EXTREME ACTIVE MOLECULAR JETS IN L1448C

Journal Article · Thu Jul 01 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/717/1/58· OSTI ID:21452897

Hirano, Naomi; Ho, Paul P.T.; Liu, Sheng-Yuan; Shang, Hsien; Lee, Chin-Fei ^[1]

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1. Academia Sinica, Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China)

The protostellar jet driven by L1448C was observed in the SiO J = 8-7 and CO J = 3-2 lines, and 350 GHz dust continuum at {approx}1'' resolution with the Submillimeter Array. A narrow jet from the northern source L1448C(N) was observed in the SiO and the high-velocity CO. The jet consists of a chain of emission knots with an inter-knot spacing of {approx}2'' (500 AU) and a semi-periodic velocity variation. These knots are likely to be the internal bow shocks in the jet beam that were formed due to the periodic variation of the ejection velocity with a period of {approx}15-20 yr. The innermost pairs of knots, which are significant in the SiO map but barely seen in the CO, are located at {approx}1'' (250 AU) from the central source, L1448C(N). Since the dynamical timescale for the innermost pair is only {approx}10 yr, SiO may have been formed in the protostellar wind through the gas-phase reaction, or formed on the dust grain and directly released into the gas phase by means of shocks. It is found that the jet is extremely active with a mechanical luminosity of {approx}7 L{sub sun}, which is comparable to the bolometric luminosity of the central source (7.5 L{sub sun}). The mass accretion rate onto the protostar derived from the mass-loss rate is {approx}10{sup -5} M{sub sun} yr{sup -1}. Such a high mass accretion rate suggests that the mass and the age of the central star are 0.03-0.09 M{sub sun} and (4-12)x10{sup 3} yr, respectively, implying that the central star is in the very early stage of protostellar evolution. The low-velocity CO emission delineates two V-shaped shells with a common apex at L1448C(N). The kinematics of these shells are reproduced by the model of a wide-opening angle wind. The co-existence of the highly collimated jets and the wide-opening angle shells can be explained by the 'unified X-wind model' in which highly collimated jet components correspond to the on-axis density enhancement of the wide-opening angle wind. The CO J = 3-2 map also revealed the second outflow driven by the southern source L1448C(S) located at {approx}8.''3 (2000 AU) from L1448C(N). Although L1448C(S) is brighter than L1448C(N) in the mid-IR bands, the momentum flux of the outflow from L1448C(S) is 2 or 3 orders of magnitude smaller than that of the L1448C(N) outflow. It is likely that the evolution of L1448C(S) has been strongly affected by the powerful outflow from L1448C(N).

• OSTI ID: 21452897
• Journal Information: Astrophysical Journal, Vol. 717, Issue 1; Other Information: DOI: 10.1088/0004-637X/717/1/58; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BOLOMETERS
CARBON MONOXIDE
DUSTS
GALACTIC EVOLUTION
LUMINOSITY
MASS
SHOCK WAVES
SILICON OXIDES
STAR EVOLUTION
STARS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
EVOLUTION
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
SILICON COMPOUNDS