2015A&A...581A...4L


Query : 2015A&A...581A...4L

2015A&A...581A...4L - Astronomy and Astrophysics, volume 581A, 4-4 (2015/9-1)

The structure of the Cepheus E protostellar outflow: The jet, the bowshock, and the cavity.

LEFLOCH B., GUSDORF A., CODELLA C., EISLOEFFEL J., NERI R., GOMEZ-RUIZ A.I., GUESTEN R., LEURINI S., RISACHER C. and BENEDETTINI M.

Abstract (from CDS):

Protostellar outflows are a crucial ingredient of the star-formation process. However, the physical conditions in the warm outflowing gas are still poorly known. We present a multi-transition, high spectral resolution CO study of the outflow of the intermediate-mass Class 0 protostar CepE-mm. The goal is to determine the structure of the outflow and to constrain the physical conditions of the various components in order to understand the origin of the mass-loss phenomenon.We have observed the J=12-11, J=13-12, and J=16-15 CO lines at high spectral resolution with SOFIA/GREAT and the J=5-4, J=9-8, and J=14-13 CO lines with HIFI/Herschel towards the position of the terminal bowshock HH377 in the southern outflow lobe. These observations were complemented with maps of CO transitions obtained with the IRAM 30 m telescope (J=1-0, 2-1), the Plateau de Bure interferometer (J=2-1), and the James Clerk Maxwell Telescope (n(H2)=(0.5-1)x106cm–3), lower column density (N(CO)=1.5x1016cm–2) gas component. Similarly, in the outflow cavity, two components are detected: the emission of the low-J lines is dominated by a gas layer of column density N(CO)=7x1017cm–2 at Tkin=55-85K and density in the range (1-8)x105cm–3; the emission of the high-J lines is dominated by a hot, denser gas layer with Tkin=500-1500K, n(H2)=(1-5)x106cm–3, and N(CO)=6x1016cm–2. A temperature gradient as a function of the velocity is found in the high-excitation gas component. In the terminal bowshock HH377, we detect gas of moderate excitation, with a temperature in the range Tkin≃ 400-500K, density n(H2)≃(1-2)x106cm–3 and column density N(CO)=1017cm–2. The amounts of momentum carried away in the jet and in the entrained ambient medium are similar. Comparison with time-dependent shock models shows that the hot gas emission in the jet is well accounted for by a magnetized shock with an age of 220-740yr propagating at 20-30km/s in a medium of density n(H2)=(0.5-1)x105cm–3, consistent with that of the bulk material.The CepE protostellar outflow appears to be a convincing case of jet bowshock driven outflow. Our observations trace the recent impact of the protostellar jet into the ambient cloud, produing a non-stationary magnetized shock, which drives the formation of an outflow cavity.

Abstract Copyright:

Journal keyword(s): stars: formation - ISM: individual objects: Cep E - ISM: kinematics and dynamics - shock waves - infrared: ISM - ISM: jets and outflows

Simbad objects: 4

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Number of rows : 4
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
#notes
1 LDN 1157 DNe 20 39 06.4 +68 02 13           ~ 571 0
2 HH 377 HH 23 03 +61.7           ~ 22 2
3 NAME Cep E HII 23 03 12.779 +61 42 25.75           ~ 171 0
4 NAME III CEP ASSOC As* 23 04.2 +63 24           ~ 322 0

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