Sökning: onr:"swepub:oai:research.chalmers.se:3cee7f38-b2ca-4337-a3f9-d36da77ac73b" >
Herschel-PACS obser...
Herschel-PACS observations of shocked gas associated with the jets of L1448 and L1157
-
- Santangelo, G. (författare)
- Osservatorio Astronomico di Roma
-
- Nisini, B. (författare)
- Osservatorio Astronomico di Roma
-
- Antoniucci, S. (författare)
- Osservatorio Astronomico di Roma
-
visa fler...
-
- Codella, C. (författare)
- Osservatorio Astrofisico di Arcetri,Arcetri Astrophysical Observatory
-
- Cabrit, S. (författare)
- LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres, France
-
- Giannini, T. (författare)
- Osservatorio Astronomico di Roma
-
- Herczeg, G. J. (författare)
- Beijing University of Technology
-
- Liseau, René, 1949 (författare)
- Chalmers tekniska högskola,Chalmers University of Technology
-
- Tafalla, M. (författare)
- Observatorio Astronómico Nacional (OAN),Spanish National Observatory (OAN)
-
- van Dishoeck, E. F. (författare)
- Universiteit Leiden (UL),Leiden University (UL),Max Planck Gesellschaft zur Förderung der Wissenschaften e.V. (MPG),Max Planck Society for the Advancement of Science (MPG)
-
visa färre...
-
(creator_code:org_t)
- 2013-08-20
- 2013
- Engelska.
-
Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 557
- Relaterad länk:
-
http://publications.... (primary) (free)
-
visa fler...
-
https://www.aanda.or...
-
https://research.cha...
-
https://doi.org/10.1...
-
visa färre...
Abstract
Ämnesord
Stäng
- Aims. In the framework of the Water In Star-forming regions with Herschel (WISH) key program, several H2O (E-u > 190 K), high-J CO, [OI], and OH transitions are mapped with Herschel-PACS in two shock positions along two prototypical outflows around the low-luminosity sources L1448 and L1157. Previous Herschel-HIFI H2O observations (E-u = 53-249 K) are also used. The aim is to derive a complete picture of the excitation conditions at the selected shock positions.Methods. We adopted a large velocity gradient analysis (LVG) to derive the physical parameters of the H2O and CO emitting gas. Complementary Spitzer mid-IR H-2 data were used to derive the H2O abundance.Results. Consistent with other studies, at all selected shock spots a close spatial association between H2O, mid-IR H-2, and high-J CO emission is found, whereas the low-J CO emission traces either entrained ambient gas or a remnant of an older shock. The excitation analysis, conducted in detail at the L1448-B2 position, suggests that a two-component model is needed to reproduce the H2O, CO, and mid-IR H-2 lines: an extended warm component (T similar to 450 K) is traced by the H2O emission with E-u = 53-137 K and by the CO lines up to J = 22-21, and a compact hot component (T = 1100 K) is traced by the H2O emission with E-u > 190 K and by the higher-J CO transitions. At L1448-B2 we obtain an H2O abundance (3-4) x 10(-6) for the warm component and (0.3-1.3) x 10(-5) for the hot component and a CO abundance of a few 10-5 in both components. In L1448-B2 we also detect OH and blue-shifted [OI] emission, spatially coincident with the other molecular lines and with [FeII] emission. This suggests a dissociative shock for these species, related to the embedded atomic jet. On the other hand, a non-dissociative shock at the point of impact of the jet on the cloud is responsible for the (HO)-O-2 and CO emission. The other examined shock positions show an H2O excitation similar to L1448-B2, but a slightly higher (HO)-O-2 abundance (a factor of similar to 4).Conclusions. The two gas components may represent a gas stratification in the post-shock region. The extended and low-abundance warm component traces the post-shocked gas that has already cooled down to a few hundred Kelvin, whereas the compact and possibly higher-abundance hot component is associated with the gas that is currently undergoing a shock episode. This hot gas component is more affected by evolutionary effects on the timescales of the outflow propagation, which explains the observed H2O abundance variations.
Ämnesord
- NATURVETENSKAP -- Fysik -- Astronomi, astrofysik och kosmologi (hsv//swe)
- NATURAL SCIENCES -- Physical Sciences -- Astronomy, Astrophysics and Cosmology (hsv//eng)
Nyckelord
- stars: formation
- ISM: molecules
- stars: low-mass
- ISM: individual objects: L1157
- ISM: jets and outflows
- ISM: individual objects: L1448
Publikations- och innehållstyp
- art (ämneskategori)
- ref (ämneskategori)
Hitta via bibliotek
Till lärosätets databas
- Av författaren/redakt...
-
Santangelo, G.
-
Nisini, B.
-
Antoniucci, S.
-
Codella, C.
-
Cabrit, S.
-
Giannini, T.
-
visa fler...
-
Herczeg, G. J.
-
Liseau, René, 19 ...
-
Tafalla, M.
-
van Dishoeck, E. ...
-
visa färre...
- Om ämnet
-
- NATURVETENSKAP
-
NATURVETENSKAP
-
och Fysik
-
och Astronomi astrof ...
- Artiklar i publikationen
-
Astronomy and As ...
- Av lärosätet
-
Chalmers tekniska högskola