THE FIRST X-SHOOTER OBSERVATIONS OF JETS FROM YOUNG STARS
- INAF-Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze (Italy)
- Laboratoire d'Astrophysique de l'Observatoire de Grenoble, UMR 5521 du CNRS, 38041 Grenoble Cedex (France)
- INAF-Osservatorio di Capodimonte, Via Moiariello 16, 80131 Napoli (Italy)
- INAF-Osservatorio di Roma, Via di Frascati 33, 00040, Monteporzio Catone (Italy)
- Kapteyn Astronomical Institute, Landleven 12, 9747 AD Groningen (Netherlands)
- INAF-Osservatorio di Palermo, Piazza del Parlamento 1, 90134 Palermo (Italy)
- INAF-Osservatorio di Trieste, Via Tiepolo 11, 34143 Trieste (Italy)
We present the first pilot study of jets from young stars conducted with X-shooter, on the ESO/Very Large Telescope. As it offers simultaneous, high-quality spectra in the range 300-2500 nm, X-shooter is uniquely important for spectral diagnostics in jet studies. We chose to probe the accretion/ejection mechanisms at low stellar masses examining two targets with well-resolved continuous jets lying on the plane of the sky: ESO-HA 574 in Chameleon I and Par-Lup3-4 in Lupus III. The mass of the latter is close to the sub-stellar boundary (M{sub *} = 0.13 M{sub sun}). A large number of emission lines probing regions of different excitation are identified, position-velocity diagrams are presented, and mass outflow/accretion rates are estimated. Comparison between the two objects is striking. ESO-HA 574 is a weakly accreting star for which we estimate a mass accretion rate of log ( M-dot{sub acc}) = -10.8{+-}0.5 (in M{sub sun} yr{sup -1}), yet it drives a powerful jet with M-dot{sub out} {approx} 1.5-2.7 x 10{sup -9} M{sub sun} yr{sup -1}. These values can be reconciled with a magneto-centrifugal jet acceleration mechanism assuming that the presence of the edge-on disk severely depresses the luminosity of the accretion tracers. In comparison, Par-Lup3-4, with stronger mass accretion ( log ( M-dot{sub acc}) = -9.1{+-}0.4 M{sub sun} yr{sup -1}), drives a low-excitation jet with about M-dot{sub out} {approx} 3.2 x 10{sup -10} M{sub sun} yr{sup -1} in both lobes. Despite the low stellar mass, M-dot{sub out}/ M-dot{sub acc} for Par-Lup3-4 is at the upper limit of the range usually measured for young objects, but still compatible with a steady magneto-centrifugal wind scenario if all uncertainties are considered.
- OSTI ID:
- 21562471
- Journal Information:
- Astrophysical Journal Letters, Vol. 737, Issue 2; Other Information: DOI: 10.1088/2041-8205/737/2/L26; ISSN 2041-8205
- Country of Publication:
- United States
- Language:
- English
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