Accretion and outflow activity in proto-brown dwarfs
Abstract
We present a near-infrared study of accretion and outflow activity in six Class 0/I proto-brown dwarfs (proto-BDs) using VLT/SINFONI spectroscopy and spectroimaging observations. The spectra show emission in several [Fe II] and H2 lines associated with jet/outflow activity, and in the accretion diagnostics of Pa β and Br γ lines. The peak velocities of the [Fe II] lines (>100 km s-1) are higher than the H2 lines. The Class 0 proto-BDs show strong emission in the H2 lines but the [Fe II] lines are undetected, while the Class I objects show emission in both [Fe II] and H2 lines, suggesting an evolutionary trend in the jets from a molecular to an ionic composition. Extended emission with knots is seen in the [Fe II] and H2 spectroimages for three proto-BDs, while the rest show compact morphologies with a peak on-source. The accretion rates for the proto-BDs span the range of (2 × 10-6-2 × 10-8) M⊙ yr-1, while the mass-loss rates are in the range of (4 × 10-8-5 × 10-9) M⊙ yr-1. These rates are within the range measured for low-mass protostars and higher than Class II brown dwarfs. We find a similar range in the jet efficiency for proto-BDs as measured in protostars. We have performed a study of the Brackett decrement from the Br 7-19 lines detected in the proto-BDs. The upper Brackett lines of Br 13-19 are only detected in the earlier stage systems. The ratios of the different Brackett lines with respect to the Br γ line intensity are consistent with the ratios expected from Case B recombination.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- March 2021
- DOI:
- 10.1093/mnras/staa3905
- arXiv:
- arXiv:2012.08612
- Bibcode:
- 2021MNRAS.501.3781R
- Keywords:
-
- brown dwarfs;
- stars: jets;
- stars: winds;
- outflows;
- ISM: individual objects: Mayrit 1701117;
- HH 1165;
- MHO 2156;
- MHO 3256;
- MHO 3257;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted in MNRAS