Accretion and Outflow in the Substellar Domain: Magellan Spectroscopy of LS-RCrA 1

We present low-, medium-, and high-resolution optical spectra, obtained with the Magellan Baade 6.5 m telescope, of LS-RCrA 1, a late-type object identified recently by Fernandez & Comeron in the R Coronae Australis star-forming region. We confirm both pre-main-sequence status and membership in the R CrA region for this object, through the detection of Li I, presence of narrow K I indicative of low gravity, and measurement of radial velocity. The Halpha emission profile is very broad, with a 10% full width of 316 km s super(-1) at high resolution, implying the presence of ongoing accretion. Our spectra also exhibit many forbidden emission lines indicative of mass outflow, in agreement with the Fernandez & Comeron results. We derive a spectral type, independent of extinction, of M6.5 plus or minus 0.5 IV. Using new Two Micron All Sky Survey (2MASS) near-infrared photometry, no significant near-infrared (NIR) excess is found. Our optical veiling measurements yield a mass accretion rate of 10 super(-10) ~ M ~ 10 super(-9) M sub(o) yr super(-1). The presence of prominent outflow signatures at these low accretion rates is initially puzzling. We consider, and discard as improbable, the possibility that these signatures arise in a line-of-sight Herbig-Haro knot unassociated with LS-RCrA 1 itself. However, if LS-RCrA 1 possesses a nearly edge-on disk, a natural outcome would be the enhancement of any outflow signatures relative to the photosphere; we favor this view. A low accretion/outflow rate, combined with an edge-on orientation, is further supported by the absence of high-velocity components and any significant asymmetries in the forbidden lines. An edge-on geometry is also consistent with the lack of NIR excess in spite of ongoing accretion and explains the relatively large Halpha 10% width compared to other low-mass objects with similar accretion rates. Through comparison with the latest synthetic spectra, we infer T sub(eff) ~ 2700 plus or minus 100 K, somewhat lower than the previous estimate (2900 plus or minus 200 K). Theoretical evolutionary tracks then imply an age of [approx]20 Myr (as derived from T sub(eff) and luminosity) or [approx]8 Myr (T sub(eff) vs. gravity) for LS-RCrA 1. This last value is consistent with the estimated age of other T Tauri stars in R CrA (~10 Myr), and it is substantially less than the [approx]50 Myr derived previously. Therefore, LS-RCrA 1 indeed appears subluminous relative to expectations for an R CrA member. By comparin