Title: 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 {sub 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 {sub 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 [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H{sub 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{sub 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 Hαmore » 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 {sub ☉}) 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 {sub Jup}) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates.« less

Authors:
 [1]; ;  [2]
  1. California Institute of Technology, Division of Geological and Planetary Sciences, 1200 East California Boulevard, Pasadena, CA 91101 (United States)
  2. Institute for Astronomy, University of Hawai'i, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
Publication Date:
OSTI Identifier:
22351472
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 784; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ACCRETION DISKS; EMISSION; GRAVITATION; HYDROGEN; INFRARED SPECTRA; MASS; ORBITS; RESOLUTION; SPECTROSCOPY; STARS; SURFACES; VISIBLE RADIATION

Citation Formats

Bowler, Brendan P., Liu, Michael C., Mann, Andrew W., and Kraus, Adam L., E-mail: bpbowler@caltech.edu. Spectroscopic confirmation of young planetary-mass companions on wide orbits. United States: N. p., 2014. Web. doi:10.1088/0004-637X/784/1/65.
Bowler, Brendan P., Liu, Michael C., Mann, Andrew W., & Kraus, Adam L., E-mail: bpbowler@caltech.edu. Spectroscopic confirmation of young planetary-mass companions on wide orbits. United States. https://doi.org/10.1088/0004-637X/784/1/65
Bowler, Brendan P., Liu, Michael C., Mann, Andrew W., and Kraus, Adam L., E-mail: bpbowler@caltech.edu. 2014. "Spectroscopic confirmation of young planetary-mass companions on wide orbits". United States. https://doi.org/10.1088/0004-637X/784/1/65.
@article{osti_22351472,
title = {Spectroscopic confirmation of young planetary-mass companions on wide orbits},
author = {Bowler, Brendan P. and Liu, Michael C. and Mann, Andrew W. and Kraus, Adam L., E-mail: bpbowler@caltech.edu},
abstractNote = {We present moderate-resolution (R ∼ 4000-5000) near-infrared integral field spectroscopy of the young (1-5 Myr) 6-14 M {sub 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 {sub 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 [S II], [O I], Hα, Ca II, [Fe II], Paβ, and H{sub 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{sub 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 {sub ☉}) 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 {sub Jup}) companions GSC 6214-210 B and SR 12 C and find they best resemble low-gravity M9.5 and M9 substellar templates.},
doi = {10.1088/0004-637X/784/1/65},
url = {https://www.osti.gov/biblio/22351472}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 1,
volume = 784,
place = {United States},
year = {Thu Mar 20 00:00:00 EDT 2014},
month = {Thu Mar 20 00:00:00 EDT 2014}
}