First detection of acceleration and deceleration in protostellar Jets? Time variability in the Chamaeleontis II outflows

Caratti O Garatti, A. and Eisloffel, J. and Froebrich, D. and Nisini, B. and Giannini, T. and Calzoletti, L. (2009) First detection of acceleration and deceleration in protostellar Jets? Time variability in the Chamaeleontis II outflows. Astronomy and Astrophysics, 502 (2). pp. 579-597. ISSN 0004-6361. (doi: (Full text available)


Context. Kinematical and time variability studies of protostellar jets are fundamental for understanding the dynamics and the physics of these objects. Such studies remain very sporadic, since they require long baselines before they can be accomplished. Alms. We present for the first time a multi-epoch (20 years baseline) kinematical investigation of HH 52, 53, and 54 at optical and near-IR wavelengths, along with medium (optical) and high resolution (NIR) spectroscopic analyses, probing the kinematical and physical time variability conditions of the gas along the flows. Methods. By means of multi-epoch and multi-wavelength narrow-band images, we derived proper motions (PMs), tangential velocities, velocity and flux variability of the knots. Radial velocities and physical parameters of the gas were derived from spectroscopy. Finally, spatial velocities and inclination of the flows were obtained by combining both imaging and spectroscopy. Results. The PM analysis reveals three distinct, partially overlapping outflows. Spatial velocities of the knots vary from 50 km s -1 to 120 km s-1. The inclinations of the three flows are 58 ± 3°, 84 ± 2°, and 67 ± 3° (HH 52, HH 53, and HH 54 flows, respectively). In 20 years, about 60% of the observed knots show some degree of flux variability. Our set of observations apparently indicates acceleration and deceleration in a variety of knots along the jets. For about 20% of the knots, mostly coincident with working surfaces or interacting knots along the flows, a relevant variability in both flux and velocity is observed. We argue that both variabilities are related and that all or part of the kinetic energy lost by the interacting knots is successively radiated. The physical parameters derived from the diagnostics are quite homogeneous along and among the three outflows. The analysis indicates the presence of very light (NH � 103 cm-3), ionised (Te,. � 0.2-0.6), and hot (Te � 14000-26000 K) flows, impacting a denser medium. Several knots are deflected, especially in the HH 52 flow. At least for a couple of them (HH 54 G and GO), the deflection originates from the collision of the two. For the more massive parts of the flow, the deflection is likely the result of the flow collision with a dense cloud or with clumps. Finally, we discuss the possible driving sources of the flows. ©ESO 2009.

Item Type: Article
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - Astron. Astrophys. [Field not mapped to EPrints] AD - Thüringer Landessternwarte Tautenburg, Sternwarte 5, 07778 Tautenburg, Germany [Field not mapped to EPrints] AD - Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2, Ireland [Field not mapped to EPrints] AD - Centre for Astrophysics and Planetary Science, University of Kent, Canterbury, CT2 7NH, United Kingdom [Field not mapped to EPrints] AD - INAF, Osservatorio Astronomico di Roma, via Frascati 33, 00040 Monte Porzio, Italy [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: ISM: Herbig-haro objects, ISM: Jets and outflows, ISM: Kinematics and dynamics, Stars: Pre-main sequence, Acceleration and deceleration, Driving source, Flux variability, High resolution, ISM: Herbig-haro objects, ISM: Jets and outflows, ISM: Kinematics and dynamics, Long base line, Multiwavelength, Narrow bands, Near-IR, Physical parameters, Proper motion, Radial velocity, Spatial velocity, Stars: Pre-main sequence, Tangential velocities, Time variability, Acceleration control, Aerospace vehicles, Jets, Kinematics, Light transmission, Spectroscopic analysis, Stars, Velocity, Dynamics
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculties > Sciences > School of Physical Sciences > Centre for Astrophysics and Planetary Sciences
Depositing User: Giles Tarver
Date Deposited: 21 Jul 2015 10:10 UTC
Last Modified: 27 Jun 2017 13:24 UTC
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