Banyan. VIII. New low-mass stars and brown dwarfs with candidate circumstellar disks

Journal Article · Sun Nov 20 04:00:00 EST 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/832/1/50· OSTI ID:22868456

Boucher, Anne; Lafrenière, David; Doyon, René ^[1]; Gagné, Jonathan; Faherty, Jacqueline K. ^[2]; Malo, Lison ^[3]

---

1. Institut de Recherche sur les Exoplanètes (iREx), Université de Montréal, Département de Physique, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada)
2. Department of Terrestrial Magnetism, Carnegie Institution for Science, 5241 Broad Branch Road NW, Washington, DC 20015 (United States)
3. Canada–France–Hawaii Telescope, 65-1238 Mamalahoa Hwy, Kamuela, HI 96743 (United States)

We present the results of a search for new circumstellar disks around low-mass stars and brown dwarfs with spectral types >K5 that are confirmed or candidate members of nearby young moving groups. Our search input sample was drawn from the BANYAN surveys of Malo et al. and Gagné et al. Two Micron All-Sky Survey and Wide-field Infrared Survey Explorer data were used to detect near- to mid-infrared excesses that would reveal the presence of circumstellar disks. A total of 13 targets with convincing excesses were identified: 4 are new and 9 were already known in the literature. The new candidates are 2MASS J05010082–4337102 (M4.5), J08561384–1342242 (M8γ), J12474428–3816464 (M9γ), and J02265658–5327032 (L0δ); they are candidate members of the TW Hya (∼10±3 Myr), Columba (∼42{sub −4}{sup +6} Myr), and Tucana-Horologium (∼45±4 Myr) associations, with masses of 120 and 13–18 M{sub Jup}. The M8–L0 objects in Columba and Tucana-Horologium are potentially among the first substellar disk systems aged ∼40 Myr. Estimates of the new candidates’ mean disk temperatures and fractional luminosities are in the ranges ∼135--520 K and 0.021--0.15, respectively. New optical spectroscopy of J0501–4337 reveals strong Hα emission, possibly indicating ongoing accretion, provides a detection of lithium absorption, and shows a radial velocity measurement that is consistent with a membership to Columba. We also present a near-infrared spectrum of J0226–5327 that reveals Paschen β emission and shows signs of low surface gravity, consistent with accretion from a disk and a young age.

• OSTI ID: 22868456
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 832; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
DWARF STARS
EMISSION
GRAVITATION
INFRARED SPECTRA
INFRARED SURVEYS
LUMINOSITY
MASS
PROTOPLANETS
RADIAL VELOCITY
SPECTROSCOPY
STARS
SURFACES