2009A&A...506..763M


Query : 2009A&A...506..763M

2009A&A...506..763M - Astronomy and Astrophysics, volume 506, 763-777 (2009/11-1)

HST/STIS observations of the RW Aurigae bipolar jet: mapping the physical parameters close to the source.

MELNIKOV S.Y., EISLOEFFEL J., BACCIOTTI F., WOITAS J. and RAY T.P.

Abstract (from CDS):

We present the results of new spectral diagnostic investigations applied to high-resolution long-slit spectra obtained with the Hubble Space Telescope Imaging Spectrograph (HST/STIS) of the jet from the T Tauri star RW Aur. Our primary goal is to determine basic physical parameters (electron density ne and electron temperature Te, hydrogen ionisation fraction xe, total hydrogen density nH, radial velocity vr and the mass outflow rate {dot}(M)j) along both the red- and blueshifted lobes of the RW Aur jet. The input dataset consists of seven long-slit spectra, of 0.1" spatial resolution, taken with the STIS slit parallel to the jet, and stepped across it. We use the Bacciotti & Eisloeffel (1999A&A...342..717B) method to analyse the forbidden doublets [OI]λλ6300,6363, [SII]λλ6716,6731, and [NII]λλ6548,6583Å to extract ne, Te, xe, and nH. We were able to extract the parameters as far as 3.9" in the red- and 2.1" in the blueshifted beam. The electron density at the base of both lobes is close to the critical density for [SII] emission but then it decreases gradually with distance from the source. The range of electron temperatures derived for this jet (Te=104-2x104K) is similar to those generally found in other outflows from young stars. The ionisation fraction xe varies between 0.04 and 0.4, increasing within the first few arcseconds and then decreasing in both lobes. The total hydrogen density, derived as nH=ne/xe, is on average 3.2x104cm–3 and shows a gradual decrease along the beam. Variations of the above quantities along the jet lobes appear to be correlated with the position of knots. Combining the derived parameters with vr measured from the HST spectra and other characteristics available for this jet, we estimate {dot}(M)j following two different procedures. The mass-outflow rate {dot}(M)j is moderate and similar in the two lobes, despite the fact that the well-known asymmetry in the radial velocity persists close to the source. Using the results of the BE diagnostics we find averages along the first 2.1" of both flows (a region presumably not yet affected by interaction with the jet environment) of 2.6x10–9M/yr for the red lobe and 2.0x10–9M/yr for the blueshifted flow, with an uncertainty of ±logM=1.6. The fact that the derived mass outflow rate is similar in the two lobes appears to indicate that the central engine is constrained on the two sides of the system and that the observed asymmetries are due to environmental conditions. Possible suggestions for the origin of the differences are discussed. The RW Aur jet appears to be the second densest outflow from a T Tauri star studied so far, but its other properties are quite similar to those found in other jets from young stars, suggesting that a common acceleration mechanism operates in these sources.

Abstract Copyright:

Journal keyword(s): ISM: jets and outflows - stars: circumstellar matter - stars: pre-main sequence - stars: mass-loss - stars: individual: RW Aur

CDS comments: Knots A11, A12, J1 to J6 are not in Simbad.

Simbad objects: 12

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Number of rows : 12
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 V* XX Tri RS* 02 03 47.1141597864 +35 35 28.665702672   9.52 8.42     K0III 123 0
2 V* V410 Tau Or* 04 18 31.1081296680 +28 27 16.155955728   12.13 10.75 8.45 9.408 K3Ve 447 0
3 V* BP Tau Or* 04 19 15.8339827632 +29 06 26.926959492   13.13 12.12 11.89   K5/7Ve 645 0
4 V* DG Tau Or* 04 27 04.6921275888 +26 06 16.060169268 13.57 13.97 10.50 12.28   K6Ve 1000 1
5 V* V1213 Tau Or* 04 31 37.5055489536 +18 12 24.383952396           K7 548 0
6 V* HL Tau Or* 04 31 38.5107609312 +18 13 57.859747968   15.89 14.49 14.39   K5 1357 0
7 IRAS 04287+1807 mul 04 31 38.8 +18 13 57           ~ 796 0
8 V* RW Aur TT* 05 07 49.5662483 +30 24 05.177426   10.86 9.60 9.95   K1/5e+K5e 763 0
9 M 42 OpC 05 35 17 -05 23.4           ~ 3970 0
10 NAME HH 46-47 HH 08 25 43.6 -51 00 36           ~ 192 2
11 EM* SR 9 Or* 16 27 40.2857881416 -24 22 04.130226300   12.91 11.533 11.11 10.00 K5e 276 0
12 EM* LkHA 233 Ae* 22 34 40.9923134958 +40 40 04.251892858   14.5       A7Ve 143 0

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2023.01.31-07:37:36

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